Timothy Assal

Timothy Assal
Kent State University | KSU · Department of Geography

PhD; Colorado State University

About

41
Publications
10,949
Reads
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572
Citations
Citations since 2017
23 Research Items
541 Citations
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Introduction
I’m a spatial ecologist interested in the impacts of disturbance (e.g. mountain pine beetle, drought and fire) on forest and shrubland ecosystems. I combine field studies, satellite sensors, and computer modeling to identify when, where and why change took place. My goal is to provide sound science to both resource managers and policy makers to help shape ecosystem management and conservation as we move into an uncertain future.
Additional affiliations
August 2019 - present
Kent State University
Position
  • Professor (Assistant)
April 2016 - July 2019
United States Geological Survey
Position
  • Research Ecologist
July 2007 - March 2016
United States Geological Survey
Position
  • Ecologist
Education
August 2010 - September 2015
Colorado State University
Field of study
  • Ecology

Publications

Publications (41)
Technical Report
Full-text available
The purpose of the Pre-assessment Report for the Southern Great Plains Rapid Ecoregional Assessment (REA) is to document the selection process for and final list of Conservation Elements, Change Agents, and Management Questions developed during Phase I. The overall goal of the REAs being conducted for the Bureau of Land Management (BLM) is to provi...
Article
Full-text available
Drought has long been recognized as a driving mechanism in the forests of western North America and drought-induced mortality has been documented across genera in recent years. Given the frequency of these events are expected to increase in the future, understanding patterns of mortality and plant response to severe drought is important to resource...
Article
Full-text available
Aim The aim of the study was to investigate postfire regeneration patterns of Araucaria‐Nothofagus forests on the west slope of the Andes; to evaluate the relationship between remotely sensed burn severity and forest mortality; and to assess controls of burn severity on forest response at local spatio‐temporal scales. Location Araucanía region in...
Article
Full-text available
Riparian ecosystems provide critical habitat for many species, yet assessment of vegetation condition at local scales is difficult to measure when considering large areas over long time periods. We present a framework to map and monitor two deciduous cover types, upland and riparian, occupying a small fraction of an expansive, mountainous landscape...
Article
Full-text available
For nearly 40 years, the Conservation Reserve Program (CRP) has implemented practices to reduce soil erosion, improve water quality, and provide habitat for wildlife and pollinators on highly erodible cropland in the United States. However, an approximately 40,470 ha (10 million acres) decline in enrolled CRP land over the last decade has greatly r...
Preprint
Full-text available
Aim: Understanding drivers of insect population declines is essential for the development of successful conservation plans, but data limitations restrict assessment across spatial and temporal scales. Museum records represent a unique source of historical data that can be leveraged to investigate temporal trends in insect communities. Native lady b...
Preprint
Full-text available
Aim Understanding drivers of insect population declines is essential for the development of successful conservation plans, but data limitations restrict assessment across spatial and temporal scales. Museum records represent a unique source of historical data that can be leveraged to investigate temporal trends in insect communities. Native lady be...
Conference Paper
The Conservation Reserve Program (CRP), administered by the U.S. Department of Agriculture, has allocated funds to private landowners in exchange for implementation of conservation practices since 1985. Initially, the CRP targeted marginal cropland for soil conservation, however, it has since been recognized for provision of additional benefits suc...
Conference Paper
Background/Questions/Methods Riparian ecosystems provide critical habitat for many species, yet assessment of vegetation condition at local scales is difficult to measure when considering large areas over long time periods. Nevertheless, local monitoring is critical for natural resource managers to establish baseline conditions by which future cha...
Article
Full-text available
The U.S. Department of Agriculture’s Conservation Reserve Program (CRP) is one of the largest private lands conservation programs in the United States, establishing perennial vegetation on environmentally sensitive lands formerly in agricultural production. Over its 35 year existence, the CRP has evolved to include diverse conservation practices (C...
Conference Paper
The Sundarbans mangrove forest, one of the world’s largest of its kind situated at the southwest of Bangladesh (approximately 60%), plays a vital role in safeguarding the country from the wrath of tropical cyclones and other disaster events. It is known to act as a buffer to protect cyclonic wind's initial threat during any tropical cyclone towards...
Article
Full-text available
Context Given widespread population declines of birds breeding in North American grasslands, management that sustains wildlife while supporting rancher livelihoods is needed. However, management effects vary across landscapes, and identifying areas with the greatest potential bird response to conservation is a pressing research need. Objectives We...
Article
Full-text available
Changing disturbance regimes and climate can overcome forest ecosystem resilience. Following high-severity fire, forest recovery may be compromised by lack of tree seed sources, warmer and drier postfire climate, or short-interval reburning. A potential outcome of the loss of resilience is the conversion of the prefire forest to a different forest...
Article
Full-text available
As domestic energy development activity continues in the western United States, wildlife conservation planning in affected regions is increasingly important. The geologic basins where oil and gas energy exploration is occurring are primarily sagebrush steppe rangelands. Sagebrush steppe habitats may support more than 20 vertebrate species of conser...
Data
This is a portion of the data used in the analysis for the manuscript "Monitoring long-term riparian vegetation trends to inform local habitat management in a mountainous environment" by Assal et al. The manuscript has been published in the journal Ecological Indicators. The data were used in the trend analysis portion of the analysis for this proj...
Chapter
Full-text available
Perhaps no other species of tree jumps to mind as quickly as Quaking aspen (Populus tremuloides Michx.) when one waxes poetically about the iconic vistas of the Rocky Mountain West. Quaking aspen, so called for its trembling leaves, have been the focus of countless paintings and photographs, from Ansel Adams to John Fielder to scores of amateur pho...
Data
