黄土高原苹果园蒸腾导度大气驱动规律比较  

Laws of transpiration conductance variables driven by atmospheric were compared in apple orchards on the Loess Plateau

作　　者：陈帅 党宏忠[1,2] 丛日春[1,2] 王檬檬 李明阳 刘春颖 CHEN Shuai;DANG Hongzhong;CONG Richun;WANG Mengmeng;LI Mingyang;LIU Chunying(Institute of Desertification Studies,Chinese Academy of Forestry,Beijing 100091,China;Institute of Ecosystem Conservation and Restoration,Chinese Academy of Forestry,Beijing 100091,China;College of Desert Control Science and Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China)

机构地区：[1]中国林业科学研究院荒漠化研究所,北京100091 [2]中国林业科学研究院生态保护与修复研究所,北京100091 [3]内蒙古农业大学沙漠治理学院,呼和浩特010018

出　　处：《生态学报》2022年第18期7553-7576,共24页Acta Ecologica Sinica

基　　金：中央级公益性科研院所基本科研业务费专项(CAFYBB2020ZB007);国家自然科学基金(32071836);国家重点研发计划(2016YFC0501704)。

摘　　要：植物蒸腾导度是表征土壤-植物-大气连续体(SPAC)中植物-大气间水汽传导过程、反映植物水分调控能力的一类重要变量,常见有冠层导度(G_(c))、冠层气孔导度(G_(s))与叶片气孔导度(g_(s)),明确三者在反映冠层蒸腾过程时的异同或关联性对于理解植物水分利用机制具有重要意义。本研究基于对黄土高原果园苹果树生长季内树干液流(Js)及环境因子的连续观测,计算了G_(c)、G_(s)及脱耦联系数(Ω)等变量,并与短期连续观测的叶片气孔导度(g_(s))比较,分析了G_(c)、G_(s)和g_(s)在反映冠层蒸腾特征方面的异同及其关系。结果表明,日变化过程中G_(s)、g_(s)呈“单峰”型曲线,而G_(c)则呈“先增后减,午后抬升”的“双峰”型曲线。g_(s)与G_(s)存在较紧密的线性关系(R^(2)=0.80),但与G_(c)的线性关系较弱(R^(2)=0.02)。G_(c)、G_(s)均随大气水汽压亏缺(VPD)的变化呈现确定的规律,其中,上边界函数呈递减的对数函数关系,平均值则符合先增后减的Log-Normal函数关系(R^(2)>0.95),拐点对应的VPD值分别为1.33和1.16 kPa。在一日内,G_(s)对VPD变化的响应过程与g_(s)对VPDL(基于叶片温度计算的水汽压亏缺)变化的响应过程总体一致,其一致性高于G_(c)对VPD变化的响应。整个生长季(4—10月)中果树的Ω平均值为0.12,随着Ω递减,G_(c)与G_(s)的线性相关性愈趋紧密,其斜率呈递增趋势,G_(c)越来越趋近于G_(s)。研究结果表明,在北方地区,基于树干液流的监测能较准确的推导整株并估算林分的冠层蒸腾导度。与实测g_(s)的变化过程比较,G_(s)比G_(c)具有更高的一致性,G_(s)可以作为描述苹果树水分利用过程响应大气驱动的更为恰当的变量。Plant transpiration conductance variables,including canopy conductance(G_(c)),canopy stomatal conductance(G_(s))and leaf stomatal conductance(g_(s)),were able to characterize quantitatively the vapor transmission process between plant and atmosphere in the soil-plant-atmosphere continuum(SPAC)and to reflect the water regulation ability of plants.It was very important to discriminate the similarities and differences between the three factors mentioned above in reflecting the process of plant water use and the correlation among them for figuring out mechanism of plant water use.Based on the continuous observation of apple trees sap flow velocity(Js)and environmental factors during the growing season on the Loess Plateau,G_(c),G_(s) and decoupling coefficient(Ω)were calculated and compared with the g_(s) measured continuously for a few sunny days in field,and the relationships between G_(c),G_(s) and g_(s) and the similarities and differences of them in estimating canopy transpiration rate were analyzed.Results showed that diurnal courses of G_(s) and g_(s) showed a“unimodal”curve while that of G_(c) showed a“bimodal”curve that was increase followed by decrease and recovered slightly in the afternoon.The linear relationship between G_(s) and g_(s) was close(R^(2)=0.80)while that of G_(c) and g_(s) was weak(R^(2)=0.02).G_(c) or G_(s) varied with vapor pressure deficit(VPD)were clear with the upper boundary function of decreasing logarithmic function while the relationship between means of that and VPD could be fitted well by Log-Normal function of first increase and then decrease(R^(2)>0.95).The means of G_(c) and G_(s) varied with VPD showed turn points at 1.33 and 1.16 kPa,respectively.In daytime,the response process of G_(s) to VPD was consistent with that of g_(s) to VPDL(vapor pressure deficit calculated based on leaf surface temperature),and the consistency was higher than that of G_(c) to VPD.In the whole growing season(from April to October),the averageΩwas 0.12.G_(c) linear correlated with G_(s) an

关 键 词：冠层蒸腾 冠层导度 冠层气孔导度 叶片气孔导度 液流 

分 类 号：S661.1[农业科学—果树学]