ARIDITY INDEX AND ITS APPLICATIONS IN GEO-ECOLOGICAL STUDY
地理生态学的干燥度指数及其应用评述

The aridity Index (AI, here defined as the climatic aridity) is an index tha t de scribes the dry and wet conditions of a site. Historically, the AI has been ofte n used in long-term studies of geography and ecology. Recently it has became one of the most frequently used climatic factors in studies of global change, espec ially in studies of climate change, ariditification and desertification. A total of 22 AIs used worldwide were briefly introduced in this paper, and of thes e ei ght of the more commonly used AIs were evaluated. We discussed their princip les, c alculation methods, their applications in ecological and geographical studies, a nd the advantages and shortcomings of each indice were analyzed based on their a pplications and practice in China. Our analyses indicated that three AIs, th e mo dified Selianinov AI, the de Martonne AI and the Holdridge potential eva potranspiration ratio (another AI to some extent) have clear applicability and significa nce for physics and ecology. These AIs are suitable for characterizing the phys ical environment of China and can be used in future studies of climate change, a ridification and desertification in China.