INCAS Standard Method – Forest Growth and Turnover

The Standard method—forest growth and turnover: describes the process used by the INCAS for defining the forest growth and turnover used as inputs for quantifying GHG emissions and removals from activities occurring on forestlands in Indonesia. This includes data collation, data analysis, quality control, and quality assurance.

Rate of growth, turnover of above-ground and below-ground biomass, and decomposition rate of debris are quantified for each component of each biomass class. This is based on information collated from time-series measurement data from permanent measurement plots (PMP) established in logged-over forests and other forest inventory data. This includes permanent sample plots established specifically for long-term research to monitor forest growth/increment and stand dynamics. This is in addition to data and information available in published literature, including research reports. Time-series data obtained from permanent sample plots established in logged-over forests were analysed to quantify above-ground mass increment over time after logging.

All data from inventory and research plots as well as information available from the literature were reviewed through a quality control process, to ensure only valid data were used.

Calculations of above-ground biomass were carried out using the approach described in the monograph and guidelines on allometric models for estimating tree biomass at various forest ecosystem types in Indonesia. Please see monograph here. Information available from stand yield tables were also re-analysed to produce average growth curves of various site index classes for each plantation species. Regression models that form the sigmoid curve of growth (i.e. Weibull, root, modified exponential, logistic, logistics power, Gompertz, two-exponential association, three-exponential association) were tested to generate growth curves. The final selection was based on a combination of statistical and logical criteria. These analyses are documented in the INCAS growth database.

Full details of the Standard method—forest growth and turnover are available here.