Digital Commons Network^™

Controls On Interannual Variability In Lightning-Caused Fire Activity In The Western Us, John T. Abatzoglou, Crystal A. Kolden, Jennifer K. Balch, Bethany A. Bradley

Environmental Conservation Faculty Publication Series

Lightning-caused wildfires account for a majority of burned area across the western United States (US), yet lightning remains among the more unpredictable spatiotemporal aspects of the fire environment and a challenge for both modeling and managing fire activity. A data synthesis of cloudto-ground lightning strikes, climate and fire data across the western US from 1992 to 2013 was conducted to better understand geographic variability in lightning-caused wildfire and the factors that influence interannual variability in lightning-caused wildfire at regional scales. Distinct geographic variability occurred in the proportion of fires and area burned attributed to lightning, with a majority of fires …

Plant Distribution Data Show Broader Climatic Limits Than Expert-Based Climatic Tolerance Estimates, Caroline A. Curtis, Bethany A. Bradley

Environmental Conservation Faculty Publication Series

Background

Although increasingly sophisticated environmental measures are being applied to species distributions models, the focus remains on using climatic data to provide estimates of habitat suitability. Climatic tolerance estimates based on expert knowledge are available for a wide range of plants via the USDA PLANTS database. We aim to test how climatic tolerance inferred from plant distribution records relates to tolerance estimated by experts. Further, we use this information to identify circumstances when species distributions are more likely to approximate climatic tolerance.

Methods

We compiled expert knowledge estimates of minimum and maximum precipitation and minimum temperature tolerance for over 1800 …

Globalization Impacts On Local Commons: Multiscale Strategies For Socioeconomic And Ecological Resilience, Timothy O. Randhir

Environmental Conservation Faculty Publication Series

Globalization can have substantial impact on local commons by reducing sustainability of ecosystems and their vital services. Without effective local institutions, these resources are at high risk of exploitation, especially to feed global markets. This study proposes a multiscale ecosystem framework (MEF) that incorporates information on ecosystem components, socioeconomic processes, and their interactions. This includes inter and intra common interactions and multi-scale processes to evaluate inter and intra scale changes
in socioeconomic and ecological processes of commons. Local participation and multi-disciplinary information are critical in achieving sustainability. Using a global dataset of selected indicators, a general decline is observable in …

Spatial Capture–Recapture Models Allowing Markovian Transience Or Dispersal, J. Royle, Angela Fuller, Chris Sutherland

Environmental Conservation Faculty Publication Series

Spatial capture–recapture (SCR) models are a relatively recent development in quantitative ecology, and they are becoming widely used to model density in studies of animal populations using camera traps, DNA sampling and other methods which produce spatially explicit individual encounter information. One of the core assumptions of SCR models is that individuals possess home ranges that are spatially stationary during the sampling period. For many species, this assumption is unlikely to be met and, even for species that are typically territorial, individuals may disperse or exhibit transience at some life stages. In this paper we first conduct a simulation study …

Discontinuities Concentrate Mobile Predators: Quantifying Organism-Environment Interactions At A Seascape Scale, Cristina G. Kennedy, Martha E. Mather, Joseph M. Smith, John T. Finn, Linda A. Deegan

Environmental Conservation Faculty Publication Series

Understanding environmental drivers of spatial patterns is an enduring ecological problem that is critical for effective biological conservation. Discontinuities (ecologically meaningful habitat breaks), both naturally occurring (e.g., river confluence, forest edge, drop-off) and anthropogenic (e.g., dams, roads), can influence the distribution of highly mobile organisms that have land- or seascape scale ranges. A geomorphic discontinuity framework, expanded to include ecological patterns, provides a way to incorporate important but irregularly distributed physical features into organism–environment relationships. Here, we test if migratory striped bass (Morone saxatilis) are consistently concentrated by spatial discontinuities and why. We quantified the distribution of 50 …

Quantifying The Human Influence On Fire Ignition Across The Western Usa, Emily J. Fusco, John T. Abatzoglou, Jennifer K. Balch, John T. Finn, Bethany Bradley

Environmental Conservation Faculty Publication Series

Humans have a profound effect on fire regimes by increasing the frequency of ignitions. Although ignition is an integral component of understanding and predicting fire, to date fire models have not been able to isolate the ignition location, leading to inconsistent use of anthropogenic ignition proxies. Here, we identified fire ignitions from the Moderate Resolution Imaging Spectrometer (MODIS) Burned Area Product (2000–2012) to create the first remotely sensed, consistently derived, and regionally comprehensive fire ignition data set for the western United States. We quantified the spatial relationships between several anthropogenic land-use/disturbance features and ignition for ecoregions within the study area …

The Influence Of Sex And Season On Conspecific Spatial Overlap In A Large, Actively-Foraging Colubrid Snake, Javan M. Bauder, David R. Breininger, M. Rebecca Bolt, Michael L. Legare, Christopher L. Jenkins, Betsie B. Rothermel, Kevin Mcgarigal

