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Ecological Meltdown in Predator-Free Forest Fragments

Published on Nov 30, 2001in Science 41.06
· DOI :10.1126/science.1064397
John Terborgh72
Estimated H-index: 72
(Duke University),
Lawrence Lopez4
Estimated H-index: 4
(Florida International University)
+ 8 AuthorsLuis Balbas1
Estimated H-index: 1
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.
  • References (22)
  • Citations (1041)
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References22
Published on May 17, 1997
William J. McShea32
Estimated H-index: 32
,
H. Brian Underwood1
Estimated H-index: 1
,
John H. Rappole23
Estimated H-index: 23
295 Citations
Published on Jan 1, 1993in Evolutionary Ecology 2.13
Egbert Giles LeighJr1
Estimated H-index: 1
(Smithsonian Tropical Research Institute),
S. Joseph Wright72
Estimated H-index: 72
(Smithsonian Tropical Research Institute)
+ 1 AuthorsFrancis E. Putz56
Estimated H-index: 56
(University of Florida)
Six islands, each less than a hectare in area, were isolated in about 1913 from the mainland of central Panama by the rising waters of Gatun Lake. By 1980, the diversity of trees on all but one of these islands was far lower than on mainland plots of comparable size. A restricted subset of tree species has spread on these islands, notablyProtium panamense, Scheelea zonensis, Oenocarpus panamanus andSwartzia simplex. We constructed a null model to predict how chance would change tree diversity an...
186 Citations Source Cite
Published on Jan 1, 1981in Bulletin of the Torrey Botanical Club
David Bramwell1
Estimated H-index: 1
128 Citations Source Cite
Published on Nov 1, 1960in The American Naturalist 4.26
Nelson G. Hairston16
Estimated H-index: 16
,
Frederick E. Smith3
Estimated H-index: 3
,
Lawrence B. Slobodkin4
Estimated H-index: 4
In summary, then, our general conclusions are: (1) Populations of producers, carnivores, and decomposers are limited by their respective resources in the classical density-dependent fashion. (2) Interspecific competition must necessarily exist among the members of each of these three trophic levels. (3) Herbivores are seldom food-limited, appear most often to be predator-limited, and therefore are not likely to compete for common resources.
2,444 Citations Source Cite
Published on May 1, 1994in BioScience 5.88
J. E. Ellis23
Estimated H-index: 23
,
Kathleen A. Galvin25
Estimated H-index: 25
(Colorado State University)
Comparative regional analysis of Africa provides insights into the effects of climatic variation on land use. This information can be used to predict effects of future climatic change. This article discusses the following two areas in depth: precipitation patterns and land use including temporal precipitation patterns, seasonality, interannual variability, and long term trends; Seasonality, interannual variability and land use including agriculture and range vegetation and pastoralism. Numerous ...
118 Citations Source Cite
Published on Jun 1, 1999in Oikos 3.71
Lennart Persson60
Estimated H-index: 60
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...
201 Citations Source Cite
Published on Jul 1, 1997in Ecology 4.62
John Terborgh72
Estimated H-index: 72
(Duke University),
Lawrence Lopez4
Estimated H-index: 4
,
S José Tello1
Estimated H-index: 1
(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...
79 Citations Source Cite
Published on Aug 25, 1995in Science 41.06
Charles J. Krebs66
Estimated H-index: 66
(University of British Columbia),
Stan Boutin62
Estimated H-index: 62
(University of Alberta)
+ 5 AuthorsRoy Turkington34
Estimated H-index: 34
(University of British Columbia)
Snowshoe hare populations in the boreal forests of North America go through 10-year cycles. Supplemental food and mammalian predator abundance were manipulated in a factorial design on 1-square-kilometer areas for 8 years in the Yukon. Two blocks of forest were fertilized to test for nutrient effects. Predator exclosure doubled and food addition tripled hare density during the cyclic peak and decline. Predator exclosure combined with food addition increased density 11-fold. Added nutrients incre...
504 Citations Source Cite
Published on Mar 1, 2000in Journal of Tropical Ecology 1.06
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...
57 Citations Source Cite
Published on May 1, 1996in The American Naturalist 4.26
Gary A. Polis30
Estimated H-index: 30
(Vanderbilt University),
Donald R. Strong44
Estimated H-index: 44
(University of California, Davis)
Food webs in nature have multiple, reticulate connections between a diversity of consumers and resources. Such complexity affects web dynamics: it first spreads the direct effects of consumption and productivity throughout the web rather than focusing them at particular "trophic levels." Second, consumer densities are often donor controlled with food from across the trophic spectrum, the herbivore and detrital channels, other habitats, life-history omnivory, and even trophic mutualism. Although ...
1,521 Citations Source Cite
Cited By1041
Published on Dec 1, 2010in Tropical Conservation Science 1.15
Rita de Cássia Quitete Portela3
Estimated H-index: 3
(State University of Campinas),
E. Bruna44
Estimated H-index: 44
(University of Florida),
Flavio Antonio Maës dos Santos20
Estimated H-index: 20
(State University of Campinas)
We compared the demography of the palm Euterpe edulis in a large forest fragment that is protected from palm harvesting with that in three smaller fragments where harvesting has occurred. Palms were censused from 2005 to 2007 in nine 30 m x 30 m plots in each forest fragment. Each individual was assigned to one of five stage classes: seedling, infant, juvenile, immature, and reproductive. Using summary matrices constructed for the fragments and a matrix for the population in the protected area, ...
