Comparison of modeling approaches for carbon partitioning: Impact on estimates of global net primary production and equilibrium biomass of woody vegetation from MODIS GPP
Comparison of modeling approaches for carbon partitioning: Impact on estimates of global net primary production and equilibrium biomass of woody vegetation from MODIS GPP
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DOI：
10.1029/2010jg001326
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发表时间：
2010-11-17
影响因子：
3.7
通讯作者：
Ito, Akihiko
中科院分区：
文献类型：
--
作者：
Ise, Takeshi;Litton, Creighton M.;Ito, Akihiko
初级生产总值（GPP）划分为地上与地下、生长与呼吸、短寿命组织与长寿命组织，对生态系统结构和功能产生强烈影响，对全球碳收支具有潜在的重大影响。最近对森林生态系统的一项元分析表明，碳分配到叶、茎和根的变化与GPP一致，净初级生产量（NPP）与GPP的比值在整个环境梯度中都是保守的。为了检验全球生态系统模型所采用的碳分配方案的影响，我们使用基于meta分析的模型和基于卫星（MODIS）的陆地GPP数据集来估算全球木质NPP和平衡生物量，并将其与使用相同GPP数据集的两个基于过程的生态系统模型（Biome-BGC和VISIT）进行比较。我们假设不同的碳分配方案会导致木本NPP和平衡生物量的全球估计值存在很大差异。与基于meta分析的模型相比，Biome-BGC和VISIT估算的北方针叶林Woody NPP分别高出25%和29%，温带和热带差异较小。根据模型特定的NPP估计值和单一组组织周转率计算得出，与基于元分析的模型相比，Biome-BGC和VISIT的全球平衡木质生物量高出48和226 Pg C，反映了碳分配到结构组织和代谢活跃组织的差异。综上所述，我们发现不同的碳分配方案导致全球木本碳通量和储量估计值存在较大差异，这表明林分水平对碳分配的控制尚未在生态系统模型中得到准确反映。
Partitioning of gross primary production (GPP) to aboveground versus belowground, to growth versus respiration, and to short versus long-lived tissues exerts a strong influence on ecosystem structure and function, with potentially large implications for the global carbon budget. A recent meta-analysis of forest ecosystems suggests that carbon partitioning to leaves, stems, and roots varies consistently with GPP and that the ratio of net primary production (NPP) to GPP is conservative across environmental gradients. To examine influences of carbon partitioning schemes employed by global ecosystem models, we used this meta-analysis-based model and a satellite-based (MODIS) terrestrial GPP data set to estimate global woody NPP and equilibrium biomass, and then compared it to two process-based ecosystem models (Biome-BGC and VISIT) using the same GPP data set. We hypothesized that different carbon partitioning schemes would result in large differences in global estimates of woody NPP and equilibrium biomass. Woody NPP estimated by Biome-BGC and VISIT was 25% and 29% higher than the meta-analysis-based model for boreal forests, with smaller differences in temperate and tropics. Global equilibrium woody biomass, calculated from model-specific NPP estimates and a single set of tissue turnover rates, was 48 and 226 Pg C higher for Biome-BGC and VISIT compared to the meta-analysis-based model, reflecting differences in carbon partitioning to structural versus metabolically active tissues. In summary, we found that different carbon partitioning schemes resulted in large variations in estimates of global woody carbon flux and storage, indicating that stand-level controls on carbon partitioning are not yet accurately represented in ecosystem models.