USDA’s Animal and Plant Health Inspection Service (APHIS) has teamed up with the North American Invasive Species Management Association and The Nature Conservancy to sponsor the first-ever national PlayCleanGo Awareness Week beginning Saturday – June 1-8. The program’s goal is to help outdoor enthusiasts understand how they can help stop the spread of invasive plants and pests—while still enjoying the great outdoors.
APHIS’ announcement suggests some helpful steps people going outdoors can take:
Before moving from one location to another, clean your shoes with a brush to remove any soil, plants or seeds that might be trapped in your treads. This action will help prevent your accidentally spreading damaging microscopic organisms or invasive weeds to new areas.
tanoaks killed by Phytophtora ramorum (sudden oak death) Big Sur, California
Avoid giving hitchhiking pests a free ride in your firewood by purchasing your firewood where you plan to burn it or taking only heat-treated firewood with you. Careless movement of wood can spread tree-killing beetles and other pests that can harm our forests.
tangle of dead ash in Michigan killed by emerald ash borer photo by Ned Siegert, USDA Forest Service
If you are driving, remove any visible pests, plants, soil, or egg masses from your vehicle, RV or camper. It only takes a few minutes to stop tree-killing insects and other potentially harmful plant pests from traveling with you to your next destination.
spotted lanternfly photo by Holly Raguza, Pennsylvania Department of Agriculture
The websitehprovides educational materials as well as such tools for interaction as pledges and hashtags!
Help spread the word while doing
your part.
Posted by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
frogs in California killed by chytrid fungus photo by Rick Kyper, US Fish and Wildlife Service
I expect you have heard about the report issued on May 6 by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. The executive summary is available here
Based on thousands of scientific
studies, the report concludes that the biosphere, upon which humanity as a whole
depends, is being altered to an unparalleled degree across all spatial scales. The
trends of decline are accelerating. As many as 1 million species (75% of which are
insects) are threatened with extinction, many within decades.
Humans dominate Earth: natural
ecosystems have declined by 47% on average. Especially hard-hit are inland
waters and freshwater ecosystems: only 13% of the wetland present in 1700
remained by 2000. Losses have continued rapidly since then.
The report lists the most important
direct drivers of biodiversity decline – in descending order – as habitat loss
due to changes in land and sea use; direct exploitation of organisms; climate
change; pollution; and invasive species. The relative importance of each driver
varies across regions.
If you have been paying attention, these
conclusions are not “news”.
However, the report serves two valuable
purposes. First, it provides a global overview, a compilation of all the data
and trends. Second, the report ties the direct drivers to underlying causes
which are in turn underpinned by societal values and behaviors. Specifically
mentioned are production and consumption patterns, human population dynamics
and trends, trade, technological innovations, and governance (decision making
at all levels, from local to global).
The report goes to great lengths to
demonstrate that biological diversity and associated ecosystem services are
vital for human existence and good quality of life – especially for supporting
humanity’s ability to choose alternative approaches in the face of an uncertain
future. The report concludes that while more food, energy and materials than
ever before are now being supplied to people, future supplies are undermined by
the impact of this production and consumption on Nature’s ability to provide.
The report also emphasizes that both the
benefits and burdens associated with the use of biodiversity and ecosystem
services are distributed and experienced inequitably among social groups,
countries and regions. Furthermore, benefits provided to some people often come
at the expense of other people, particularly the most vulnerable. However, there are also synergies – e.g., sustainable agricultural practices
enhance soil quality, thereby improving productivity and other ecosystem
functions and services such as carbon sequestration and water quality
regulation.
The report contains vast amounts of data
on the recent explosion of human numbers and – especially – consumption – of
agricultural production, fish harvests, forest products, bioenergy production …
and on the associated declines in “regulating” and “non-material contributions”
ecosystem services. In consequence, the report concludes, these recent gains in
material contributions are often not sustainable.
While invasive species rank fifth as a
causal agent of biodiversity decline globally, alien species have increased by
40% since 1980, associated with increased trade and human population dynamics
and trends. The authors report that nearly 20% of Earth’s surface is at risk of
bioinvasion. The rate of invasive species introduction seems higher than ever
and shows no signs of slowing.
The report notes that the extinction
threat is especially severe in areas of high endemism. Invasive species play a
more important role as an extinction agent in many such areas, especially
islands. However, some bioinvaders also have devastating effects on mainlands;
the report cites the threat of the pathogen Batrachochytrium
dendrobatidis to nearly 400 amphibian species worldwide.
The report also mentions that the combination
of species extinctions and transport of species to new ecosystems is resulting
in biological communities – both managed and unmanaged — becoming more similar
to each other — biotic homogenization.
The report notes that human-induced
changes are creating conditions for fast biological evolution of species in all
taxonomic groups. The authors recommend adopting conservation strategies
designed to influence evolutionary trajectories so as to protect vulnerable species
and reduce the impact of unwanted species (e.g.,
weeds, pests or pathogens).
The report says conservation efforts
have yielded positive outcomes – but they have not been sufficient to stem the
direct and indirect drivers of environmental deterioration. Since 1970, nations
have adopted six treaties aimed at protection of nature and the environmental,
but few of the strategic objectives and goals adopted by the treaties’ parties
are being realized. One objective that is on track to partial achievement is
the Aichi Biological Diversity Target that calls for identification and
prioritization of invasive species.
That might well be true – but I would not consider global efforts to manage invasive species to be a success story in any way. I have blogged often about studies showing that introductions continue unabated … and management of established bioinvaders only rarely results in measurable improvements. [For example, see here and here.]
The report gives considerable attention
to problems caused by some people’s simultaneous lack of access to material
goods and bearing heavier burden from pollution and other negative results of
biodiversity collapse. Extraction of living biomass (e.g. crops, fisheries) to meet the global demand is highest in
developing countries whereas material consumption per capita is highest in developed countries. The report says that
conservation of biodiversity must be closely linked to sustainable approaches
to more equal economic development. The authors say both conservation and economic
goals can be achieved – but this will require transformative changes across
economic, social, political and technological factors.
One key transformation is changing
people’s conception of a good life to downplay consumption and waste. Other
attitudinal changes include emphasizing social norms promoting sustainability
and personal responsibility for the environmental impacts of one’s consumption.
Economic measures and goals need to address inequalities and integrate impacts
currently considered to be “economic externalities”. The report also calls for inclusive
forms of decision-making and promoting education about the importance of
biodiversity and ecosystem services.
Economic instruments that promote
damaging, unsustainable exploitation of biological resources (or their damage
by pollution) include subsidies, financial transfers, subsidized credit, tax
abatements, and commodity and industrial goods prices that hide environmental
and social costs. These need to be changed.
Finally, limiting global warming to well
below 2oC would have multiple co-benefits for protecting
biodiversity and ecosystem services. Care must be exercised to ensure that large-scale
land-based climate mitigation measures, e.g.,
allocating conservation lands to bioenergy crops, planting of monocultures,
hydroelectric dams) do not themselves cause serious damage to biodiversity or
other ecosystem services.
The threats to biodiversity and
ecosystem services are most urgent in South America, Africa and parts of Asia. North
America and Europe are expected to have low conversion to crops and continued
reforestation.
Table SPM.1 lays out a long set of approaches
to achieve sustainability and possible actions and pathways for achieving them.
The list is not exhaustive, but rather illustrative, using examples from the
report.
Posted by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
In
recent months there have been several developments affecting efforts to manage
the sudden oak death infestation in West Coast states and to prevent its spread
to other parts of the country.
1) APHIS
regulations
Most notably, APHIS has formalized revisions to its regulations governing nursery stock. This revision was proposed last June (see my blog about this here). The revisions largely implement changes to practices that APHIS had adopted in 4014 and 1015 through Federal Orders. The final regulation is posted here. The new regulation goes into effect on May 20th.
APHIS received only 10 comments (posted here) on the proposal – from researchers, State agriculture and conservation agencies, environmental advocacy groups, research foundations, and private citizens. I summarized points raised in their comments by CISP and others in an earlier blog.
APHIS
responded to most of these comments by reiterating that it has been operating
under the current program since 2014 and believes the existing testing
protocols and conditions are sufficient to mitigate the risk. The measures to monitor
nurseries for infections include testing soil and water, that is, they do not
rely exclusively on visual inspection of the plants. This is a step forward. In
response to comments by CISP and California Oak Mortality Task Force that all
nurseries that grow host plants are a potential source of contamination, APHIS points
out that it is not authorized to regulate nurseries that don’t ship plants
interstate. This limitation is a serious problem arising from the underlying
statute – the Plant Protection Act. APHIS said it would continue to monitor
detection of the pathogen, and would reevaluate program protocols “should the
need arise” – but it made no promise on how frequently it would reevaluate the program.
APHIS
did make some adjustments, based on comments. It agreed to one state’s request
that it clarify the minimum
number of samples that must be taken during annual inspection of nurseries that
had not previously tested positive for the pathogen when those nurseries are
located in counties that have SOD infestations in the environment. (Such
counties are found only in California and Oregon.)
The
agency also said it plans to restructure the list of host species so that it
can be updated more quickly. APHIS plans to remove the lists from formal regulations
(which require public notice and comment to amend) and post them on the APHIS
website. APHIS also expects to merge the lists of proven and associated hosts
into a single host list. However, these plans would, themselves, constitute
rulemaking and require another public comment period.