Environmental Conservation Faculty Publication Series

Understanding the factors influencing the degree of spatial overlap among conspecifics is important for understanding multiple ecological processes. Compared to terrestrial carnivores, relatively little is known about the factors influencing conspecific spatial overlap in snakes, although across snake taxa there appears to be substantial variation in conspecific spatial overlap. In this study, we described conspecific spatial overlap of eastern indigo snakes (Drymarchon couperi) in peninsular Florida and examined how conspecific spatial overlap varied by sex and season (breeding season vs. non-breeding season). We calculated multiple indices of spatial overlap using 6- and 3-month utilization distributions (UD) of dyads …

Continent-Wide Survey Reveals Massive Decline In African Savannah Elephants, Michael J. Chase, Scott Schlossberg, Curtice R. Griffin, Philippe J.C. Bouché, Sintayehu W. Djene, Paul W. Elkan, Sam Ferreira, Falk Grossman, Edward Mtarima Kohi, Kelly Landen, Patrick Omondi, Alexis Peltier, S.A. Jeanetta Selier, Robert Sutcliffe

Environmental Conservation Faculty Publication Series

African elephants (Loxodonta africana) are imperiled by poaching and habitat loss. Despite global attention to the plight of elephants, their population sizes and trends are uncertain or unknown over much of Africa. To conserve this iconic species, conservationists need timely, accurate data on elephant populations. Here, we report the results of the Great Elephant Census (GEC), the first continent-wide, standardized survey of African savannah elephants. We also provide the first quantitative model of elephant population trends across Africa. We estimated a population of 352,271 savannah elephants on study sites in 18 countries, representing approximately 93% of all savannah …

Testing The Accuracy Of Aerial Surveys For Large Mammals: An Experiment With African Savanna Elephants (Loxodonta Africana), Scott Scholossberg, Michael J. Chase, Curtice R. Griffin

Environmental Conservation Faculty Publication Series

Accurate counts of animals are critical for prioritizing conservation efforts. Past research, however, suggests that observers on aerial surveys may fail to detect all individuals of the target species present in the survey area. Such errors could bias population estimates low and confound trend estimation. We used two approaches to assess the accuracy of aerial surveys for African savanna elephants (Loxodonta africana) in northern Botswana. First, we used double-observer sampling, in which two observers make observations on the same herds, to estimate detectability of elephants and determine what variables affect it. Second, we compared total counts, a complete …

Spatial Capture–Recapture: A Promising Method For Analyzing Data Collected Using Artificial Cover Objects, Chris Sutherland, David Mun'oz, David Miller, Evan Grant

Environmental Conservation Faculty Publication Series

Spatial capture–recapture (SCR) is a relatively recent development in ecological statistics that provides a spatial context for estimating abundance and space use patterns, and improves inference about absolute population density. SCR has been applied to individual encounter data collected noninvasively using methods such as camera traps, hair snares, and scat surveys. Despite the widespread use of capture based surveys to monitor amphibians and reptiles, there are few applications of SCR in the herpetological literature. We demonstrate the utility of the application of SCR for studies of reptiles and amphibians by analyzing capture–recapture data from Red-Backed Salamanders, Plethodon cinereus, collected using …

Effects Of Photo And Genotype-Based Misidentification Error On Estimates Of Survival, Detection And State Transition Using Multistate Survival Models, Kristopher J. Winiarski, Kevin Mcgarigal

Environmental Conservation Faculty Publication Series

We simulated multistate capture histories (CHs) by varying state survival (ϕ), detection (p) and transition (ψ), number of total capture occasions and releases per capture occasion and then modified these scenarios to mimic false rejection error (FRE), a common misidentification error, resulting from the failure to match samples of the same individual. We then fit a multistate model and estimated accuracy, bias and precision of state-specific ϕ, p and ψ to better understand the effects of FRE on different simulation scenarios. As expected, ϕ, and p, decreased in accuracy with FRE, with lower accuracy when CHs were …

Identification And Density Estimation Of American Martens (Martes Americana) Using A Novel Camera-Trap Method, Alexej P. K. Sirén, Peter J. Pekins, Peter L. Abdu, Mark J. Ducey

Environmental Conservation Faculty Publication Series

Camera-traps are increasingly used to estimate wildlife abundance, yet few studies exist for small-sized carnivores or comparing efficacy against traditional methods. We developed a camera-trap to identify the unique ventral patches of American martens (Martes americana). Our method was designed to: (1) determine the optimal trap configuration to photograph ventral patches; (2) evaluate the use of temporally clustered photographs to determine independence and improve identification; and (3) determine factors that influence identification probability. We tested our method by comparing camera- and live-trap density estimates using spatial capture–recapture (SCR) models. The ventral patches of radio-collared martens were most visible when traps …