CAM Plants: Their Importance in Epiphyte Communities and Prospects with Global Change.

We question the view of a disproportionate importance of CAM among epiphytes and its role as a "key innovation" for epiphytism but do identify ecological conditions under which epiphytic existence seems to be indeed contingent on the presence of this photosynthetic pathway. Possibly divergent responses of CAM and C3 epiphytes to future changes in climate and land use are discussed with the help of experimental evidence, current distributional patterns, and the results of several long-term descriptive community studies. The results and their interpretation aim at stimulating a fruitful discussion on the role of CAM in epiphytes, under current and under altered climatic conditions in the future.