Fig. 1
Plant functional types map of deciduous trees and shrubs derived from MODIS land cover data. Areas in white represent open water and other areas outside the study area.
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Table 1. Carbon allocation coefficients and specific leaf area parameters used in IBIS
Tropical broadleaf drought-deciduous trees0.300.500.2025Temperate broadleaf cold-deciduous trees0.300.500.2025Boreal broadleaf cold-deciduous trees0.300.500.2025Boreal conifer cold-deciduous tree0.300.500.2025Cold-deciduous shrubs0.450.200.3525
Fig. 2
The locations of biomass sampling plots collected in this study.
Fig. 3
Histogram to indicate frequency distribution of parameters derived from Bayesian Markov chain Monte Carlo inversion. l 0, s 0 and r 0 are carbon allocation coefficients to leaf, stem and root for non-limiting condition. The insets show the frequency distributions of parameters with smaller X-axis range.
Table 2. Comparison of the inversely predicted carbon allocation coefficients under the optimal environments
Tropical broadleaf drought-deciduous trees0.420±0.004a0.413±0.009a0.167±0.008aTemperate broadleaf cold-deciduous trees0.334±0.007b0.385±0.009b0.281±0.004bBoreal broadleaf cold-deciduous trees0.363±0.003c0.344±0.004c0.292±0.003cBoreal conifer cold-deciduous tree0.409±0.002d0.334±0.004d0.258±0.004dCold-deciduous shrubs0.296±0.018e0.387±0.020e0.317±0.004e
Fig. 4
Root-mean-square error (RMSE) (a) and coefficient of determination (R 2) (b) of LAI simulations based on two allocation methods. The LAIRACA refers to the LAI simulated by the resource availability carbon allocation model. The LAIIBIS refers to the LAI simulated by the original IBIS carbon allocation coefficients. The letters above the bars indicate the significance of the differences between the LAI estimates (p<0.05).
Fig. 5
Difference between the simulated maximum leaf area index (LAI) and satellite-based maximum LAI (LAIRS). (a) and (b) are the spatial and frequency distributions of difference between the maximum LAI simulated using the resource availability carbon allocation model (LAIRACA) and LAIRS, respectively. (c) and (d) are the spatial and frequency distributions of difference between the maximum LAI simulated by the original IBIS (LAIIBIS) and LAIRS, respectively.
Fig. 6
Root-mean-square error (RMSE) of aboveground biomass simulations by the IBIS model. IBISRACA denotes IBIS model with resource availability carbon allocation model. The IBIS denotes the original IBIS model with constant carbon allocation coefficients. The ‘n’ above the bars is the site number for model validation.
Fig. 7
Spatial distribution of the annual mean (ANN) light (L), water (W) and nitrogen (N) availabilities from 2000 to 2006 (a–c) and in March–May (MAM) (d–f), June–August (JJA) (g–i), September–November (SON) (j–l) and December–February (DJF) (m–o).
Fig. 8
Spatial distribution of the annual mean (ANN) carbon allocation ratios to leaf (aleaf), stem (astem) and root (aroot) from 2000 to 2006 (a–c) and in March–May (MAM) (d–f), June–August (JJA) (g–i), September–November (SON) (j–l) and December–February (DJF) (m–o).
Fig. 9
Allocation fractions for leaf, stem and root components as functions of light (L) and minimum value of water and nitrogen (WN) availabilities for five deciduous plant functional types.
Fig. 10
Carbon allocation ratios (a–e) in a number of terrestrial ecosystem models (CASA (Potter et al., 1993); IBIS (Foley et al., 1996; Kucharik et al., 2000); Hybrid (Friend et al., 1997); Post's model (Post et al., 1997); CASA-DGVM (Potter and Klooster, 1999); Biome-BGC (White et al., 2000); Hyland (Levy et al., 2004); CASACNP (Wang et al., 2010); VISIT (Ise et al., 2010). Carbon allocation ratios of resource availability carbon allocation (RACA) model (f–j) were compared with the terrestrial ecosystem models. r 0, s 0 and l 0 are the carbon allocation ratios for plant grown under non-limiting conditions.
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Table 3. Comparison of the annual mean resource availability carbon allocation coefficients under the limiting condition
Tropical broadleaf drought-deciduous trees (TrBD)0.453±0.094a0.269±0.170a0.278±0.084aTemperate broadleaf cold-deciduous trees (TeBD)0.282±0.061b0.356±0.147c0.362±0.139bBoreal broadleaf cold-deciduous trees (BoBD)0.338±0.091c0.300±0.098b0.362±0.111bBoreal conifer cold-deciduous tree (BoND)0.392±0.033d0.253±0.051a0.355±0.062bCold-deciduous shrubs (ShrD)0.222±0.059e0.192±0.099d0.586±0.153c