The Importance of Habitat Heterogeneity in Understanding the Effect of Forest Management Practices on Salamanders

The Importance of Habitat Heterogeneity in Understanding the Effect of Forest Management Practices on Salamanders
Author: Lauren Harris Blyth
Publisher:
Total Pages: 81
Release: 2014
Genre:
ISBN:

It is important to determine how forest management practices affect non-target species such as salamanders. Analyses commonly done at treatment or stand level suggest that salamander abundances decline after disturbance. However, salamanders have small home ranges on the scale of within-treatment habitat heterogeneity that is created by background conditions and silvicultural treatments A finer scale within-treatment assessment of salamander responses is needed to determine how salamander species associate with the available range of habitats. Oak management regimes utilize prescribed fire, which affects forest stands unevenly due to differences in fire intensity. Salamander community data was collected from 2013-2014 in the unglaciated Appalachian plateau of Ohio three years after a series of treatments designed to mimic natural heterogeneous disturbance. The treatment consisted of thinning in 2000 followed by prescribed fires in 2001, 2005, 2010. Discriminant function analyses showed that sites did not group by treatment or replicate, and redundancy analysis showed that different salamander species associated with the range of microhabitats along a habitat gradient. Occupancy analyses were used to examine habitat relationships of the two most abundant species that represent two different life-history guilds. The common upland breeder, Plethodon cinereus (eastern red-backed salamander), associated with mesic habitats. In contrast, Ambystoma opacum (marbled salamander), a pool-breeding species, associated with increased oak composition in the overstory. Therefore, silvicultural management designed to regenerate oaks creates habitat heterogeneity that supports salamander species diversity. One species or group is not sufficient as an indicator representing all salamanders as silviculture may differentially impact species with different habitat associations. This study showed that salamander biodiversity is maintained in oak forests managed with disturbance where heterogeneity provides habitat for a range of species.

Beyond the Edge

Beyond the Edge
Author: John A. Crawford
Publisher:
Total Pages: 360
Release: 2007
Genre: Amphibians
ISBN:

While there are many types of habitat loss and degradation (e.g., agriculture, land development), many studies have focused on the impacts of logging on wildlife populations and on ecosystem processes. Little information, however, exists on the effects of logging on amphibians that require streams for reproduction. In order to mitigate the impacts of habitat alteration on stream amphibians, it is necessary to have a clear understanding of the role abiotic and biotic factors play in determining habitat use and abundance. Additionally, we must determine the effects of forest management practices, such as timber harvesting, have on amphibian populations in order to develop alternative management strategies. My data show that core terrestrial habitat use, microhabitat use, and overall stream salamander abundance are dependent on leaf litter depth and soil moisture. Furthermore, as leaf litter depth and soil moisture are reduced as a result of even-aged timber harvesting, the core terrestrial habitat use and abundance of salamanders decrease as a result of fewer microhabitats being available. The decrease in suitable microhabitats available is accompanied by a resulting increase in competition between stream salamander species. Lastly, I found that current USFS regulations for riparian buffer widths are vastly inadequate to protect stream salamander populations from activities such as timber harvesting.

Connectivity, Metapopulation Dynamics, and Genetic Structure of Tiger Salamanders in a Heterogeneous Landscape

Connectivity, Metapopulation Dynamics, and Genetic Structure of Tiger Salamanders in a Heterogeneous Landscape
Author: Bradley J. Cosentino
Publisher:
Total Pages:
Release: 2011
Genre:
ISBN:

