The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Pierre-michel Forget - One of the best experts on this subject based on the ideXlab platform.
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Frugivores and seed removal at Tetragastris altissima (Burseraceae) in a fragmented forested landscape of French Guiana
Journal of Tropical Ecology, 2005Co-Authors: Sandra Ratiarison, Pierre-michel ForgetAbstract:We aimed at (1) determining how Community-wide disruptions affect visitation by frugivores at trees and (2) estimating the impact of visitation shifts on seed fate following fruit consumption, especially seed removal. We compared the seed fate of a frugivore-dispersed tree species (Tetragastris altissima, Burseraceae) in four forested islands with that for a mainland continuous forest at Saint-EugFrench Guiana. Tetragastris trees attracted opportunistic frugivore species available in the area, the most productive trees attracting more consumer species. Only primates, which are more susceptible to forest disturbances than birds and have low abilities to cross a non- forested matrix, were more frequent at Tetragastris on the mainland than on islands. Only opportunistic frugivorous primate species acting as low-efficiency seed dispersers were recorded. As a result, seed removal was equally low among habitats (nearly 26%), high percentages of seeds dropping below tree crowns. The scarcity of large-bodied specialist frugivorous primates throughout the landscape probably explained this low removal. Our results underline how difficult it is to generalize the cascading effects of disruptions in a frugivore Community on tree seed fate, these effects likely varying according to the tree species and Animal Community involved.
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Frugivores and seed removal at Tetragastris altissima (Burseraceae) in a fragmented forested landscape of French Guiana
Journal of Tropical Ecology, 2005Co-Authors: Sandra Ratiarison, Pierre-michel ForgetAbstract:We aimed at (1) determining how Community-wide disruptions affect visitation by frugivores at trees and (2) estimating the impact of visitation shifts on seed fate following fruit consumption, especially seed removal. We compared the seed fate of a frugivore-dispersed tree species (Tetragastris altissima, Burseraceae) in four forested islands with that for a mainland continuous forest at Saint-Eugène, French Guiana. Tetragastris trees attracted opportunistic frugivore species available in the area, the most productive trees attracting more consumer species. Only primates, which are more susceptible to forest disturbances than birds and have low abilities to cross a non-forested matrix, were more frequent at Tetragastris on the mainland than on islands. Only opportunistic frugivorous primate species acting as low-efficiency seed dispersers were recorded. As a result, seed removal was equally low among habitats (nearly 26%), high percentages of seeds dropping below tree crowns. The scarcity of large-bodied specialist frugivorous primates throughout the landscape probably explained this low removal. Our results underline how difficult it is to generalize the cascading effects of disruptions in a frugivore Community on tree seed fate, these effects likely varying according to the tree species and Animal Community involved.
Sheng Yu - One of the best experts on this subject based on the ideXlab platform.
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characteristics of soil Animal Community in the subalpine alpine forests of western sichuan during onset of freezing
Acta Ecologica Sinica, 2010Co-Authors: Fuzhong Wu, Wanqin Yang, Sheng YuAbstract:Abstract Seasonal freeze–thaw cycle is a common phenomenon in the subalpine/alpine forest region, and may have a significant influence on the structure and function of soil Animal Community. To understand the characteristics and dynamics of soil Animal Community as well as its response to repeated freeze–thaw events in this region during onset of freezing, a field experiment was conducted to investigate the composition, abundance, and diversity of soil fauna in primary fir (Abies faxoniana) forest, fir and birch (Betula albosinensis) mixed forest and secondary fir (A. faxoniana) forest, which were three representative forests in the subalpine and alpine forest region in western Sichuan. Soil samples were collected from November 3 to November 27, 2008, which was defined as onset of freezing based on the simultaneous monitoring of soil temperature. Soil macrofauna were picked up by hand in the fields. Mesofauna were separated and collected from the soil samples by Baermann and Tullgren methods, respectively. By preliminary identification, 40,942 individuals were collected, which belonged to 7 phyla, 15 classes and 25 orders in the three sampling forests. 16,557, 14,669 and 9716 individuals were found in primary forest, mixed forest and secondary forest, respectively. In comparison with the mineral soil layer, the soil organic layer had higher density and groups of soil fauna. Furthermore, following the repeated freeze–thaw events, density and groups of soil fauna experienced a distinct decrease in both soil organic layer and mineral soil layer, and this trend in soil organic layer was more significant in the primary forest, owing to higher intense and more frequent freeze–thaw cycles in soil organic layer of the primary forest. The results revealed that soil Animals were sensitive bio-indicators to environmental changes, such as repeated freeze–thaw events and dry–wet cycle. Meanwhile, the results also implied that the dynamics of the structure and function of soil Animal Community during the onset of freezing was of ecological significance to understand the wintertime ecological process in soils.
