Identifying important areas for orchid conservation in Crete

Abstract

Crete is especially rich in orchids and their distribution is well known and documented by many floristic accounts. This information, however, is yet to be used to set conservation plans and priorities. We used MaxEnt incorporating both published and unpublished distribution data together with environmental variables to predict the potential distribution of orchids on Crete. The resulting probabilistic maps of species occurrence were used to identify the important areas for orchid conservation on the island. Sites prioritization was performed by applying a species weighting scheme, which was based on species niche breadth. The existence of ecological patterns determining site prioritization was determined using a regression tree analysis based on environmental variables and scores derived from Zonation analysis. The high importance sites were found on Mts Thripti, Ida and Lefka Ori, as well as at low altitude areas east of Heraklion and at the easternmost part of the island. Most of the variation in the site scores was explained by geological substrate, latitude and altitude. Based on the regression tree analysis, sites with the highest scores were at medium and high altitude areas, which are located at the interior of the island. These areas have soils mainly derived from limestones, ophiolites and deposits of calcareous rocks. The lack of a significant effect of vegetation type in explaining the distribution of high importance areas highlights the need for the establishment of micro-reserves for the conservation of orchids in Crete. Finally, endangered orchid species in need of specific conservation actions are indicated.