Dundas, Shannon J.Ruthrof, Katinka X.Hardy, Giles E. St J.Fleming, Patricia A....
8页查看更多>>摘要：Vegetation changes as a direct result of climatic shifts changes are likely to influence reptile communities reliant on forest habitat structure and health. Extreme heat and drought over the summer of 2010/11 caused canopy collapse and decline in a Mediterranean-type forest, southwest Western Australia. The loss of canopy and altered abiotic and biotic conditions changed habitat availability for fauna. A survey of reptile assemblages and vegetation was carried out over the summer of 2013/14, three years after the drought event. Reptiles were captured using camera traps and pitfall traps. Surveys were carried out at four independent locations, where trap stations were set up across drought-affected and adjacent healthy (not visibly affected) sites (total 32 trap stations). Habitat variables likely to influence reptile assemblages (leaf litter, coarse woody debris) were measured, and iButtons were used to capture temperatures within microhabitats likely to be used by reptiles. Reptile assemblages observed at drought-affected sites differed to assemblages observed at healthy sites. These differences could be related to warmer and colder temperature extremes in drought-affected sites compared with healthy sites. Coarse woody debris was readily available in drought-affected sites but leaf litter accumulation was significantly less in drought-affected sites compared to healthy sites. Drought events are becoming more commonplace and it is important to understand the repercussions of forest decline on reptile assemblages. More proactive approaches for maintaining native habitat, such as shelter structures, may be required to protect species in affected sites to ensure that ecosystem processes are not lost.
原文链接:
NSTL
Elsevier
Singh, LakhbeerThakur, DineshSharma, Manish KumarChawla, Amit...
12页查看更多>>摘要：Litter decomposition plays a vital role in carbon and nutrient budget of forest ecosystems, but our understanding of this process for high altitude ecosystems, especially the timberline zone, is not very clear. We studied leaf litter decomposition of Betula utilis, which is the main timberline species of Western Himalaya. We placed 144 litterbags (each containing 10 g of oven dried litter) at three 'spatially well separated sites' in Oct 2014, to study the direction and magnitude of change in key variables associated with leaf litter decomposition and to test for generality of decomposition process across these spatially distant sites. The results revealed that initial nutrient concentration and lignin content of litter was significantly different for the sites. Further, magnitude of mass loss and decay rate was found to be greater for up to 34 weeks (19.03 +/- 4.55% and 0.35 +/- 0.06 yr(-1) respectively), which reached 47.01 +/- 1.98% and 0.17 +/- 0.01 yr(-1) respectively, after 4 years. N, P and K concentrations showed sharp decease for up to 34 weeks, after which N consistently increased with incubation time, whereas P and K concentrations were relatively stable. The lignin and cellulose contents decreased consistently with incubation time (from 12.29 +/- 1.21% to 5.21 +/- 0.50% and from 16.87 +/- 1.01% to 8.25 +/- 0.50% respectively). There were significant increases in C:N and lignin:N ratios for up to 34 weeks, followed by a continuous decrease thereafter. The change in various variables associated with litter decomposition was not consistent among the sites and the magnitude of change was greater during initial stages due to leaching of labile components. The increase in N and decreases in C:N and lignin:N ratios with incubation time might be due to microbial immobilization of N and are important for nutrient conservation in timberline ecosystems, as such changes are related to faster decomposition of recalcitrant fraction of litter, N mineralization and building of soil nutrient pool.
原文链接:- NSTL
- Elsevier
Bedson, Carlos P. E.Devenish, ChristianSymeonakis, EliasMallon, David...
13页查看更多>>摘要：The congeneric lagomorphs Lepus timidus and L. europaeus share allopatric distributions in many areas of Europe characterised by competitive exclusion and hybridisation. We investigated prospects for these species under climate change in northern England uplands. We created ensemble models predicting niche realisation for these species, influenced by abiotic and biotic factors, estimating niche overlap in geo-environmental space. The two species occupy distinctly different niches, influenced more by vegetation preferences than climatic differences. The current climate niche for L. timidus featured higher elevations with cooler temperatures and 168 km(2) range extent. Its current habitat niche scale was larger at 269 km(2) , comprised entirely of upland dwarf shrubs: heather, cotton grass, moorland grasses. By contrast, the current climate niche predicted L. europaeus occupying lowland areas with a milder climate and range extent of 252 km(2). Its current habitat niche was also greater, 401 km(2) , being mostly improved grassland. Competition was presently limited. The current niche predictions showed very little geographic overlap between the species. Niche overlap measured by Schoener Index was low: current climate niche 0.16; current habitat niche 0.07. The future climate niches for 2050 (IPCC RCP2.6), predicted L. timidus range contracting to 19 km(2), on hilltops and L. europaeus range expanding to 765 km(2). Consequently L. timidus range would be wholly within the L. europaeus range. In many contact zones throughout Europe, L. europaeus outcompetes L. timidus; however, in the Peak District their distributions are largely distinct. Future replacement of L. timidus by L. europaeus may be engendered by dietary convergence, should a warmer climate cause a transition of upland dwarf shrub vegetation to grasses.
