Regional Biodiversity Planning and Lemur Conservation with GIS in Western Madagascar

Abstract

Primary forest cover in western Madagascar declined from 12.5% in 1950 to 2.8% in 1990. Approximately 23% of remaining forest is located within reserves, but this is no guarantee of protection. Forest cover in the Andranomena Reserve in western Madagascar has been reduced by 44% since 1950. The identification of priority areas for establishment of development projects has been constrained by lack of information on the distribution, abundance, and habitat requirements of threatened species and the size, condition, and threats to survival of forest remnants. We evaluate a rapid fauna survey and habitat modeling procedure specifically designed to generate information for reserve selection and design using Geographical Information Systems (GIS). The study was conducted in the largest remnant (94,000 ha) of primary monsoon rainforest in western Madagascar, using lemurs as an indicator group. Lemur abundance and microhabitat variables were measured at 64 stratified survey sites dispersed throughout the region. These records were incorporated into a GIS with other environmental and landuse data derived from maps and satellite imagery. Statistical procedures were applied to analyze species habitats, predict and map species distributions, and estimate species population sizes throughout the study area. Patterns of slash and burn agriculture and anthropogenic disturbance were also analyzed to identify areas at low risk of cultural disturbance. A map of disturbance risk was overlaid with a map of relative lemur biodiversity to identify conservation priority areas with high biodiversity and low risk of short term disturbance. Lemur diversity was most strongly influenced by habitat clearing and human disturbance (harvesting, stock grazing, and hunting) within 8 km of villages. Lemur diversity was highest in a region of higher elevation and rainfall, distant from villages and roads. The only existing reserve in the study area was located in a region of high disturbance risk. Almost half the reserve has been degraded during the past 45 years. There is considerable scope for re‐allocation of land use within the study area to include a core protected area, a buffer zone with controlled hunting and timber harvesting, and an adjacent ecotourism facility. We found that information generated by a stratified biodiversity and landuse survey at a sampling intensity of less than 0.1% was sufficient to provide an objective foundation for regional biodiversity planning.

Analysis of deforestation patterns in the central Menabe, Madagascar, between 1973 and 2010

“…Although their study periods are not directly comparable to ours and their forest definition seems to be broader than the one we applied, the magnitude of annual deforestation rates corresponds to our results (Table 3), with a general acceleration over the years despite the fact that forest clearance for agriculture has been illegal since 1987 (Décret no 87-143, 20 April 1987 by the Ministère de l'Environnement, des Eaux et Forêts). Deforestation of the area was already documented by Smith (1997) and Smith et al (1997). Deforestation in Menabe is regarded as an almost irreversible process, because these forests have poor regenerative power due to the scarcity or lack of secondary colonizing species and Fig.…”

“…\Reasons for deforestation are manifold as in other parts of Madagascar (Brooks et al 2009;Gorenflo et al 2011). In the case of central Menabe, forest clearance for agriculture is the most important proximate factor (Smith 1997;Smith et al 1997). This is particularly obvious in the vicinity of already existing slash-and-burn areas such as the hatsake of Lambokely, Kirindy Village, Beroboka North and South and Marofandilia.…”

“…This accounts for the lower ecological value of second-growth forests (lower floral and faunal diversity), since the species composition of plant and animal communities often differs between secondary and old-growth forests (Chazdon 2003;Dunn 2004;Lugo and Helmer 2004;Gardner et al 2007). The ecological value of secondary forest in the central Menabe has not been studied in detail (Sorg 2006), but by comparing largely undisturbed and secondary forests in the region, it became obvious that lemur diversity and population sizes are lower in secondary forests and endemic species, such as Madame Berthe's mouse lemur or the giant jumping rat depend on dense old-growth dry forest and are not found in secondary regrowth (Smith 1997;Smith et al 1997;Ganzhorn et al 1999;Sommer et al 2002;Dammhahn and Kappeler 2008).…”

Berenty 2006: Census of Propithecus verreauxi and Possible Evidence of Population Stress

“…Lemur density varies with the type and level of habitat perturbation (Ganzhorn 1995;Smith et al 1997). Lower densities are usually associated with heavy disturbance because disturbance can affect food availability, as observed in Propithecus edwardsi and Varecia variegata variegata (Lehman et al 2006a), Avahi meridionalis meridionalis (Norscia 2008), and Eulemur collaris (Ralison et al 2006).…”

Habitat evaluation of wild Amur tiger (Panthera tigris altaica) and conservation priority setting in north-eastern China

“…This study uses GIS that integrates various spatial data including current information on prey occurrence and/or abundance, vegetation, roads, human settlements, etc. to conduct the GAP analysis (Smith et al, 1997;Wang et al, 2008). The model also served to identify protection and management gaps by comparing existing nature reserves with core habitats including the most suitable and highly suitable habitats.…”