Papers by Louis R Iverson
Forest Science, 2015
We present an aerial mapping method to efficiently and effectively identify seed clusters of the ... more We present an aerial mapping method to efficiently and effectively identify seed clusters of the invasive tree, Ailanthus altissima (Mill.) Swingle across deciduous forest landscapes in the eastern United States. We found that the ideal time to conduct aerial digital surveys is early to middle winter, when Ailanthus seed clusters persist and there is no interfering leaf cover. Because of the color, quantity, and seedpod arrangement, female seed-bearing Ailanthus trees are very conspicuous from the air. With use of digital sketchmapping technology from helicopters, seed-bearing Ailanthus trees were mapped at a rate of 2,000-4,000 acres/hour (809-1,618 ha/hour). We estimated mapping costs at approximately $0.40/acre ($1.00/ha). We were able to relocate, within 100-200 ft, 88-95% of the aerially mapped seed-bearing Ailanthus trees using handheld consumer-grade global positioning systems (GPS) units. This provided enough accuracy to locate seed-bearing Ailanthus for single-stem injection herbicide treatments. To apply these methods to map seed-bearing Ailanthus, land management agencies that already use digital mapping technology (equipment and software) for surveys of insect and disease outbreaks will have minimal costs beyond helicopter time.
Journal of Forestry, 2014
There is an ever-growing body of literature on forest management strategies for climate change ad... more There is an ever-growing body of literature on forest management strategies for climate change adaptation; however, few frameworks have been presented for integrating these strategies with the real-world challenges of forest management. We have developed a structured approach for translating broad adaptation concepts into specific management actions and silvicultural practices for forest adaptation, as well as an associated set of resources to assist managers in using this approach. A variety of public, private, nongovernmental, and tribal natural resource managers are using this approach to develop projects that implement a diversity of adaptation actions while also meeting manager-identified goals. We describe how managers can integrate climate change information into management planning and activities and provide examples of real-world forest management projects that identify actions to help forests adapt to changing conditions.
This paper describes the potential impacts of warming temperatures and changing precipitation on ... more 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.
The emerald ash borer (EAB, Agrilus planipennis) is decimating native ashes (Fraxinus sp.) throug... more The emerald ash borer (EAB, Agrilus planipennis) is decimating native ashes (Fraxinus sp.) throughout midwestern North America, killing millions of trees over the years. With plenty of ash available throughout the continent, the spread of this destructive insect is likely to continue. We estimate that the insect has been moving along a ''front'' at about 20 km/year since about 1998, but more alarming is its long-range dispersal into new locations facilitated by human activities. We describe a spatially explicit cell-based model used to calculate risk of spread in Ohio, by combining the insect's flight and short-range dispersal (''insect flight'') with human-facilitated, long-range dispersal (''insect ride''). This hybrid model requires estimates of EAB abundance, ash abundance, major roads and traffic density, campground size and usage, distance from the core infested zone, wood products industry size and type of wood usage, and human population density. With the ''insect flight'' model, probability of movement is dependent on EAB abundance in the source cells, the quantity of ash in the target cells, and the distances between them. With the ''insect-ride'' model, we modify the value related to ash abundance based on factors related to potential human-assisted movements of EAB-infested ash wood or just Electronic supplementary material The online version of this article (
Climatic Change, 2019
Forests provide myriad ecosystem services, many of which are vital to local and regional economie... more Forests provide myriad ecosystem services, many of which are vital to local and regional economies. Consequently, there is a need to better understand how predicted changes in climate will impact forest dynamics and the implications of such changes for society as a whole. Here we focus on the impacts of climate change on Indiana forests, which are representative of many secondary growth broadleaved forests in the greater Midwest region in terms of their land use history and current composition. We found that predicted changes in climate for the state-warmer and wetter winters/springs and hotter and potentially drier summers-will dramatically shape forest communities, resulting in new assemblages of trees and wildlife that differ from forest communities of the past or present. Overall, suitable habitat is expected to decline for 17-29% of tree species and increase for 43-52% of tree species in the state, depending on the region and climate scenario. Such changes have important consequences for wildlife that depend on certain tree species or have ranges with strong sensitivities to climate. Additionally, these changes will have potential economic impacts on Indiana industries that depend on forest resources and products (both timber and non-timber).
