Large-Scale Habitat Corridors for Biodiversity Conservation: A Forest Corridor in Madagascar

Abstract

In biodiversity conservation, habitat corridors are assumed to increase landscape-level connectivity and to enhance the viability of otherwise isolated populations. While the role of corridors is supported by empirical evidence, studies have typically been conducted at small spatial scales. Here, we assess the quality and the functionality of a large 95-km long forest corridor connecting two large national parks (416 and 311 km2) in the southeastern escarpment of Madagascar. We analyze the occurrence of 300 species in 5 taxonomic groups in the parks and in the corridor, and combine high-resolution forest cover data with a simulation model to examine various scenarios of corridor destruction. At present, the corridor contains essentially the same communities as the national parks, reflecting its breadth which on average matches that of the parks. In the simulation model, we consider three types of dispersers: passive dispersers, which settle randomly around the source population; active dispersers, which settle only in favorable habitat; and gap-avoiding active dispersers, which avoid dispersing across non-habitat. Our results suggest that long-distance passive dispersers are most sensitive to ongoing degradation of the corridor, because increasing numbers of propagules are lost outside the forest habitat. For a wide range of dispersal parameters, the national parks are large enough to sustain stable populations until the corridor becomes severely broken, which will happen around 2065 if the current rate of forest loss continues. A significant decrease in gene flow along the corridor is expected after 2040, and this will exacerbate the adverse consequences of isolation. Our results demonstrate that simulation studies assessing the role of habitat corridors should pay close attention to the mode of dispersal and the effects of regional stochasticity.

Unexpectedly diverse forest dung beetle communities in degraded rain forest landscapes in Madagascar

“…More than half of the forest cover in Madagascar was already lost by the 1950s, but most of the deforestation in our study area has happened after that (Allnutt et al, ; Harper et al, ). During the time period of 1990–2005, the deforestation rate in the study area was around 1.3%–1.5% per year (Puhakka, ), and in a nearby forest corridor between the Ranomafana and Andringitra National Parks in 2000–2012, the annual deforestation rate was estimated as 0.88 and 1.5% in degraded and primary forest, respectively (Ramiadantsoa, Ovaskainen, Rybicki, & Hanski, ). Certain species of lemurs are known to be able to survive in fragments and degraded habitats between Ranomafana and Vatovavy, although in reduced numbers (Dehgan, ; Holmes et al, ).…”

Impending extinction crisis of the world’s primates: Why primates matter

“…A recent study of the fauna, including lemurs, of a 90-km-long biodiversity corridor connecting two national parks in Madagascar showed the need to differentiate among passive dispersers (species that settle randomly around the source population), active dispersers (species that settle only in favorable habitats), and gap-avoiding dispersers (species that avoid dispersing across nonhabitat areas). Thus, a better understanding of the natural history of different primates is critical to identify which taxa might be sustained within forested corridors and those for which no substitute or alternative habitat exists ( 127 ). …”

State‐ and Regional‐Scale Patterns and Drivers of Freshwater Fish Functional Diversity in the Southeastern USA

“…; Ramiadantsoa et al. ). However, the systematic and informative collection of pertinent ecological or biological data over regional or landscape scales of relevance is often unfeasible due to time, funding, and resource constraints.…”