Influence of the soil on the spatial structure of forest species – preliminary results in a terra firme secondary forest plot, Amapá, Brazil
In recent years there has been increasing interest in the relationships between edaphic factors in tropical forests due to the complexity and the dynamic nature of plant interactions with the physical environment. This research sought to investigate the correlation of edaphic factors with the spatial distribution patterns of the 16 main tree species in a dense ombrophilous forest of terra firme in Macapá, Amapá, Brazil. Forty subplots along a topographic gradient were installed for floristic studies as well as to collect composite soil samples. The spatial distribution pattern was described by the Payandeh and Morisita indexes. Canonical correspondence analysis (CCA) and geostatistical techniques were used to describe the relationship between species distribution and environmental variables. It was confirmed that the factors influencing the spatial behaviour of plants in the vegetation can be associated with both the endogenous (dispersion mode) and exogenous (the environmental conditions to which they are subjected) processes. Variations in spatial distribution patterns of species in relation to existing environmental heterogeneity were observed based on the CCA, mainly associated with the contents of pH, potential acidity, organic matter (OM), phosphorus (P) and potassium (K) in soil. Finally, based on ordinary kriging there was evidence that the OM contents in the soil presented a spatial dependence structure in the vegetation. Our findings show that natural disturbances (e.g. natural fall of trees) and human land use (e.g. logging) induce changes in species composition and abiotic resource availability. The results highlight the importance of understanding the processes that influence the strengthening of environment–plant interactions by the lasting effects of successional recovery.
Keywords: canonical correlation, geostatistics, ombrophilous forest, soil-ve getation relationship