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Ecological Meltdown in Predator-Free Forest Fragments

Published on Nov 30, 2001in Science 41.04
· DOI :10.1126/science.1064397
John Terborgh76
Estimated H-index: 76
(Duke University),
Lawrence Lopez4
Estimated H-index: 4
(FIU: Florida International University)
+ 8 AuthorsLuis Balbas1
Estimated H-index: 1
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Abstract
The manner in which terrestrial ecosystems are regulated is controversial. The “top-down” school holds that predators limit herbivores and thereby prevent them from overexploiting vegetation. “Bottom-up” proponents stress the role of plant chemical defenses in limiting plant depredation by herbivores. A set of predator-free islands created by a hydroelectric impoundment in Venezuela allows a test of these competing world views. Limited area restricts the fauna of small (0.25 to 0.9 hectare) islands to predators of invertebrates (birds, lizards, anurans, and spiders), seed predators (rodents), and herbivores (howler monkeys, iguanas, and leaf-cutter ants). Predators of vertebrates are absent, and densities of rodents, howler monkeys, iguanas, and leaf-cutter ants are 10 to 100 times greater than on the nearby mainland, suggesting that predators normally limit their populations. The densities of seedlings and saplings of canopy trees are severely reduced on herbivore-affected islands, providing evidence of a trophic cascade unleashed in the absence of top-down regulation.
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  • References (22)
  • Citations (1053)
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References22
Newest
Published on Jun 1, 2001in Conservation Biology 6.19
Madhu Rao16
Estimated H-index: 16
(Duke University),
John Terborgh76
Estimated H-index: 76
(Duke University),
Percy Nuñez7
Estimated H-index: 7
: Understanding processes driving population declines and, ultimately, species loss in forest isolates has significant implications for the long-term maintenance of species diversity. We investigated a potential mechanism driving loss of plant species in small, medium, and large land-bridge islands in Lago Guri, a 4300-km2 hydroelectric impoundment in the State of Bolivar, Venezuela. Our hypothesis was that elevated Atta ( leaf-cutter ants) herbivory on small Guri islands, attributable to releas...
Published on Mar 1, 2001in Journal of Tropical Ecology 1.19
Kalan Ickes11
Estimated H-index: 11
(LSU: Louisiana State University),
Saara J. DeWalt15
Estimated H-index: 15
(LSU: Louisiana State University),
S. Appanah1
Estimated H-index: 1
(Forest Research Institute Malaysia)
Large mammals often play important roles in determining the struc- ture and composition of plant communities. This study focused on the extent to which wild pigs (Sus scrofa) influence the dynamics of tree seedlings and saplings in a lowland rain forest at Pasoh Forest Reserve in West Malaysia. Native wild pigs are common in the study area and may significantly influence growth and survivorship of woody plants in the understorey through several activities - namely, nest building, soil rooting an...
Published on Jun 1, 2000in The American Naturalist 3.85
Lauri Oksanen42
Estimated H-index: 42
(Umeå University),
Tarja Oksanen26
Estimated H-index: 26
(Umeå University)
abstract: Hypotheses on trophic dynamics in terrestrial ecosystems fall into two major categories: those in which plants are assumed to be invulnerable to their consumers and those in which the build‐up of plant biomass is assumed to require top‐down control of folivores. The hypothesis of exploitation ecosystems (EEH) belongs to the latter category and focuses particularly on the consequences of the high energetic costs of maintenance of endotherms. Carnivorous endotherms require relatively hig...
Published on Mar 1, 2000in Journal of Tropical Ecology 1.19
Madhu Rao16
Estimated H-index: 16
(Duke University)
The potential role of predation as a factor underlying variation in leaf-cutter ant (Atta sp.) densities was investigated on recently isolated land-bridge islands in Lago Guri, Venezuela. A survey of mature Atta colonies revealed a sharp increase in densities on small and medium islands (5.6 and 2.3 colonies ha-' respectively) compared to large islands (0.72 colonies ha-') and the mainland (0 nests in 5.5 ha). Incipient colonies showed the reverse trend with higher densities on larger landmasses...
