中国农业科学 ›› 2018, Vol. 51 ›› Issue (2): 302-314.doi: 10.3864/j.issn.0578-1752.2018.02.010

• 土壤肥料·节水灌溉·农业生态环境 • 上一篇    下一篇

黄土高原植被生态系统水分利用效率时空变化及驱动因素

刘宪锋,胡宝怡,任志远   

  1. 陕西师范大学地理科学与旅游学院,西安 710119
  • 收稿日期:2017-06-23 出版日期:2018-01-16 发布日期:2018-01-16
  • 作者简介:刘宪锋,Tel:029-85310447;E-mail:liuxianfeng7987@163.com
  • 基金资助:
    国家自然科学基金(41371523)、中央高校基本科研业务费项目(GK201703049)

Spatiotemporal Variation of Water Use Efficiency and Its Driving Forces on the Loess Plateau During 2000-2014

LIU XianFeng, HU BaoYi, REN ZhiYuan   

  1. School of Geography and Tourism, Shaanxi Normal University, Xian 710119
  • Received:2017-06-23 Online:2018-01-16 Published:2018-01-16

摘要: 【目的】明晰黄土高原植被生态系统水分利用效率(water use efficiency,WUE)时空变化特征及其影响因素,为深刻理解生态恢复和气候变化双重背景下黄土高原植被生态系统与水文相互作用研究提供依据。【方法】利用趋势分析和逐步回归方法,对2000—2014年黄土高原植被生态系统WUE时空变化特征及其驱动因素进行了探讨。【结果】近15年黄土高原植被生态系统WUE呈显著增加趋势,增速为0.02 gC·kg-1H2a-1P<0.001),不同植被生态系统年内WUE主要呈“双峰”模式,峰值分布在4—5月和9—10月;空间上,黄土高原植被生态系统WUE整体呈现上升趋势,其中上升趋势和显著上升(P<0.05)面积分别占研究区的95.04%和66.96%,但不同季节变化趋势特征差异较大;不同植被生态系统WUE均值和趋势差异显著,其中稀疏灌丛和草地WUE均值较低,而针叶林WUE趋势下降明显;进一步对坡度统计表明,25—50°范围内植被生态系统WUE呈持续增加趋势。当年蒸散量小于3 700 mm时,总初级生产力(gross primary productivity,GPP)随着蒸散量(evapotranspiration,ET)的增加而增加,随后GPP则随ET的增加呈下降趋势,且研究区中东部(57.25%)WUE主要由GPP控制,而西部区域(42.75%)WUE则受ET影响。近15年黄土高原植被生态系统WUE与LAI呈显著的正相关关系(P<0.001),表明LAI的增加能够有效促进WUE的提升。逐步回归分析表明,降水量、日照时数和相对湿度3种气候因子是导致WUE及其组分GPP和ET变化的主要气候因子。【结论】在气候变化和人类活动双重影响下,2000—2014年黄土高原植被生态系统WUE呈显著上升趋势,且大部分植被类型年内分布呈现双峰结构。生态恢复工程不仅改善了黄土高原植被覆盖状况,同时显著提高了植被生态系统的WUE,成为近年来黄土高原WUE变化的主要驱动因素。

关键词: 植被生态系统, 水分利用效率, 时空变化, 驱动因素, 黄土高原

Abstract: 【Objective】Clarifying the spatiotemporal changes of water use efficiency (WUE) and its driving forces in the vegetation ecosystem over the Loess Plateau (LP) provide the basis for greater understanding the interaction of ecosystem and hydrology on the LP under the dual disturbance of ecological restoration and climate change.【Method】Using trend analysis and stepwise regression analysis, our study investigates spatiotemporal variation in WUE of vegetation ecosystem and its driving forces on the LP during the period 2000-2014. 【Result】The WUE reveals a significant increasing trend on the LP during 2000-2014 (linear tendency 0.02 gC·kg-1 H2O·a-1, P<0.001). Intra-annual analysis shows that the WUE of different vegetation ecosystems mainly showed a bimodal pattern, which the two peaks appeared in April to May and September to October, respectively. Spatially, the WUE of the LP generally reveals an increasing trend, and the area of increasing trend and significantly increasing trend (P<0.05) accounting for 95.04% and 66.96% of the total study area, respectively, but the patterns of trend in different seasons vary significantly. The mean and trend of WUE among different vegetation ecosystems also vary significantly, among which the mean of WUE of the open shrublands and grasslands are lower than that of other vegetation ecosystems, while the trend of WUE of needleleaf forest decrease significantly. The results of slope statistic show that the WUE of vegetation ecosystem reveals a continuous increase trend in the range of 25°-50°. When annual evapotranspiration (ET) is below 3 700 mm, Gross Primary Productivity (GPP) is positive correlated with ET increase, while when annual ET above 3 700 mm, GPP decrease with the increase of ET. In addition, the WUE of the central and eastern part of the study area is mainly controlled by GPP (57.25%), while ET (42.75%) mainly affects the WUE of the western part of the study area. Moreover, WUE is significantly positive correlated with Leaf Area Index (LAI), indicating the increase of LAI will promote increase in WUE. Stepwise regression analysis shows that precipitation, sunshine duration, and relative humidity are the main climatic factors that lead to the change of WUE and its components in recently 15 years. 【Conclusion】Under the dual disturbance of climate change and anthropogenic activities, the WUE of the LP shows a significantly increasing trend in the past 15 years, and most of the vegetation types show a bimodal pattern within the year. Meanwhile, the ecological restoration project not only improve the vegetation coverage of the LP, but also significantly improve the WUE of vegetation ecosystem of the LP, becoming the main driving forces for explaining changes in WUE on the LP during recent 15 years.

Key words: vegetation ecosystem, water use efficiency, spatiotemporal variation, driving forces, the Loess Plateau