Vol.:(0123456789) 1 3 Rendiconti Lincei. Scienze Fisiche e Naturali https://doi.org/10.1007/s12210-020-00928-4 SOCOTRA BIODIVERSITY RESEARCH AND NATURE CONSERVATION Land productivity dynamics in Socotra Island (Yemen) Marcelo Rezende 1,2  · Tullia Riccardi 1  · Luca Malatesta 1  · Fabio Attorre 1  · Kay Van Damme 3 Received: 5 May 2020 / Accepted: 26 June 2020 © Accademia Nazionale dei Lincei 2020 Abstract Socotra, the largest of four islands in the Socotra archipelago (Yemen), is characterized by high geo-morphological and biological diversity. Traditional management of land resources has been impacted by cultural shifts, globalization and urban expansion. In addition, the island has been afected by climate impacts, such as droughts and recent cyclones causing signifcant economic and environmental damage. Our study presents an analysis of the dynamics of the vegetation on the island for the period 2001–2019 and highlights the status of diferent landscapes. We used Earth Observation techniques and the Normalized Diference Vegetation Index to assess land productivity dynamics basing on vegetation indexes derived from average resolution satellite images. The results show that although the arid landscapes of Socotra seem resilient, over 30% of the central mountainous areas of the Hageher (hosting a unique and high biodiversity) are decreasing in productiv- ity, whereas in the lowlands (where plant diversity is relatively lower) productivity has increased signifcantly for the same time period, up to 40% in some areas. Given the diference in biological diversity of the sites, this study can help prioritize conservation areas and activities, which are crucial for Socotra’s terrestrial environment. The methodology applied could be replicated for continuous monitoring in the future. Keywords Land productivity · NDVI · Remote sensing · Socotra 1 Introduction Island ecosystems are often rich in biodiversity and may harbor unique taxa (Kier et al. 2009), however, their biotas are vulnerable and face higher extinction risks than conti- nents because of the isolation and limited population sizes of endemic species (Caujapé-Castells et al. 2010). The Socotra archipelago, situated in the western Indian Ocean and part of the Republic of Yemen (Fig. 1), has been recognized as a UNESCO World Heritage Site for its high biodiversity, endemism and cultural importance (Cheung and DeVantier 2006; Van Damme and Banfeld 2011). Over the past decades, the archipelago has seen a rapid rise in tourism, infrastructure development, efects of global warm- ing and changes in traditional land-use practices, altering the Socotran landscape (Morris 2002; Miller and Morris 2004; Van Damme and Banfeld 2011; Scholte et al. 2011). The impact of diferent environmental and anthropic drivers has been extensively studied on Socotra, although, mostly focus- ing on their efect on species or communities (Attorre et al. 2007; Van Damme and Banfeld 2011; Madera et al. 2019). Isolation, limited access to the island and the conserva- tion eforts of the local community have contributed to the This paper belongs to a Topical Collection on “Twenty years of biodiversity research and nature conservation in the Socotra Archipelago” edited by Fabio Attorre and Kay Van Damme and originated at Socotra Conference (18th Friends of Socotra Conference), 26–29 September, 2019, Orto Botanico di Palermo, Palermo, Italy. Disclaimer The views expressed in this publication are those of the author(s) and do not necessarily refect the views or policies of the Food and Agriculture Organization of the United Nations. * Marcelo Rezende marceloarvore@gmail.com 1 Department of Environmental Biology, Sapienza - University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy 2 Food and Agriculture Organization of the United Nations, Via delle Terme di Caracalla, 00153 Rome, Italy 3 Senckenberg Research Institute and Natural History Museum Frankfurt, Senckenberganlage 25, 60325 Frankfurt am Main, Germany