Published on Feb 1, 2000in The American Naturalist 3.85
Oswald J. Schmitz49
Estimated H-index: 49
,
Peter A. Hambäck25
Estimated H-index: 25
,
Andrew P. Beckerman31
Estimated H-index: 31
abstract: We present a quantitative synthesis of trophic cascades in terrestrial systems using data from 41 studies, reporting 60 independent tests. The studies covered a wide range of taxa in various terrestrial systems with varying degrees of species diversity. We quantified the average magnitude of direct effects of carnivores on herbivore prey and indirect effects of carnivores on plants. We examined how the effect magnitudes varied with type of carnivores in the study system, food web diver...
Published on Dec 1, 1999in Trends in Ecology and Evolution 15.24
Michael L. Pace71
Estimated H-index: 71
,
Jonathan J. Cole80
Estimated H-index: 80
+ 1 AuthorsJames F. Kitchell66
Estimated H-index: 66
(UW: University of Wisconsin-Madison)
Abstract New studies are documenting trophic cascades in theoretically unlikely systems such as tropical forests and the open ocean. Together with increasing evidence of cascades, there is a deepening understanding of the conditions that promote and inhibit the transmission of predatory effects. These conditions include the relative productivity of ecosystems, presence of refuges and the potential for compensation. However, trophic cascades are also altered by humans. Analyses of the extirpation...
Published on Jul 1, 1999in Oikos 3.47
Gary A. Polis31
Estimated H-index: 31
This paper evaluates the multiple factors that determine the production of plant biomass and its distribution among producers and various trophic groups of con_ ?^)^ Osumers. In rough order of their importance, water and nutrient availability, factors 0*S that deter herbivores (plant defenses, environmental heterogeneity and disturbance, nutrient stoichiometry), and consumption by herbivores appear to be the most universal determinants of the production and distribution of plant biomass. In some...
Published on Jun 1, 1999in Oikos 3.47
Lennart Persson63
Estimated H-index: 63
Trophic cascades have been the subject for considerable research during the last decade. A review of the literature suggests that trophic cascades have been observed in many kinds of systems and organisms. However, the extent to which trophic cascades have community-wide effects (e.g. affecting total primary producer biomass density) is only indisputably demonstrated in aquatic systems. The lack of unequivocal evidence for community-wide trophic cascades from terrestrial systems may be due to (1...
Published on Jul 1, 1997in Ecology 4.29
John Terborgh76
Estimated H-index: 76
(Duke University),
Lawrence Lopez4
Estimated H-index: 4
,
S José Tello1
Estimated H-index: 1
(MU: University of Missouri)
We report on the bird communities of a set of 12 7-yr-old forested land- bridge islands in Lago Guri, a 4300 km2 hydroelectric impoundment in the State of Bolivar, Venezuela. Birds were censused on all islands and at mainland control sites by spot mapping in 1993, and via point counts in 1995. Instead of orderly "nested sets" of species on landmasses of graded size, the species composition of small (- 1 ha) and medium (11-12 ha) islands was highly variable. Spot mapping substantiated the occurre...
Published on May 17, 1997
William J. McShea34
Estimated H-index: 34
,
H. Brian Underwood2
Estimated H-index: 2
,
John H. Rappole23
Estimated H-index: 23
Cited By1053
Newest
Published on Jan 1, 2020
Venkatesh Dutta2
Estimated H-index: 2
(BBAU: Babasaheb Bhimrao Ambedkar University),
Urvashi Sharma (BBAU: Babasaheb Bhimrao Ambedkar University), Ravindra Kumar2
Estimated H-index: 2
Most of the major river basins throughout the world are under stress due to cumulative impact of droughts, over-allocation of water resources and water quality deterioration. Various previous and ongoing water resource development projects have caused both short-term and long-term ecological degradation resulting in interrupted fluxes of water, sediment and nutrition and declining river health across all the river basins. It is evident that most of the key manipulations of flow regimes are assoc...
Rong W A Ng6
Estimated H-index: 6
(ECNU: East China Normal University),
Yi-Su Shi1
Estimated H-index: 1
(ECNU: East China Normal University)
+ -3 AuthorsXiaoyong Chen17
Estimated H-index: 17
(ECNU: East China Normal University)
Negative distance-dependence of conspecific seedling mortality (NDisDM) is a crucial stabilizing force that regulates plant diversity, but it remains unclear whether and how fragment size shifts the strength of NDisDM. Here, we surveyed the seed‒seedling transition process for a total of 25,500 seeds of a local dominant tree species on islands of various sizes in a reservoir and on the nearby mainland. We found significant NDisDM on the mainland and large and medium islands, with significantly s...
