Theodore Weber

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Theodore C. Weber is a Climate Adaptation Analyst for Defenders of Wildlife. He engages in public land and natural resources management and other relevant planning processes to ensure that federal departments and agencies address climate change impacts and adaptation for wildlife. He has worked as an ecologist for over 20 years, primarily in forest, wetland, wildlife, landscape, and systems ecology, as well as ecosystem valuation. He holds a M.S. in Environmental Science, a Graduate Certificate in Wetlands, and a B.S. in Physics from the University of Florida. He is a Certified Ecologist by the Ecological Society of America and a certified forest professional by the state of Maryland, and a member of the Ecological Society of America, American Society of Adaptation Professionals, The Wildlife Society, and the Society for Conservation Biology.
Phone: 1-800-385-9712
Address: 1130 17th Street NW
Washington, DC 20036

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Papers by Theodore Weber

Landscape Ecological Assessment of the Chesapeake Bay Watershed

Environmental Monitoring and Assessment, Jun 1, 2004

The Chesapeake Bay Watershed, located in the Mid-Atlantic Region of the United States, is experie... more The Chesapeake Bay Watershed, located in the Mid-Atlantic Region of the United States, is experiencing rapid habitat loss and fragmentation from sprawling low-density development. The bay itself is heavily stressed by excess sediment and nutrient runoff. Three states, the District of Columbia, and the federal government signed an agreement in 2000 to address these problems. The commitments included an assessment of the watershed's resource lands, and targeting the most valued lands for protection. As part of this task, the Resource Lands Assessment identified an ecological network comprised of large contiguous blocks (hubs) of forests, wetlands, and streams, interconnected by corridors to allow animal and plant propagule dispersal and migration. Hubs were prioritized by ecoregion, by analyzing a variety of ecological parameters, including: rare species presence, rarity and population viability; vegetation and vertebrate richness; habitat area, condition, and diversity; intactness and remoteness; connectivity potential; and the nature of the surrounding landscape. I found that much of the watershed was still fairly intact, although this varied dramatically by ecoregion. Current protection also varied, and an assessment of vulnerability will help focus protection efforts among the most valuable hubs and corridors.

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Survey of Habitat and Otter Population Status

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Green Infrastructure Hubs and Corridors

These data map hub and corridor elements within the green infrastructure. The Green Infrastructur... more These data map hub and corridor elements within the green infrastructure. The Green Infrastructure Assessment was developed to provide decision support for Maryland's Department of Natural Resources land conservation programs. Methods used to identify and rank green infrastructure lands are intended soley for this use. Other applications are at the discretion of the user. The Maryland Department of Natural Resources is not responsible for any inaccuracies in the data and does not necessarily endorse any uses or products derived from the data other than those for which the data were originally intended. Maryland's green infrastructure is a network of undeveloped lands that provide the bulk of the state's natural support system. Ecosystem services, such as cleaning the air, filtering water, storing and cycling nutrients, conserving soils, regulating climate, and maintaining hydrologic function, are all provided by the existing expanses of forests, wetlands, and other natural lands. These ecologically valuable lands also provide marketable goods and services, like forest products, fish and wildlife, and recreation. The Green Infrastructure serves as vital habitat for wild species and contributes in many ways to the health and quality of life for Maryland residents. To identify and prioritize Maryland's green infrastructure, we developed a tool called the Green Infrastructure Assessment (GIA). The GIA was based on principles of landscape ecology and conservation biology, and provides a consistent approach to evaluating land conservation and restoration efforts in Maryland. It specifically attempts to recognize: a variety of natural resource values (as opposed to a single species of wildlife, for example), how a given place fits into a larger system, the ecological importance of natural open space in rural and developed areas, the importance of coordinating local, state and even interstate planning, and the need for a regional or landscape-level view for wildlife conservation. The GIA identified two types of important resource lands - "hubs" and "corridors." Hubs typically large contiguous areas, separated by major roads and/or human land uses, that contain one or more of the following: Large blocks of contiguous interior forest (containing at least 250 acres, plus a transition zone of 300 feet) Large wetland complexes, with at least 250 acres of unmodified wetlands; Important animal and plant habitats of at least 100 acres, including rare, threatened, and endangered species locations, unique ecological communities, and migratory bird habitats; relatively pristine stream and river segments (which, when considered with adjacent forests and wetlands, are at least 100 acres) that support trout, mussels, and other sensitive aquatic organisms; and existing protected natural resource lands which contain one or more of the above (for example, state parks and forests, National Wildlife Refuges, locally owned reservoir properties, major stream valley parks, and Nature Conservancy preserves). In the GIA model, the above features were identified from Geographic Information Systems (GIS) spatial data that covered the entire state. Developed areas and major roads were excluded, areas less than 100 contiguous acres were dropped, adjacent forest and wetland were added to the remaining hubs, and the edges were smoothed. The average size of all hubs in the state is approximately 2200 acres. Corridors are linear features connecting hubs together to help animals and plant propagules to move between hubs. Corridors were identified using many sets of data, including land cover, roads, streams, slope, flood plains, aquatic resource data, and fish blockages. Generally speaking, corridors connect hubs of similar type (hubs containing forests are connected to one another; while those consisting primarily of wetlands are connected to others containing wetlands). Corridors generally follow the best ecological or "most natural" routes between hubs. Typically these are streams with wide riparian buffers and healthy fish communities. Other good wildlife corridors include ridge lines or forested valleys. Developed areas, major roads, and other unsuitable features were avoided. Please to the Green Infrastructure web site (http://www.dnr.state.md.us/greenways/gi/gi.html) for additional information.

