Abstract：
Fine-root architecture is critical feature reflecting root explorative and exploitative strategies for soil resources and soil space occupancy. Yet, studies on the variation of fine-root architecture across different species are scare and little work has been done to integrate the potential drivers on these variations along a biogeographical gradient in arid ecosystems. We measured root branching intensity, topological index, and root branching ratios as well as morphological traits (root diameter and length) in dry valley along a 1000 km latitudinal gradient. Influence of phylogeny, environmental factors on fine-root architecture and trade-offs among root traits were evaluated. With increasing latitude, the topological index and second to third root order branching ratio decreased, whereas first-to-second branching ratio increased. Root branching intensity was associated with short and thin fine roots, but has no significant latitudinal pattern. As a whole, soil microbial biomass was the most important driver in the variation of root branching intensity, and soil texture was the strongest predictor of topological index. Additionally, mean annual temperature was an important factor influencing first-to-second branching ratio. Our results suggest variations in fine-root architectures were more dependent on environmental variables than phylogeny, signifying that fine-root architecture is sensitive to environmental variations.
摘要：
细根结构是反映土壤资源和土壤空间占用的根探索和利用策略的关键特征。然而，关于不同物种的细根结构变化的研究很少，在干旱生态系统中沿着生物地理梯度整合这些变化的潜在驱动因素的工作很少。我们测量了根的分枝强度,拓扑索引，沿1000km的纬度梯度，干燥山谷中的根分枝比以及形态特征（根直径和长度）。系统发育的影响，对细根结构的环境因素和根系性状之间的权衡进行了评估。随着纬度的增加,拓扑指数和第二至第三根序分支比降低，而第一至第二分支比增加。根分枝强度与短而细的细根有关，但没有显著的纬度模式。作为一个整体,土壤微生物生物量是根系分枝强度变化的最重要驱动因素,土壤质地是拓扑指数的最强预测指标。此外,年平均温度是影响第一至第二分支比的重要因素。我们的结果表明，细根结构的变化比系统发育更依赖于环境变量，这表明细根建筑对环境变化很敏感。
