Tree species distribution in canopy gaps and mature forest in an area of cloud forest of the Ibitipoca Range, south-eastern Brazil

The tree community of both canopy gaps and mature forest was surveyed in a 5 ha plot of cloud forest in the Ibitipoca Range, south-eastern Brazil, aiming at: (a) comparing the tree community structure of canopy gaps with that of three strata of the mature forest, and (b) relating the tree community structure of canopy gaps with environmental and biotic variables. All saplings of canopy trees with 1-5 m of height established in 31 canopy gaps found within the plot were identified and measured. Mature forest trees with dbh greater than or equal to 3 cm were sampled in four 40x40 quadrats laid on the four soil sites recognised in the local soil catena. All surveyed trees were identified, measured and distributed into three forest strata: understorey (< 5 m of height), sub-canopy (5.1-15 m) and canopy (15.1-30 m). The following variables were obtained for each gap: mode of formation, age, soil site, slope grade, size, canopy openness and abundance of bamboos and lianas. A detrended correspondence analysis indicated that the tree community structure of gaps in all soil sites was more similar to that of the mature forest understorey, suggesting that the bank of immatures plays an important role in rebuilding the forest canopy and that gap phases may be important for understorey shade-tolerant species. There was evidence of gap-dependence for establishment for only one canopy tree species. Both canonical correspondence analysis and correlation analysis demonstrated for a number of tree species that the distribution of their saplings in canopy gaps was significantly correlated with two variables: soil site and canopy openness. The future forest structure at each gap is probably highly influenced by both the present structure of the adjacent mature forest and the gap creation event.