Improved allometric equations for tree aboveground biomass estimation in tropical dipterocarp forests of Kalimantan,Indonesia

Background： Currently, the common and feasible way to estimate the most accurate forest biomass requires ground measurements and allometric models.Previous studies have been conducted on allometric equations development for estimating tree aboveground biomass（AGB） of tropical dipterocarp forests（TDFs） in Kalimantan（Indonesian Borneo）.However, before the use of existing equations, a validation for the selection of the best allometric equation is required to assess the model bias and precision.This study aims at evaluating the validity of local and pantropical equations; developing new allometric equations for estimating tree AGB in TDFs of Kalimantan; and validating the new equations using independent datasets.Methods： We used 108 tree samples from destructive sampling to develop the allometric equations, with maximum tree diameter of 175 cm and another 109 samples from previous studies for validating our equations.We performed ordinary least squares linear regression to explore the relationship between the AGB and the predictor variables in the natural logarithmic form.Results： This study found that most of the existing local equations tended to be biased and imprecise, with mean relative error and mean absolute relative error more than 0.1 and 0.3, respectively.We developed new allometric equations for tree AGB estimation in the TDFs of Kalimantan.Through a validation using an independent dataset,we found that our equations were reliable in estimating tree AGB in TDF.The pantropical equation, which includes tree diameter, wood density and total height as predictor variables performed only slightly worse than our new models.Conclusions： Our equations improve the precision and reduce the bias of AGB estimates of TDFs.Local models developed from small samples tend to systematically bias.A validation of existing AGB models is essential before the use of the models.

The Dependency of Coastal Livelihood on Forest Resources, and Alternative Options in the Periphery of the Sundarbans Reserve Forest, Patharghata, Bangladesh

Dependency on forest resources poses a threat to the environment in Patharghata, Bangladesh. Therefore, this study explores the role of forest resource in the life and livelihood of coastal people as well as to understand the effectiveness of forest and status of forest dependency in and around south-central coast in Patharghata, Bangladesh. We collected data randomly from 105 household heads through both open and close-ended questionnaire. To investigate the forest dependency and people’s perception regarding alternative solutions, Microsoft excel software program has been applied. The findings reveal that usage of fuelwood in cooking, housing structure, fish catching, honey & fodder collection significantly contributes to household dependency on forest resources, while other variables seem to be insignificant. Our study amplifies that the share of forest income to the total household income was only 19% while other earning sources provided 81% income. The result shows that respondent people collect forest resources primarily for cooking purpose with a share of 71% where 9% forest resources are collected as fodder followed by 8% forest resource collection as food and sheltering purposes. Moreover, the study found that using alternative cooking system, artificial instruments, declaring the forest as tourist spot, changes in housing structure, occupation are some effective options to reduce forest dependency. The study concludes that these alternative options need more financial and other support from the government, non-government and other civil society organizations to cut down forest resource dependency.