Sustainable Land Use Management Needed to Conserve the Dragon’s Blood Tree of Socotra Island, a Vulnerable Endemic Umbrella Species

Petr Maděra,Jan Vybíral,Josef Divín,Hana Kalivodová,Daniel Volařík,Samuel Lvončík,Martin Rejžek,David Jeník,Pavel Hanáček,Abdullateef Saad Amer,Zdeněk Patočka,Petr Vahalík

doi:10.3390/su11133557

Abstract

Unsustainable overgrazing is one of the most important threats to the endemic and endangered population of dragon’s blood tree (Dracaena cinnabari) on Socotra Island (Republic of Yemen). However, there is a lack of information about the exact population size and its conservation status. We estimated the population size of D. cinnabari using remote sensing data. The age structure was inferred using a relationship between crown projection area and the number of branch sections. The conservation importance of each sub-population was assessed using a specially developed index. Finally, the future population development (extinction time) was predicted using population matrices. The total population size estimated consists of 80,134 individuals with sub-populations varying from 14 to 32,196 individuals, with an extinction time ranging from 31 to 564 years. Community forestry controlled by a local certification system is suggested as a sustainable land management approach providing traditional and new benefits and enabling the reforestation of endemic tree species on Socotra Island.

Highlights

Socotra Island is the largest island (3600 km2 ) in the Socotra Archipelago (Figure 1).This archipelago is continental in origin and was separated from Africa during the middle Miocene at about 17 Ma [1], at which time pre-adaptation of the modern lineage of Dracaena to arid environments started [2]
Community forestry controlled by a local certification system is suggested as a sustainable land management approach providing traditional and new benefits and enabling the reforestation of endemic tree species on Keywords: Soqotra; population decline; overgrazing; Conservation Importance Index
The objectives of the present study were to document the abundance of D. cinnabari as accurately as possible using remote sensing and ground data, and to evaluate the conservation importance of its overall population and sub-populations including the modelling of extinction time

Summary

Introduction

Socotra Island is the largest island (3600 km2 ) in the Socotra Archipelago (Figure 1). This archipelago is continental in origin and was separated from Africa during the middle Miocene at about 17 Ma [1], at which time pre-adaptation of the modern lineage of Dracaena to arid environments started [2]. The climate of Socotra Island is in accord with its occurrence in the arid tropical zone [3], with the island hosting xeromorphic, desert and semi-desert plant communities [4,5,6,7,8]. The main source of livelihood for its inhabitants has been raising goats and sheep, and, less frequently, cattle and camels [4]

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