Geodaysit 2023

Cristina Giacoma


A Possible Role of NDVI Time Series from Landsat Mission to Characterize Lemurs’ Habitats Degradation in Madagascar
Enrico Borgogno-Mondino, Federica Ghilardi, Samuele De Petris, Valeria Torti, Cristina Giacoma

Deforestation is one of the main drivers of environmental degradation around the world. Slash-and-burn is a common practice, performed in tropical forests to create new agricultural lands for local communities. In Madagascar, this practice affects many natural areas including lemurs’ habitats. Reforestation within natural reserves is desirable combining native species with fast-growing ones, aiming at habitats restoration. In this context, the extensive detection of forest disturbances can effectively support restoration actions, providing an overall framework to address priorities and maximizing ecological benefits. In this work and with respect to a study area located around the Maromizaha New Protected Area (Madagascar), an analysis was conducted based on a time series of NDVI maps from Landsat missions (GSD = 30 m). The period 1991-2022 was investigated to detect location and moment of forest disturbances with the additional aim of quantifying the level of damage and of the recovery process at every disturbed location. It is worth to remind that the Maromizaha New Protected Area presently hosts 12 species of lemurs. Detection was operated at pixel level by analyzing the local temporal profile of NDVI (yearly step). Time of the eventual detected disturbance was found within the profile looking for the first derivative minimum. Significance of NDVI change was evaluated testing the Cebyšëv condition and the following parameters mapped: (i) level of damage; (ii) year of disturbance; (iii) year of the eventual “total” recovery; (iv) rate of recovery. Finally, temporal trends of both forest lost and recovery were analyzed to investigate potential impacts onto local lemurs population and, more in general, to the entire Reserve.

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