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Invited Review: Quantifying surface albedo and other direct biogeophysical climate forcings of forestry activities
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By altering fluxes of heat, momentum, and moisture exchanges between the land surface and atmosphere, forestry and other land-use activities affect climate. Although long recognized scientifically as being important, these so-called biogeophysical forcings are rarely included in climate policies for forestry and other land management projects due to the many challenges associated with their quantification. Here, we review the scientific literature in the fields of atmospheric science and terrestrial ecology in light of three main objectives: (i) to elucidate the challenges associated with quantifying biogeophysical climate forcings connected to land use and land management, with a focus on the forestry sector; (ii) to identify and describe scientific approaches and/or metrics facilitating the quantification and interpretation of direct biogeophysical climate forcings; and (iii) to identify and recommend research priorities that can help overcome the challenges of their attribution to specific land-use activities, bridging the knowledge gap between the climate modeling, forest ecology, and resource management communities. We find that ignoring surface
biogeophysics may mislead climate mitigation policies, yet existing metrics are unlikely to be sufficient. Successful metrics ought to (i) include both radiative and nonradiative climate forcings; (ii) reconcile disparities between biogeophysical and biogeochemical forcings, and (iii) acknowledge trade-offs between global and local climate benefits. We call for more coordinated research among terrestrial ecologists, resource managers, and coupled climate modelers to harmonize datasets, refine analytical techniques, and corroborate and validate metrics that are more amenable to analyses at the scale of an individual site or region.
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Climate Science Documents
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A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests
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Greenhouse gas emissions have significantly altered global climate, and will continue to do so in the
future. Increases in the frequency, duration, and/or severity of drought and heat stress associated with
climate change could fundamentally alter the composition, structure, and biogeography of forests in
many regions. Of particular concern are potential increases in tree mortality associated with climateinduced
physiological stress and interactions with other climate-mediated processes such as insect
outbreaks and wildfire. Despite this risk, existing projections of tree mortality are based on models that
lack functionally realistic mortality mechanisms, and there has been no attempt to track observations of
climate-driven tree mortality globally. Here we present the first global assessment of recent tree
mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of
climate change, studies compiled here suggest that at least some of the world’s forested ecosystems
already may be responding to climate change and raise concern that forests may become increasingly
vulnerable to higher background tree mortality rates and die-off in response to future warming and
drought, even in environments that are not normally considered water-limited. This further suggests
risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric
feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently
hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a
globally coordinated observation system. Overall, our review reveals the potential for amplified tree
mortality due to drought and heat in forests worldwide.
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Climate Science Documents
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Impacts of mountaintop mining on terrestrial ecosystem integrity: identifying landscape thresholds for avian species in the central Appalachians, United States
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Reclaimed mine-dominated landscapes (less forest and more grassland/shrubland cover) elicited more negative (57 %) than positive (39 %) species responses. Negative thresholds for each landscape metric generally occurred at lower values than positive thresholds, thus negatively responding species were
detrimentally affected before positively responding species benefitted. Forest interior birds generally
responded negatively to landscape metric thresholds, interior edge species responses were mixed, and early
successional birds responded positively. The forest interior guild declined most at 4 % forest loss, while
the shrubland guild increased greatest after 52 % loss
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Climate Science Documents
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Temporal dynamics of a commensal network of cavity-nesting vertebrates: increased diversity during an insect outbreak
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Network analysis offers insight into the structure and function of ecological
communities, but little is known about how empirical networks change over time during
perturbations. ‘‘Nest webs’’ are commensal networks that link secondary cavity-nesting
vertebrates (e.g., bluebirds, ducks, and squirrels, which depend on tree cavities for nesting)
with the excavators (e.g., woodpeckers) that produce cavities. In central British Columbia,
Canada, Northern Flicker (Colaptes auratus) is considered a keystone excavator, providing
most cavities for secondary cavity-nesters. However, roles of species in the network, and
overall network architecture, are expected to vary with population fluctuations. Many
excavator species increased in abundance in association with a pulse of food (adult and larval
beetles) during an outbreak of mountain pine beetle (Dendroctonus ponderosae), which peaked
in 2003–2004. We studied nest-web dynamics from 1998 to 2011 to determine how network
architecture changed during this resource pulse.Cavity availability increased at the onset of the beetle outbreak and peaked in 2005. During and after the outbreak, secondary cavity-nesters increased their use of cavities made by five species of beetle-eating excavators, and decreased their use of flicker cavities. We found low link turnover, with 74% of links conserved from year to year. Nevertheless, the network
increased in evenness and diversity of interactions, and declined slightly in nestedness and
niche overlap. These patterns remained evident seven years after the beetle outbreak,
suggesting a legacy effect. In contrast to previous snapshot studies of nest webs, our dynamic approach reveals how the role of each cavity producer, and thus quantitative network architecture, can vary over
time. The increase in interaction diversity with the beetle outbreak adds to growing evidence
that insect outbreaks can increase components of biodiversity in forest ecosystems at various
temporal scales. The observed changes in (quantitative) network architecture contrast with the
relatively stable (qualitative) architecture of empirical mutualistic networks that have been
studied to date. However, they are consistent with recent theory on the importance of
population fluctuations in driving network architecture. Our results support the view that
models should allow for the possibility of rewiring (species switching partners) to avoid
overestimation of secondary extinction risk.
