Floristic and structural changes during old-field succession in the Mexican tropics in relation to site history and species availability

Abstract

Community patterns along a successional sequence of abandoned fields within a tropical rain forest environment are described in terms of floristic composition and structure. Temporal patterns were summarized and main axes of variation extracted by multivariate methods. External factors – length of cropping period, regrowth age, and proportion of the perimeter occupied by forest communities or remnants (here called forested perimeter) – were related to floristic and structural data on 40 sites. Multivariate direct gradient analysis showed overall floristic development to be positively related to regrowth age and forested perimeter, and negatively related to length of cropping period. Structural development was shown by multiple regression to be positively related to regrowth age and negatively to length of cropping period; but forested perimeter had no significant relation to site structure. The type of crop grown showed no significant relation with floristic or structural development of the regrowth. These results indicate that the conditions of the vegetation around a site have a great effect on community recovery, particularly in its species composition, whilst structure seems to be affected more directly by parameters which imply time.