A biogeographical and ecological classification of orchids in Turkey

Abstract

Aims: With its diverse vascular flora Turkey is well-known as a bridge between the Mediterranean basin, the Caucasus, and the Irano-Turanian region. Orchids are an important component of this diversity with 191 taxa, of which 39 taxa are Turkish endemics. This study aims to group the country's orchid taxa into different phytogeographical regions, natural vegetation types, and altitudinal zones. Study area: Turkey. Methods: Field surveys were carried out from 1988 to 2017. The sampling areas were selected with good prior knowledge of orchid-containing terrains and habitats. Distribution data were revised and presented in a 10 km UTM grid. Geospatial data were classified and processed by ArcGIS software. Results: The Mediterranean region (70 taxa, 17 endemics) is the richest for orchid taxa distributed in only one phytogeographical region, followed by the Euro-Siberian (13 taxa, 2 endemics) and the Irano-Turanian (7 taxa, all endemics) regions. Species richness per habitat varied from Mediterranean landscapes of "natural Pinus brutia forests" (105 taxa, 12 endemics), followed by landscapes with "Quercus frainetto forest" (59 taxa, 3 endemics), "Oak-hornbeam forest" (55 taxa, 3 endemics), "Beech-spruce forest" (38 taxa, 1 endemic), "Quercus brantii forest steppe (arid)" (38 taxa, 5 endemics) to "Subalpine Juniper forest steppe" (34 taxa, 7 endemics). Orchids were found mainly at elevations of 0 to 500 m (138 taxa) and 501 to 1,000 m (123 taxa). At elevations over 1,000 m, the number of orchid taxa decreases, but 21 taxa were found at over 2,000 m. Some orchid taxa were found to be restricted to a particular altitudinal zone and phytogeographical region. Conclusion: This study provides a general framework for relevant orchid conservation efforts in Turkey. Key habitats from different phytogeographical regions and altitudinal zones should be prioritised. For such areas, a multi-layered conservation planning approach from country to habitat level across Turkey needs to be developed. Complementary approaches should be promoted in neighbouring countries too.