4 Citations Source Cite
Published on Sep 1, 2015in Food Webs
Nigel E. Hussey21
Estimated H-index: 21
(University of Windsor),
M. Aaron MacNeil24
Estimated H-index: 24
(Australian Institute of Marine Science)
+ 3 AuthorsAaron T. Fisk47
Estimated H-index: 47
(University of Windsor)
Abstract To understand the effects of predator removal in marine ecosystems requires accurate estimates of trophic position and trophic structure that have been difficult to obtain to date. For example, most sharks are classified as diet generalists that feed around trophic position 4, but this classification contradicts observations of diverse feeding behaviour among large species, suggesting that trophic structure has been oversimplified among upper trophic level species. To test this assumpti...
22 Citations Source Cite
Published on Jan 1, 2015in Global Ecology and Conservation
Mauro Galetti42
Estimated H-index: 42
(Sao Paulo State University),
Ricardo S. Bovendorp8
Estimated H-index: 8
(Sao Paulo State University),
Roger Guevara15
Estimated H-index: 15
Abstract Defaunation can trigger cascading events in natural communities and may have strong consequences for plant recruitment in tropical forests. Several species of large seed predators, such as deer and peccaries, are facing dramatic population collapse in tropical forests yet we do not have information about the consequences of these extinctions for seed predation. Using remote camera traps we tested if defaunated forests have a lower seed predation rate of a keystone palm ( Euterpe edulis ...
35 Citations Source Cite
Published on Jul 1, 2015in Biological Conservation 4.66
Maíra Benchimol6
Estimated H-index: 6
(University of East Anglia),
Carlos A. Peres81
Estimated H-index: 81
(University of East Anglia)
Abstract Hydropower projects are rapidly expanding across lowland Amazonia, driving the conversion of large tracts of once-continuous forests into archipelagos embedded within a vast open-water matrix. Forest vertebrate populations thus become stranded in habitat islands, with their persistence governed by a combination of species life-history traits, habitat patch, and landscape context. We investigate the patterns of species extinction of 34 arboreal and terrestrial vertebrate species within t...
76 Citations Source Cite
Published on Dec 1, 2012in Current Zoology 2.39
Alistair S. Glen19
Estimated H-index: 19
(Landcare Research)
Numerous recent studies present evidence that Australian dingoes Canis lupus dingo can benefit native biodiversity by suppressing mesopredators and large herbivores. Allen and colleagues have challenged the reliability of this evidence. Al- though they make some valid criticisms, I question some of their assertions. While the existing evidence is inconclusive, I argue that to dismiss it completely would be just as dangerous as to embrace it uncritically. I aim to establish a middle ground (Curre...
9 Citations Source Cite
Published on Oct 1, 2015in Biological Conservation 4.66
Tim S. Doherty10
Estimated H-index: 10
(Edith Cowan University),
Chris R. Dickman55
Estimated H-index: 55
(University of Sydney)
+ 1 AuthorsEuan G. Ritchie26
Estimated H-index: 26
(Deakin University)
Invasive species have reshaped the composition of biomes across the globe, and considerable cost is now associated with minimising their ecological, social and economic impacts. Mammalian predators are among the most damaging invaders, having caused numerous species extinctions. Here, we review evidence of interactions between invasive predators and six key threats that together have strong potential to influence both the impacts of the predators, and their management. We show that impacts of in...
70 Citations Source Cite
Published on Nov 1, 2015in Biological Conservation 4.66
Deborah M. Visco2
Estimated H-index: 2
(Tulane University),
Nicole L. Michel9
Estimated H-index: 9
(University of Saskatchewan)
+ 3 AuthorsThomas W. Sherry33
Estimated H-index: 33
(Tulane University)
Tropical forest understory birds are declining globally for unknown reasons, indicating an urgent need to understand the causes. We review and synthesize studies investigating causes of these declines focusing on the Sarapiqui region of the Caribbean slope of Costa Rica. We discuss evidence for five potential causes of population declines motivated by current understanding of the effects of fragmentation, disturbance of remnant forests, climate change, and their possible interactions: (1) reduce...
9 Citations Source Cite
Published on Dec 1, 2015in Food Webs
Tomas Jonsson17
Estimated H-index: 17
(University of Skövde),
Sofia Berg5
Estimated H-index: 5
(Linköping University)
+ 1 AuthorsAlexander Pimenov10
Estimated H-index: 10
(University College Cork)
Abstract Global change continues to push individual species towards extinction and in many cases these species cannot be expected to disappear silently, without a trace, from the communities in which they reside. Importantly, the loss of certain species can trigger a cascade of secondary extinctions, resulting in further degradation of a system with potential effects on ecosystem functioning. It is thus crucial to better our understanding of the types of species which, if lost, will affect commu...
5 Citations Source Cite