APHIS
also agreed to reinstate its quarterly program updates, beginning in April of
2019. I have not yet seen an alert telling me how to find the first such update,
though.
2) P. ramorum in California and Washington
According to the most recent (April 2019) newsletter of the California Oak Mortality Task Force, tanoak (Notholithocarpus densiflorus) mortality in California attributed to Phytophthora ramorum increased by more than 1.6 million trees across 106,000 acres in 2018. The dead trees are concentrated west of the coastal range.
In
the meantime, P. ramorum continues to
be detected in nurseries shipping plants from West Coast nurseries. As of
April, the California Department of Food and Agriculture had detected P. ramorum in nine nurseries – six from
previous years, three new in 2019. (Sixty-four additional infected plants were
found in one nursery that had been confirmed positive in an earlier year –
raising questions in my mind about the efficacy of the Confirmed Nursery
Protocol for eliminating the pathogen.)
As I noted in a previous blog, Washington is finding it difficult to eliminate P. ramorum from the soil of a botanical garden in Kitsap County. For the third time in less than a year, a pond that is downhill from previously “mitigated” sites has tested positive for P. ramorum.
I remind you that scientists do not believe that P. ramorum persists in water – it must be surviving on some plant tissue in both Washington and the Eastern states (see below).
3) P. ramorum in Oregon
The Oregon Department of Forestry (ODF) commissioned a study of the economic impact of Phytophthora ramorum in the state. The study found that to date, sudden oak death has caused minor impacts on the regional economy. There was no impact on timber harvest, export or log prices or recreation or tourism revenues and only anecdotal reports of losses to real estate transaction values in some areas. Meantime, the state and several federal agencies are spending $1.5 million per year to try to contain the outbreak.
However, sudden oak death has the potential to cause harm to core values that elude economic quantification, particularly to tribal cultural values and the “existence value” of tanoak-dominated forests. SOD may be an existential threat to tanoak and associated obligate species (e.g., dusky-footed woodrats, Northern flying squirrels, and Allen’s chipmunks – which are important prey items for northern spotted owl, cougar, coyote, and Pacific fisher. More widespread wildlife — e.g., deer, elk, bear, Coho salmon, and a variety of bird species – might also be harmed.)
Immediate
termination of the ODF treatment regime might lead to serious impacts due to
more rapid expansion of sudden oak death into Coos County, Oregon. These could
include Asian governments restricting timber and fiber exports from southwest
Oregon and resulting loss of 1,200 jobs and forest products harvest tax. There
might also be a collapse of residential property value and real estate
transaction revenues. Finally, there might be a decline in recreation and
tourism in affected areas. Maintaining the current treatment regime was
expected to delay the spread of SOD north of the Rogue River until 2028, and
prevent infestation of Coos County beyond 2038. Continued funding SOD
treatments for a total cost of $30 million over the next 20 years could offset
loss of 1,200 jobs by 2028 and $580 million in wages from 2028 to 2038.
The study
authors note that other factors – such as major wildfires or trade wars – could
render these impacts moot.
4) P. ramorum in the East
According to the most recent newsletter of the California Oak Mortality Task Force, over the nine years since 2010, the pathogen has been detected from 11 streams in six eastern states – four in Alabama; one in Florida; two in Georgia; one in Mississippi; one in North Carolina; and two in Texas. P. ramorum has been found multiple times in eight of these streams; it is consistently present in two steams in Alabama, one each in Mississippi and North Carolina.
In
2018, seven states participated in the stream survey (which is operated by the
USDA Forest Service): (AL, GA, MS, NC,
PA, SC, and TX). This was the smallest number of participating states, which
has fallen from14 in 2010 to seven in 2018.
The
number of streams surveyed annually has ranged from 45 to 95. The number of
streams sampled in 2018 was also close to the smallest number: 47. P. ramorum was detected from six streams
– four in Alabama, one each in Mississippi and North Carolina. All positive
streams were associated with previously P.
ramorum-positive nurseries.
Remember
that P. ramorum continues to be detected in West Coast nurseries that ship
plants interstate (see the second section of this blog).
Posted
by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
dead redbay in Claxton, GA 2009; photo by Scott Cameron
Several groups of scientists are using two large datasets to analyze impacts of invasion by non-native tree-killing pests. The first dataset used is official Forest Service monitoring data from the Forest Inventory and Analysis (FIA). These data are collected on a “rolling” annual basis from 130,210 forest plots in 2,098 counties in the 48 conterminous states. (Go here to learn more about FIA.)
The second dataset covers the distribution of non-native forest pests and is contained in the Alien Forest Pest Explorer database, also a Forest Service product.
Some of these studies (those led by Kevin Potter) have been carried out under the auspices of “Project CAPTURE” (Conservation Assessment and Prioritization of Forest Trees Under Risk of Extirpation) as part of a multi-partner effort to categorize and prioritize US tree species for conservation actions based on the threats and the trees’ ability to adapt to those threats. Partners include North Carolina State University; Forest Service Forest Health Protection, Southern Research Station, and forest health monitoring program; Eastern Forest Environmental Threat Assessment Center; and the Forest.Health program.
Here I highlight several key studies that use FIA data to examine:
1) the relationship
between the diversity of forest tree species
and the number of non-native insects and pathogens established there;
2) the mortality rate of forest trees due to non-native pests; and
3)
impacts i in the form of “geographic hot
spots;”
4)
application of these findings to setting conservation priorities.
1. Impact of
Host Diversity on Pest Establishment
One group of scientists (Guo et al.; reference at the end of this
blog) extracted distribution data for 66 non-native pests (51 insects, 15
pathogens) taken from the Alien Forest Pest Explorer database. Then, the
authors compared these pest’ distributions to FIA data on the diversity of tree
species in the same invaded forests — for both “host” and non-host tree
species. (Guo et al. classified a
tree species as a “host” only if the relevant pest was present in the county.)
Guo
et al. found that the number of alien
pest species established in a county increased commensurate with tree diversity
– as long as that tree diversity was fairly low, i.e., below 39 tree species. The number of established pests
increased particularly strongly for specialist pests. However, at higher levels
of tree diversity the number of established pests fell. Another factor was the
diversity of non-host tree species present. When considering generalist pests,
fewer pests became established when non-host tree diversity exceeded 15 species.
When considering specialist pests, that cutoff was 25 species.
Among
other possible factors
explaining numbers of pests established, Guo et
al. also found that
only propagule pressure – measured by the proxy of human population density –
had a significant
positive correlation with increased pest numbers.
2. Measuring the
Impacts of Non-Native Pests – Tree Mortality Data
A different approach has been undertaken by Randall Morin, working with a variety of coauthors. Dr. Morin has used FIA survey data to detect whether the impact of various non-native pests can be seen in heightened levels of mortality of the pests’ hosts. I reported these findings in a previous blog.
eastern hemlock killed by hemlock woolly adelgid in Nova Scotia photo by Celia Boone, Nova Scotia Department of Lands and Forestry
As I noted in the earlier blog, Dr. Morin found that non-native forest pests had caused an approximately 5% increase in total mortality by tree volume nation-wide. The degree to which mortality levels rose in any county depended on the killing power of the individual pest species and the relative density of tree species vulnerable to the pests present. The number or diversity of non-native tree-killing pests established in the county (see the Guo et al. study) did not determine the county’s morality level. See maps in the earlier blog.
The greatest increase in mortality rates (a four-fold increase) was for redbay, under attack by laurel wilt disease. Three-fold increases in annual mortality rates were detected for ash, beech, and hemlock. To learn the specific mortality rates for individual pest-host relationships, visit here and read the descriptions of butternut, chestnut, redbay, beech, hemlock, ash, tanoak (sudden oak death), Port-Orford cedar, oak wilt, and European gypsy moth
tanoak killed by sudden oak death (Phytophthora ramorum), Big Sur, California
3.Overview of Impacts,
Identification of Geographic “Hotspots” and Use in Setting Conservation
Priorities
To
carry out “Project CAPTURE,” Potter, Escanferla, Jetton, and Man 2019a (full
reference at the end of this blog) sought to identify regions at greatest risk
of significant ecological and economic impacts from damaging insects,
pathogens, or parasitic plants, especially non-native, introduced pests.
They
first compiled a list of 339 serious pests threatening one or more of 419
native tree species in the continental United States. The list comprised 168
diseases, 151 insects, and 20 parasitic higher plants. It included both native
and introduced pests – 142 native, 55 non-native, and 142 of unknown or
disputed origin.
They
analyzed up to five of the most serious pests for each native tree species.
This analysis resulted in 1,378 pest-host combinations.
The
authors assigned a severity rating for each pest-host combination. Instead of
using counties, as Guo et al. did,
they evaluated pests and hosts in hexagons covering approximately 800km2.
They used FIA data to determine in which hexagons each pest-host combination is
present. Finally, the authors determined the “importance value at risk” (IVAR) for
each hexagon based on the number of pest-host combinations present and the
relative severity of those combinations.
[See the article – referenced below – for detailed explanations of these
calculations.]
General Findings
Analyses
addressing all the pests, including native ones, found different results than
analyses focused on the non-native pests. Thus, analyses of all pests found greater
impacts in the West, whereas non-native pests caused potentially greater impacts
in the East. The authors note that the non-native pest risk could be greatly
magnified across much of the eastern United States if the alien pests are able
to spread to the entirety of their hosts’ ranges.