Reliability and maintainability in space systems design

Maryland's Strategic Forest Lands Assessment

… , DC, November 16 …, 2001

Advancing the national fish, wildlife, and plants climate adaptation strategy into a new decade

Survey of Habitat and Otter Population Status

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Land Conservation, Restoration, and Management For Water Quality Benefits in Cecil County, Maryland Technical Report for the Cecil County Green Infrastructure Plan December 2007

Streams in Cecil County, Maryland provide the majority of the county's drinking water, drain ... more Streams in Cecil County, Maryland provide the majority of the county's drinking water, drain into the nationally significant Chesapeake Bay, and support fish and other aquatic life. Yet many of the county's streams are impaired. The Conservation Fund examined biological and chemical stream data collected statewide and countywide, and compared these to watershed and site conditions to search for possible relationships. These analyses were consistent with previous studies that indicated that forest cover and impervious surfaces had a significant impact on water quality. As indicated by the benthic macroinvertebrate community, nitrate levels, and phosphorus levels, water quality in Cecil County was generally highest in watersheds with 50% forest and wetland cover. We used these thresholds to develop goals and models for land conservation and restoration for water quality benefits. To meet water quality goals, Cecil County should minimize conversion of forest to development, lim...

Development and application of a statewide conservation network in Delaware, U.S.A

The Delaware Ecological Network (DEN) is a statewide conservation network developed from GIS and ... more The Delaware Ecological Network (DEN) is a statewide conservation network developed from GIS and field-collected data. The DEN, based on principles of landscape ecology and conservation biology, provides a consistent framework to help identify and prioritize areas for natural resource protection. The DEN is composed of the following elements: core areas, which contain relatively intact natural ecosystems, and provide high-quality habitat for native plants and animals; hubs, which are slightly fragmented aggregations of core areas, plus contiguous natural cover; and corridors, which link core areas together, allowing wildlife movement and seed and pollen transfer between them. Core areas were validated using independent field data, and verified using aerial photos. Core areas and hubs were ranked by ecoregion according to their ecological importance, critical linkages were identified, and a top-priority network was identified within the overall network. Next, relative protection of c...

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Maximum entropy habitat modeling of four endangered mussels in the Ohio River basin, USA

Freshwater mussels are the most imperiled taxa in North America. This study examined the utility ... more Freshwater mussels are the most imperiled taxa in North America. This study examined the utility of maximum entropy (Maxent) modeling and spatial application to identify potential habitat for four endangered mussels in the Ohio River basin in the USA: Pleurobema clava, Cyprogenia stegaria, Epioblasma torulosa rangiana, and Plethobasus cyphyus. We compared occurrence data for each of these four mussel species to flow, geomorphic, buffer, and impairment data by stream segment, as well as land cover, permeability, and impairments within their cumulative catchment. Maxent models predicted between 0.2 and 1.3% of the basins to contain suitable habitat. Further, most suitable stream segments identified by the model and also containing endangered mussels were >10 km. Within stream segments, microhabitat features like substrate and bank stability may be important factors. However, catchment-scale geomorphic and land use conditions also influence the distribution of aquatic species. Coars...

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Maximum entropy modeling of mature hardwood forest distribution in four U.S. states

Forest Ecology and Management, 2011

In the eastern United States, mature hardwood forest provides habitat for many species of native ... more In the eastern United States, mature hardwood forest provides habitat for many species of native flora and fauna, but is much less common now than historically. This study examined the utility of maximum entropy modeling and spatial application to identify ecosystem types like mature hardwood forest. I performed pilot modeling in Charles County, Maryland, where I compared fine-scale geographic data available locally to coarse-scale data available nationally. As expected, a model constructed with the best locally available data, including LiDAR-derived canopy height and fine-scale soil maps, outperformed a model constructed with nationally consistent data. However, the model using national data nevertheless accurately identified most mature hardwood forest sites and excluded most young forest. I then applied the coarse-scale approach to four states: Pennsylvania, Ohio, Kentucky, and Tennessee. Average test AUC (area under the receiver operating curve) based on 10 replicates varied from 0.76 to 0.80 when comparing mature hardwood forest locations to general forest locations. The maximum training or test sensitivity plus specificity threshold, depending on the state, captured 78-79% of positive locations while rejecting 74-81% of negative locations. The maximum entropy approach is versatile, and can be applied to other ecosystems and species.

