黑河上游森林生态系统植物水分来源

Water sources of plants in the forest ecosystem in the upper reaches of the Heihe River Basin

通过对黑河上游青海云杉森林生态系统优势植物青海云杉、金露梅、珠芽蓼和针茅木质部水、土壤水及降水稳定氢氧同位素组成(δD、δ18O)的测定,利用多源线性混合模型分析了不同潜在水源对上述植物的贡献.结果表明:黑河上游土壤水主要来源于降水,植物水分来源于降水补给的土壤水.青海云杉、金露梅、珠芽蓼和针茅对不同土层土壤水的吸收策略有明显的时空变化.植物在雨季吸收利用的水分主要来源于浅层土壤水,其原因是雨季降水对浅层土壤水补给增多,植物优先利用降水补给的浅层土壤水.非雨季,由于植物蒸腾作用的增加和浅层土壤水分的消耗,植物趋向于吸收更深层的土壤水.本研究揭示了黑河上游青海云杉植物的水分利用模式及适应干旱环境的策略,为气候变化背景下干旱半干旱区森林生态系统的水量平衡和生态水文过程研究提供理论依据.

Based on the stable hydrogen and oxygen isotope compositions(δD andδ18 O)of soil water,precipitation and plant xylem water(Picea crassifolia,Potentilla fruticosa,Polygonum viviparum and Stipa capillata)of the Picea crassifolia forest ecosystem in the upper reaches of the Heihe River Basin,water sources of the above dominant plants were studied.The results showed that soil water mainly came from precipitation,plant water from soil water supplied by precipitation in the forest ecosystem.Significantly different water use patterns were found in Picea crassifolia,Potentilla fruticosa,Polygonum viviparum and Stipa capillata.Shallow soil water was the main water source in the rainy season due to the high precipitation.In the dry season,plants tended to absorb deep soil water due to increase the transpiration rate and consumption of shallow soil water.This study revealed the plant water use patterns and the strategies in adapting to the arid environment of dominated plants of the Picea crassifolia forest ecosystem,can provide a theoretical basis for understanding the water balance and eco-hydrological processes of a forest ecosystem in arid and semi-arid regions under the background of changing climate.