Comparison of estimated forest biomass increment rate based on a process-based ecological model and forest inventory data

Based on a remote sensing driven,processed-based ecological model(Boreal Ecosystem Productivity Simulator,BEPS),National Forest Continues Inventory(NFCI) data(surveyed in 2001 and 2006) and Forest Management Inventory(FMI) data(surveyed in 2003 and 2009),the forest annual biomass increment rate in Ji'an city was calculated,respectively.The differences among the forest biomass increment rates estimated using these three different methods were analyzed for various spatial scales and forest types.Our results showed that at the plot scale the forest biomass increment rate(4.18 Mg·hm-2·a-1) simulated by the BEPS model was close to the overstory biomass increment rate(OBIR,4.29 Mg·hm-2·a-1),and lower than the biome biomass increment rate(BBIR,5.86 Mg·hm-2·a-1) estimated using the NFCI data.The R2of OBIR and BBIR simulated by the BEPS model against estimates with the NFCI data were 0.43 and 0.48,respectively.The regional mean forest biomass increment rate simulated by the BEPS model was 4.65 Mg·hm-2·a-1while the OBIR and BBIR estimated using the FMI data were 4.36 and 3.34 Mg·hm-2·a-1,respectively.The R2values of county-level forest biomass increment rate simulated by the BEPS model against OBIR and BBIR were 0.84(p0.01) and0.83(p0.01),respectively.The OBIR and BBIR estimated using the NFCI data were higher than those estimated using the FMI data.The forest biomass increment rate simulated by BEPS modeled was close to the OBIR value based on NFCI and the CBIR value based on FMI.As to two dominant forest types,evergreen broadleaf forests grow faster than evergreen coniferous forests.The agreement between simulated and estimated forest biomass increment rate is better for evergreen coniferous forests than for evergreen broadleaf forests.This study confirms that the output from BEPS can be used for updating forest biomass.