Fragmented landscapes in Western Australia: Introduction
1993; Elsevier BV; Volume: 64; Issue: 3 Linguagem: Inglês
10.1016/0006-3207(93)90319-v
ISSN1873-2917
Autores Tópico(s)Species Distribution and Climate Change
ResumoAnthropogenic habitat fragmentation combined with differential defaunation triggers complex trophic cascades. Here we test a Fragmentation-Defaunation Cascade Hypothesis by examining how a medium-sized monkey population outbreak, occurring in a predator-free forest fragment, lead to the decline of a dominant plant. We computed long-term population dynamics of Euterpe edulis ("palmito") plants in a Brazilian Atlantic Forest landscape, where the palmito predator, capuchin monkey, becomes hyper-abundant in fragments devoid of monkey predators. Palmito plants (N = 1193) were marked and measured to define stage (height and diameter) categories in 2005, and then annually censused (2006–2015). Newly recruited plants within plots were marked and monitored throughout the 10-year period. Lefkovitch matrices for each transition year, population growth rate (λ), elasticity, and plant stage distribution showed a strong trend of demographic decline due to monkey lethal consumption of palm hearts. Indeed, λ calculations revealed that, by the end of the study period, palmito population was decreasing by 34% annually. A major shift in plant stage distribution occurred, in which the population became increasingly dominated by infants, while reproductives continuously declined, indicating that palmito will soon become extinct in this predator-free fragment. We conclude that differential defaunation in a forest fragment resulted insmall- and medium-sized mammal outbreaks negatively impacting the demography of a previously dominant host plant population. We posit that fragmentation-selective defaunation can disrupt animal communities, driving cascading effects which include plant demographic collapse and, potentially, severely altered forest community structure.
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