This data was used in the analysis for the article “Burn Severity Controls on Post-fire Araucaria-Nothofagus Regeneration in the Andean Cordillera” by T. Assal, M. Gonzalez and J. Sibold. The aim of the study was to investigate post-fire regeneration patterns of forests on the west slope of the Andes; to evaluate the relationship between remotely s...
Data
This data collection is associated with the project: “Status and Trends of Deciduous Communities in the Bighorn Mountains”. It contains the project study area, model evaluation data, model input data, and model output data in the form of probability of occurrence rasters for deciduous and coniferous species, as well as a synthesis map. The aim of t...
Data
The standardized precipitation evapotranspiration index (SPEI) was summarized for the Upper Green River Basin to quantify climate variability over the last century. The SPEI incorporates both precipitation and temperature data, therefore the index has the capacity to include the effects of temperature variability on drought. The SPEI considers the...
Conference Paper
Full-text available
Background/Question/Methods Fire is a primary disturbance agent in the Andean cordillera, and strongly influences the Araucaria-Nothofagus forests on the landscape. In Tolhuaca National Park, forests have been shaped by a mixed-severity fire regime over the last several centuries. Changes in land-use practices have influenced the fire regime during...
Article
Full-text available
Spruce beetle (Dendroctonus rufipennis) outbreaks are rapidly spreading throughout subalpine forests of the Rocky Mountains, raising concerns that altered fuel structures may increase the ecological severity of wildfires. Although many recent studies have found no conclusive link between beetle outbreaks and increased fire size or canopy mortality,...
Article
Full-text available
Human land use, such as livestock grazing, can have profound yet varied effects on wildlife interacting within common ecosystems, yet our understanding of land-use effects is often generalized from short-term, local studies that may not correspond with trends at broader scales. Here we used public land records to characterize livestock grazing acro...
Conference Paper
Sagebrush (Artemisia spp.) mortality has recently been reported in the Upper Green River Basin (Wyoming, USA) of the sagebrush steppe of western North America. Numerous causes have been suggested, but recent drought (2012-13) is the likely mechanism of mortality in this water-limited ecosystem which provides critical habitat for many species of wil...
Article
Full-text available
Drought is a global issue that is exacerbated by climate change and increasing anthropogen-ic water demands. The recent occurrence of drought in California provides an important opportunity to examine drought response across ecosystem classes (forests, shrublands, grasslands, and wetlands), which is essential to understand how climate influences ec...
Conference Paper
Background/Question/Methods Native bark beetles are capable of causing widespread mortality during outbreak events in the forests of western North America. These disturbances can have vast effects on forest structure and there is concern that such changes could influence subsequent wildfire behavior and its impact on ecosystems. New research has co...
Conference Paper
Full-text available
Drought-induced forest mortality has been documented across genera in recent years in western North America. Understanding patterns of mortality and plant response to severe drought is important to resource managers, given the frequency of these events are expected to increase in the future. Remote sensing studies have documented changes in forest...
Data
This is a portion of the data used in the analysis for the article “Mapping forest functional type in a forest-shrubland ecotone using SPOT imagery and predictive habitat distribution modelling” by T. Assal, P. Anderson, and J. Sibold, Remote Sensing Letters (2015).
Article
Full-text available
The availability of land cover data at local scales is an important component in forest management and monitoring efforts. Regional land cover data seldom provide detailed information needed to support local management needs. Here we present a transferable framework to model forest cover by major plant functional type using aerial photos, multi-dat...
Article
Full-text available
Geospatial data play an increasingly important role in natural resources management, conservation, and science-based projects. The management and effective use of spatial data becomes sig- nificantly more complex when the efforts involve a myriad of landscape-scale projects combined with a multiorganizational col- laboration. There is sparse litera...
Article
Full-text available
Public land management agencies, such as the Bureau of Land Management (BLM), are charged with managing rangelands throughout the western United States for multiple uses, such as livestock grazing and conservation of sensitive species and their habitats. Monitoring of condition and trends of these rangelands, particularly with respect to effects of...
Article
Full-text available
This paper describes a spatiotemporal land use map for a rural county in the western United States. Sublette County, Wyoming has undergone recent land use change in the form of heightened rural residential development on private land and increased energy development on both public and private land. In this study we integrate energy production data,...
Data
Full-text available
The data contained in this report were compiled, modified, and analyzed for the Wyoming Landscape Conservation Initiative (WLCI) Integrated Assessment (IA). The WLCI is a long-term science based effort to assess and enhance aquatic and terrestrial habitats at a landscape scale in southwest Wyoming while facilitating responsible energy development t...
Data
Full-text available
The data contained in this series were compiled, modified, and analyzed for the U.S. Geological Survey (USGS) report " Range-Wide Assessment of Livestock Grazing Across the Sagebrush Biome. " This report can be accessed through the USGS Publications Warehouse (online linkage: http://pubs.usgs.gov/of/2011/1263/). The dataset contains spatial and tab...
Article
Full-text available
Domestic livestock grazing occurs in virtually all sagebrush habitats and is a prominent disturbance factor. By affecting habitat condition and trend, grazing influences the resources required by, and thus, the distribution and abundance of sagebrush-obligate wildlife species (for example, sage-grouse Centrocercus spp.). Yet, the risks that livesto...
Conference Paper
Background/Question/Methods Sagebrush steppe is a highly endangered ecosystem in the western United States, and the majority occurs on public lands. Public land management agencies manage sagebrush communities for multiple uses including livestock grazing. We conducted a survey of the type and quality of existing data regarding rangeland condition...
Article
The locations of black-tailed prairie dog (Cynomys ludovicianus [Ord]) colonies on a 550-km2 study site in northeastern Wyoming, United States, were estimated using 3 remote sensing methods: raw satellite imagery (Landsat 7 ETMþ), enhanced satellite imagery (integration of imagery with thematic layers via a Geographic Information System), and aeria...