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Use of LiDAR and supplemental data to estimate forest maturity in Charles County, MD, USA

Forest Ecology and Management, 2009

This study evaluated the utility of remotely sensed data to estimate forest maturity within Charl... more This study evaluated the utility of remotely sensed data to estimate forest maturity within Charles County, MD. We calculated tree canopy height using airborne scanning LiDAR (light detection and ranging) data over the entire county, and compared this to crown top height, stand age, and other data collected from randomly selected plots on the ground. Canopy height was a strong predictor of forest age, and we improved predictive power by including other variables such as land cover, slope, stream proximity, wetlands, and floodplains. These comparisons allowed us to construct a spatial model classifying forest in the study area into three age categories: 30 years old, 30-70 years old, and >70 years old, corresponding to young, intermediate, and mature. This spatial model was used to help characterize ecosystem condition and wildlife habitat, and help prioritize conservation decisions in the study area.

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Field Validation of a Conservation Network on the Eastern Shore of Maryland, USA, Using Breeding Birds as Bio-Indicators

Environmental Management, 2008

Maryland's Green Infrastructure (GI) is a network of large, intact natural areas (hubs), intercon... more Maryland's Green Infrastructure (GI) is a network of large, intact natural areas (hubs), interconnected by linear swaths of riparian or upland vegetation (corridors). The GI serves significant ecological functions and provides the bulk of the state's natural support system. This study examined whether the GI as mapped does, in fact, identify Maryland's most ecologically valuable forested lands, using forest interior dwelling birds (hereafter called ''forest birds'') as bio-indicators. We conducted bird point counts within forest both inside and outside of hubs on Maryland's Eastern Shore. We also collected a wide variety of habitat data. We found that both the condition of a forest and its surrounding landscape influenced the bird communities. On average, forest bird richness was significantly higher within hubs; furthermore, almost all sites with at least five forest bird species present were in hubs. Forest bird richness and abundance were highest in undisturbed, mature broadleaf forest with wetlands and streams nearby. We detected a significant relationship between forest bird richness and the ecological score of a finer-scale landscape assessment, focused on ''cells'' of about 0.1 ha in size. This field study also validated the Rapid Field Assessment (RFA) protocol developed in 2001 to assess, on the ground, the relative condition of individual sites or properties within the GI. Forest bird richness and abundance were positively correlated with the RFA community scores. Our results underscore the importance of maintaining regional biological diversity by retaining large blocks of forest, especially mature forest containing streams and wetlands.

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Statewide modeling of bobcat, Lynx rufus, habitat in Illinois, USA

Biological Conservation, 2002

... development following human settlement. Bobcats in Illinois and elsewhere in the Midwest did ... more

Ecosystem services in Cecil County's green infrastructure

The Conservation Fund, Annapolis, MD, 2007

This document examines a suite of 16 ecosystem services provided by forests and wetlands in Cecil... more

Maryland's Green Infrastructure Assessment: A Comprehensive Strategy for Land Conservation and Restoration

Restoration Targeting in Maryland's Green Infrastructure

Maryland Dept. Nat. Res., …, 2004

2. Desktop Assessment of Green Infrastructure Gaps 5 a. Identification of Green I... more

Maryland's Green Infrastructure—Using Landscape Assessment Tools to Identify a Regional Conservation Strategy

Environmental Monitoring and Assessment, 2000

Maryland is growing at a very rapid pace. Compounding the problems associated with rapid growth i... more Maryland is growing at a very rapid pace. Compounding the problems associated with rapid growth is the scattered pattern of development that consumes an excessive amount of land and fragments the landscape. As land use changes, wildlife habitat and migration corridors are lost and normal ecosystem functions are disturbed or destroyed. While land use planners and developers are attempting to

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CECIL COUNTY, MARYLAND Green Infrastructure Plan

The Conservation Fund forges partnerships to conserve America's legacy of land and water reso... more The Conservation Fund forges partnerships to conserve America's legacy of land and water resources. Through land acquisition, sustainable programs, and leadership training, the Fund and its partners demonstrate balanced conservation solutions that emphasize the integration of economic and environmental goals. Since 1985 The Conservation Fund and its partners have permanently protected more than 5.5 million acres of important wildlife habitat, working landscapes and recreation areas.

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Green Infrastructure Design and Benefit-Cost Optimization in Transportation Planning: Maximizing Conservation and Restoration Opportunities in Four Southern Maryland Watersheds

Theodore Weber

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