Stephen N. Matthews

PREDICTING EXTINCTIONS AS A RESULT OF CLIMATE CHANGE

Widespread extinction is a predicted ecological consequence of global warming. Extinction risk under climate change scenarios is a function of distribution breadth. Focusing on trees and birds of the eastern United States, we used joint climate and environment models to examine fit and climate change vulnerability as a function of distribution breadth. We found that extinction vulnerability increases with decreasing distribution size. We also found that model fit decreases with decreasing distribution size, resulting in high prediction uncertainty among narrowly distributed species. High prediction uncertainty creates a conservation dilemma in that excluding these species under-predicts extinction risk and favors mistaken inaction on global warming. By contrast, including narrow endemics results in over-predicting extinction risk and promotes mistaken inaction on behalf of individual species prematurely considered doomed to extinction.

The impacts of increasing drought on forest dynamics, structure, and biodiversity in the United States

We synthesize insights from current understanding of drought impacts at stand-to-biogeographic scales, including management options, and we identify challenges to be addressed with new research. Large stand-level shifts underway in western forests already are showing the importance of interactions involving drought, insects, and fire. Diebacks, changes in composition and structure, and shifting range limits are widely observed. In the eastern US, the effects of increasing drought are becoming better understood at the level of individual trees, but this knowledge cannot yet be confidently translated to predictions of changing structure and diversity of forest stands. While eastern forests have not experienced the types of changes seen in western forests in recent decades, they too are vulnerable to drought and could experience significant changes with increased severity, frequency, or duration in drought. Throughout the continental United States, the combination of projected large climate-induced shifts in suitable habitat from modeling studies and limited potential for the rapid migration of tree populations suggests that changing tree and forest biogeography could substantially lag habitat shifts already underway. Forest management practices can partially ameliorate drought impacts through reductions in stand density, selection of drought-tolerant species and genotypes, artificial regeneration, and the development of multistructured stands. However, silvicultural treatments also could exacerbate drought impacts unless implemented with careful attention to site and stand characteristics. Gaps in our understanding should motivate new research on the effects of interactions involving climate and other species at the stand scale and how interactions and multiple responses are represented in models. This assessment indicates that, without a stronger empirical basis for drought impacts at the stand scale, more complex models may provide limited guidance.

Ecosystem vulnerability assessment and synthesis: a report from the Climate Change Response Framework Project in northern Wisconsin

The forests of northern Wisconsin will likely experience dramatic changes over the next 100 years as a result of climate change. This assessment evaluates key forest ecosystem vulnerabilities to climate change across northern Wisconsin under a range of future climate scenarios. Warmer temperatures and shifting precipitation patterns are expected to influence ecosystem drivers and increase stressors, including more frequent disturbances and increased amount or severity of pests and diseases. Forest ecosystems will continue to adapt to changing conditions. Identifying vulnerable species and forests can help landowners, managers, regulators, and policymakers establish priorities for management and monitoring.

