Distribution patterns, ecological characteristic and conservation status of endemic plants of Tadzhikistan - A global hotspot of diversity

摘要

Based on literature data and own fieldwork in Tadzhikistan (Middle Asia), the taxonomic structure, distribution, habitat preferences as well as conservation state of a group of 1486 species of vascular plants of endemic and sub-endemic character are presented. In addition to verifying the number of endemics, the present study has shown that Tadzhik endemics are the most numerous in the northwest of the country, in the Gissar-Darvasian and Zeravshan regions. An analysis of average richness of endemics per surface unit has revealed that Gissar-Darvasian F is the richest area. An assessment of the taxonomic similarity of geob-otanical regions based on endemic species composition has shown that differences in general correspond to the geobotanical subdivision of Tadzhikistan. The endemics studied are stenochoric species with a distributional area for endemics sensu stricto varying between ca. 486 and 111 ,489 km~2 (average 12,478 km~2) and between 11,830 and 349,473 km~2 (mean 74,097 km~2) for sub-endemics. The habitats harbouring the richest group of endemics are steppes and semi-savannas, alpine forests, xerothermophilous shrubs, alpine meadows and swards. The most numerous endemic groups have been recorded from altitudes of around 1800, 2000 and 2500 m above sea level. The most important threats to Tadzhik endemics are intensive grazing and erosion of soils, as well as denudation. Vegetation types most vulnerable to human impact are forest and scrub communities. For effective protection of endemics a greater involvement of international organisations as well as legal and organisational changes in the Republic of Tadzhikistan are needed.