The conversion of forests into agricultural lands can be a threat because the forests carbon stored could be a source of emissions. The capacity to improve the predictions on the consequences of land use change depends on the identification of factors that influence carbon pools. We investigated the key driving factors of tree biomass and soil carbon pools in xerophytic forests in northeastern Argentina. Based on analyses of forest structure variables and abiotic factors (topography and soil properties) from 18 mature forests, we evaluated carbon pools using uni- and multivariate (redundancy analysis) methods. The total carbon pool was estimated at 102.4 ± 24.0 Mg ha−1. Soil organic carbon storage is the single largest carbon pool relative to tree biomass, representing 73.1% of total carbon. Tree canopy cover and basal area were positively correlated with biomass carbon pool (r = 0.77 and r = 0.73, p < 0.001, respectively), proving to be significant drivers of carbon storage in this compartment. Slope, soil clay content and cation-exchange capacity had a better explanation for the variability in soil carbon pools, and all showed significant positive correlations with soil carbon pools (r = 0.64, 0.60 and 0.50; p < 0.05, respectively). The vertisols showed a 27.8% higher soil carbon stock than alfisols. The relevance of our study stems from a dearth of information on carbon pools and their drivers in xerophytic forests, and in particular, the importance of this ecosystems’ type for Argentina, because they cover 81.9% of native forest area. Basal area and tree canopy cover exert a strong effect on the carbon pool in tree biomass but not in the soil. The results suggests that there is a potentially major SOC accumulation in forests located in slightly sloping areas and soils with higher topsoil clay content, such as vertisols. This could provide an important reference for implementing forestry carbon sink projects.

中文翻译：

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阿根廷东北部旱生林树木生物量和土壤碳库的驱动因素

将森林转变为农田可能会构成威胁，因为森林储存的碳可能成为排放源。改进对土地利用变化后果的预测的能力取决于对影响碳库的因素的识别。我们研究了阿根廷东北部旱生林树木生物量和土壤碳库的关键驱动因素。基于对 18 个成熟森林的森林结构变量和非生物因素（地形和土壤特性）的分析，我们使用单变量和多变量（冗余分析）方法评估了碳库。总碳库估计为 102.4 ± 24.0 Mg ha−1。土壤有机碳储量是相对于树木生物量最大的单一碳库，占总碳的73.1%。树冠覆盖度和断面积与生物量碳库呈正相关（分别为 r = 0.77 和 r = 0.73，p < 0.001），证明是该区域碳储存的重要驱动因素。坡度、土壤粘土含量和阳离子交换能力对土壤碳库的变异性有较好的解释，且均与土壤碳库呈显着正相关（分别为r = 0.64、0.60和0.50；p < 0.05）。变性土的土壤碳储量比碱土高 27.8%。我们研究的相关性源于缺乏关于旱生森林碳库及其驱动因素的信息，特别是这种生态系统类型对阿根廷的重要性，因为它们覆盖了 81.9% 的原生森林面积。断面积和树冠覆盖度对树木生物量中的碳库有很大影响，但对土壤中的碳库没有影响。结果表明，位于稍倾斜地区的森林和表土粘土含量较高的土壤（例如变性土）中可能存在大量 SOC 积累。这可为实施林业碳汇项目提供重要参考。