LANDBIRD USE OF RIPARIAN AND UPLAND FOREST STOPOVER HABITATS IN AN URBAN LANDSCAPE

Abstract Stopover habitat relationships of landbirds are not well known and this constitutes a shortcoming in conservation plans for migratory birds. We compared migrant use of mature upland and riparian forests during spring in an urbanizing landscape within central Ohio. We surveyed stopover migrants along 250-m transects, and quantified both local- and landscape-level habitat characteristics (percent urban and forest land). During spring stopover, migrant abundance was 86% and 118% higher in upland forests for Nearctic-Neotropical transient (long-distance migrants) and temperate transients (short-distance migrants), respectively. Of 27 transient species, 22 species differed in their use of riparian and upland forests, and 20 of those were most abundant in upland forest (e.g., Blue-headed Vireo [Vireo solitarius], Least Flycatcher [Empidonax minimus], Swainsons Thrush [Catharus ustulatus], Nashville Warbler [Vermivora ruficapilla], Magnolia Warbler [Dendroica magnolia], Bay-breasted Warbler [D. castanea], and Ovenbird [Seiurus aurocapillus]). Species richness was 58% and 75% higher in upland forests relative to riparian forests for Neotropical transient and temperate transient groups, respectively. Percent urbanization within 1 km was unrelated to abundance of Neotropical transients and temperate transients. Abundance of Neotropical transients and temperate transients was unrelated to percent forest cover within 1 km. Mature upland and riparian forests differed in that riparian sites had lower percentage of shrub cover, higher percentage of canopy cover, and different species composition of trees. Abundance of Neotropical transients was positively associated with mean canopy height; temperate transients were positively associated with mean number of trees >38 cm DBH and mean percentage of shrub cover. Our data indicate that mature upland forests were more heavily used by migrating landbirds than riparian forests within an urbanizing Midwestern landscape and may represent valuable habitats for the conservation of migratory landbirds within highly fragmented landscapes. Uso de Bosques Riparios y de Llanuras por Aves Terrestres como Hábitats de Paradas Migratorias en un Paisaje Urbano Resumen. Las relaciones de los hábitats que sirven como paradas migratorias para las aves terrestres no están bien conocidas, y esto constituye una deficiencia en los planes de conservación de las aves migratorias. Comparamos el uso de bosques maduros de llanuras y de bosques riparios por parte de aves migratorias durante la primavera en un paisaje que está siendo urbanizado en Ohio central. Registramos aves migratorias en las paradas de migración a lo largo de transectos de 250 m y cuantificamos las características del hábitat tanto a nivel local como a nivel del paisaje (porcentaje de cobertura urbana y de bosque). Durante la parada migratoria de primavera, la abundancia de las aves migratorias en bosques de llanura fue un 86% mayor para las aves transitorias del Neártico-Neotrópico (aves migratorias de larga distancia) y un 118% mayor para las aves transitorias templadas (aves migratorias de corta distancia). De 27 especies transitorias, 22 especies se diferenciaron en su uso de bosque ripario y de llanura, y 20 de éstas fueron más abundantes en bosques de llanura (e.g., Vireo solitarius, Empidonax minimus, Catharus ustulatus, Vermivora ruficapilla, Dendroica magnolia, D. castanea, Seiurus aurocapillus). La riqueza de especies en bosques de llanura con relación a el bosque ripario fue un 58% mayor para los grupos de aves transitorias Neotropicales y un 75% mayor para las aves transitorias templadas. El porcentaje de cobertura de urbanización en un radio de 1 km no se relacionó con la abundancia de aves transitorias Neotropicales ni con las transitorias templadas. La abundancia de las aves transitorias Neotropicales y templadas no se relacionó con la cobertura de bosque dentro de un radio de 1 km. Los bosques maduros de llanura y los bosques riparios se diferenciaron en que los sitios de bosque ripario tuvieron menor cobertura de arbustos, una mayor cobertura de dosel y una composición de especies de árboles diferente. La abundancia de las aves transitorias Neotropicales se relacionó positivamente con la altura promedio del dosel, mientras que las aves transitorias templadas se relacionaron positivamente con el número promedio de árboles con DAP >38 cm y con la cobertura promedio de arbustos. Nuestros datos indican que los bosques maduros de llanuras fueron utilizados con mayor intensidad por aves migratorias terrestres que los bosques riparios en un paisaje urbanizado del medio-oeste, y que estos bosques pueden representar un tipo de hábitat valioso para la conservación de las aves migratorias terrestres en un paisaje altamente fragmentado.

Exploring tree species colonization potentials using a spatially explicit simulation model: implications for four oaks under climate change

Climate change impacts tree species differentially by exerting unique pressures and altering their suitable habitats. We previously predicted these changes in suitable habitat for current and future climates using a species habitat model (DISTRIB) in the eastern United States. Based on the accuracy of the model, the species assemblages should eventually reflect the new quasi-equilibrium suitable habitats (~2100) after accounting for the lag in colonization. However, it is an open question if and when these newly suitable habitats will be colonized under current fragmented landscapes and realistic migration rates. To evaluate this, we used a spatially explicit cell-based model (SHIFT) that estimates colonization potentials under current fragmented habitats and several estimates of historical migration rates at a 1 km resolution. Computation time, which was previously the biggest constraint, was overcome by a novel application of convolution and Fast Fourier Transforms. SHIFT outputs, when intersected with future suitable habitats predicted by DISTRIB, allow assessment of colonization potential under future climates. In this article, we show how our approach can be used to screen multiple tree species for their colonization potentials under climate change. In particular, we use the DISTRIB and SHIFT models in combination to assess if the future dominant forest types in the north will really be dominated by oaks, as modelled via DISTRIB. Even under optimistic scenarios, we conclude that only a small fraction of the suitable habitats of oaks predicted by DISTRIB is likely to be occupied within 100 years, and this will be concentrated in the first 10-20 km from the current boundary. We also show how DISTRIB and SHIFT can be used to evaluate the potential for assisted migration of vulnerable tree species, and discuss the dynamics of colonization at range limits.

Central Hardwoods ecosystem vulnerability assessment and synthesis: a report from the Central Hardwoods Climate Change Response Framework project

The forests in the Central Hardwoods Region will be affected directly and indirectly by a changing climate over the next 100 years. This assessment evaluates the vulnerability of terrestrial ecosystems in the Central Hardwoods Region of Illinois, Indiana, and Missouri to a range of future climates. Information on current forest conditions, observed climate trends, projected climate changes, and impacts to forest ecosystems was considered in order to assess vulnerability to climate change. Mesic upland forests were determined to be the most vulnerable to projected changes in climate, whereas many systems adapted to fire and drought, such as open woodlands, savannas, and glades, were perceived as less vulnerable. Projected changes in climate and the associated ecosystem impacts and vulnerabilities will have important implications for economically valuable timber species, forest-dependent wildlife and plants, recreation, and long-range planning.