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Characteristics of soil Animal Community in the subalpine/alpine forests of western Sichuan during onset of freezing
Acta Ecologica Sinica, 2010Co-Authors: Fuzhong Wu, Wanqin Yang, Sheng YuAbstract:Abstract Seasonal freeze–thaw cycle is a common phenomenon in the subalpine/alpine forest region, and may have a significant influence on the structure and function of soil Animal Community. To understand the characteristics and dynamics of soil Animal Community as well as its response to repeated freeze–thaw events in this region during onset of freezing, a field experiment was conducted to investigate the composition, abundance, and diversity of soil fauna in primary fir (Abies faxoniana) forest, fir and birch (Betula albosinensis) mixed forest and secondary fir (A. faxoniana) forest, which were three representative forests in the subalpine and alpine forest region in western Sichuan. Soil samples were collected from November 3 to November 27, 2008, which was defined as onset of freezing based on the simultaneous monitoring of soil temperature. Soil macrofauna were picked up by hand in the fields. Mesofauna were separated and collected from the soil samples by Baermann and Tullgren methods, respectively. By preliminary identification, 40,942 individuals were collected, which belonged to 7 phyla, 15 classes and 25 orders in the three sampling forests. 16,557, 14,669 and 9716 individuals were found in primary forest, mixed forest and secondary forest, respectively. In comparison with the mineral soil layer, the soil organic layer had higher density and groups of soil fauna. Furthermore, following the repeated freeze–thaw events, density and groups of soil fauna experienced a distinct decrease in both soil organic layer and mineral soil layer, and this trend in soil organic layer was more significant in the primary forest, owing to higher intense and more frequent freeze–thaw cycles in soil organic layer of the primary forest. The results revealed that soil Animals were sensitive bio-indicators to environmental changes, such as repeated freeze–thaw events and dry–wet cycle. Meanwhile, the results also implied that the dynamics of the structure and function of soil Animal Community during the onset of freezing was of ecological significance to understand the wintertime ecological process in soils.
Philippe Clergeau - One of the best experts on this subject based on the ideXlab platform.
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Small urban woodlands as biodiversity conservation hot-spot: a multi-taxon approach
Landscape Ecology, 2008Co-Authors: Solène Croci, Alain Butet, Anita Georges, Rahim Aguejdad, Philippe ClergeauAbstract:To evaluate the importance of urban woodlands to serve as potential sites for biodiversity conservation, we analysed bird, carabid beetle and small mammal Community responses to urbanisation at different spatial scales. We analysed the relationships between the variations of the structure (species richness S, diversity H′ and dominance D) of Animal communities of woodlands distributed along a rural–urban gradient, and the variations along this same gradient of (1) the vegetation within woodlands, (2) the landscape at 100 m and (3) 600 m around the woodlands. We identified the spatial scales whose variations along the gradient most affected each Animal Community structure, and characterised Community responses to these variations. Our results showed that urbanisation affected taxa differently according to their dispersal ability. Carabid beetles, less mobile, seem to be sensitive to increasing fragmentation and built surfaces from periurban to town centre which could make their movement within the urban landscape difficult. Birds, mobile species, seem to be more sensitive to variations of the vegetation structure within woodlands from periurban to town centre that could affect their capacity to maintain in habitat patches. Although our study did not allow relating the small mammal Community structure to urbanisation, it suggests that this taxa is sensitive to urban local disturbances. A relevant management scale of woodlands can be specified for each taxa conservation. Urban woodlands accommodate over 50% of the species present in periurban woodlands, and effective management could enhance this number. Woodlands seem to be a good choice for promoting biodiversity conservation in towns.
