Species composition, diversity and structure of novel forests of Castilla elastica in Puerto Rico

Attributes of novel forests (secondary forests containing introduced species) were compared with those of native secondary forests of similar age. The study area was the biological reserve called El Tallonal, in Puerto Rico. Species composition, tree density, basal area and soil bulk density were characterized; Importance value index (IVI), Shannon's diversity index (H) and total aboveground biomass (TAGB) were calculated for stands of novel forests for Castilla elastica, an introduced naturalized tree. The IVI of C. elastica was 37 percent; that for Guarea guidonia, a native species, was 14 percent. Compared to native secondary forests, C. elastica forests had similar species richness (27 species in an area of 0.3 ha), low diversity (H' = 0.63) and tree density (1039 trees ha(-1)), moderate basal area (42 m(2) ha(-1)) and TAGB (216 Mg ha(-1)), and low soil bulk density (0.5 to 0.7 g cm(-3)). The structural features of novel forests of C. elastica are in the normal range of variation for those of native secondary forests in the tropics.