A system to monitor climate change with epilithic lichens

The issue of biological monitoring of the local consequences of anticipated global climate change is considered for the Central Negev Highlands, Israe l. Epilithic lichens are suggested as biological monitors. The proposed met hodology of such monitoring consists of a sampling scheme, including lichen measurement along transects on flat calcareous rocks, and construction of a trend detection index (TDI). TDI is a sum of lichen species cover with co efficients chosen so as to ensure maximum ability to detect global climate trends. Coefficients have been estimated in a study of Lichens along an alt itudinal gradient from 500 to 1000 m a.s.l. The gradient study demonstrated that the TDI index is performed better than other integrated indices. Reco mmendations on this system to monitor climate change with epilthic lichens are given. Measuring, for instance, a hundred transects in fifty plots (two transet per plot scheme) allows one to detect a climate-driven change in t he epilithic lichen community corresponding to a 0.8 degrees C shift in ann ual mean temperature. Such resolution appears sufficient in view of global warming of 2.5 degrees C considered by the Intergovernmental Panel on Clima te Change as a realistic prediction for the end of the next century.