Digital Commons Network^™

Planttracker: An R Package To Translate Maps Of Plant Occurrence Into Demographic Data, Alice E. Stears, Peter B. Adler, Shannon E. Albeke, David H. Atkins, Jared Studyvin, Daniel C. Laughlin

Wildland Resources Faculty Publications

1. Long-term demographic data are rare yet invaluable for conservation, management, and basic research on the underlying mechanisms of population and community dynamics. Historical and contemporary mapped datasets of plant location and basal area present a relatively untapped source of demographic records that, in some cases, span over 20 years of sequential data collection. However, these maps do not uniquely mark individual plants, making the process of collecting growth, survival, and recruitment data difficult.
2. Recent efforts to translate historical maps of plant occurrence into shapefiles make it possible to use computer algorithms to track individuals through time and determine individual growth …

Dna Persistence In Predator Saliva From Multiple Species And Methods For Optimal Recovery From Depredated Carcasses, Antoinette J. Piaggio, Susan A. Shriner, Julie K. Young, Doreen L. Griffin, Peggy Callahan, Darren J. Wostenberg, Eric M. Gese, Matthew W. Hopken

Wildland Resources Faculty Publications

Molecular forensics is an important component of wildlife research and management. Using DNA from noninvasive samples collected at predation sites, we can identify predator species and obtain individual genotypes, improving our understanding of predator–prey dynamics and impacts of predators on livestock and endangered species. To improve sample collection strategies, we tested two sample collection methods and estimated degradation rates of predator DNA on the carcasses of multiple prey species. We fed carcasses of calves (Bos taurus) and lambs (Ovis aires) to three captive predator species: wolves (Canis lupus), coyotes (C. latrans), and …

Estimating Historical Forest Density From Land‐Survey Data: A Response To Baker And Williams (2018), Carrie R. Levine, Charles V. Cogbill, Brandon M. Collins, Andrew J. Larson, James A. Lutz, Malcolm P. North, Christina M. Restaino, Hugh D. Safford, Scott L. Stephens, John J. Battles

Wildland Resources Faculty Publications

In the Western United States, historical forest conditions are used to inform land management and ecosystem restoration goals (North et al. 2009, Stephens et al. 2016). This interest is based on the premise that historical forests were resilient to ecological disturbances (Keane et al. 2018). Researchers throughout the United States have used the General Land Office (GLO) surveys of the late 19th and early 20th centuries to estimate historical forest conditions (Bourdo 1956, Schulte and Mladenoff 2001, Cogbill et al. 2002, Paciorek et al. 2016). These surveys were conducted throughout the United States …

Additional Thoughts On Rigor In Wildlife Science: Unappreciated Impediments, John A. Bissonette

Wildland Resources Faculty Publications

Traditionally, most scientists accepted reductionist and mechanistic approaches as the rigorous way to do science. Sells et al. (2018) recently raised the argument about reliability in wildlife science. Chamberlin (1890), Platt (1964), Romesburg (1981, 1991, 2009), and Williams (1997) were rightly referenced as very influential papers. My intention in this letter is not to refute the essence of the Sells et al. (2018) commentary but to add seldom addressed but important aspects that influence the attainment of rigor and certainty in wildlife studies. The elements of …

Is Grassfed Meat And Dairy Better For Human And Environmental Health?, Frederick D. Provenza, Scott L. Kronberg, Pablo Gregorini

Wildland Resources Faculty Publications

The health of livestock, humans, and environments is tied to plant diversity—and associated phytochemical richness—across landscapes. Health is enhanced when livestock forage on phytochemically rich landscapes, is reduced when livestock forage on simple mixture or monoculture pastures or consume high-grain rations in feedlots, and is greatly reduced for people who eat highly processed diets. Circumstantial evidence supports the hypothesis that phytochemical richness of herbivore diets enhances biochemical richness of meat and dairy, which is linked with human and environmental health. Among many roles they play in health, phytochemicals in herbivore diets protect meat and dairy from protein oxidation and lipid …

Relative Selection Strength: Quantifying Effectsize In Habitat- And Step-Selection Inference, Tal Avgar, Subhash R. Lele, Jonah L. Keim, Mark S. Boyce

Wildland Resources Faculty Publications

Habitat-selection analysis lacks an appropriate measure of the ecological significance of the statistical estimates-a practical interpretation of the magnitude of the selection coefficients. There is a need for a standard approach that allows relating the strength of selection to a change in habitat conditions across space, a quantification of the estimated effect size that can be compared both within and across studies. We offer a solution, based on the epidemiological risk ratio, which we term the relative selection strength (RSS). For a "used-available" design with an exponential selection function, the RSS provides an appropriate interpretation of the magnitude of the …

