Climate more important than soils for predicting forest biomass at the continental scale

Above-ground biomass in forests is critical to the global carbon cycle as it stores and sequesters carbon from the atmosphere. Climate change will disrupt the carbon cycle hence understanding how climate and other abiotic variables determine forest biomass at broad spatial scales is important for validating and constraining Earth System models and predicting the impacts of climate change on forest carbon stores. We examined the importance of climate and soil variables to explaining above-ground biomass distribution across the Australian continent using publicly available biomass data from 3130 mature forest sites, in 6 broad ecoregions, encompassing tropical, subtropical, and temperate biomes. We used the Random Forest algorithm to test the explanatory power of 14 abiotic variables (8 climate, 6 soil) and to identify the best-performing models based on climate-only, soil-only, and climate plus soil. The best performing models explained ~50% of the variation (climate-only: R2 = 0.47 ± 0....

森林地上生物量（above-ground biomass）对全球碳循环至关重要，其可储存并固存大气中的碳。气候变化将干扰碳循环，因此在大空间尺度上厘清气候与其他非生物变量（abiotic variables）如何决定森林生物量，对于验证和约束地球系统模型（Earth System models）、预测气候变化对森林碳储量的影响具有重要意义。本研究依托公开获取的澳大利亚大陆3130个成熟森林样地的生物量数据，这些样地分布于6个覆盖热带、亚热带与温带生物群系的大型生态区，探究了气候与土壤变量对解释该大陆范围内地上生物量分布的重要性。本研究采用随机森林（Random Forest）算法，对14个非生物变量（8个气候变量、6个土壤变量）的解释能力进行检验，并基于仅气候、仅土壤以及气候-土壤联合的变量组合筛选最优模型。最优模型可解释约50%的变异（仅气候模型：决定系数R²=0.47±0……）