表层阻力和环境因素对杨树(Populus sp.)人工林蒸散发的控制

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 表层阻力和环境因素对杨树(Populus sp.)人工林蒸散发的控制 DOI: 10.5846/stxb201502250381 作者: 作者单位: 北京林业大学,北京市八达岭林场,北京市园林绿化局,北京林业大学,北京林业大学,北京林业大学,北京市农业环境监测站,北京林业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家林业行业科研专项（201204102）；北京市教育委员会共建项目；北京市林业碳汇工作办公室观测运行基金；中美碳联盟USCCC国际合作项目 Control of evapotranspiration by surface resistance and environmental factors in poplar (Populus×euramericana) plantations Author: Affiliation: Beijing forestry university,,,,,,,Beijing forestry university Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在水资源短缺地区大面积栽植高耗水的人工林相比于低矮农作物会加剧地区的水分短缺，因而其可持续性正受到越来越多的关注。但是，在不同地域复杂的水、能量和气候条件下的人工林蒸散发的控制机制仍不清楚。基于涡度相关（EC）系统和微气象系统对北京市大兴区杨树（Populus euramericana CV.“74/76”）人工林生态系统与大气间水分交换的连续监测，（a）分析了2006-2009年生长季中生态系统蒸散发（ET）、表层阻力（Rs）、气候阻力（Ri）和空气动力学阻力（Ra）在干湿年份间的变化动态；（b）以偏相关分析法探讨了干旱和湿润年份中不同土壤水分条件下生物因素Rs和环境因素（Ri和Ra）对杨树人工林ET的直接控制作用。研究结果表明：在年际尺度上，干旱年份杨树人工林的日平均ET（2.23±1.30）mm/d低于湿润年份约17%，对应地，干旱年份的表层阻力（Rs ：LAI）高于湿润年份（71.2 s/m）约50%，而Ri和Ra未表现出干湿年份间的差异。在季节尺度上，季节性的干旱胁迫显著影响杨树人工林的ET和Rs、Ri的变化，水分供应（降雨量与灌溉量之和）是该尺度上影响杨树人工林ET的主导因素，其解释了ET变化的71%（P<0.01）。偏相关分析结果表明，除了在土壤水分严重胁迫（REW<0.1）情况外，其他土壤水分条件下表层阻力Rs是日尺度上控制ET变化的主导因素，其与ET呈负相关关系，二阶相关系数（SOCC）变化范围为-0.518--0.293（P<0.01），且干旱年份中Rs对ET的控制程度高于湿润年份；环境因素中气候阻力Ri和空气动力学阻力Ra各自对ET的控制作用远小于表层阻力Rs；相对土壤含水量（REW）只在干旱年份中干旱胁迫时段（REW<0.4）直接影响ET（Pearson相关系数为0.217-0.323，P<0.01），其他情况下则是通过影响表层阻力Rs、气候阻力Ri和空气动力学阻力Ra对ET的作用来间接影响ET的。另外，相比于偏相关分析，简单的相关性分析会对各因素对ET的控制作用造成估计偏差。 Abstract:There is increasing concern about the sustainability of large-scale plantations in water-limited regions, with most studies indicating that the higher water use of forest plantations compared to herbaceous crops exacerbates water shortages in such areas. However, the mechanisms that control evapotranspiration in forest plantations under complex water, energy, and climatic conditions and across diverse geographical regions remain unclear. Here, we report continuous water flux data for a poplar plantation (Populus×euramericana ‘74/76’) in Daxing District, Beijing, China, collected with an eddy covariance (EC) and microclimate monitoring system. Our objectives were to a) quantify the dynamics of evapotranspiration (ET), surface resistance (Rs), and climatological resistance (Ri) over dry and wet years; b) examine the direct controlling effects of biological and environmental factors on ET by using partial correlation analysis under different soil moisture conditions over dry and wet years. On the interannual scale, average daily ET in dry years (2.23±1.30) mm/d was 17% lower than that in wet years; surface resistance (Rs:LAI) increased by 50% in dry years, but there were no significant differences in Ri and Ra between dry and wet years. At the seasonal scale, seasonal drought stress had a discernible impact on ET, Rs, and Ri of the poplar plantation, and water supply (precipitation+irrigation) caused 71% of seasonal variation in ET (P<0.01). Partial correlation analysis indicated that Rs was the main factor controlling daily ET, except under severe water stress (REW<0.1), and daily ET was negatively related to Rs (second-order correlation coefficient of -0.518 to -0.293, P<0.01). The effect of Rs on ET was stronger in dry years than in wet years, and the effects of Ri and Ra on daily ET were irregular and weaker than that of Rs. Daily ET of the poplar plantation was directly affected by relative extractable soil water (REW) only under water stress (REW<0.4) in dry years (Pearson coefficient 0.217-0.323, P<0.01), and it was indirectly influenced by REW under other soil water conditions. Compared to partial correlation analysis, correlation analysis would incorrectly evaluate the effects of Rs, Ri, and Ra on ET. 参考文献 相似文献 引证文献