Identification of crucial stepping stone habitats for biodiversity conservation in northeastern Madagascar using remote sensing and comparative predictive modeling

Abstract

Madagascar is a global biodiversity hotspot of conservation concern. The decline of natural forest habitats due to shifting cultivation has been one of the major land use changes during the last decades. We analyzed satellite images between 1990 and 2018 from northeastern Madagascar to evaluate the contribution of nine variables (e.g., topographic, demographic, forest protection) to explain past forest loss, predict future deforestation probabilities to define important areas that require further conservation attention. Forest cover declined by 21% since 1990 and the once continuous rain forest belt of the region is disrupted twice, in the center and at the southern limit of the study region. Status of forest protection and proximity to the forest edge were identified as most important predictors, but all variables contributed to explaining the observed pattern of deforestation. At least 20% of the 3136 villages in the area were established since 1990 at the expense of previously forested areas. This housing sprawl was mainly driven by accessibility, decreasing landscape connectivity. To conserve the unique biodiversity of the region, the expansion of protected forests and active reforestation measures are urgently needed. Sustainable land use planning and forest management integrating the needs of local land users and conservation priorities should be promoted. We see the highest potential for external stakeholders (e.g., national NGOs) to implement targeted interventions embedded in community-based approaches. Our land cover maps and predictive modeling highlight crucial areas that could act as stepping stone habitats for dispersing or retreating species and therefore important locations to intensify conservation measures.

Ecology and morphology of mouse lemurs (Microcebusspp.) in a hotspot of microendemism in northeastern Madagascar, with the description of a new species

“…These taxa share a narrow altitudinal range and a small estimated EOO. Alarmingly, lowland rainforest habitats have disappeared from most of the east coast and our study region is no exception (Schüßler et al, 2020; Vieilledent et al, 2018). Under these circumstances, population declines are unavoidable, and ongoing anthropogenic land‐use change and forest cover loss (Schüßler et al, 2020) will probably accelerate and increase this threat to the newly described species.…”

“…#3 occurs in one National Park, Mananara‐Nord NP, which is already isolated from surrounding forests. Anticipated environmental disruptions due to future climatic changes and the need for species to flexibly adapt to altered environments may be severely compromised, if conservation planning does not generate and maintain possible dispersal pathways for migrating species (Brown & Yoder, 2015; Schüßler et al, 2020).…”

“…Northeastern Madagascar is characterized by a humid climate with abundant precipitation (2,086 ± SD 530 mm SD; Fick & Hijmans, 2017) and tropical rainforests as primary vegetation (Kottek, Grieser, Beck, Rudolf, & Rubel, 2006). Forest cover has been steadily declining for decades, with lowland rainforests being particularly prone to deforestation (Schüßler, Mantilla‐Contreras, Stadtmann, Ratsimbazafy, & Radespiel, 2020; Vieilledent et al, 2018). By 2018, about half of the remaining forested areas were under protection by governmental institutions or nongovernmental organizations (Schüßler et al, 2020).…”

“…Forest cover has been steadily declining for decades, with lowland rainforests being particularly prone to deforestation (Schüßler, Mantilla‐Contreras, Stadtmann, Ratsimbazafy, & Radespiel, 2020; Vieilledent et al, 2018). By 2018, about half of the remaining forested areas were under protection by governmental institutions or nongovernmental organizations (Schüßler et al, 2020). The study region is subdivided by more than seven large rivers that flow from the highlands of the central plateau (west of the study region; Figure 1) eastwards into the Indian Ocean.…”

“…Map depicting the study region with confirmed species occurrences (Hotaling et al, 2016; Kappeler et al, 2005; Louis et al, 2006; Radespiel et al, 2008, 2012; Weisrock et al, 2010). New sampling locations for this study are indicated with “*” and forest cover in 2017/2018 was derived from Vieilledent et al (2018) and Schüßler et al (2020). NP, National Park; SNR, Special Nature Reserve; SR, Special Reserve…”