原文链接:- NSTL
- Elsevier
Parolin, Lays CherobimLacher Jr, Thomas E.Bianconi, Gledson VigianoMikich, Sandra Bos...
8页查看更多>>摘要：The olfactory capacity in bats and their strong preference for some fruits has led to the development of a forest restoration tool that uses the essential oils of their preferred fruit. The idea is based on the assumption that, once these bats were attracted by olfactory cues from the essential oils to a "new food source," they would spend a certain amount of time flying around these new food sources. This technique has great potential for natural methods of regeneration assisted by dispersers, increasing arrival of chiropterochoric seeds in areas that otherwise may not be frequently visited by frugivorous bats. Although we developed this technique on Neotropical species, we believe it has the potential to be used around the world to recover degraded forests. Here, we explore parallels between New (Phyllostomidae) and Old World (Ptempodidae) seed dispersing bats to support this proposal. Review data showed that Cynopterus, Pteropus, and Rousettus seem to be the closest functional genera to those (Artibeus, Carollia, Sturnira) tested in the Neotropical region, based on their wide distribution, diet diversity and great consumption of Ficus - whose oils are known to attract fruit bats. Experiments need to be designed to further develop the technique to apply it to the Old World and contribute to the restoration of degraded forests.
原文链接:- NSTL
- Elsevier
Rada, FerminGarcia-Varela, SoniaSarmiento, Lina
7页查看更多>>摘要：The paramo, a high tropical Andean ecosystem, presents very distinct climatic, floristic and ecological features. Paramo plants have adapted to pronounced daily temperature fluctuations, freezing temperatures any night of the year, high incoming radiation and seasonal unfavorable water availability conditions. Long fallow agricultural systems are common in the paramo, permitting partial recuperation of the vegetation through a secondary succession. Different hypothesis related to plant traits (water relations and gas exchange characteristics or biomass allocation patterns) during succession have been proposed. Particular traits have been associated to the stages along successional gradients from early species (traits related to high resource acquisition abilities) to late species (traits linked to internal conservation of resources). Our purpose was to study plant functional responses of different herbaceous species in an old-field succession in the high tropical Andes. Plant traits (specific leaf area (SLA), maximum CO2 assimilation rates (A(max)), leaf nitrogen content (N-leaf), leaf water relations and biomass allocation) were studied in grasses and forbs along different successional stages. Clear trends in SLA, A(max) on a mass basis, N-leaf and aboveground/belowground biomass allocation were found along the successional gradient for grasses, while patterns were not as well-defined for forbs in the latter two traits. No patterns in leaf water relations characteristics were observed for either plant-growth forms. Strategies associated to plant traits significantly influence plant species dominance and community assembly during secondary succession in tropical alpine open environments like the paramos. Plant traits linked to rapid growth (SLA, A(max) and N-leaf) dominate during early succession. In contrast to previous studies, drought resistance traits were not found to dominate in late succession stages for either grasses or forbs.
原文链接:- NSTL
- Elsevier
Osman, NormanizaDorairaj, DeivaseenoHalim, AimeeAbu Zelan, Nurul Izzaty...
10页查看更多>>摘要：Slope cuts caused by road construction, influence vegetation and soil properties which lead to ecological degradation and soil erosion. Cut-slope soils are infertile, creating unfavourable conditions for plant growth and a reduction of plant species. We investigated plant communities and species regeneration at a cut-slope area in Malaysia whilst examining the relationship between species diversity and soil erosion. Experimental plots were set at three different vegetation coverage intensities; 0% (A), 10% (B), and 50% (C). Treatment C recorded the highest plant coverage, plant density, species richness, plant diversity, and evenness index over time. In contrast, as there was no vegetation at the start of the experiment, succession rate was the highest in treatment A (bare plot) followed by B and C. The succession rate was lower in C due to high competition between the existing plant communities for space, nutrients, sunlight and water. The plot with the highest vegetation coverage (C) showed improved slope stability for it recorded a significant reduction in soil saturation level and erosion rate whilst increasing the shear strength. Dicranopteris linearis, a fern species was the most dominant species in all treatments for it is a pioneer species that thrives in harsh environment. High plant diversity was effective in enhancing soil properties thus, improving soil shear strength as plant coverage increased. Hence, treatment A consistently displayed the highest soil shear strength followed by treatments B and C.