Considering
the pests:
Of
the 1,378 host/agent combinations, 51.5% involve diseases, 43.6% involve
insects, and 4.9% involve parasitic plants.
Among
the insects, 77 are phloem or wood-borers, 51 are foliage-feeders, and 23 are
sap-feeders. Of the total of 601 insect-host combinations (both native and
exotic), borers are the agents in 224 (37%) of the combinations.
54%
of the host tree species (228) are infested by an exotic pest – although only
28% of the 1,378 host/agent combinations involved known exotic pests.
Considering
the host tree species:
two non-native pests affect the largest number of hosts: European gypsy moth – 65 hosts; and oak wilt (Bretziella fagacearum) – 61 hosts. A third alien species, Asian longhorned beetle, ranked fourth overall with 43 hosts.
Nearly 70% of the host/agent combinations involve angiosperm species, 30% gymnosperms. Regarding all combinations, the severity of the gymnosperm/agent combinations was significantly higher than angiosperm/agent combinations. However, when considering only non-native pests, the opposite was true: host/agent combinations for angiosperms had greater average severity.
Severity
of Impacts
Disease
impacts are more severe, on average, than insect pests.
Wood-borers
are more damaging than other types of insect pests.
Exotic
agents have, on average, considerably more severe impacts than native pests.
The
risk estimate – especially for the East – is an underestimate because established pests could spread to additional
vulnerable areas and there is a high likelihood that new pests will be
introduced.
Of
the 15 host-agent combinations with the highest severity, seven are caused by
an insect, seven by a disease, one by an insect-disease complex. These 15 tree
species at highest risk are:
Florida
torreya (Torreya taxifolia) –
pathogen,
American
chestnut (Castanea dentata) –
pathogen,
Allegheny
chinquapin (C. pumila) – pathogen,
Ozark
chinquapin (C. pumila var. ozarkensis) – pathogen,
redbay
(Persea borbonia) – disease complex,
Carolina
ash (Fraxinus caroliniana) – insect,
pumpkin
ash (F. profunda) – insect,
Carolina
hemlock (Tsuga caroliniana) – insect,
Port-Orford
cedar (Chamaecyparis lawsoniana) –
pathogen,
tanoak
(Notholithocarpus densiflorus) –
pathogen,
butternut
(Juglans cinerea) – pathogen,
eastern
hemlock (Tsuga canadensis) – insect,
white
ash (Fraxinus americana) – insect,
black
ash (F. nigra) – insect, and
green
ash (F. pennsylvanica) – insect.
emerald ash borer – cause of threat to five of the “top 15”
Four
host families are at the highest risk to alien pests, as measured by both the
numbers of tree species affected and by the most host/agent combinations –
Fagaceae (oaks, tanoaks, chestnuts, beech); Pinaceae (pines); Sapindaceae
(soapberry family; includes maples, Aesculus
(buckeye, horsechestnut); Salicaceae (willows, poplars, aspens). The authors
point out that these families comprise the most tree species in North America
and that the species are widespread.
The
families under greatest threat varied somewhat when measured by the severity of
the host/pest threat. While Fagaceae was still at greatest risk, and
Sapindaceae was still in the top four, Ulmaceae (elms) and Oleaceae (includes Fraxinus) replaced pines and willows.
Analyses addressing all the pests found geographic “hotspots” only in the West. Analyses addressing non-native pests, based on their current extent, also resulted in Western areas appearing at highest risk. However, analyses addressing non-native pests but assuming that these pests had spread to the full extent of their hosts revealed “hotspots” in the Northeast and Great Lakes States. The Southeast is consistently a “coldspot” – clearly the near extirpation of one understory tree – redbay – is not sufficient to affect top-level data.
Note that none of the maps in the article shows all exotic pests separately from native pests; even the map in Figure 4b illustrates non-native insects only. Dr. Potter has told me that it proved too difficult to determine the origin of many pathogens (K. Potter pers. comm. April 2019).
Setting
Conservation Priorities
In a second publication, Potter Escanferla, Jetton, Man, and Crane (2019b) applied the severity ranking for host-pest relationships to set priorities for conservation actions targetting the host – especially conservation of genetic diversity and implementation of programs aimed at enhancing hosts’ resistance to the pest through breeding.
They
created 11 classes of species based on three factors:
each
tree species’ exposure to an extrinsic threat – as measured by the extent to
which a threat could diminish a species’ adaptive genetic variation;
each
tree species’ sensitivity to the threat – as indicated by the species’ rarity,
and size of range, or the degree to which a species’ total genetic resource
base is susceptible to a threat; and
each
species’ ability to adapt to the pest threat – as determined by extent to which
a species is unable to adapt, through micro-evolutionary change and phenotypic
plasticity; unable to maintain evolutionary resilience
(These
definitions are taken from Potter, Crane, and Hargrove 2017; reference below)
The
highest ranked species (in three classes) are the 15 listed above.
How to Use These
Data / Findings
The purpose of the CAPTURE project is to guide USDA Forest Service prioritization of forest tree species and populations for genetic conservation and monitoring efforts. It began as a response to a request from the National Forest System regional geneticist in the Southern Region (Region 8); it was then expanded to the entire country – including Puerto Rico, the Virgin Islands, and Hawai`i. (Dr. Potter told me that he has most of the data needed for Hawai`i, but is still collecting data for the Caribbean. He still needs to query experts in order to customize the framework for the two regions.)
Now
that the project has set priorities for continental species, it will be interesting
to see the extent to which these
findings guide actual allocation of resources. For example, will additional
resources be assigned to protecting such non-commercial species as Florida
torreya and redbay? Will existing resistance breeding efforts – which mostly
struggle to obtain funding – now have better access to funds?
The Forest.Health project – which promotes use of biotechnology to breed resistant hosts – has adopted the priority list.
Potter
et al. 2019b call also for incorporating their findings into regular
national reports such as those issued per
the Resources Planning Act Assessment and the National Report on Sustainable
Forests. These data are essential to assessing the degree to which U.S. forests
can continue to meet demand for a broad range of goods and services, safeguard
biological diversity, and contribute to the resilience of ecosystems and economies.
I
hope that the data on regeneration, growth, and succession of individual
species compiled by Morin, et al., —
which are not part of the CAPTURE project — would also be included in such
reports.
I
applaud these studies and hope they will prove influential. They avoid some of
the flaws in other priority-setting processes, which tend to focus on species
with commercial value. However, I would like to suggest that some other factors
should also be included in calculating priorities:
Are some host species especially significant in their ecosystems? That is:
Do some create unique biomes, e.g., hemlocks in stream valleys in the middle and southern Appalachians; Fraser fir (and red spruce) on southern Appalachian mountain tops; black ash in wooded swamps from Minnesota to New Brunswick; Port-Orford cedar as part of the unique flora of the serpentine soils of the Siskiyou Mountains; whitebark pine at high elevations of Western mountains.
Are some hosts important providers of rare resources, e.g., hard mast – tanoak in California coniferous forests, beech in northern part of its range, whitebark pine at high elevations. Or calcium to the leaf litter and soil – e.g., dogwoods.
Are particularly high numbers of faunal species associated with the host? Or rare fauna?
Should pests that threaten entire genera – or monotypic genera – receive a higher priority? E.g., emerald ash borer threatening Fraxinus; Phytophthora ramorum threatening tanoak?
SOURCES
Guo, Q., S. Feib, K.M. Potter, A.M. Liebhold, and J. Wenf. 2019. Tree diversity regulates forest pest invasion. PNAS. www.pnas.org/cgi/doi/10.1073/pnas.1821039116
Morin, R.S., K.W. Gottschalk, M.E. Ostry, A.M. Liebhold. 2018. Regional patterns of declining butternut (Juglans cinerea L.) suggest site characteristics for restoration. Ecology and Evolution.2018;8:546-559
Morin,
R. A. Liebhold, S. Pugh, and S. Fie. 2019. Current Status of Hosts and Future Risk of EAB Across the Range of Ash:
Online Tools for Broad-Scale Impact Assessment. Presentation at the 81st
Northeastern Forest Pest Council, West Chester, PA, March 14, 2019
Potter,
K.M., B.S. Crane, W.W. Hargrove. 2017. A US national prioritization framework
for tree species vulnerability to climate change. New Forests (2017) 48:275–300
DOI 10.1007/s11056-017-9569-5
Potter,
K.M., M.E. Escanferla, R.M. Jetton, and G. Man. 2019a. Important Insect and
Disease Threats to United States Tree Species
and Geographic Patterns of Their Potential Impacts. Forests. 2019 10 304.
Potter,
K.M., M.E. Escanferla, R.M. Jetton, G. Man, and B.S. Crane. 2019b. Prioritizing
the conservation needs of United States tree species: Evaluating vulnerability
to forest insect and disease threats. Global Ecology and Conservation. (2019)
post-EAB ash forest in southern Michigan; photo by Nate Siebert, USFS
1) The Risks of Reliance
on Biological Control
An article published lately indicates yet another complication that might undercut reliance on biocontrol to counter mortality of eastern ash populations caused by the emerald ash borer (EAB) (See my blogs from November — here and here) regarding APHIS’ proposal to eliminate EAB quarantines in favor of relying chiefly on biocontrol – with little data to back up the change.)