Ecosphere, 2017
By tracking oak-hickory (Quercus-Carya) regeneration for 13 yr across management-manipulated ligh... more By tracking oak-hickory (Quercus-Carya) regeneration for 13 yr across management-manipulated light and topographically driven moisture gradients after partial harvest and three prescribed fires, we document best-case conditions to promote advanced oak regeneration, and thereby provide a promising management tool to reverse the downward spiral in oak that plagues much of the Central Hardwoods within the eastern United States. This study was established in 2000 to assess regeneration following prescribed fire (spring of 2001, 2005, and 2010) in combination with partial harvest (late 2000) across two sites in southern Ohio. Each of the four 20+ ha treatment units (two partial harvest and burn, two controls) were modeled and mapped for long-term moisture regime using the Integrated Moisture Index (IMI) , and a 50-m grid of sampling points established throughout the units. Vegetation and light were sampled at each gridpoint before and after treatments,
Landscape Ecol, 2004
colonization of newly available tree-species habitat under climate change: an analysis for five e... more colonization of newly available tree-species habitat under climate change: an analysis for five eastern US species
Forest Science, 2015
We present an aerial mapping method to efficiently and effectively identify seed clusters of the ... more We present an aerial mapping method to efficiently and effectively identify seed clusters of the invasive tree, Ailanthus altissima (Mill.) Swingle across deciduous forest landscapes in the eastern United States. We found that the ideal time to conduct aerial digital surveys is early to middle winter, when Ailanthus seed clusters persist and there is no interfering leaf cover. Because of the color, quantity, and seedpod arrangement, female seed-bearing Ailanthus trees are very conspicuous from the air. With use of digital sketchmapping technology from helicopters, seed-bearing Ailanthus trees were mapped at a rate of 2,000-4,000 acres/hour (809-1,618 ha/hour). We estimated mapping costs at approximately $0.40/acre ($1.00/ha). We were able to relocate, within 100-200 ft, 88-95% of the aerially mapped seed-bearing Ailanthus trees using handheld consumer-grade global positioning systems (GPS) units. This provided enough accuracy to locate seed-bearing Ailanthus for single-stem injection herbicide treatments. To apply these methods to map seed-bearing Ailanthus, land management agencies that already use digital mapping technology (equipment and software) for surveys of insect and disease outbreaks will have minimal costs beyond helicopter time.
Journal of Forestry, 2014
There is an ever-growing body of literature on forest management strategies for climate change ad... more There is an ever-growing body of literature on forest management strategies for climate change adaptation; however, few frameworks have been presented for integrating these strategies with the real-world challenges of forest management. We have developed a structured approach for translating broad adaptation concepts into specific management actions and silvicultural practices for forest adaptation, as well as an associated set of resources to assist managers in using this approach. A variety of public, private, nongovernmental, and tribal natural resource managers are using this approach to develop projects that implement a diversity of adaptation actions while also meeting manager-identified goals. We describe how managers can integrate climate change information into management planning and activities and provide examples of real-world forest management projects that identify actions to help forests adapt to changing conditions.
Landscape Ecology, 2009
The emerald ash borer (EAB, Agrilus planipennis) is decimating native ashes (Fraxinus sp.) throug... more The emerald ash borer (EAB, Agrilus planipennis) is decimating native ashes (Fraxinus sp.) throughout midwestern North America, killing millions of trees over the years. With plenty of ash available throughout the continent, the spread of this destructive insect is likely to continue. We estimate that the insect has been moving along a ''front'' at about 20 km/year since about 1998, but more alarming is its long-range dispersal into new locations facilitated by human activities. We describe a spatially explicit cell-based model used to calculate risk of spread in Ohio, by combining the insect's flight and short-range dispersal (''insect flight'') with human-facilitated, long-range dispersal (''insect ride''). This hybrid model requires estimates of EAB abundance, ash abundance, major roads and traffic density, campground size and usage, distance from the core infested zone, wood products industry size and type of wood usage, and human population density. With the ''insect flight'' model, probability of movement is dependent on EAB abundance in the source cells, the quantity of ash in the target cells, and the distances between them. With the ''insect-ride'' model, we modify the value related to ash abundance based on factors related to potential human-assisted movements of EAB-infested ash wood or just Electronic supplementary material The online version of this article (
The concept of ecosystem services from landscapes is rapidly gaining momentum as a lan-guage to c... more The concept of ecosystem services from landscapes is rapidly gaining momentum as a lan-guage to communicate values and benefits to scientists and lay alike. Landscape ecology has an enormous contribution to make to this field, and one could argue, uniquely so. Tools developed or adapted for landscape ecology are being increasingly used to assist with the quantification, modelling, mapping, and valuing of ecosystem services. Several of these tools and meth-ods encased therein are described among the eleven papers presented in this special issue, and their application has the potential to facilitate the manage-ment and promotion of services within ecosystems. Papers are associated with each of the four key categories of services that ecosystems provide to
We evaluated 134 tree species from the eastern United States for potential response to several sc... more We evaluated 134 tree species from the eastern United States for potential response to several scenarios of climate change, and summarized those responses for nine northeastern United States. We modeled and mapped each species individually and show current and potential future distributions for two emission scenarios (A1fi [higher emission] and B1 [lower emission]) and three climate models: the Parallel Climate, the Hadley CM3, and the Geophysical Fluid Dynamics Laboratory model. Climate change could have large impacts on suitable habitat for tree species in this region, especially under a high emissions trajectory. Results indicate that while species with potentially increasing areas of suitable habitat in the Northeastern US substantially outnumber those with decreasing areas of habitat, there are key species that show diminishing habitat area: balsam fir (Abies balsamea), paper birch (Betula papyrifera), red spruce (Picea rubens), bigtooth and quaking aspen (Populus grandidentata...
