Circular distribution of an epiphytic herb on trees in a subtropical rain forest

The distribution of the endangered epiphytic orchid Lepanthes eltoroensis on the bole of trees was investigated in the Yunque National Forest, Puerto Rico. Using circular statistics, we evaluated if there was preference for cardinal position on the bole of trees along two trails (Tradewinds and El Toro). In addition we tested if larger trees had larger population, and if the distribution of the orchids varied between the two walking trails. Orchids were preferentially distributed on the northwestern side of the bole of trees. Moreover, we found no evidence that the size of trees affected the number of individual orchids. This survey suggests that there is a preference for specific cardinal position on trees for the orchid and thus relocation or establishment of new populations should consider this information to maximize survivorship of this rare orchid.