北京山区油松和元宝槭冠层气孔导度特征及其环境响应  

Canopy stomatal conductance characteristics of Pinus tabulaeformis and Acer truncatum and their responses to environmental factors in the mountain area of Beijing

作　　者：陈胜楠 陈左司南 张志强[1] CHEN Sheng-Nan;CHEN Zuo-Si-Nan;ZHANG Zhi-Qiang(College of Soil and Water Conservation,Beijing Forestry University,Beijing 100083,China)

机构地区：[1]北京林业大学水土保持学院,北京100083

出　　处：《植物生态学报》2021年第12期1329-1340,共12页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31872711)。

摘　　要：叶片气孔是植物进行水汽交换的通道,影响着植物的蒸腾和光合作用。然而叶片气孔行为受环境条件和树种类型的影响,不同树种冠层气孔导度对环境因子响应的差异性,以及在生长季不同时期叶片气孔对冠层蒸腾的调节作用是否会发生改变,仍不清楚。该研究目的是通过探究各环境因子对不同树种冠层气孔导度的相对贡献率以及叶片气孔对冠层蒸腾的调节作用,为深入了解植物水分利用状况和山区森林经营提供参考依据。于2018年生长季以北京八达岭国家森林公园内的58年生油松(Pinus tabuliformis)和39年生元宝槭(Acer truncatum)为研究对象,利用热扩散技术对其树干液流进行连续监测,并同步监测环境因子。利用彭曼公式计算冠层气孔导度(G_(s))。主要结果:(1)油松和元宝槭日间G_(s)在日、月时间尺度上存在明显差异。5–7月油松和元宝槭日动态G_(s)均随饱和水汽压差(VPD)和太阳辐射(GR)的增加呈上升趋势,上升持续时间比8月和9月长;在月尺度上,随着VPD、GR的降低和土壤湿度(VWC)的升高,G_(s)从5月到9月整体上升。(2)利用增强回归树法分析得到VWC和VPD对G_(s)的贡献率最大,其次是GR、气温和风速。VWC和VPD对油松G_(s)的贡献率分别为66.4%和17.4%,对元宝槭G_(s)的贡献率分别为54.8%和21.0%。(3)油松和元宝槭的dG_(s)/dln VPD值与参考冠层气孔导度之间的斜率均显著高于0.6,气孔调节作用相对较强。综上所述,气孔对环境因子的响应在树种以及生长季不同时期之间存在差异,为防止水分过度散失,两树种在不同土壤水分条件下均通过严格的气孔调节控制蒸腾量。Aims Leaf stomata are channels for plants to exchange water vapor that affects transpiration and photosynthesis.However,leaf stomatal behaviors are affected by environmental factors and tree species.It is still unclear whether the responses of canopy stomatal conductance to environmental factors differ between tree species and whether the stomatal regulations on canopy transpiration change with different periods of the growing season.The objective of this study was to explore the relative contribution of environmental factors to canopy stomatal conductance and the regulation of leaf stomata on canopy transpiration for different tree species,which could provide references for further understanding the water use status of trees and forest management in mountain areas.Methods During the growing season of 2018,Pinus tabuliformis(58-year-old)and Acer truncatum(39-yearold)at Badaling National Forest Park in Beijing were selected.Sap flow was measured by using the thermal dissipation method.Environmental factors were also measured synchronously.Canopy stomatal conductance(G_(s))was estimated by using the Penman-Monteith equation.Important findings(1)The daytime G_(s)of P.tabulaeformis and A.truncatum varied evidently at daily and monthly scales.From May to July,daily dynamic G_(s)of P.tabulaeformis and A.truncatum increased with vapor pressure deficit(VPD)and solar radiation(GR),in which the rising periods were longer than that during August and September.At the monthly scale,as VPD and GR decreased,soil moisture(VWC)increased,G_(s)generally increased from May to September.(2)VWC and VPD contributed to the major variation of the G_(s),and then the GR,air temperature,and wind speed followed based on the boosted regression tree method.The relative contributions of VWC and VPD to G_(s)were 66.4% and 17.4% for P.tabulaeformis and 54.8% and 21.0% for A.truncatum,respectively.(3)The slopes between d G_(s)/dln VPD and the reference canopy stomatal conductance for both P.tabulaeformis and A.truncatum were significantly larger t

关 键 词：冠层气孔导度 环境响应 气孔行为 林分蒸腾 

分 类 号：Q948[生物学—植物学]