Olson
and Rieske (full citation at the end of this blog) found that one of the
principal biocontrol agents now in use, and on which APHIS proposes to rely, Tetrastichus planipennisi, does not parasitize
EAB larvae living in white fringetree, Chionanthus
virginicus. While this tree is a suboptimal host for EAB – lower numbers of
the beetle survive – the white fringetree would support survival of some EAB –
thereby undermining efficacy of the biocontrol program.
Since white fringetree grows a cross much of the eastern range of ash trees — from New York to Texas, as shown by the map posted here, the presence of this reservoir that can be exploited by EAB will challenge the efficacy of biocontrol.
Olson
and Rieske believe the reason that T.
planipennisi does not attack EAB living in white fringetree is that the
fringetree’s wood is so dense that the wasp cannot detect the presence of EAB
in the tree (T. planipennisi apparently
relies on tactile and vibratory clues to find its prey).
2) A Possible New
Biopesticide to Suppress EAB?
A presentation at the 81st Northeastern Forest Pest Council by Mark Ardis of C.D.G. Environment described tests in the United States and Canada of methods for killing EAB by contaminating the beetles with the fungus Beauveria bassiana. The company is testing traps in which male beetles enter, become covered by fungal spores, then they fly out. The males not only become ill themselves, they also contaminate females during mating. Average overall beetle mortality from several test sites is 25%.
Given the terrible
impact of the EAB invasions, I find it exciting to contemplate development of
additional tools to be used in suppressing the beetles. However, I worry about
possible impacts on non-target insects which might also be exposed to the
fungal spores. A decade ago, David Wagner identified 21 species of insects that
were specialists on Fraxinus, and said
he expected additional species would also be associated with ash trees (full
citation at end of blog). Mr. Ardis assured me that they had detected no
insects other than EAB in the traps. I wish to see additional research on this
issue.
The US Environmental Protection Agency would have
to approve use of this biopesticide. I suggest that we all keep an eye on this
process.
3) Citizen
Scientists Searching for EAB- resistant “Lingering Ash”
Jonathan Rosenthal
and Radka Wildova of the Ecosystem Research Institute have established a
citizen science program to find ash trees that have survived the EAB invasion. These
trees will become the foundation of efforts to breed more trees resistant to
the EAB, which could be used to restore our forests.
The program is called
“MaMa” – Monitoring and Managing Ash. So far, about 30 plots have been set up
in New York, New Jersey, and Vermont where citizens are monitoring ash trees
that have apparently survived the EAB invasion. The program seeks additional
partners from other areas.
Searches for
lingering ash must be strategically timed to ensure that the trees identified
are truly resistant to EAB – not just late to become infested. But you can’t
wait too long after the infestation wave has gone through an area, because the
tree might die due to wind throw or human activity. Or, if a tree has just partial
resistance (an important attribute for breeding!), it might eventually succumb.
It is also imperative to avoid confusing stump sprouts with truly lingering
ash. The conclusion: monitor the infestation and search for lingering trees two
years after 95% of ash have been killed, or four years after 50% have been
killed.
The MaMa program
provides guidance, maps, electronic reporting systems … so you can help!
If you wish to participate
– or to learn more – contact the program at monitoringAsh.org or 845-419-5229.
SOURCES
Olson,
D.G. and L.K. Rieske. 2019. Host range expansion may provide enemy free space
for the highly invasive emerald ash borer. Biol Invasions (2019) 21:625–635
Wagner, D.L. Emerald Ash Borer Threatens Ash-feeding Lepidoptera. 2007. News of the Lepidopterists’ Society. Volume 49, No. 1 (Spring 2007)
Posted
by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
We
have long known that significant damage to our forests have been caused by
non-native insects and diseases. Now USFS scientists have found that
exacerbated mortality caused by these pests is showing up in official
monitoring data – the Forest Inventory and Analysis (FIA) data. In a presentation
at the 81st Northeastern Forest Pest Council, Randall Morin
described the results of applying FIA data to determine mortality levels caused by several of the most
damaging invaders. He found an approximately 5% increase in total mortality
volume nation-wide.
Morin also compared a map prepared by Andrew Liebhold showing the number of non-native tree-killing pests established in each county of the continent to the mortality rates for those counties based on the FIA data. (See two maps below.)
map showing number of non-native forest pests established in each county of the Continental States; from Liebhold/USFSDr. Randall Morin’s map showing levels of tree mortality, based on FIA data
Counties showing the highest mortality rates in FIA data do not align with counties with highest numbers of invasive species. Morin thinks the discrepancy is explained by such human factors as invasion pressure and the ease of pest movement through the good transportation network in the Northeast. He assigns less importance to habitat invasibility.
The increase in mortality above the background rate was the worst for redbay due to laurel wilt disease – the annual mortality rate rose from 2.6% to 10.9% — slightly more than a four-fold increase. Almost as great an increase in mortality rates – to approximately three-fold – was found for ash trees attacked by the emerald ash borer (from 2.6% to 10.9%); beech dying from beech bark disease (from 0.7% to 2.1%); and hemlock killed by hemlock woolly adelgid, hemlock looper, and other pests (from 0.5% to 1.7%).
Some species are presumed to have an elevated mortality rate, but the pre-invasion “background” rate could not be calculated. These included American chestnut (mortality rate of 7%), butternut succumbing to butternut canker (mortality rate of 5.6%), and elm trees succumbing to “Dutch” elm disease (mortality rate of 3.5%).
The non-native pests and pathogens that have invaded the largest number of counties are white pine blister rust (955 counties), European gypsy moth (630 counties), dogwood anthracnose (609 counties in the East; the western counties were not calculated); emerald ash borer (479 counties); and hemlock woolly adelgid (432 counties).
The invaders posing the most widespread threat as measured by the volume of wood of host species are European gypsy moth (230.9 trillion ft3), Asian longhorned beetle (120.5 trillion ft3), balsam woolly adelgid (61 trillion ft3), sudden oak death (44.6 trillion ft3), and white pine blister rust (27.7 trillion ft3).
The proportion of
the host volume invaded by these non-native pests is 94% for white pine blister
rust, 48% for balsam wooly adelgid, 29% for European gypsy moth, 12% for sudden
oak death, and one half of one percent for Asian longhorned beetle.
Of
course, measuring impact by wood volume excludes some of the species suffering
the greatest losses because the trees are small in stature. This applies
particularly to redbay, but also dogwoods. Also, American chestnut was so
depleted before FIA inventories began that it is also not included – despite
the species’ wide natural range and large size.
[You can see the details for particular species by visiting the FIA “dashboards”. A particularly good example is that for hemlock woolly adelgid, available here.
USFS Response
Of
course, the Forest Service has been trying to counter the impact of invasive
insects and pathogens for decades, long before this study documented measurable
changes in mortality rates.
Unfortunately, funding for the agency’s response has been falling for decades – with concomitant reduction in staffs needed to carry out the work. See the graph below from p. 108 of my report, Fading Forests III, available here.
The
President’s FY2020 budget proposes additional cuts.
The proposal would cut funding for
the USFS Research division by $42.5 million
(14%); cut staff by 212 staff years
(12.5%). It would refocus the research program on inventory and monitoring;
water and biological resources; forest and rangeland management issues, especially
fire; forest products innovations; and people and the environment.
As shown by the above graph, this
proposed cut follows years of loss of expertise and research capacity.
The President’s budget
proposes to slash the State & Private Forestry account by 45.6% – from $335
million to just $182 million. The critically important Forest Health Management
program is included under State & Private Forestry. The cuts proposed for
FHM are 7% for work done on federal lands (from $44.9 million to $41.7 million;
and 16% for work done on non-federal “cooperative” lands (from $38 million to
$31.9 million). Staffing would be reduced by 4% for those working on federal
lands, a startling 38% for those working on cooperative lands.
For
details, view the USDA Forest Service budget justification, which can be found
by entering into your favorite search engine “FY2020 USFS Budget”. Funding
details begin on p. 12; staffing number details on p. 15.
These
severe cuts are proposed despite the fact that the budget justification notes
that pests (native as well as exotic) threaten more than four million acres and
that those pests know no boundaries. The document claims that the Service continues
to apply an “all lands” approach.
When
considering individual invasive pest species, these proposed cuts exacerbate reductions
in previous years. Some cuts are probably justified by changes in
circumstances, such as improved understanding of a species’ life cycle
resulting from past research. However, some are still troubling. (Again, for
details, view the USDA Forest Service budget justification, which can be found
by entering into your favorite search engine “FY2020 USFS Budget”. A table
listing species-specific expenditures in recent years, and the proposed FY2020
levels, is on pp. 38-39.)
The budget proposes to eliminate spending to manage Port-Orford-cedar root disease – which was funded at just $20,000 in recent years but received $200,000 as recently as FY2016. Forest Health Management would cease funding restoration for whitebark pine pests, including white pine blister – despite widespread recognition of the ecological importance of this species. Research on blister rust would continue, but at just over half the funding of recent years. Spending on oak wilt disease would be cut by 45%; funding for protecting hemlocks by 40% (the latter received $3.5 million in FY16). Funding for management of sudden oak death is proposed to be cut by 31% . Cuts to these programs seem particularly odd given that much of the threat is on federal lands – the supposed priority of the Administration’s budget.