Multi-model comparison on the effects of climate change on tree species in the eastern U.S.: results from an enhanced niche model and process-based ecosystem and landscape models

ContextSpecies distribution models (SDM) establish statistical relationships between the current distribution of species and key attributes whereas process-based models simulate ecosystem and tree species dynamics based on representations of physical and biological processes. TreeAtlas, which uses DISTRIB SDM, and Linkages and LANDIS PRO, process-based ecosystem and landscape models, respectively, were used concurrently on four regional climate change assessments in the eastern Unites States.ObjectivesWe compared predictions for 30 species from TreeAtlas, Linkages, and LANDIS PRO, using two climate change scenarios on four regions, to derive a more robust assessment of species change in response to climate change.MethodsWe calculated the ratio of future importance or biomass to current for each species, then compared agreement among models by species, region, and climate scenario using change classes, an ordinal agreement score, spearman rank correlations, and model averaged change ratios.ResultsComparisons indicated high agreement for many species, especially northern species modeled to lose habitat. TreeAtlas and Linkages agreed the most but each also agreed with many species outputs from LANDIS PRO, particularly when succession within LANDIS PRO was simulated to 2300. A geographic analysis showed that a simple difference (in latitude degrees) of the weighted mean center of a species distribution versus the geographic center of the region of interest provides an initial estimate for the species’ potential to gain, lose, or remain stable under climate change.ConclusionsThis analysis of multiple models provides a useful approach to compare among disparate models and a more consistent interpretation of the future for use in vulnerability assessments and adaptation planning.

Michigan forest ecosystem vulnerability assessment and synthesis: a report from the Northwoods Climate Change Response Framework project

Forests in northern Michigan will be affected directly and indirectly by a changing climate during the next 100 years. This assessment evaluates the vulnerability of forest ecosystems in Michigans eastern Upper Peninsula and northern Lower Peninsula to a range of future climates. Information on current forest conditions, observed climate trends, projected climate changes, and impacts to forest ecosystems was considered in order to draw conclusions on climate change vulnerability. Upland spruce-fir forests were determined to be the most vulnerable, whereas oak associations and barrens were determined to be less vulnerable to projected changes in climate. Projected changes in climate and the associated ecosystem impacts and vulnerabilities will have important implications for economically valuable timber species, forest-dependent wildlife and plants, recreation, and long-range planning.

Development of risk matrices for evaluating climatic change responses of forested habitats

We present an approach to assess and compare risk from climate change among multiple species through a risk matrix, in which managers can quickly prioritize for species that need to have strategies developed, evaluated further, or watched. We base the matrix upon earlier work towards the National Climate Assessment for potential damage to infrastructures from climate change. Risk is defined here as the product of the likelihood of an event occurring and the consequences or impact of that event. In the context of species habitats, the likelihood component is related to the potential changes in suitable habitat modeled at various times during this century. Consequences are related to the adaptability of the species to cope with the changes, especially the increasing intensity and/or frequency of disturbance events that are projected. We derived consequence scores from nine biological and 12 disturbance characteristics that were pulled from literature for each species. All data were generated from an atlas of climate change for 134 trees of the eastern United States (www.nrs.fs.fed.us/atlas). We show examples which depict a wide range of risk for tree species of northern Wisconsin, including species that may gain substantial habitat as well as lose substantial habitat, both of which will require the development of strategies to help the ecosystems adapt to such changes.

Climate Change Impacts on Terrestrial Ecosystems in Metropolitan Chicago and Its Surrounding, Multi-State Region

ABSTRACT This paper describes the potential impacts of warming temperatures and changing precipitation on plants, wildlife, invasive species, pests, and agricultural ecosystems across the multi-state region centered on Chicago, Illinois. We examine a geographic area that captures much of Lake Michigan, including a complex mosaic of urbanization and agriculture surrounding southern Lake Michigan. We consider species currently present within this broad region as well as species that are expected to move into or out of the area as climate zones shift northward through the coming century. Our analysis draws upon disparate data sources to compile projections. We conclude that a complex mixture of land use poses particular challenges to natural ecosystems in this region under climate change. Dispersal is likely to be limited for some species, and some populations of native taxa may already be reduced due to habitat loss. Other species can persist, even thrive, within a mixed landscape mosaic, provided natural areas and green spaces are available. If such spaces are somehow connected, they can provide opportunities for native species to inhabit and move through the metropolitan region (perhaps even better than the landscapes previously dominated by agriculture). Strategies for adapting regional agriculture and minimizing pest outbreaks also call for creative management intervention. With additional research, Chicago and its surrounding environs have an opportunity to provide leadership on effective management of natural resources under climate change.