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Climate Science Documents
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A drought-induced pervasive increase in tree mortality across Canada’s boreal forests
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Drought-induced tree mortality is expected to increase worldwide under projected future climate changes (1–4). The Canadian boreal forests, which occupy about 30% of the boreal forests worldwide and 77% of Canada’s total forested land, play a critical role in the albedo of Earth’s surface (5) and in its global carbon budget (6). Many of the previously reported regional-scale impacts of drought on tree mortality have affected low- and middle-latitude tropical regions (2) and the temperate forests of the western United States (3), but no study has examined high-latitude boreal regions with multiple species at a regional scale using long-term forest permanent sampling plots (7–9). Here, we estimated tree mortality in natural stands throughout Canada’s boreal forests using data from the permanent sampling plots and statistical models. We found that tree mortality rates increased by an overall average of 4.7%yr−1 from 1963 to 2008, with higher mortality rate increases in western regions than in eastern regions (about 4.9 and 1.9% yr−1 ,respectively).The water stress created by regional drought may be the dominant contributor to these widespread increases in tree mortality rates across tree species, sizes, elevations, longitudes and latitudes. Western Canada seems to have been more sensitive to drought than eastern Canada.
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Climate Science Documents
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Forest Service Report Highlights Restoration Progress Made Despite Growing Challenges
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The U.S. Forest Service has increased the pace and scale of forest restoration by nine percent since 2011, according to a report released today. The significant progress comes in the face of mounting challenges to the agency including record droughts, longer wildfire seasons and the increasing percentage of the agency’s budget spent fighting wildland fires.
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News & Events
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LANDFIRE Data Applications for Research in Fire Ecology, Forest Mgmt in California
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Brandon Collins presents the second in a series of webinars that LANDFIRE co-hosts with the California Fire Science Consortium. Collins is a USFS Research Forester based in Davis, CA, whose interests involve characterizing effects of fire and fuels treatments on forests at both the stand and landscape levels. He says, "My research intends to provide meaningful information to managers interested in improving forest resiliency and incorporating more natural fire-vegetation dynamics across landscapes."
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Training
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Videos and Webinars
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Global Vulnerability of Forests to Climate Change-Related Tree Mortality is Widely Underestimated
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Forests worldwide are vulnerable to growing risks of drought- and heat-induced tree mortality and forest die-off because of a rapidly warming Earth, according to just-published research in the scientific journal Ecosphere. The paper is an invited “ESA Centennial Paper” to commemorate the 100th anniversary of the Ecological Society of America.
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Researchers Seek a Sneak Peek Into the Future of Forests
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In May 2015, scores of scientists from dozens of research institutions descended on a patch of forest in central North Carolina, taking samples of everything from ants and mites to other microbes – samples they hope will offer a glimpse into the future of forest ecosystems.
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Partnership benefits two Kentucky landscapes
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The Forecastle Foundation, a 501(c)(3) non-profit dedicated to preserving areas of abundant biodiversity, today begins a new charitable partnership with The Nature Conservancy’s Kentucky Chapter.
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