Published in Behavioral Ecology and Sociobiology 2.10
Chris J. Jolly2
Estimated H-index: 2
(University of Melbourne),
Jonathan K. Webb35
Estimated H-index: 35
(UTS: University of Technology, Sydney)
+ -3 AuthorsBen L. Phillips28
Estimated H-index: 28
(University of Melbourne)
Brooke E. Crowley16
Estimated H-index: 16
(UC: University of Cincinnati),
Claudia Wultsch6
Estimated H-index: 6
(CUNY: City University of New York),
Marcella J. Kelly23
Estimated H-index: 23
(VT: Virginia Tech)
ABSTRACTFaecal isotopic analysis may complement other non-invasive wildlife survey tools for monitoring landscape use by carnivores, such as motion-detecting cameras and non-invasive genetic sampli...
Published on Aug 1, 2019in Basic and Applied Ecology 2.47
Chuanwu Chen (Nanjing Normal University), Aichun Xu2
Estimated H-index: 2
(China Jiliang University)
+ 1 AuthorsYanping Wang10
Estimated H-index: 10
(ZJU: Zhejiang University)
Abstract Large hydroelectric dams have become a major driver of habitat loss and fragmentation worldwide. The small-island effect (SIE) and nestedness are two general biogeographical patterns that have important implications for biodiversity conservation in fragmented systems. In this study, we tested for the existence of the SIE and nestedness patterns in medium and large-bodied mammals (> 1 kg) (hereafter mammals) on land-bridge islands created by a large hydroelectric dam in the Thousand Isla...
Published on Jun 3, 2019in Biodiversity and Conservation 3.14
Mariana B. Nagy-Reis6
Estimated H-index: 6
(State University of Campinas),
Milton Cezar Ribeiro18
Estimated H-index: 18
(UNESP: Sao Paulo State University)
+ 1 AuthorsAdriano Garcia Chiarello15
Estimated H-index: 15
(USP: University of São Paulo)
Protected areas can mediate negative effects of habitat loss and human-related pressures on key ecological groups. However, different protected area categories can vary substantially in their degree of enforcement, which may ensure different levels of effectiveness for biodiversity protection. Because little attempt has been made to quantify this, we investigated the protection effectiveness of different levels of protection (low, intermediate, and high) in maintaining the ecological functions o...
Published on Apr 11, 2019
Ana Filipa Palmeirim2
Estimated H-index: 2
(UFRJ: Federal University of Rio de Janeiro),
Ana Filipa Palmeirim2
Estimated H-index: 2
(UFRJ: Federal University of Rio de Janeiro)
+ 1 AuthorsMarcus Vinícius Vieira19
Estimated H-index: 19
(UFRJ: Federal University of Rio de Janeiro)
The Neotropical region hosts one of the highest levels of small non-volant mammal species diversity worldwide, but sampling therein is often intractable due to high logistic and labour costs. While most common sampling methods include live trapping (LT) and pitfall trapping (PT), camera trapping (CT) is potentially a useful technique. Studies assessing data acquisition efficiency for neotropical small mammals are mostly limited to LT and PT, and no small mammal study to date included CT. We prov...
Published on Jan 25, 2019
Yuriana Gómez-Ortiz3
Estimated H-index: 3
(UAEM: Universidad Autónoma del Estado de México),
Octavio Monroy-Vilchis13
Estimated H-index: 13
(UAEM: Universidad Autónoma del Estado de México),
Ivan Castro-Arellano14
Estimated H-index: 14
(Texas State University)
Species coexistence at a given locality generally implies segregation along one of the three resource dimensions of the ecological niche: spatial, trophic or temporal. Temporal activity patterns of species are ecologically important as they expose how species exploit their environments. Using camera traps, we evaluated the temporal activity patterns and temporal overlap for a mammalian carnivore assemblage from Sierra Nanchititla Natural Park, central Mexico. We characterized and compared tempor...
Published on Jun 19, 2019in Behavioral Ecology 2.69
Carolyn R. Shores4
Estimated H-index: 4
(UW: University of Washington),
Justin A. Dellinger1
Estimated H-index: 1
(CDFW: California Department of Fish and Wildlife)
+ 2 AuthorsAaron J. Wirsing32
Estimated H-index: 32
(UW: University of Washington)