Precipitation gradient determines the tradeoff between soil moisture and soil organic carbon, total nitrogen, and species richness in the Loess Plateau, China.
Precipitation gradient determines the tradeoff between soil moisture and soil organic carbon, total nitrogen, and species richness in the Loess Plateau, China.
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DOI：
10.1016/j.scitotenv.2016.10.047
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Cong Wang;Shuai Wang;B. Fu;Zongshan Li;Xing Wu;Q. Tang
中科院分区：
文献类型：
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作者：
Cong Wang;Shuai Wang;B. Fu;Zongshan Li;Xing Wu;Q. Tang
干旱地区的土壤地球化学循环与水的供应之间存在着紧密的耦合。然而，有关土壤水分（SM），土壤碳/氮，植物之间的耦合的研究在文献中是罕见的，并澄清这些关系随气候梯度的变化是具有挑战性的。因此，选择土壤有机碳（SOC）、全氮（TN）和物种丰富度（SR）作为土壤-植物系统变量，定量分析了土壤-植物系统变量与土壤有机碳的权衡关系及其沿着降水梯度的变化。结果表明，除林地和草地的土壤电阻率和草地的有机碳外（p> 0.05），林地、灌丛和草地的土壤电阻率和有机碳均沿降水梯度沿着呈线性增加。相关性分析表明，3种植被类型土壤有机碳和总氮的平衡与年平均降水量（MAP）呈显著相关，草地和林地土壤有机碳和总氮的平衡与MAP呈显著相关。线性分段分位数回归被用来确定这些权衡响应的拐点的降水梯度。SM-SOC平衡的拐点出现在MAP = 570 mm处; SM-TN平衡未出现拐点; SM-SR平衡在林地和草地的变化趋势不同，拐点分别出现在MAP = 380 mm和MAP = 570 mm处。在转折点之前，相对干旱区土壤水分对土壤有机碳和土壤比表面积的约束作用存在，而相对湿润区土壤水分对土壤有机碳和土壤比表面积的约束作用消失或减弱。结果表明，这种权衡在降水梯度上表现出明显的沿着变化趋势，并受植被类型的影响。因此，权衡可以作为黄土高原生态恢复管理的指标和工具。在进一步的研究中，降水梯度和植被类型如何影响这种平衡的机制还有待进一步阐明。
A tight coupling exists between biogeochemical cycles and water availability in drylands. However, studies regarding the coupling among soil moisture (SM), soil carbon/nitrogen, and plants are rare in the literature, and clarifying these relationships changing with climate gradient is challenging. Thus, soil organic carbon (SOC), total nitrogen (TN), and species richness (SR) were selected as soil-plant system variables, and the tradeoff relationships between SM and these variables and their variations along the precipitation gradient were quantified in the Loess Plateau, China. Results showed these variables increased linearly along the precipitation gradient in the woodland, shrubland, and grassland, respectively, except for the SR in the woodland and grassland, and SOC in the grassland (p> 0.05). Correlation analysis showed that the SM-SOC and SM-TN tradeoffs were significantly correlated with mean annual precipitation (MAP) across the three vegetation types, and SM-SR tradeoff was significantly correlated with MAP in grassland and woodland. The linear piece-wise quantile regression was applied to determine the inflection points of these tradeoffs responses to the precipitation gradient. The inflection point for the SM-SOC tradeoff was detected at MAP = 570 mm; no inflection point was detected for SM-TN tradeoff; SM-SR tradeoff variation trends were different in the woodland and grassland, and the inflection points were detected at MAP = 380 mm and MAP = 570 mm, respectively. Before the turning point, constraint exerted by soil moisture on SOC and SR existed in the relatively arid regions, while the constraint disappears or is lessened in the relatively humid regions in this study. The results demonstrate the tradeoff revealed obvious trends along the precipitation gradient and were affected by vegetation type. Consequently, tradeoffs could be an ecological indicator and tool for restoration management in the Loess Plateau. In further study, the mechanism of how the tradeoff is affected by the precipitation gradient and vegetation type should be clarified.