干旱区生态环境知识资源中心

Taking the view that morphological characteristics represent behavioral strategies of plants to cope with environmental pressures, we defined 18 life-forms, using multivariate classification techniques in a tropical semiarid ecosystem in Central Mexico. A multiple discriminant analysis confirmed the existence of these groups. A null model of random membership of species to life-forms was significantly different from our classification. Vegetation-environ ment relationships were examined with Detrended Canonical Correspondence Analysis (DCCA). Ordination axes were interpreted mainly by altitude and soil moisture. Response curves of life-forms along these gradients were explored fit ting generalized linear models (GLIM’s). We believe that the life-forms approach for the study of vegetation-environment relationships is a valid alternative to the traditional species approach usually used in phytosociological research because: i) life-forms number was found to be an excellent species diversity predictor, ii) this approach enables considerable reduction in the bulk of data without losing ecological information, and iii) life-forms represent ecological strategies per se and, they constitute an index of the number of different ways the desert’s resources are utilized.