Climate Drives Fire Synchrony But Local Factors Control Fire Regime Change In Northern Mexico, Larissa L. Yocom Kent, Peter Z. Fule, J. Brown, E. Cerano, E. Cornejo-Oviedo, C. Cortés Montaño, S. A. Drury, D. A. Falk, J. Meunier, H. M. Poulos, C. N. Skinner, S. L. Stephens, J. Villanueva-Diaz

Wildland Resources Faculty Publications

The occurrence of wildfire is influenced by a suite of factors ranging from “top-down” influences (e.g., climate) to “bottom-up” localized influences (e.g., ignitions, fuels, and land use). We carried out the first broad-scale assessment of wildland fire patterns in northern Mexico to assess the relative influence of top-down and bottom-up drivers of fire in a region where frequent fire regimes continued well into the 20th century. Using a network of 67 sites, we assessed (1) fire synchrony and the scales at which synchrony is evident, (2) climate drivers of fire, and (3) asynchrony in fire regime changes. We found high …

Temporal Foraging Patterns Of Nonnative Frogs (Eleutherodactylus Coqui) In Hawaii, Arthur C. Wallis, Robyn L. Smith, Karen H. Beard

Wildland Resources Faculty Publications

The Puerto Rican Coqui Frog (Eleutherodactylus coqui) is a nocturnal, invasive species that was introduced into Hawaii in the 1980s. Because they reach extremely high densities (up to 90,000 frogs/ha), they have the potential to affect invertebrate prey communities. Previously, researchers used frogs collected only at night to characterize their prey. Because Coquis use retreat sites near the forest floor during the day and understory perch sites at night, frogs collected at night might show different amounts and types of prey than would frogs collected in the morning. We analyzed stomach contents of 435 frogs collected in the morning (0300–0600 …

Different Prey Resources Suggest Little Competition Between Non-Native Frogs And Insectivorous Birds Despite Isotopic Niche Overlap, Robyn L. Smith, Karen H. Beard, Aaron B. Shiels

Wildland Resources Faculty Publications

Non-native amphibians often compete with native amphibians in their introduced range, but their competitive effects on other vertebrates are less well known. The Puerto Rican coqui frog (Eleutherodactylus coqui) has colonized the island of Hawaii, and has been hypothesized to compete with insectivorous birds and bats. To address if the coqui could compete with these vertebrates, we used stable isotope analyses to compare the trophic position and isotopic niche overlap between the coqui, three insectivorous bird species, and the Hawaiian hoary bat. Coquis shared similar trophic position to Hawaii amakihi, Japanese white-eye, and red-billed leiothrix. Coquis were about 3 ‰ …

A Life-History Perspective On The Demographic Drivers Of Structured Population Dynamics In Changing Environments, David N. Koons, David T. Iles, Michael Schaub, Hal Caswell

Wildland Resources Faculty Publications

Current understanding of life-history evolution and how demographic parameters contribute to population dynamics across species is largely based on assumptions of either constant environments or stationary environmental variation. Meanwhile, species are faced with non-stationary environmental conditions (changing mean, variance, or both) created by climate and landscape change. To close the gap between contemporary reality and demographic theory, we develop a set of transient life table response experiments (LTREs) for decomposing realised population growth rates into contributions from specific vital rates and components of population structure. Using transient LTREs in a theoretical framework, we reveal that established concepts in population biology …

Modelling Water Uptake Provides A New Perspective On Grass And Tree Coexistence, Michael G. Mazzacavallo, Andrew Kulmatiski

Wildland Resources Faculty Publications

Root biomass distributions have long been used to infer patterns of resource uptake. These patterns are used to understand plant growth, plant coexistence and water budgets. Root biomass, however, may be a poor indicator of resource uptake because large roots typically do not absorb water, fine roots do not absorb water from dry soils and roots of different species can be difficult to differentiate. In a sub-tropical savanna, Kruger Park, South Africa, we used a hydrologic tracer experiment to describe the abundance of active grass and tree roots across the soil profile. We then used this tracer data to parameterize …

Thermal Patterns Constrain Diurnal Behavior Of A Ground-Dwelling Bird, J. Matthew Carroll, Craig A. Davis, R. Dwayne Elmore, Samuel D. Fuhlendorf, Eric T. Thacker

