DISTRIBUTION AND IMPORTANCE OF SOME ENDEMIC Astragalus L. SPECIES IN SEMI-ARID ENVIRONMENTALLY SENSITIVE AREAS: A CASE STUDY FROM NORTHERN TURKEY
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The objective of this study is to determine the distribution of some endemic Astragalus L. (Astragalus anthylloides Lam., Astragalus lycius Boiss. and Astragalus xylobasis var. angustus (Freyn&Sint.) Freyn&Bornm.) species, and the interaction between soil and climatic characteristics and desertification risks which are effective in the distribution of these species in a semi-arid environment in Çankırı, northwest Turkey. During the vegetation period in 2017, soil and plant samples were collected from 180 points. Desertification Risk (DR) and Environmentally Sensitive Area Index (ESAI) were calculated for each sampling point using Desertification Indicator System for Mediterranean Europe (DIS4ME). Because of calculations using DIS4ME system, A. anthylloides and A. lycius in the forest areas where species were distributed, DR was lowest with 0.49 with no risk and highest with 3.73 as moderate risk, and with an average of 2.20 in the field as low risk. For A. xylobasis var. angustus, DR levels ranged from lowest to highest at 5.01 and highest at 5.42 in grassland. The values of ESAI type ranged from 1.34-1.50 in the forest areas where the species A. anthylloides and A. lycius were distributed, and they ranged between 1.33 and 1.47 for A. xylobasis var. angustus in the ranged grassland areas. The result of the correlation analysis between the DR and Astragalus L. species changes according to the land use types and distribution of plants. When the relationship between all the three species of DR evaluated together, these endemic species emerged as the indicator plant species to determining desertification status.