The budget calls for a 12% cut in funding for the emerald ash borer – at the very time that USDA APHIS plans to terminate its regulatory program and state agencies and conservationists are looking to the Forest Service to provide leadership.
According to Bob Rabaglia, entomologist for the Forest Health Management program, the proportion of the FHM budget allocated to invasive alien species (as distinct from native pests) has been rising in recent years. Some of this increase is handled through a new “emerging pest” account. Species targeted by these funds, I have been told, include beach leaf disease; goldspotted oak borer; and the invasive polyphagous and Kuroshio shot hole borers.
Unfortunately, the
“emerging pest” account funds are not included in the table on pp. 38-39 of the
budget justification. Nor have I been able to learn from program staff how much
money is in the fund and how much has been allocated to these or other pest or
disease threats.
Adequate
funding of the USFS Research and Forest Health Management programs could allow
the agency to support, inter alia,
efforts by agency and academic scientists to breed trees resistant to the
damaging pest. I am aware, for example, of efforts to find “lingering” ash,
beech, hemlock, whitebark pine, and possibly also redbay. None is adequately
funded.
Please contact your member of Congress and Senators
and urge them to support adequate funding for these two Forest Service
programs. Research should be funded at $310 million (usually 5% or less of these funds is devoted to invasive species);
Forest Health should be funded at $51 million for
cooperative lands and $59 million for federal lands. It
is particularly important to advocate for funding for the “cooperative lands”
account since both the Administration and many members of Congress think the
Forest Service should focus more narrowly on federal lands.
It is particularly important to contact your member if
s/he is on the Interior Appropriations subcommittees. Those members are:
House:
Betty McCollum, Chair (MN 4th)
Chellie Pingree (ME 1st)
Derek Kilmer (WA 6th)
José Serrano (NY 15th)
Mike Quigley (IL 5th)
Bonnie Watson Coleman (NJ 12th)
Brenda Lawrence (MI 14th)
David Joyce, Ranking Member (OH 14th)
Mike Simpson (ID 2nd)
Chris Stewart (UT 2nd)
Mark Amodei (NV 2nd)
Senate:
Lisa
Murkowski, Chair (AK)
Lamar
Alexander (TN)
Roy
Blunt (MO)
Mitch
McConnell (KY)
Shelly
Moore Capito (WV)
Cindy
Hyde-Smith (MS)
Steve
Daines (MT)
Marco
Rubio (FL)
Tom
Udall, Ranking (NM)
Diane
Feinstein (CA)
Patrick
Leahy (VT)
Jack
Reed (RI)
Jon
Tester (MT)
Jeff
Merkley (OR)
Chris
van Hollen (MD)
Posted by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
As I have written often, inadequate funding is a major cause of shortfalls in USDA APHIS’ efforts to detect new invasions by tree-killing pests and to respond to those invasions in effective ways. So, I ask you to contact your Representative and Senators in support of appropriations for APHIS and –National Institute for Food and Agriculture (NIFA) for the next fiscal year – (FY)2020.
APHIS’
efforts to detect and respond to non-native tree-killing pests were rudely interrupted
by the five-week Government Shutdown from 22 December until late January. While
inspection of incoming shipments continued, U.S.-based activities were halted. Chaos
and confusion continued until 15 February, when the President signed
legislation that funds APHIS (and other government agencies) until the end of
September – the remainder of FY2919.
Surprise!
The funding bill provides increased funds for two key APHIS programs:
$60
million for the “tree and wood pests” program — $4 million above the funding provided
in recent years; and
$186
million for “specialty crop” pests (including sudden oak death) — $7.8 million
above recent levels.
I ask you to ask the Congress to maintain these funding levels for these budget “lines”.
I ask you also to support continuing the FY19 levels for two other programs:
Methods Development — $27.4 million; and
“Detection Funding” – $20. 7 million.
New this year, I hope you will support a $10 million appropriation to the National Institute of Food and Agriculture to fund a competitive grant program intended to restore to forests tree species significantly damaged by non-native insects and plant pathogens.
Justification for
the Funding Requests
As we know, non-native insects and pathogens that threaten native tree species have been and continue to be introduced to the United States. These pests impose significant costs: Aukema et al. 2011 (full reference at the end of the blog) estimated
municipal governments spend more than $2 billion per year to remove trees on city property that have been killed by these
pests.
homeowners spend $1 billion every year to remove and replace trees on their properties
homeowners absorb an additional $1.5
billion in reduced property values.
Costs are rising: the polyphagous and Kuroshio shot
hole borers are projected to cost municipalities and homeowners in California
$36.2 billion if their further spread is not prevented (McPherson 2017)
When you contact
your Representative or Senators, tell them about the impact of non-native pests
in your location!
The
significant ecological impacts are poorly quantified.
USDA APHIS is responsible for preventing such pests’ entry, detecting newly introduced pests, and initiating rapid eradication programs. Yet, despite rising risks of pest introduction commensurate with rising import volumes, funding for APHIS’ program targetting the “tree and wood pests” associated with crates and pallets has remained at or below $55 million since FY2012 – until the modest increase last year to $60 million. Among the forest pests detected during this period are the spotted lanternfly and here and Kuroshio shot hole borer.
Among the pests probably introduced on a second pathway, imports of living plants, are the two pathogens threatening Hawaii’s most widespread tree, ʻōhiʻa lehua and here, and beech leaf disease and here in the Northeastern states. The better-funded “specialty crops” account could help fund responses to these damaging pathogens.
Ask your Congressional representatives to urge APHIS to apply part of the increased funding for the “tree and wood pest” program to continue the regulatory program for the emerald ash borer (EAB) and here. In September, APHIS has proposed to terminate the EAB regulatory program. Program termination would greatly increase the risk that EAB will spread to the mountain and Pacific Coast states. California has five native species of ash vulnerable to EAB. Ash trees provide a higher percentage (8%) of Los Angeles’ tree canopy than any other species. This proportion will rise as other tree species succumb to the polyphagous and Kuroshio shot hole borers. Oregon’s one native species of ash is widespread in riparian areas and many urban plantings consist of ash. Ash trees are the fifth most common genus among Portland’s urban trees. Many stakeholders have urged APHIS to continue to regulate movement of firewood and other materials that facilitate EAB’s spread.
The “Specialty
Crops” program currently funds APHIS’ regulation of nursery operations to
prevent spread of the sudden oak death pathogen. In future, this budget line would be the logical source of
funds to manage the spotted lanternfly, which has been carried out through a
combination of emergency funding under 7 U.S.C. §7772 and grants funded through the Plant Pest and Disease
Management and Disaster Program (§7721
of the Plant Protection Act). (See below.)
Ask your Congressional representatives to support continued funding of APHIS’ “Methods Development” program at the
FY19 level of $27.4 million. This program assists APHIS in developing detection
and eradication tools essential for an effective response to new pests.
Similarly, ask your Congressional
representatives to support continued funding of the “Detection” budget
line at the FY19 level of $20.7 million. This program supports the critically
important collaborative state –federal program pest-detection program that is
critical to successful eradication and containment programs.
APHIS’ Additional sources
of funds
APHIS has always had authority to obtain “emergency” funds through 7 U.S.C. §7772. Emergency funds come from permanent USDA funding; they are not subject to annual appropriations. This authority has been tightly controlled by the Office of Management and Budget; I believe the last time APHIS obtained “emergency” funds for a tree pest was the emerald ash borer a decade or more ago. A year ago, APHIS accessed $17 million in emergency funding to address the expanding spotted lanternflyoutbreak [USDA Press Release No. 0031.18 February 7, 2018] and OMB also requires that APHIS quickly transfer programs started with emergency funds to the regular budget. As I note above, response to the expanding spotted lanternfly outbreak should logically be shifted to the “specialty crops” budget account.
For
a decade, APHIS has had access to a separate source of funds: the Plant Pest and Disease Management and Disaster Prevention Program.
This program is also funded through permanent funds, not subject to the
vagaries of annual budgeting and appropriations. Until last year, this program
operated under Section
10007 of the 2014 Farm Bill; with passage of a new Farm Bill last year, it is
now designated as Section 7721 of the Plant Protection Act. Beginning in Fiscal
Year 2018, APHIS has authority to spend up to $75 million per year.
Funds are provided under a competitive grants program to universities, states, Federal agencies, nongovernmental organizations, non-profits, and Tribal organizations “to conduct critical projects that keep U.S. crops, nurseries, and forests healthy, boost the marketability of agricultural products within the country and abroad, and help us do right and feed everyone.” [USDA press release “USDA Provides $66 Million in Fiscal Year 2019 to Protect Agriculture and Natural Resources from Plant Pests and Diseases”February 15, 2019]
Over the decade since the program began, it has funded, but my calculation, about $77 million in projects targetting tree-killing pests. The proportion of total program funding allocated to tree-killing pests has risen in the most recent years, driven largely by funding to counter the spotted lanternfly outbreak which began in Pennsylvania but has since spread (see above). In the current year (FY2019), APHIS used this program to fund $10 million in projects to address the spotted lanternfly. The SLF funds equaled 57% of the total funding for tree pests provided under the program in FY2019.