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Projects

Projects (8)
Project
The intent of this research is to investigate how changing disturbance and climate conditions (e.g., drought) are affecting lower-elevation aspen forests in the northern Great Basin. To accomplish this, we will use a combination of field sampling, geographic analysis, remote sensing, and statistical modeling. The primary outcomes will be a regional assessment of where and under what conditions lower-elevation aspen are most vulnerable to undesirable ecological change (i.e., potential decline in forest health). Collaborators: Doug Shinneman (Lead PI, US Geological Survey), Susan McIlroy (USGS), Paul Rogers (Utah State University) and Don Major (US Bureau of Land Management).
Project
We are mapping tree mortality from Hurricane Sandy in remnant Atlantic white cedar (Chamaecyparis thyoides) forests that are ecologically important in southern New Jersey. The frequency of ghost forests (standing dead trees killed by exposure to salt water) has increased in recent years and there is evidence that Superstorm Sandy contributed a large wave of mortality. We are interested in quantifying these very recent ghost forests caused by pulses of salt water pushed up tidal rivers during extreme events. We are using remote sensing (dense time series) and field based (dendrochronology, regeneration measurements, etc.) approaches to quantify the extent and severity of mortality from this event.
Project
Develop a framework to map and monitor two deciduous cover types, upland and riparian, occupying a small fraction of an expansive, mountainous landscape in north-central Wyoming. 1. Develop broad-scale predictions of predominant woody vegetation types by integrating Landsat data into species distribution models and combining sub- sequent outputs into a synthesis map. 2. Evaluate a 35-year Landsat time series (1985–2019) to identify significant trends in the condition of upland and riparian deciduous vegetation and assessed the rate and direction of change. 3. Use plot level data to assess the utility of the framework to detect bottom-up controls (ungulate browse pressure and management actions) on vegetation condition.