Wildland Resources Faculty Publications

Recently, gaining knowledge about thermal refuges for vulnerable species has been a major focal point of ecological studies, and this focus has been heightened by predicted temperature increases associated with global climate change. To better understand how organisms respond to thermal landscapes and extremes, we investigated the thermal ecology of a gallinaceous bird species (northern bobwhite; Colinus virginianus, hereafter bobwhite) during a key life history period. Specifically, our study focused on the brood-rearing period of precocial bobwhite chicks associated with brood-attending adults. We measured site-specific black bulb temperatures (Tbb) and vegetation characteristics across 38 brood tracking days and 68 random …

Soil Water Retention Curves For The Major Soil Types Of The Kruger National Park, Robert Buitenwerf, Andrew Kulmatiski, Steven I. Higgins

Wildland Resources Faculty Publications

Soil water potential is crucial to plant transpiration and thus to carbon cycling and biosphere–atmosphere interactions, yet it is difficult to measure in the field. Volumetric and gravimetric water contents are easy and cheap to measure in the field, but can be a poor proxy of plant-available water. Soil water content can be transformed to water potential using soil moisture retention curves. We provide empirically derived soil moisture retention curves for seven soil types in the Kruger National Park, South Africa. Site-specific curves produced excellent estimates of soil water potential from soil water content values. Curves from soils derived from …

Continental-Scale Assessment Of Genetic Diversity And Population Structure In Quaking Aspen (Populus Tremuloides), Colin M. Callahan, Carol A. Rowe, Ronald J. Ryel, John D. Shaw, Michael D. Madritch, Karen E. Mock

Wildland Resources Faculty Publications

Aim: Quaking aspen (Populus tremuloides) has the largest natural distribution of any tree native to North America. The primary objectives of this study were to characterize range-wide genetic diversity and genetic structuring in quaking aspen, and to assess the influence of glacial history and rear-edge dynamics.

Location: North America.

Methods: Using a sample set representing the full longitudinal and latitudinal extent of the species’ distribution, we examined geographical patterns of genetic diversity and structuring using 8 nuclear microsatellite loci in 794 individuals from 30 sampling sites.

Results: Two major genetic clusters were identified across the range: a southwestern cluster and …

Linking Old-Growth Forest Composition, Structure, Fire History, Climate And Land-Use In The Mountains Of Northern México, Citlali Cortes Montano, Peter Z. Fule, Donald A. Falk, Jose Villanueva-Diaz, Larissa L. Yocom Kent

Wildland Resources Faculty Publications

Old-growth forests are biologically and ecologically valuable systems that are disappearing worldwide at a rapid rate. México still holds large areas covered by temperate forests in the mountains of the Sierra Madre Occidental, but few of these retain old-growth characteristics. We studied four sites with remnant old-growth forests in Mesa de las Guacamayas, a site in the Sierra Madre Occidental in northwestern Chihuahua, to assess their composition, structure, and age characteristics. Overstory tree densities and basal areas at each site were based on measurements of all trees >1.3 m tall. The overstory was dominated by large Pinus durangensis, P. strobiformis, …

Methods To Quantify Variable Importance: Implications For Theanalysis Of Noisy Ecological Data, Kim Murray, Mary M. Conner

Wildland Resources Faculty Publications

Determining the importance of independent variables is of practical relevance to ecologists and managers concerned with allocating limited resources to the management of natural systems. Although techniques that identify explanatory variables having the largest influence on the response variable are needed to design management actions effectively, the use of various indices to evaluate variable importance is poorly understood. Using Monte Carlo simulations, we compared six different indices commonly used to evaluate variable importance; zero-order correlations, partial correlations, semipartial correlations, standardized regression coefficients, Akaike weights, and independent effects. We simulated four scenarios to evaluate the indices under progressively more complex circumstances …

Influence Of Pocket Gopher Mounds On Nonnative Plant Establishment In A Shrubsteppe Ecosystem, G. P. Kyle, Andrew Kulmatiski, Karen H. Beard

Wildland Resources Faculty Publications

Soil disturbances across a wide range of spatial scales have been found to promote the establishment of invasive plant species. This study addresses whether mounds built by northern pocket gophers (Thomomys talpoides) in the shrubsteppe environment of north central Washington are facilitating plant invasions into native-dominated fields. Research was conducted in native-dominated plant communities adjacent to ex-arable, nonnative-dominated fields. To determine the effect of mounds on plant growth, we recorded new establishment and persistence of all plant species over 2 growing seasons on 10–19 mound and intermound areas in 10 fields. Nonnative plant establishment was not affected by mounds, but …

