摘要
树木水分利用效率特征存在地域及树种差异,北京山区作为华北土石山区典型森林生态系统,其主要树种侧柏水分利用效率(WUE)长期变化的研究未见报道.本研究通过测定侧柏树轮稳定碳同位素值(δ^(13)C),计算年均水分利用效率(WUE_i),分析其长期变化趋势及对环境条件变化的响应,并结合树轮宽度,探究侧柏WUE_i与净固碳量的关系.结果表明:1918—2013年期间,北京山区年均气温呈逐渐升高趋势,年降水量波动较大.在此期间,侧柏树轮δ^(13)C逐渐减小,WUE_i呈逐渐增大趋势.侧柏WUE_i对气温变化的响应最为敏感,呈显著正相关关系,且WUE_i对气温升高的响应敏感性大于气温降低.侧柏WUE_i与年降水量的相关性不明显,该地区降水量不是影响侧柏WUE_i的主要因素.侧柏去趋势树轮宽度值呈现先上升后下降趋势,近20年下降趋势明显.结合WUE_i与环境因子的相关性分析,认为气温升高导致气孔导度(g_s)降低,蒸腾量减少,同时增加了呼吸损耗,结果导致WUE_i升高,但侧柏净固碳量减少,生长减缓.
Water use efficiency （WUE） is different among species and regions. Few literatures have been reviewed related to long-term WUE of Platycladus orientalis in mountainous areas of Beijing, China. Tree-ring δ13C of P. orientalis was used to determine the long-term variation of annual intrin- sic water use efficiency （WUEi ） and its response to environmental change. Combining with quanti- fication of tree-ring width, the relationship between net carbon sequestration and WUEi of P. orien- talis was eventually explored. The results showed that mean annual temperature increased with the increase of time from 1918 to 2013, whereas annual precipitation fiercely fluctuated. Tree-ring δ13C decreased and WUEi increased over time. WUEi was positively related and more sensitive to air tem- perature increasing than temperature decreasing. Correlation between WUEi and fluctuated annual precipitation was ambiguous, which indicated the precipitation was not the main factor affecting WUEi. The de-trend tree-ring width of P. orientalis increased initially and then decreased, especial- ly in recent 20 years. According to the correlation between WUEi and environmental factors, tem- perature resulted in stomatal conductance （g,） decreasing, which caused a reduction in evapotrans- piration and an increase in respiratory loss, leading to the increase of WUEi and a down trend in net carbon sequestration and tree growth.
出处
《应用生态学报》
CAS
CSCD
北大核心
2017年第7期2128-2134,共7页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(41430747)
科技创新服务能力建设-协同创新中心-林果业生态环境功能提升协同创新中心(PXM2016_014207_000038)资助~~
关键词
树轮稳定碳同位素值
水分利用效率
树轮宽度
气孔导度
tree-ring stable carbon isotope
water use efficiency
tree-ring width
stomata] con-ductance.
