Forest fragmentation affects early successional patterns on shifting cultivation fields near Indian Church, Belize

摘要

This study examines whether vegetation and soils sampled in slash-and-burn fields in an agricultural landscape near Indian Church, Belize varied as a function of cropping status (in use, 1-2 year fallow, 3-10 year fallow) and distance to older forest (adjacent to or >150 m from forest). Multi-response permutation procedures (MRPPs) indicated that species composition (woody species density, herbaceous species cover) differed significantly among all treatments (woody: P = 0.006; herbaceous: P = 0.0001) and between distance classes (woody: P = 0.03; herbaceous: P = 0.002). The frequency of herbaceous life forms also differed between distance classes (MANOVA: P = 0.04), with lianas (P = 0.03) and legumes (P = 0.008) being more common at greater distances from forest. Soil macronutrients (P, K) were significantly lower in long-term fallows than in use fields due to sequestration by the regenerating vegetation but ammonium nitrogen was significantly lower far from older forests (two-way ANOVA: P < 0.05). Despite these differences in vegetation and soil characteristics, there were no significant differences in species diversity (richness, evenness) or vegetation structure (woody density, frequency, basal area) as a function of distance to forest (two-way ANOVA: P > 0.05), most likely due to seed inputs from surrounding early successional habitats. This study indicates that changes in landscape structure may influence ecological processes such as succession in fragmented tropical landscapes and underscores the need to reject a conceptualization of the landscape matrix as a featureless, inhospitable habitat in favor of one that recognizes and incorporates the influence of matrix quality and heterogeneity.