Implications
of the Tangle of Funding Sources
What is the significance of funding programs through the Plant Pest and Disease Management and Disaster Prevention Program as distinct from appropriated funds? Clearly, having access to $75 million that is not subject to the limits imposed by Administration budget priorities or Congressional appropriations allows considerable freedom. Does this freedom allow APHIS to support work on pests that might not qualify to be “quarantine” pests? For example, under the Plant Protection Act, APHIS normally does not engage on pests found only in one state. The polyphagous and Kuroshio shot hole borers fall into this category. So did the spotted lanternfly for the first several years – until its detection in Delaware and Virginia in late 2017. If so, then the presence of the lanternfly in several states would seem now to indicate that funding sources should be shifted – at least in part – to appropriated funds. But would such a shift result in less funding – a result I think would be most unwise!
The beech leaf disease doesn’t clearly qualify for designation as a “quarantine pest” because of the uncertainty about the causal agent. So far, there has been no Section 7721 funding to support efforts to identify the causal agent or to improve detection or curtail spread of the disease.
a blight-resistant chestnut bred by the American Chestnut Foundation; photographed in Fairfax County, Virginia by F.T. Campbell
Funding for
Resistance Breeding through NIFA
As we know, dozens of America’s tree species have been severely reduced or virtually eliminated from significant parts of their ranges by non-native insects and pathogens. Last year’s Farm Bill – the Agriculture Improvement Act of 2018 – included an amendment (Section 8708) that establishes a new priority for an existing grant program to support restoration to the forest of native tree species that have suffered severe levels of mortality caused by non-native insects, plant pathogens, or other pests. Grant-receiving programs would incorporate one or more of the following components: collection and conservation of native tree genetic material; production of sufficiently numerous propagules to support landscape-scale restoration; and planting and maintenance of seedlings in the landscape.
In January a panel of the National Academies of Sciences, Engineering, and Medicine recommended that the U.S. apply multifaceted approaches to combat these threats to forest health. One component strategy is breeding of trees resistant to the pest.
Ask Congress to begin applying the Academies’
recommendation by providing $10 million to NIFA to fund the
Competitive Forestry, Natural Resources, and Environmental Grants Program under
Section 1232(c)(2) of the Food, Agriculture, Conservation, and Trade Act of
1990 (16 U.S.C. 582A-8, as amended.
I
hope everyone will contact your Representative and Senators. If your Congressional representative is
listed below, your contact is particularly helpful because these are the
members of the House or Senate Agriculture Appropriations subcommittees – the
people with the greatest influence over what gets funded:
House Agriculture
Appropriations subcommittee members:
Aukema, J.E., B. Leung, K. Kovacs, C.
Chivers, K. O. Britton, J. Englin, S.J. Frankel, R. G. Haight, T. P. Holmes, A.
Liebhold, D.G. McCullough, B. Von Holle.. 2011. Economic
Impacts of Non-Native
Forest Insects in the
Continental United States
PLoS One September 2011
(Volume 6 Issue 9)
McPherson,
Gregory. September 28, 2017. Memorandum to John Kabashima re: Potential Impact
of ISHB-FD on Urban Forests of Southern California
spotted lanternfly; photo by Holly Raguza, Penn. Dept. of Agriculture
I last blogged about the spotted lanternfly (Lycorma delicatula) two years ago. At that time, this insect from Asia (where else?) was established in some portions of six counties in southeastern Pennsylvania. While its principal host is tree of heaven (Ailanthus altissima), it was thought to feed on a wide range of plants, especially during the early stages of its development. Apparent hosts included many of the U.S.’s major canopy and undertory forest trees, e.g., maples, birches, hickories, dogwoods, beech, ash, walnuts, tulip tree, tupelo, sycamore, poplar, oaks, willows, sassafras, basswood, and elms. The principal focus of concern, however, is the economic damage the lanternflies cause to grapes, apples and stone fruits (e.g., peaches, plums, cherries), hops, and other crops.
In
the two years since my first blog, the spotted lanternfly has spread – both
through apparent natural flight (assisted by wind) and through human transport
of the egg masses and possibly adults. By autumn 2018, detections of one or a
few adults – alive or dead – had been found in six additional states:
Connecticut, Delaware, Maryland, New Jersey, New York, and Virginia.
spotted lanternfly quarantines (blue) & detection locations (yellow) prepared by Cornell University
How
many of these detections signal an outbreak?
It is too early to know.
Impacts of the
Government Shutdown
Unfortunately
the federal government shutdown forced the cancellation of the annual USDA
invasive species research meeting that occurs each January. The spotted
lanternfly was to be the focus of six presentations. The most important of
these was probably APHIS’ explanation of “where we are and where we are going.”
The cancellation eliminated one of the most important opportunities for
researchers to exchange information and ideas that could spur important
insights. Equally important, the cancellation hampered communication of
insights to practitioners trying to improve the pest’s management.
One
pressing question was not on the meeting’s agenda, however. Would a much more
aggressive and widespread response in 2014, when the lanternfly was first
detected, have eradicated this initial
outbreak? I have long thought that this
question should be asked for every new pest program, so that we learn whether a
too-cautious approach has doomed us to failure. However, authorities never
address the issue – at least not in a public forum.
The shutdown also had an even more alarming impact. It interruptedaid by USDA APHIS and the Forest Service to states that should be actively trying to answer this question. Winter is the appropriate season to search for egg masses. It is also the season to plan for eradication projects.
spotted lanternfly egg mass; New York Department of Environmental Conservation
For the first several years, funding of studies of the lanternfly’s lifecycles and host preferences, research on possible biological or chemical treatments, and outreach and education came in the form of competitive grants under the auspices of the Farm Bill Section 10007. This funding totaled $5.5 million to Pennsylvania.
This commitment pales compared to Asian longhorned beetle or emerald ash borerh— which were also poorly known when they were first detected in the United States.
At the same time, the Pennsylvania infestation spread. It is now known to be established in portions of 13 counties and outbreaks were detected in neighboring Delaware and Virginia. h
This spread – and resulting political pressure – persuaded APHIS to multiply its engagement. A year ago, USDA made available $17.5 million in emergency funds from the Commodity Credit Corporation (that is, the funds are not subject to annual Congressional appropriation). APHIS said it would use the additional funds to expand its efforts to manage the outer perimeter of the infestation while the Pennsylvania Department of Agriculture would focus on the core infested area. APHIS said it would use existing (appropriated) resources to conduct surveys, and control measures if necessary, in Delaware, Maryland, New Jersey, New York and Virginia.
Pennsylvania: infestation established (quarantine declared) in portions of thirteen counties (Berks, Bucks, Carbon, Chester, Delaware, Lancaster, Lebanon, Lehigh, Monroe, Montgomery, Northampton, Philadelphia, Schuylkill). The quarantine regulates movement of any living stage of the insect brush, debris, bark, or yard waste; remodeling or construction waste; any tree parts including stumps and firewood; nursery stock; grape vines for decorative or propagative purposes; crated materials; and a range of outdoor household articles including lawn tractors, grills, grill and furniture covers, mobile homes, trucks, and tile or stone. See the regulation here: https://www.agriculture.pa.gov/Plants_Land_Water/PlantIndustry/Entomology/spotted_lanternfly/quarantine/Pages/default.aspx
Delaware: The state had been searching for the insect since the Pennsylvania outbreak was announced. After detection of a single adult female in New Castle County in November 2017, survey efforts and outreach to the public were intensified. Another dead adult spotted lanternfly was found in Dover, Delaware, in October 2018.
Virginia: infestation established (quarantine declared) in one county. Multiple live adults and egg cases of spotted lanternfly were confirmed in the town of Winchester, Virginia (Frederick County), in January 2018. As noted in my earlier blog, this region is important for apple and other orchard crops and near Virginia’s increasingly important wine region.
New Jersey: The New Jersey Department of Agriculture began surveying for lanternflies along the New Jersey-Pennsylvania border (the Delaware River) once the infestation was known. It found no lanternflies before 2018. In the summer, however, live nymphs were detected in two counties, Warren and Mercer. In response, the state quarantined both those counties and one located between them, Hunterdon. The state planned to continue surveillance in the immediate areas where the species has been found as well as along the Delaware River border in New Jersey.
New York: In 2017, a dead adult lanternfly was found in Delaware County.
State authorities expressed concern about possible transport of lanternflies from the Pennsylvania infested area.
In Autumn 2018, New York authorities confirmed several detections, including a single adult in Albany and a second single adult in Yates County. In response, the departments of Environmental Conservation and Agriculture and Marketing began extensive surveys throughout the area. Initially they found no additional lanternflies.
However, a live adult was later detected in Suffolk County (on Long Island).
Connecticut: a single dead adult was found lying on a driveway at a private residence in Farmington, CT, in October 2018. The homeowner was a state government employee educated about the insect. Relatives had recently visited from Pennsylvania (Victoria Smith, Connecticut Agricultural Experiment Station, pers. comm.). Searches found no other spotted lanternflies on the property. The state plans additional surveys in the area to confirm that no other spotted lanternflies are present.
Maryland: A single adult spotted lanternfly (male) was caught in a survey trap in the northeast corner of Cecil County near the border of Pennsylvania and Delaware (an area of known infestation) in October 2018. Because of the lateness of the season and sex of the insect, the Maryland Department of Agriculture does not believe that the lanternfly has established there.
All
the affected states are encouraging citizens to report any suspicious finds.