原文链接:- NSTL
- Elsevier
Rabelo, Mariana AzevedoAngotti, Marina Aceroda Silva, Graziele SantiagoReis, Ariel da Cruz...
7页查看更多>>摘要：Ants act as important agents in the secondary dispersion of diaspores in natural and degraded habitats, but few studies evaluate factors that influence the removal of diaspores. The present study aimed to evaluate the removal of diaspores by ants, relating the removal to: 1) assemblage factors of the diaspore-removing ants (distance and number of nests from the source of artificial diaspores) and 2) intrinsic factors of the diaspore-removing species (identity of the species, removal time by the species and distance from its nest to the source of artificial diaspores). The study was conducted in areas of Cerrado, where we measured the distances traveled by the ants between the diaspore source and the entrance to their nests, quantified the nests in each area and recorded the removal time by individuals of each species. We identified 42 nests that ranged from 0.35 to 15.32 m in distance from diaspore sources and belonged to 11 species of ants. Of the evaluated factors, only those intrinsic to each species, identity of species (Ectatomma edentatum) and distance of the nest influenced the removal of the diaspores. Thus, a given factor can influence removal depending on the perspective evaluated, considering the entire assemblage or only those intrinsic to the diaspore-removing species. This highlights the importance of conducting a more complete evaluation of the aspects related to the assemblage and the identity of diaspore-removing species that may contribute to the success of diaspore removal by ants., Directing efforts on which factors related to removal should be prioritized in assessments of the performance of this ecological process can contribute to a more effective monitoring of the dispersion of diaspores. This information is essential to advance and direct efforts in management actions aimed at the conservation, restoration and monitoring of degraded areas thar make use of de ecological processes carried out by ants.
原文链接:- NSTL
- Elsevier
Lee, Zachary A.Baranowski, Alex K.Preisser, Evan L.
4页查看更多>>摘要：Predation risk is a key factor that impacts the growth and behavior of organisms. The ability to detect and react to potential predators provides a major competitive advantage, but the energetic costs associated with antipredator behaviors can be severe. Monarch (Danaus plexippus) (Lepidoptera: Nymphalidae) caterpillars detect airborne predators through auditory predator cues, identifying the sound of a potential threat and exhibiting anti-predator behavior accordingly. Previous work on this species has examined only short-term behavioral changes in response to predation risk. We exposed monarch caterpillars to recorded predator cues in order to provoke anti-predator behaviors over an extended period of time in an effort to determine the long-term fitness costs associated with these behaviors. Our results show that exposure to wasp buzzing reduces development time and final pupal weight. These results imply that the stress of predation risk causes monarch caterpillars to accelerate their development, pupating more quickly in order to avoid the threat of predation. This shorter developmental time leads to the caterpillars pupating at a suboptimal weight, potentially reducing their future fecundity and lowering their ecological fitness as a whole.
原文链接:- NSTL
- Elsevier
Altomare, MonizeVasconcelos, Heraldo L.Raymundo, DiegoLopes, Sergio...
11页查看更多>>摘要：Changes in savanna's fire regimes, either through fire suppression or through an increase in fire frequency, can negatively affect their resilience. We evaluated the extent to which the aboveground biomass, diversity (taxonomic and functional) and resilience (functional redundancy and functional response indices) of savanna tree communities differ between burned and unburned plots. Burned plots experienced two fire events over the tenyears prior to sampling, while unburned plots experienced fire suppression over the same time period. We found that aboveground biomass was 40% smaller in burned plots, indicating that fire regimes must be included as a source of variation in models estimating the potential of savannas to store carbon. Burned plots had a higher functional diversity of vegetative traits but a smaller functional diversity of reproductive traits, indicating that generalizations about the effect of fire on tree functional diversity should be viewed with caution. Periodic fires can benefit savanna tree biodiversity by maintaining the balance between light-demanding and shade-tolerant species but can also increase the dominance of species with less specialized reproductive traits that do not rely on animal interactions. Burned plots had slightly lower functional redundancy but similar functional response diversity compared to unburned plots, suggesting that both communities harbor tree species that might respond positively or negatively to fire and, therefore, will be able to maintain the ecosystem functions considered under a future scenario of fire-suppression or increased fire frequency. Therefore, a longer-term fire suppression (>10 years) or a return fire interval of less than 4 years may be necessary to reduce the resilience of the savanna tree component, considering the ecosystem functions analyzed in this study.
原文链接:- NSTL
- Elsevier
