Studies on the Biomass and Productivity in a Series of Montane Rain Forests in Jamaica

Abstract

(1) The biomass of the standing crop in five Upper Montane forest-types in Jamaica was estimated for forty-four plots of 10 x 10 m size. Two plots were destructively sampled, one in Mor Ridge forest and one in well-developed Mull Ridge forest. (2) The total above-ground biomass (kg m-2) of each forest-type was estimated from regression equations derived from the total above-ground tree biomass on tree area at breast height: 22.9 in Mor Ridge forest, 31-2 in Mull Ridge forest, 40.7 in well-developed Mull Ridge forest, 23.0 in Wet Slope forest and 23.8 in Gap forest. (3) Regression equations derived for tree leaf biomass on tree area at breast height were not used to predict tree leaf biomass because of the large amount of variability present in the data. (4) Below-ground biomass was determined only in Mor Ridge forest. An area of 3.5 x 50 m was excavated; the biomass of roots and underground stems was estimated as being 5-4 kg m (5) The biomass of seedlings and saplings, tree ferns, herbs, climbers, epiphytes, hemi-parasites and standing dead trees was also determined. (6) The total leaf area index was 5-5 in the Mor Ridge forest plot and 5.7 in the well-developed Mull Ridge forest plot. (7) First estimates by dendrometers of increase in live biomass of the standing crop (kg m-2 yr-1) were: c. 0-05 in Mor Ridge forest, c. 0.10 in Mull Ridge forest, c. 0 20 in Wet Slope forest and c. 0.35 in Gap forest. Estimates of loss of live aboveground biomass of the standing crop (kg m-2 yr-1) were: c. 0-20 in Mull Ridge forest, c. 0-27 in Wet Slope forest and c. 0-06 in Gap forest. (8) Comparison of the Jamaican montane forests with other tropical forests shows that as one ascends wet tropical mountains there is proportionately a greater reduction in forest canopy height than in total above-ground biomass. In contrast, leaf biomass is not less in forests at higher altitudes.