Amphibian Contributions to Ecosystem Services

Ecosystems provide essential services for human society, which include provisioning, regulating, cultural, and supporting services. Amphibians provide provisioning services by serving as a food source for some human societies, especially in Southeast Asia. They also serve as models in medical research and provide potential for new pharmaceuticals such as analgesics and anti-viral drugs derived from skin secretions. Amphibians contribute to regulating services by reducing mosquito recruitment from ephemeral wetlands, potentially controlling other pest species, and indirectly through predation of insect pollinators. Often neglected, ecosystems also provide cultural services to human societies that increase the quality of human life through recreation, religion, spirituality, and aesthetics. As an abundant and diverse class of vertebrates, amphibians also play prominent roles in the culture of human societies through pathways such as mythology, literature, and art. Most research on the role of amphibians in ecosystems has been on their contribution to supporting services. This is also the area where amphibians are likely to have the largest contribution to ecosystem services. Supporting services have structural (e.g., habitat) and functional (e.g., ecosystem functions and processes) components. Amphibians can affect ecosystem structure through soil burrowing and aquatic bioturbation and ecosystem functions such as decomposition and nutrient cycling through waste excretion and indirectly through predatory changes in the food web. They also can control primary production in aquatic ecosystems through direct consumption and nutrient cycling. Unfortunately, amphibians are experiencing major declines and humans may be losing associated ecosystem services. It is important to understand how declines affect ecosystem services for human societies, but these declines can also serve as natural experiments to understand the role of amphibians in ecosystems

Effects of Red-Backed Salamanders on Ecosystem Functions

Ecosystems provide a vast array of services for human societies, but understanding how various organisms contribute to the functions that maintain these services remains an important ecological challenge. Predators can affect ecosystem functions through a combination of top-down trophic cascades and bottom-up effects on nutrient dynamics. As the most abundant vertebrate predator in many eastern US forests, woodland salamanders (Plethodon spp.) likely affect ecosystems functions. We examined the effects of red-backed salamanders (Plethodon cinereus) on a variety of forest ecosystem functions using a combined approach of large-scale salamander removals (314-m2 plots) and small-scale enclosures (2 m2) where we explicitly manipulated salamander density (0, 0.5, 1, 2, 4 m−2). In these experiments, we measured the rates of litter and wood decomposition, potential nitrogen mineralization and nitrification rates, acorn germination, and foliar insect damage on red oak seedlings. Across both experimental venues, we found no significant effect of red-backed salamanders on any of the ecosystem functions. We also found no effect of salamanders on intraguild predator abundance (carabid beetles, centipedes, spiders). Our study adds to the already conflicting evidence on effects of red-backed salamander and other amphibians on terrestrial ecosystem functions. It appears likely that the impact of terrestrial amphibians on ecosystem functions is context dependent. Future research would benefit from explicitly examining terrestrial amphibian effects on ecosystem functions under a variety of environmental conditions and in different forest types

Exploring modality switching effects in negated sentences: further evidence for grounded representations

Theories of embodied cognition (e.g., Perceptual Symbol Systems Theory; Barsalou, 1999, 2009) suggest that modality specific simulations underlie the representation of concepts. Supporting evidence comes from modality switch costs: participants are slower to verify a property in one modality (e.g., auditory, BLENDER-loud) after verifying a property in a different modality (e.g., gustatory, CRANBERRIES-tart) compared to the same modality (e.g., LEAVES-rustling, Pecher et al., 2003). Similarly, modality switching costs lead to a modulation of the N400 effect in event-related potentials (ERPs; Collins et al., 2011; Hald et al., 2011). This effect of modality switching has also been shown to interact with the veracity of the sentence (Hald et al., 2011). The current ERP study further explores the role of modality match/mismatch on the processing of veracity as well as negation (sentences containing “not”). Our results indicate a modulation in the ERP based on modality and veracity, plus an interaction. The evidence supports the idea that modality specific simulations occur during language processing, and furthermore suggest that these simulations alter the processing of negation

Integrating visual and tactile information in the perirhinal cortex

By virtue of its widespread afferent projections, perirhinal cortex is thought to bind polymodal information into abstract object-level representations. Consistent with this proposal, deficits in cross-modal integration have been reported after perirhinal lesions in nonhuman primates. It is therefore surprising that imaging studies of humans have not observed perirhinal activation during visual–tactile object matching. Critically, however, these studies did not differentiate between congruent and incongruent trials. This is important because successful integration can only occur when polymodal information indicates a single object (congruent) rather than different objects (incongruent). We scanned neurologically intact individuals using functional magnetic resonance imaging (fMRI) while they matched shapes. We found higher perirhinal activation bilaterally for cross-modal (visual–tactile) than unimodal (visual–visual or tactile–tactile) matching, but only when visual and tactile attributes were congruent. Our results demonstrate that the human perirhinal cortex is involved in cross-modal, visual–tactile, integration and, thus, indicate a functional homology between human and monkey perirhinal cortices

