State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, 712100, China.
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
Sci Rep. 2018 Apr 18;8(1):6222. doi: 10.1038/s41598-018-24669-5.
Soil water shortage is a major factor influencing the ecology and hydrology of vegetation in China's semihumid Loess Plateau. However, few studies have experimentally assessed how expected changes in precipitation will affect sap flow in semihumid forest ecosystems. In this study, we measured the sap flow of black locust (Robinia pseudoacacia Linn.) under ambient and drought (induced by throughfall exclusion) conditions in 2015 and 2016, and investigated the relationship between stand transpiration and environmental factors in the semihumid China's Loess Plateau. Throughfall exclusion significantly decreased sap flux density and stand transpiration by 39% and 28%, respectively, in 2016, which may have been due to the cumulative droughts effect from both 2015 and 2016. Throughfall exclusion caused a significant reduction in soil moisture, leaf area index (LAI), and stem diameter. Stand transpiration was positively correlated with LAI (P < 0.01), but precipitation and soil moisture did not correlate with stand transpiration at a daily timescale, suggesting that LAI can be used as a proxy for stand transpiration. Our results highlight that precipitation must be considered when planting black locust in semihumid regions. These findings provide basic information about the management of water resources and vegetation restoration in the semihumid China's Loess Plateau and possibly other water-limited regions around the world.
土壤水分亏缺是影响中国半湿润黄土高原植被生态和水文的主要因素。然而，很少有研究实验评估预期降水变化将如何影响半湿润森林生态系统的液流。在这项研究中，我们测量了刺槐（Robinia pseudoacacia Linn.）在 2015 年和 2016 年环境条件和干旱（通过去除穿透雨来诱导）下的液流，并研究了半湿润黄土高原森林蒸腾与环境因素之间的关系。去除穿透雨显著降低了 2016 年的液流密度和林分蒸腾，分别降低了 39%和 28%，这可能是由于 2015 年和 2016 年累积干旱的影响。去除穿透雨导致土壤水分、叶面积指数（LAI）和茎直径显著减少。林分蒸腾与 LAI 呈正相关（P<0.01），但降水和土壤水分在日尺度上与林分蒸腾没有相关性，这表明 LAI 可以作为林分蒸腾的替代物。我们的结果强调，在半湿润地区种植刺槐时必须考虑降水。这些发现为半湿润黄土高原水资源管理和植被恢复提供了基本信息，可能对世界其他水资源限制地区也有一定的参考价值。
