宁夏河东沙区刺槐和丝绵木水分利用策略

刺槐和丝绵木混交林是宁夏河东沙区防护林建设的主要模式，了解刺槐和丝绵木的水分利用策略，能为区域植被恢复和防护林林分结构调整提供科学依据。以宁夏河东沙区刺槐(Robinia pseudoacacia)和丝绵木(Euonymus bungeanus)混交林为研究对象，通过监测微气象、树干液流和土壤质量含水量，结合大气降水、土壤水、植物木质部水同位素组成，采用Granier及其校正公式，运用贝叶斯混合模型(MixSIAR)和相似性比例指数(PS)研究2个树种的蒸腾耗水、水分来源和水分利用关系。结果表明：刺槐和丝绵木的蒸腾耗水量在生长季中期较高，前期和后期较小，刺槐的蒸腾耗水量是丝绵木的1.55倍；影响刺槐蒸腾耗水的主要环境因子为饱和水汽压差、太阳辐射、0—40 cm土壤质量含水量和40—120 cm土壤质量含水量；影响丝绵木蒸腾耗水的主要环境因子为饱和水汽压差、太阳辐射、平均气温、0—40 cm土壤质量含水量和40—120 cm土壤质量含水量；蒸腾耗水较高时，刺槐主要吸收利用中层土壤水，丝绵木主要吸收利用浅层土壤水，蒸腾耗水较低时，刺槐主要吸收利用浅层土壤水，丝绵木主要吸收利用中层土壤水；在...

Water use strategies of Robinia pseudoacacia and Euonymus bungeanus in the east sandy land of the Yellow River in Ningxia, China

The mixed forest of Robinia pseudoacacia and Euonymus bungeanus is the typical shelterbelt construction mode in the east sandy land of the Yellow River in Ningxia, China. Research on the water use strategies of Robinia pseudoacacia and Euonymus bungeanus could provide scientific basis for restoration regional vegetation and stand structure optimization allocation of shelter forest. In this study, the sap flow of Robinia pseudoacacia and Euonymus bungeanus was monitored continuously to clarify the characteristics of water consumption by transpiration which calculated by Granier and its correction formula, as well as simultaneous records of micro-meteorological factors and gravimetric soil water content. Combined with stable hydrogen and oxygen isotope analysis of rainfall, soil water and plant xylem water, the water source and water use relationship among symbiotic trees were quantitatively analyzed by Bayesian mixture model (MixSIAR) and the proportional similarity index (PS). The results showed that the water consumption of Robinia pseudoacacia and Euonymus bungeanus were higher in the middle growing season, but lower in the early and late growing season. The water consumption of Robinia pseudoacacia was 1.55 times larger than Euonymus bungeanus. The main environmental factors affecting water consumption of Robinia pseudoacacia were vapour pressure deficit, solar radiation, 0-40 cm gravimetric soil water content and 40-120 cm gravimetric soil water content. The main environmental factors affecting water consumption of Euonymus bungeanus were vapour pressure deficit, solar radiation, average temperature, 0-40 cm gravimetric soil water content and 40-120 cm gravimetric soil water content. Robinia pseudoacacia mainly used the middle layer soil water and Euonymus bungeanus mainly used the shallow layer soil water in the season with high water consumption. While the shallow layer soil water and the middle layer soil water were ultilized by Robinia pseudoacacia and Euonymus bungeanus separately in the season with lower tree water consumption. In addition, Robinia pseudoacacia and Euonymus bungeanus was able to deal with drought and maintain their own water consumption mainly through the spatial difference of water use strategy under drought seasons. In the seasons when gravimetric soil water content was higher, the proportional similarity index (PS) of Robinia pseudoacacia and Euonymus bungeanus was the highest, and there was a strong water competition relationship. The higher of shallow layer gravimetric soil water content might reflect a trade-off between water and nutrient requirements of plants under the effect of soil water redistribution by plant roots in the sandy land.