Forest conversion to agriculture such as coffee garden and rice field rapidly occured in the upper Way Besai watershed, Sumberjaya, Lampung, Indonesia which invo lved activities such as land clearing, soil tillage, planting, weeding and applying fertilizers and pest icides by farmers. Those activities affect the water quality along t he stream and river through sedimentation and accumulation of nutrients and pesticide residues.
Tag: gmelina arborea
Biomass equations for tropical tree plantation species using secondary data from the Philippines
Estimation of the magnitude of sinks and source s of carbon requires reliable estimates of the biomass of forests and of individual trees. Equations for predicting tree biomass have been developed using secondary data involving destructive sampling in plantations in several localities in the Philippines. These equations allow estimates of carbon sequestration to be made at much lower cost than would be incurred if detailed stand inventories were undertaken. The species included in the study reported here include Gmelina arborea, Paraserianthes falcataria, Swietenia macrophylla and Dipterocarp species in Mindanao;Leucaena leucocephala from Laguna, Antique, Cebu, Iloilo, Rizal, and Ilocos Sur, and Acacia mangium, Acacia auriculifor mis and G. arborea in Leyte. Non-linear regression was used to derive species-specific, site-specific and generic equations between yield and diameter of the form y = aDb . Equations were evaluated based on the correlation co efficient, standard error of the estimate and residual plots. Regressions result ed to high r values (>0.90). In some cases, non-homogeneous variance was encountered. The generic equation improved estimates compared with models used in previous studies.