THE EFFECT OF ABANDONED PLANTATIONS OF PINUS-PATULA AND CUPRESSUS-LUSITANICA ON SOILS AND REGENERATION OF A TROPICAL MONTANE RAIN-FOREST INCOLOMBIA

Species richness and diversity and soil physical and chemical properti es were compared between a mature lower montane rain forest (LMRF) and abandoned 21-year-old plantations of introduced Pinus patula and Cupr essus lusitanica in the central Andes of Colombia (2000 m). In 0.1 ha plots, species richness (number of species) and diversity (Shannon and Simpson indexes) were higher in the LMRF, followed by P. patula and C . lusitanica plantations. There were 56 species and 30 families of hig her plants in the LMRF, 26 species and 15 families in the P. patula pl antation, and 18 species and 10 families in the C. lusitanica plantati on. There were no statistically significant differences (p < 0.05) in soil physical or chemical properties between P. patula, C. lusitanica and native LMRF. Nevertheless, soil carbon, the C/N ratio and total ba ses tended to be higher in the native forest than in the plantations. Available P tended to be higher in the P. patula plantation. These res ults show that, although abandoned plantations can support some native species, particularly in the understorey, species richness is far fro m that of the native forest.