Quantitative-Genetic Variation In Morphological And Physiological Traits Within A Quaking Aspen (Populus Tremuloides) Population, Megan K. Kanaga, Ronald J. Ryel, Karen E. Mock, Michael E. Pfrender

Wildland Resources Faculty Publications

Genetic diversity within populations is an important component of adaptive evolution, and recent research has demonstrated that genetic variation within plant populations can have important ecological effects. In this study, we investigate quantitative-genetic variation in several traits within a quaking aspen (Populus tremuloides Michx.) population. A common garden experiment was planted with replicates of 13 aspen genotypes collected from wet and dry sites within a population in southern Utah, USA. Ten growth, leaf, physiological, and structural traits were measured. There were significant, heritable phenotypic differences among genotypes in every measured trait and differences in 4 of the 10 traits among …

Random Forests For Classification In Ecology, D. R. Cutler, Thomas C. Edwards Jr., Karen H. Beard, A. Cutler, K. T. Hess, J. C. Gibson, J. J. Lawler

Wildland Resources Faculty Publications

Classification procedures are some of the most widely used statistical methods in ecology. Random forests (RF) is a new and powerful statistical classifier that is well established in other disciplines but is relatively unknown in ecology. Advantages of RF compared to other statistical classifiers include (1) very high classification accuracy; (2) a novel method of determining variable importance; (3) ability to model complex interactions among predictor variables; (4) flexibility to perform several types of statistical data analysis, including regression, classification, survival analysis, and unsupervised learning; and (5) an algorithm for imputing missing values. We compared the accuracies of RF and …

Factors Affecting Greater Sage-Grouse Habitat Use In Utah's West Desert, J. D. Robinson, Terry A. Messmer

Wildland Resources Faculty Publications

Two species of sage-grouse occur within the western United States, the greater sage-grouse (Centrocercus urophasianus) and the Gunnison sage-grouse (C. minimus). The Gunnison sage-grouse is a candidate species for listing under the Endangered Species Act. This species occurs in a small range in southwest Colorado and southeast Utah. The greater sage-grouse occurs in a larger range throughout the western United States.

Quantitative Assessment Of Habitat Preferences For The Puerto Rican Terrestrial Frog, Eleutherdoctylus Coqui, Karen H. Beard, S. Mccullough, A. K. Eschtruth

Wildland Resources Faculty Publications

We conducted a quantitative analysis of adult and juvenile Eleutherodactylus coqui (coquí) habitat preferences in Puerto Rico. The analysis consisted of two surveys: one to quantify potential habitat and another to quantify habitat use. Coquís were found to use most habitats available to them; however, adults and juveniles preferred different plant species, habitat structural components, and heights from the forest floor. Adult and juvenile coquís had opposite associations with many important plant species in the forest (e.g., Prestoea montana and Heliconia carabea) and habitat structural components. Adults had a negative association with leaves and a positive association with leaf litter. …

Methods In Historical Ecology: A Case Study Of Tintic Valley, Utah, Jeffrey A. Creque, Neil E. West, James P. Dobrowolski

Wildland Resources Faculty Publications

Through use of repeat photography, archival research, and field observation to reconstruct landscape vegetation patterns and changes across a 120 year period in the upper Tintic Valley of central Utah, researchers found significant changes in landscape vegetation pattern over time, including change in pinyon-juniper woodland area. Previously reported massive woodland harvest associated with early mining, domestic and agricultural activities elsewhere in the Intermountain West also took place in Utah. The impact on woodland area of the agricultural "bull" fence alone was significant. More recent study area woodland expansion also occurred. Because intensive industrial activity associated with development of the Tintic …

Big Bend National Park Biosphere Reserve: A History Of Scientific Study - Volume I: A Narrative Description Of Scientific Study, John A. Bissonette, John W. Ault Iii

Wildland Resources Faculty Publications

In 1971 the United Nations Educational, Scientific, and Cultural Organization (UNESCO) created the Man and the Biosphere (MAB) Program for the purpose of promoting rational use of the earth's resources. Formal involvement by the U.S. began in 1974. By 1976, 28 biosphere reserves had been selected in the U.S., including Big Bend National Park (BBNP) (Fig. 1). The purpose of this 2-volume report was to provide an interdisciplinary reference volume of literature citations for BBNP and the surrounding Chihuahuan Desert, and to provide a synopsis of research completed at BBNP.