title: Vegetation-environment relationships based on a life-forms classification in a semiarid region of tropical Mexico.
abstract: 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-environment relationships were examined with Detrended Canonical Correspondence Analysis (DCCA). Ordination axes were interpreted mainly be altitude and soil moisture. Response curves of life-forms along these gradients were explored fitting generalized linear models (GLIM's). We believe that the life-forms approach for the study of vegatation-environment relationships is a valid alternative to the traditional species approach usually used in physiological 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.
authors.affiliation: Departamento de Biología, Universidad Autónoma Metropolitana- Iztapalapa, D.F. México. jazh@xanum.uam.mx
authors.forename: J A
authors.initials: JA
authors.lastname: Zavala-Hurtado
authors.forename: P L
authors.initials: PL
authors.lastname: Valverde
authors.forename: A
authors.initials: A
authors.lastname: Díaz-Solís
authors.forename: F
authors.initials: F
authors.lastname: Vite
authors.forename: E
authors.initials: E
authors.lastname: Portilla
mesh_terms: D017753:Ecosystem; D008800:Mexico; D015999:Multivariate Analysis; D010802:Phylogeny