Sean J Doody - One of the best experts on this subject based on the ideXlab platform.
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chronic effects of an invasive species on an Animal Community
Ecology, 2017Co-Authors: Sean J Doody, David Rhind, Brian Green, Christina M Castellano, Colin Mchenry, Simon ClulowAbstract:Invasive species can trigger trophic cascades in Animal communities, but published cases involving their removal of top predators are extremely rare. An exception is the invasive cane toad (Rhinella marina) in Australia, which has caused severe population declines in monitor lizards, triggering trophic cascades that facilitated dramatic and sometimes unexpected increases in several prey of the predators, including smaller lizards, snakes, turtles, crocodiles, and birds. Persistence of isolated populations of these predators with a decades-long sympatry with toads suggests the possibility of recovery, but alternative explanations are possible. Confirming predator recovery requires longer-term study of populations with both baseline and immediate post-invasion densities. Previously, we quantified short-term impacts of invasive cane toads on Animal communities over seven years at two sites in tropical Australia. Herein we test the hypothesis that predators have begun to recover by repeating the study 12 years after the initial toad invasion. The three predatory lizards that experienced 71-97% declines in the short-term study showed no sign of recovery, and indeed a worse fate; two of the three species were no longer detectable in 630 km of river surveys, suggesting local extirpation. Two mesopredators that had increased markedly in the short-term due to the above predator losses showed diverse responses in the medium-term; a small lizard species increased by ca. 500%, while populations of a snake species showed little change. Our results indicate a system still in ecological turmoil, having not yet reached a ‘new equilibrium’ more than a decade after the initial invasion; predator losses due to this toxic invasive species, and thus downstream effects, were not transient. Given that cane toads have proven too prolific to eradicate or control, we suggest that recovery of impacted predators must occur unassisted by evolutionary means: dispersal into extinction sites from surviving populations with alleles for toxin resistance or toad avoidance. Evolution and subsequent dispersal may be the only solution for a number of species or communities affected by invasive species for which control is either prohibitively expensive, or not possible. This article is protected by copyright. All rights reserved.
V. Huhta - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the soil fauna impact on decomposition in a simulated coniferous forest soil
Biology and Fertility of Soils, 1990Co-Authors: H. Setälä, V. HuhtaAbstract:Long-term experiments (ca. 2 years) were carried out in laboratory systems that simulated the complexity of a coniferous forest floor. The test materials were partially sterilized by freezing and thawing, and reinoculated with (1) microbes alone or (2) microbes with fauna. Removable microcosms containing birch litter, spruce litter, or humus were inserted into a humus substrate. Two experiments used organic matter only, and another included a layer of mineral soil below the humus. Both were incubated in climate chambers that simulated both summer and winter conditions. The evolution of CO_2 was measured at regular intervals. In order to determine the C content of the leachates, the macrocosms and the microcosms were watered periodically. Soil fauna significantly increased respiration in the litter, but not in the microcosms containing humus. In the later phases of decomposition the presence of fauna had a negative effect. In the total systems the fauna consistently increased the respiration rate. The loss of mass was greater in the presence of fauna, especially during the middle phases (5–11 months), but it was higher in the controls later. Throughout the whole incubation period the decomposition rate was strongly influenced by the composition of the Animal Community. The interpretation of the results is affected by the fact that the controls, to which no fauna had been added, contained dense populations of microbial feeders (nematodes, rotifers, and protozoans).