Posted
by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
a blight-resistant chestnut tree bred using traditional breeding techniques by The American Chestnut Foundation; photo by F.T. Campbell
Nearly one-third of the continental United States is covered by forests, more than 1 million square miles. As demonstrated by many authorities and – I hope! – in my blogs, these forests face increasing threats, including introduction of rising numbers of non-native insects and pathogens that kill or severely damage the tree species that comprise those forests.
One
response has been a request by the U.S. Endowment for Forestry and Communities,
the Environmental Protection Agency, and U.S. Department of Agriculture
(Agricultural Research Service, Animal and Plant Health Inspection Service,
U.S. Forest Service, and National Institute of Food and Agriculture) that the
National Academies of Sciences, Engineering, and Medicine consider the
potential for the use of biotechnology to mitigate these threats to forest
health.
The resulting report was released in January 2019 (see full citation at the end of the blog). The report is 240 pages long, very thorough, and wide-ranging. It does have a 12-page summary, listing the Panel’s many conclusions and its recommendations. While the preponderance of the report concerns forests on the North American continent, the panel did seek information about threats to endemic trees in Hawai`i, which (to my mind) are especially severe. See earlier blogs here and here.
To
me, one of the report’s most important conclusions is that while there are
multiple options for dealing with forest pests, their feasibility and success
vary widely. Saying that no single management practice is likely to be
effective by itself, the report calls
for increasing investment in the full range of strategies other than
biotechnology,i.e.,
preventing
arrival of non-native pests (recognized as the first line of defense and the
most cost-effective strategy);
site
management practices;
biocontrol;
and
enhancement
of genetic resistance naturally present in affected tree species (including developing human capital in professions related to tree
breeding).
The
panel was not asked to examine the potential for biotech to reduce threats to
forest health by altering the pests affecting North American tree species so it
does not do so.
Summarizing the
Threat
Citing
Aukema et al. 2010 and other sources,
the Academy panels reports that approximately 450 species of insects and at
least 16 species of pathogens have been introduced and have established in
continental U.S. forests. Of those, 62 insects and all of the pathogens are
determined to have a high impact. A USDA Forest Service study estimates that 81.3
million acres (about 7% of all forested or treed land in the U.S.) are at risk
of losing at least 25% of tree vegetation by 2027 due to insects and pathogens.
These pests are both non-native, introduced species and native pests that are spreading
to new regions as a result of climate change.
The
Academy panel notes that loss of a tree species can have cascading adverse
effects on the forest ecosystem and on the range of services it provides and
the values it represents to human populations.
Part A. The Technology for Trees
The
Academy panel was asked to assess the ecological, economic, and social
implications of deploying genetically engineered trees. The experts also were asked
to identify the knowledge needed to evaluate the ways such a tree might affect
the prospects for forest health. The analysis was to include social and
cultural impacts as well as impacts on forest and associated ecosystems –
including their structure, composition, processes, function, productivity, and
resilience.
This
use of biotechnology to restore healthy forests differs from applications in
industrial plantations or annual agricultural crops in that the biotech tree is
intended to proliferate in a natural forest setting.
The
authors chose four taxa — American chestnut (Castanea dentata), whitebark pine (Pinus albicaulis), ash (Fraxinus
spp.), and poplars (Populus spp.) —
to illustrate the variety of threats to forest health and efforts to date to
protect the resource.
The
committee defined forest health as:
A condition that sustains the structure,
composition, processes, function, productivity, and resilience of forest
ecosystems over time and space.
The
panel says that “forest health” is assessed based on current knowledge and is
influenced by human needs, cultural values, and land management objectives.
1. A Balanced
Analysis
The
report does not hype biotechnology for solving problems. The panel called for
research on even the foundational question: whether resistance imparted to tree
species through a genetic change will be sufficient to persist in trees that
are expected to live for decades to centuries as well as in the generations
they parent.
The
report compares the two approaches to enhancing genetic resistance to pests, i.e., selective (traditional) breeding
and relying on biotechnology. Both
involve multiple steps, expense, and risks of pursuing what ultimately turn out
to be dead ends.
Thus,
in traditional selective breeding, scientists must complete the following
steps:
1)
Determine whether genetic resistance exists within the affected tree species’
population. According to the Academy report, while many tree species have some
degree of resistance to particular native or non-native pests, finding suitable
parent trees can be difficult, and even when they are found, not all the
progeny will be resistant.
2)
Evaluate the durability of resistance in order to protect trees over decades.
3)
Propagate the resistant progeny in greenhouses or seed orchards to create
sufficient resistant genotypes for restoration and reforestation. Many tree
species are difficult to propagate using cell culture and regeneration.
In
applying biotechnology techniques, scientists must complete the following
steps:
1)
Identify the genes carrying pertinent traits – which are to be modified, introduced,
or silenced. Scientists don’t know what genetic mechanisms underlie important
traits. This discovery process is more difficult for tree species than for
agronomic crops due to the plants’ large size, long generation time, and (in
the case of conifers) immense genomes. Another problem is that forest trees
have high levels of heterozygosity due to their large population sizes and
outcrossing breeding systems, which complicates genome assembly and modification.
Still, recent technological improvements are making this identification process
easier.
2)
Insert the genes using various biotechnology tools such as transgenesis and
genome editing.
3)
Produce trees containing the desired gene sequence to
regenerate plants from disorganized callus tissue. As noted above, many tree species
are difficult to propagate using cell culture and regeneration. Even when this
approach is possible, the regeneration of a plant from a single cell may not
produce an individual that has the desired genetic change in every cell.
The
time line for applying either approach to protect forest health will depend on several
factors, including the biology of both the tree and the pest, and the
environments in which the target tree species exists. It can vary from a few
years to multiple decades.
2. Who Should
Carry Out Genetic Improvement of Trees (and by implication, all long-term
strategies to protect forest health)?
Trees
provide private as well as public benefits, such as income from timber sales. However,
the costs of developing a genetically resistant tree – whether achieved through
traditional breeding or biotechnology processes – will be incurred up front and
the benefits will follow later – often decades or even centuries later. Consequently,
the sponsors need a long time horizon!
The
panel suggests that the public sector can have greater patience when it
perceives that significant public benefits will be forthcoming. The private
sector is not likely to invest in the protection of forest health because it
cannot fully capture the benefits that may accrue. The authors define “public
sector” to include government agencies and non-profit organizations.
Part B. Impacts, Ethics, and Policy
1. Impacts
The
report provides careful analysis of the ecological impacts that should be
considered in evaluating the use of biotechnology to maintain or improve forest
health. The report emphasizes that if the modified trees are to spread and
restore the species to its role in the ecosystem, the modified trees must be
competitive in the ecosystem (while not being invasive!). The trees must be suited
to the variety of climates and other biophysical conditions found throughout
the tree species’ range. The report even said that establishing the rangewide
patterns of distribution of the target species’ natural standing genetic variation
should be researched before a project is begun aimed at inserting pest
resistance genes.
2. Public
attitudes and ethical considerations
The
panel was charged to consider social, cultural, and ethical issues related to
the potential use of biotechnology to develop trees resistant to pests. They
devote 13 pages to examining this complex set of issues, which range from
Native Americans’ use of black ash to concepts of “wildness” and competing
models of “conservation”. There have
been few surveys or other studies of Americans’ attitudes. The panel also notes
that the public lacks in-depth knowledge about genetic interventions and processes,
so their attitudes are likely to change — for or against use of the technology
— as they learn more or associate biotech with strongly held beliefs.
The
Panel notes that important ethical questions fall outside any current “impact
analysis” evaluation system, or any new analysis that focuses on “ecosystem
services”. It calls for additional research
on societal response to biotechnology applied to forest health and development
of new forms of engaging full range of stakeholders.
3. Need for a New
Impact Assessment Framework
The panel
concludes that the current regulatory system does not provide for consideration
of most aspects of forest health in assessing the safety of a tree developed
through biotechnology, including those described above. Consequently, the
panel calls for an entirely new assessment process in order to evaluate both
the ecological and social/ethical considerations.
The
long-standing Coordinated Framework for the Regulation of Biotechnology relies
on existing federal statutes. Under this system, the regulatory agencies (USDA Animal
and Plant Health Inspection Service, Environmental Protection Agency, sometimes
Food and Drug Administration) regulate specific products, not the process by
which the products are produced. For example, USDA regulates only the small
subset of biotech trees which were transformed via use of a bacterium, Agrobacterium tumefaciens, to insert the
desired trait.
The
panel says that an agency undertaking an environmental analysis under the terms
of the National Environmental Protection Act would need to add an analysis of
some components of forest health.
To rectify these analytical gaps, the panel suggests creation of an integrated impact assessment framework that combines ecological risk assessment with consideration of ecosystem services. This integrated framework would evaluate the effect of the pest threat – and responses to that threat – on forest processes –as well as on associated cultural and spiritual values. The impact assessment must make explicit the links between specific forest protections and their effects on important ecosystem services. The panel points to an EPA guidance document on economic impact analysis (see reference at the end of this blog) as a useful starting point. The panel suggests that this framework should be used to evaluate any forest health intervention, including use of selectively bred trees.
Because
of the length of time until tree reproductive maturity and long life span of
most trees, collecting data for an impact assessment might take years. The
panel suggests adopting a tiered system which would allow field trials of low-risk
transgenic trees to reach flowering stage so as to provide data on gene flow
and climatic tolerances – data that are essential for a proper impact
assessment that would evaluate the likelihood of ultimate success of the
restoration effort. Such experiments and
carefully developed models must also identify sources of uncertainty.
