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

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

The Potential For UK Portfolio Investors To Finance Sustainable Tropical Forestry

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

Effects of shade and predation on survival and growth of larval gray treefrogs (hyla versicolor) [abstract]

Abstract only availableAmphibians are experiencing population reductions and species extinctions on a worldwide scale and most biologists agree that loss or degradation of local habitats is the major factor causing declines. As part of the larger Land-use Effects on Amphibian Populations (LEAP) project, we examined some of the effects of timber harvest on the pond environment of larval gray treefrogs (Hyla versicolor). We manipulated shade and predator levels (dragonfly larvae; family Libellulidae) in cattle tanks to test the impact of clear-cutting on the tadpole populations. Survival and size of the metamorphosed frogs differed in response to shade and predation level, but larval period was unaffected. The percent survival in low shade treatments was 71.0% compared to 65.7% for high shade treatments and average mass at metamorphosis was 0.3347 g compared to 0.2960 g. This greater growth was supported by previous research and suggests open canopy ponds have more periphyton which 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 predator treatments were similar and smaller than masses in the low and medium treatments. The smaller size at metamorphosis in the high predator treatments can be attributed to reduced feeding activity in order to avoid predators. The higher survival rate from the lack of predation in low treatments resulted in greater tadpole density and less resources available resulting in smaller average mass at metamorphosis. These results imply that clear-cutting does not negatively impact amphibian populations because the tadpoles seemed to thrive from the benefits of open canopy ponds. However, this is the only the first stage in their life history and would probably differ in canopy preference as the frogs mature and begin to use trees for refugia.McNair Scholars Progra

Modality switching and negation: ERP evidence for modality-specific simulations during negation processing

The Perceptual Symbol System Theory of cognition (Barsalou, 1999) suggests that modality-specific simulations underlie representation of concepts. This is evidenced by processing costs for switching modalities. That is, participants are slower to verify a property in the auditory modality (e.g., BLENDER-loud) after verifying a property in a different modality (e.g., CRANBERRIES-tart) and faster when verifying a property in the same modality (e.g., LEAVES-rustling). The modality switch cost has also been shown to lead to a modulation of the N400 event-related potential (ERP) (Collins, Pecher, Zeelenberg & Coulson, 2011 using a property verification task; Hald, Marshall, Janssen & Garnham, 2011 using a sentence verification task). In a separate line of research, ERP studies have indicated that without a discourse context, negated sentences are more difficult to process than affirmative sentences, leading to a different N400 pattern for negative sentences than for affirmative sentences (e.g., Fischler, Bloom, Childers, Roucos, & Perry, 1983.) Unlike affirmative sentences, sentences containing negation show a larger N400 for correct, semantically coherent single sentences (i.e., factually true sentences) than for semantically incorrect sentences (i.e., false sentences). However, Nieuwland and Kuperberg (2008,) found that the pragmatics of the sentence can change this N400 pattern to one closer to affirmative sentences. The goal of the current study was to explore whether the processing of negation could be aided by modality matching information. Other evidence suggests that comprehenders create a simulation of negative sentences (Kaup, Yaxley, Madden, Zwaan, & Lüdtke, 2007), but it is unclear whether modality matching information could modulate the processing cost of negation. Essentially, can modality matching information as reported by Collins et al., (2011) and Hald et al., (2011) lead to a modulation of the N400 for true negated sentences similar to that seen when discourse pragmatics supports negation? Furthermore, we were interested in whether the modality switch effect would lead to a similar pattern in the ERPs as that found with affirmative sentences (Collins et al., 2011 & Hald et al., 2011). Using a within-subjects design we used 160 pairs of experimental pairs which were either of the same or of a different modality. All experimental items were either visual or tactile modality and were drawn from existing sets of materials (Pecher, et al., 2003; Van Dantzig, et al., 2008). For example, a different modality pair was “A light bulb is very hot” followed by “Rice isn’t black” versus a same visual modality pair “A giraffe is spotted” followed by “Rice isn’t black”. We predicted that the underlined word is where a modulation in the N400 may be seen. Additionally, we explored veracity by making half of the experimental target sentences false (“Rice isn’t white”). Participants were asked to judge whether each sentence was typically true or false. Our initial results indicate a modulation in the ERP based on both modality and veracity. For true (“Rice isn’t black”) and false target statements (“Rice isn’t white”) different modality pairs elicit a larger frontal-central N400 like effect compared to same modality pairs (Figure 1), replicating Hald et al., (2011). When comparing true versus false, the different modality pairs elicit a large posterior N400 for true compared to false sentences (replicating the effect for negated sentences, i.e., Fischler et al., 1983). However for same modality pairs there is a reduction in the N400 to true statements; no difference is seen between true and false statements in the ERP (Figure 2). These results replicate and extend previous ERP findings using the modality switch paradigm. The evidence suggests that not only do modality-specific simulations occur but they can even aid the processing of negation