The role of red-backed salamanders in ecosystems

Ecosystems provide a vast array of services that benefit human societies, which can be divided into provisioning, regulating, cultural, and supporting services. Amphibians provide provisioning services in the form of food and use in medical advances. As one of the major vertebrate groups, amphibians also play an important part in cultures throughout the world. Finally, amphibians can be extremely abundant and play important roles in ecosystem supporting services, including altering both physical structure and ecosystem functions. In aquatic systems, tadpoles can alter sedimentation, water clarity, and filamentous algae growth. Additionally, amphibians affect ecosystem functions, including nutrient cycling, decomposition, and primary production. Amphibians can alter the transfer of nutrients and energy between aquatic and terrestrial systems, but the net direction of flow varies temporally and depends on the amphibian community. After a review of these supporting services, I conducted two experiments to test the role of red-backed salamanders (Plethodon cinereus) in forested ecosystems. I examined the effects of salamanders on five 314-m² plots with reduced salamanders and five reference plots. I found no evidence that salamanders affected litter or wood decomposition rates, nitrogen mineralization, nitrification, or acorn germination. Nor did salamanders affect the densities of predatory litter-dwelling macroinvertebrates. However, there was considerable variability in the density of salamanders among plots, even within treatments. Therefore, I conducted a second experiment where I manipulated the density of red-backed salamanders in enclosures (2 m² x 1 m) and examined the effects on ecosystem functions. Despite the increased control and precision of this experiment, I did not observe effects of salamander density on decomposition, nitrogen cycling, acorn germination, or foliar insect damage. Since the timing of salamander activity could influence their role in ecosystem functions, I also examined the seasonal activity patterns of red-backed salamanders. I found that salamanders were most active in the spring and fall on warm, humid nights, following rain events. Salamander activity remained low through the summer even when conditions were favorable. Overall, red-backed salamanders had no measurable effects on the ecosystem functions I measured; however, future studies should examine the effects of salamanders in various forest types with different nutrient pools

Gray treefrog breeding site selection and offspring performance in response to forest management

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on October 26, 2007)Vita.Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2007.Dissertations, Academic -- University of Missouri--Columbia -- Biological sciences.Amphibian diversity and abundance are generally reduced following clearcut logging. These impacts often last for decades, but little is known about why diversity and abundance are depressed. I examined gray treefrog breeding site selection and subsequent offspring performance following experimental forest manipulations. Using wading pools and cattle tanks, I found that gray treefrogs select breeding sites in clearcuts more than those in forested habitats. Additionally, females preferred breeding sites close to forest edges over sites farther into clearcuts. To determine the influence of breeding site selection of the offspring, I stocked cattle tanks along a forest-clearcut gradient with gray treefrog tadpoles. Tadpole survival was greatest in the clearcut treatments. However, tadpoles in the clearcuts also had a shorter larval period. Having a shorter larval period can benefit individuals by reducing the time to maturity, thereby potentially increasing lifetime reproduction. Despite the preference for open canopy breeding sites, clearcuts can create resistance for females moving between terrestrial forest habitat and aquatic breeding sites. Although reduced canopy cover over breeding ponds provides some benefits for tadpoles, logging operations should avoid isolating aquatic habitat from forested uplands

Agro-environmental project duration and effectiveness in South-east Asia

Considerable emphasis has been placed on developing technologies for agricultural sustainability. Many bilateral projects are working to achieve this outcome. A desk review was conducted to study the importance of project duration for the effectiveness of sustainable agricultural projects. Longer-duration projects were successful in addressing more holistic issues than short projects. However, funding agencies tend to fund shorter-duration projects, so projects become progressively shorter. At the same time, the number of projects implemented each year is increasing. Despite the decrease in total development assistance, increases in project numbers, particularly since 1986, appear to be at the cost of project duration. Short project duration was one of the most cited reasons for not completing essential dissemination activities for wider adoption, whereas longer- duration projects were usually considered more successful in addressing more holistic issues. It is difficult to produce tangible outputs from agricultural and soil conservation projects within five years. Considering the slow changes in the system and in agricultural and environmental sustainability, the authors suggest that project developers should be advised to plan for a minimum of 5–10 years, depending on the nature of activities. It is time for funding agencies to reconsider their tendency to fund shorter-duration projects

Effects of Shade and Predation on Survival and Growth of Larval Gray Treefrogs (Hyla Veriscolor) [abstract]

Abstract only availableFaculty Mentor: Dr. Raymond Semlitsch, Biological SciencesWorldwide biodiversity has been most seriously endangered by the degradation of natural habitats (Groom et al., 2006). As part of the larger Land-use Effects on Amphibian Populations (LEAP) project, we examined some implications of timber harvest for larval treefrog development and survival. Shade and predator levels are two factors expected to significantly impact treefrog larvae in clearcut ponds compared with forested ponds. Our experiment consisted of 24 cattle tanks to which 100 newly hatched tadpoles were added in mid-May 2006. Each tank was randomly assigned a treatment combination, consisting of high and low shade simulated by tank covers and 4 levels predator density (dragonfly larvae; family Libellulidae). Though there was no difference in days to metamorphosis between treatments, the survival and size of the metamorphosed frogs differed greatly as shade or predation level was changed. The percent survival in low shade treatments was greater than in high shade treatments (71.0% and 65.7%, respectively), as was the average mass at metamorphosis (0.3347 g and 0.2960 g, respectively), which indicates a higher average growth rate in sunnier ponds. This was probably due to a higher level of solar radiation causing increased periphyton growth, which the tadpoles utilize as food. In the predator treatments, ponds that had no dragonfly larvae had a greater percent survival than the high predator density ponds (81.2% and 61.8%), however, the average mass of the zero and high treatments were similar and smaller than masses in the low and medium treatments. We attribute small size at metamorphosis in the high predator treatments to reduced tadpole activity in order to avoid predators. The higher survival rate in the low predator treatments resulted in greater tadpole density and less food available per individual. This density effect resulted in smaller average mass at metamorphosi

The Potential For UK Portfolio Investors To Finance Sustainable Tropical Forestry

Environmental Economics and Policy, Resource /Energy Economics and Policy,

Particle size segregation in granular flow in silos

Segregation and layering of alumina in storage silos are investigated, with a view to predicting output quality versus time, given known variations in input quality on emplacement. A variety of experiments were conducted, existing relevant publications were reviewed, and the basis for an algorithm for predicting the effect of withdrawing from a central flowing region, in combination with variations in quality due to geometric, layering and segregation effects, is described in this report