Adoption
of such a stepwise, iterative process
requires abandonment of the current regulatory system, which does not permit
the flowering of biotech trees in most cases.
My Conclusions
The
report makes clear several realities:
1)
the magnitude of the threat to our forests from non-native pests – which
warrants an effective response;
2)
the strengths and weaknesses of the several response strategies – none of which
can solve this problem in isolation;
3)
the scientific challenges that need to be overcome to apply strategies aimed at
enhancing tree species’ genetic resistance to pests;
4)
the need for greatly expanded programs to implement the various strategies.
Also, the report shows how unprepared our country is to systematically assess the full impacts of new forms of tree breeding and forest health. To rectify this gap, the report also calls for a complete overhaul of the procedures by which the government currently evaluates the environmental risks associated with applying one of the strategies, genetic transformation of the plant host – which is defined (in the Glosssary) as including transgenesis, cisgenesis, RNA interference, genome editing, and insertion of synthetic DNA.
The
recommended actions in this report – taken either individually or collectively
– require a level of commitment by government and conservation organizations
that far exceeds the current level.
I
hope the Academies’ prestige can prompt such commitment. For example,
development of a sufficiently robust coalition of groups could re-invigorate
our society’s response to the invasive pest threat. The report has received
some encouraging attention. It was reported in Nature and Scientific
American. About 130 people tuned in live to
the launch webinar on January 8th. So far, almost 1,200 people have
downloaded the report.
The
government shutdown has delayed the sponsoring agencies’ (USDA and EPA) official reactions to the report. It probably curtailed
some publicity efforts among all the sponsoring agencies. Also, the report will
be only one item in the overflowing inboxes of agency scientists and managers
after 35 days on furlough. I hope it won’t be lost, especially with the threat
of a second shut-down.
How
can those of us in the public who care about our forests ramp up our activity to
support these recommendations?
A reminder: Scott Schlarbaum and I addressed the need for a greatly expanded restoration component as part of a comprehensive response to non-native tree-killing pests in our report Fading Forests III, released five years ago. It is available here.
SOURCES
Aukema, J.E., D.G.
McCullough, B. Von Holle, A.M. Liebhold, K. Britton, & S.J. Frankel. 2010.
Historical Accumulation of Nonindigenous Forest Pests in the Continental United
States. Bioscience. December 2010 /
Vol. 60 No. 11
National
Academies of Sciences, Engineering, and Medicine. 2019. Forest Health and
Biotech: Possibilities and Considerations. Washington, DC: The National
Academies Press. doi: https://doi.org/10.17226/25221.
U.S.
Environmental Protection Agency. 2014. Guidelines for Preparing Economic
Analyses. Washington, D.C.
A year ago, I alerted you to a new threat to American beech (Fagus grandifolia). In that blog I reported that conservation and park managers in northeastern Ohio had begun noticing troubling decline and mortality of beech saplings beginning in 2012. The problem was spreading: we now know that over the four years between 2012 and 2016, the apparent disease spread from an estimated 84 ha to 2,525 ha within Lake County, Ohio (Ewing et al. 2018; full citation provided at end of the blog).
By
2018, trees with symptoms had been detected in 24 counties across three states
and one province: 10 counties in Ohio, 8 counties in Pennsylvania, 1 county in
New York, and 5 counties in Ontario). A map is
provided in Ewing et al.
The
rate of decline within beech stands varies, suggesting that trees differ in
susceptibility. This is a promising for breeding resistance (Ewing et al.).
Symptoms
A number of organizations have produced fact sheets and related material. I recommend the fact sheet available here.
Disease Progression
In
Northeast Ohio, Cleveland Metroparks’ intensive monitoring program revealed a
4% mortality rate from 2015 to 2017. More than half of the plots now have dead trees
that had previously been only symptomatic.
Most of the dead trees are small – less than 4.9 cm dbh. However, some larger
trees have died and others bore only a few leaves this past summer. Leaves with
light, medium, or heavy symptoms of infection – as well as asymptomatic leaves
– can occur on the same branch of an individual tree.
The
disease seems to spread faster between the stems of trees growing in beech clone
clusters by spreading along the interlocking roots.
Serious science
effort finally initiated – and funded!
The
cause of beech dieback and mortality has still not been definitively
determined. Most scientists agree that the cause is some kind of disease agent,
not abiotic factors. A growing number of scientists from USDA’s Agriculture
Research Service and Forest Service; Ohio’s Division of Forestry and Department
of Agriculture; the Holden Arboretum; Ohio State University; and groups in Canada
are researching possibilities.
The
most promising candidate is a previously undescribed nematode detected by David
McCann of the Ohio Department of Agriculture. That nematode has since been
described by Japanese researchers on Japanese beech F. crenata (Kanzakiet al.) and given the name Litylenchus crenatae. Thousands of live Litylenchus nematodes (at least 10,000)
can swim out from a single leaf. Scientists at the USDA Agriculture Research Service
and Holden Arboretum are waiting for bud break this spring to see whether plant
material inoculated with the nematode develops disease symptoms.
Still, other
possible disease agents could also play a role.
An
international working group has been formed to continue studies of both disease
agents and disease progression in seedlings, saplings, and mature trees.
Still, no regulation
to counter long-range spread via nurseries!
Long range spread of the disease is probably assisted by anthropogenic transport, especially of nursery stock. As I reported in May, an Ontario retailer received – and rejected – a shipment of diseased beech from an Ohio nursery.
Despite
the evident risk, no official agency has adopted regulations to prevent spread
on nursery stock. None of the states or provinces in which the disease is
present has adopted regulations. None of the neighboring states or provinces
has acted to protect its nursery industry or forests. Neither USDA APHIS nor the
Canadian Food Inspection Agency (CFIA) has adopted regulations. The disease was
not mentioned during the annual meeting of the National Plant Board – which
took place in Cleveland in August! Connie Hausman of Cleveland MetroParks did
include the issue during her presentation on the extensive park complex to the
group during the group’s field trip.
The
absence of regulation is a puzzling omission because Lake County, Ohio, has
many nurseries that grow and ship European beech — which can also be infected
by beech leaf disease.
The Importance of American Beech – and Protecting
range of American beech
Our American beech is not a major timber species – in fact, the species is actively disliked by managers focused on timber production because beech bark disease kills trees before they reach commercial size. Beech trees also often have cavities which reduce their timber value – but which are valuable to wildlife.
However,
American beech is extremely important ecologically in northern parts of the
United States and in Canada east of the Great Plains. Beech is co-dominant
(with sugar maple) in the Northern Hardwood Forest. A summary of the species’ ecological
importance can be found in Lovett et al.
2006. Beech nuts are a primary source of food for many woodland birds and
mammals. In the central part of the northern hardwood forest – including in
southern Canada – beech trees are the only
source of hard mast. Furthermore, beech trees create a dense canopy; drastic defoliation
modifies light levels at ground level, thereby affecting understory competition
and other forest ecosystem services. Beech leaf litter decays more slowly than
maple’s, which affects nutrient cycling. While beech leaf disease is unlikely
to eradicate American beech, it could cause functional eradication of the species.
Ohio alone has more than 17 million American beech trees, according to Tom Macy
of the Ohio Department of Natural Resources (Ewing et al. 2018).
The
threat appears to be widespread because both European (F. sylvatica) and Asian (F.
orientalis) beech have shown symptoms. Ewing et al. 2018 call for detection efforts across Northern Hemisphere.
Of course, the species is already under threat from beech bark disease. Promising efforts to breed beech trees resistant to BBD now face the complication of having to incorporate resistance to this new disease (Ewing et al. 2018).
European Beech Weevil
I
will remind you that last year I noted a third threat to beech trees – the
European leaf weevil. Originally detected in Nova Scotia, it continues to
spread. About 95% of beech trees in forest plots near Halifax are dead. In the
city, half the beech trees have died and the rest are in severe decline. While
neither the province nor CFIA has imposed a quarantine or other regulations to govern
the movement of beech material, Canadian officials are exploring possible
chemical treatments. They are working with European colleagues to explore
biocontrol agents (Jon Sweeney, Natural Resources Canada, pers. comm.).
Conclusion
These
new threats are getting far too little attention! Some can be blamed on the
difficulty of regulating an unknown disease agent (e.g., beech leaf disease). Attempting this would stretch
traditional policy practice and, possibly, legal authorities. And it has not
yet been demonstrated that this disease can kill mature beech. However, neither
of these caveats applies to the weevil, which is an identified species, documented to kill mature trees, and a problem
still not addressed.
Sources
Ewing,
C.J., C.E. Hausman, J. Pogacnik, J. Slot, P. Bonello. 2018. Beech leaf disease: An emerging forest
epidemic. Short Communication. Forest Pathology 2018;e12488
Lovett
et al. 2006. Forest Ecosystem
Responses to Exotic Pests and Pathogens in Eastern North America. BioScience
Vol. 56 No. 5.
Sharon
Reed’s presentation on YouTube https://www.youtube.com/watch?v=tDBbik7cUrI
Posted
by Faith Campbell
We
welcome comments that supplement or correct factual information, suggest new
approaches, or promote thoughtful consideration. We post comments that disagree
with us — but not those we judge to be not civil or inflammatory.