Metapopulation biology has been integral for understanding the impact of spatial habitat structure on ecological and evolutionary processes. In fragmented landscapes, theory predicts that species occupancy and turnover dynamics depend on habitat area and isolation, and isolation has historically been an important predictor of gene flow. However, metapopulation theory is neutral with respect to the effects of habitat heterogeneity on population processes. Landscape ecology approaches have begun to account for effects of habitat quality and matrix structure on occupancy and gene flow, but few empirical studies have integrated the area-isolation and habitat paradigms to understand metapopulation dynamics and genetic structure in the same system. Here, I employ both approaches to understand the spatial population dynamics and genetic structure of tiger salamanders (Ambystoma tigrinum tigrinum) in an agricultural landscape in Illinois. First, I assessed the degree to which matrix heterogeneity influences A. tigrinum movement behavior. Using a field experiment, I showed that a physiological constraint, desiccation risk, varied significantly among matrix habitats (corn, soybean, forest, prairie). Water loss was greater in corn and prairie than in forest and soybean, indicating that dispersal costs can vary among agricultural crops. To assess whether movement decisions were influenced by desiccation risk, I tracked the movements of individuals released on habitat boundaries for two treatment combinations: soybean-corn, soybean-prairie. I observed that movements were oriented towards soybean in both cases, suggesting that variation in desiccation risk among matrix habitats influenced salamander movement decisions. Next, I examined the effects of area, isolation, and habitat heterogeneity on metapopulation dynamics of A. tigrinum. Emphasis was placed on understanding the role of connectivity in moderating interactions between A. tigrinum and predatory fish. Occupancy and turnover of A. tigrinum were documented in 90 wetlands for three years. Since desiccation risk influenced A. tigrinum movements, I tested whether a connectivity metric that accounted for desiccation was a better predictor of occupancy and turnover than metrics based on Euclidean distance or expert opinion. Occupancy and colonization probabilities were related positively to connectivity and negatively to fish presence. Extinction probability was related positively to fish presence, but extinction risk was low in connected networks, suggesting a rescue effect. A desiccation-informed connectivity metric was a better predictor of colonization probability than alternative metrics, whereas a Euclidean model was the best predicator of occupancy and extinction probabilities. The results indicated that the effect of desiccation risk on individual movement can scale up to influence metapopulation processes, and that the effects of predatory fish on metapopulation dynamics depended on spatial connectivity. Finally, I evaluated whether ecological factors underlying occupancy and turnover were also important predictors of metapopulation genetic structure. Newly colonized populations were more genetically differentiated than established populations, indicating that founder effects influenced genetic structure. However, the degree of genetic differentiation varied spatially. Genetic differentiation was related negatively to both wetland area and spatial connectivity. Differentiation was not strongly related to habitat quality, suggesting that metapopulation factors were more effective at reflecting the historical strength of genetic drift and gene flow than current habitat suitability.

Effects of Agricultural Conservation Practices on Fish and Wildlife

Effects of Agricultural Conservation Practices on Fish and Wildlife
Author:
Publisher:
Total Pages: 404
Release: 2008
Genre: Agricultural conservation
ISBN:

"The bibliography is a guide to recent scientific literature covering effects of agricultural conservation practices on fish and wildlife. The citations listed here provide information on how conservation programs and practices designed to improve fish and wildlife habitat, as well as those intended for other purposes (e.g., water quality improvement), affect various aquatic and terrestrial fauna"--Abstract.

Effects of Agricultural Conservation Practices on Fish and Wildlife

Effects of Agricultural Conservation Practices on Fish and Wildlife
Author: National Agricultural Library (U.S.)
Publisher:
Total Pages: 380
Release: 2008
Genre: Agricultural conservation
ISBN:

"The bibliography is a guide to recent scientific literature covering effects of agricultural conservation practices on fish and wildlife. The citations listed here provide information on how conservation programs and practices designed to improve fish and wildlife habitat, as well as those intended for other purposes (e.g., water quality improvement), affect various aquatic and terrestrial fauna"--Abstract.

Forest Operations, Engineering and Management

Forest Operations, Engineering and Management
Author: Raffaele Spinelli
Publisher: MDPI
Total Pages: 417
Release: 2018-09-19
Genre: Science
ISBN: 3038971847

This book is a printed edition of the Special Issue "Forest Operations, Engineering and Management" that was published in Forests