We present an approach to modeling potential cli-mate-driven changes in habitat for tree and bird... more We present an approach to modeling potential cli-mate-driven changes in habitat for tree and bird species in the eastern United States. First, we took an empirical-statistical modeling approach, using randomForest, with species abundance data from national inventories combined with soil, climate, and landscape variables, to build abundance-based habitat models for 134 tree and 147 bird species. We produced lists of species for which suitable habitat tends to increase, decrease, or stay the same for any region. Independent assessments of trends of large trees versus seedlings across the eastern U.S. show that 37 of 40 species in common under both studies are currently trending as modeled. We developed a framework, ModFacs, in which we used the literature to assign default modification factor scores for species characteristics that cannot be readily assessed in such models, including 12 disturbance factors (for example, drought, fire, insect pests), nine biological factors (for exampl...
Among the three of us, we have attended every annual
Kerr, we emphasize that our model is a generalized vulnerability model, built from easily acquire... more Kerr, we emphasize that our model is a generalized vulnerability model, built from easily acquired data from anywhere in the world, to identify areas with probable susceptibility to large tsunamis—and dis-cuss their other criticisms in detail. We also show that a rejection of the role of trees in helping protect vulnerable areas is not justified in light of existing evidence.
The nearly unprecedented loss of life resulting from the earthquake and tsunami of December 26,20... more The nearly unprecedented loss of life resulting from the earthquake and tsunami of December 26,2004, was greatest in the province of Aceh, Sumatra (Indonesia). We evaluated tsunami damage and built empirical vulnerability models of damage1110 damage based on elevation, distance from shore, vegetation, and exposure. We found that highly predictive models are possible and that developed areas were far more likely to be dam-aged than forested zones. Modeling exercises such as this one, conducted in other vulnerable zones across the planet, would enable managers to create better warning and protection defenses, e.g., tree belts, against these destructive forces.
To continue the reflections on the 30 year anniversary of the Allerton Park Workshop as initiated... more To continue the reflections on the 30 year anniversary of the Allerton Park Workshop as initiated by Wu (2013), we present some reflections of the situation just before and developments after the workshop from two participants—one who was a chief organizer and synthesizer of the workshop as well as lead author of the subsequent document (and this piece), and one who was a brand new entrant into the newly formulated and wonderfully fascinating field of land-scape ecology at the time of the workshop. Before the workshop The convergence of several historical trends, theoretical advancements, and technological improvements led to the Landscape Ecology Workshop in 1983. Landscape geography in Europe was well established, with the
of 670 beetles were recaptured through the study, an overall recapture rate of 3.6 percent. One b... more of 670 beetles were recaptured through the study, an overall recapture rate of 3.6 percent. One beetle was recaptured at the furthest trap, 305 meters from the release point. This beetle was collected less than two weeks after its release. Male and female recapture patterns are similar. Also resident feral beetles were captured in patterns similar to marked released beetles. We also analyzed feral beetle capture rates by trap height for all three trap types. A Chi-square analysis showed that, for panel traps and purple prism traps on ash, signifi cantly more beetles were caught on high traps (P = 0.001). Chi-square analysis of puple prism trap height on nonash trees showed no signifi cant difference between beetles caught on high and low traps.
Prescribed surface fires are being investigated, in conjunction with thinning, as silvicultural t... more Prescribed surface fires are being investigated, in conjunction with thinning, as silvicultural tools for assisting in the regeneration of mixed oak forests in the Central Hardwoods Region. Fires were conducted on 2001 March 28 and 2001 April 4-5, respectively, at the Tar Hollow (TAR) and Zaleski (ZAL) State Forests, and at the Raccoon Ecological Management Area (REMA) in southern Ohio. The three sites had been previously surveyed into a 50-m grid. A total of over 400 grid points was established across the three areas.
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Papers by Louis R Iverson