植物生态学报 ›› 2021, Vol. 45 ›› Issue (12): 1350-1364.DOI: 10.17521/cjpe.2021.0220

• 研究论文 • 上一篇    下一篇

晋西黄土区典型乔灌木短期水分利用效率对环境因子的响应

韩璐1,2, 杨菲1,2, 吴应明1,2, 牛云明1,2, 曾祎明1,2, 陈立欣1,2,*()   

  1. 1北京林业大学水土保持学院, 北京 100083
    2山西吉县森林生态系统国家野外科学观测研究站, 山西吉县 042200
  • 收稿日期:2021-06-09 接受日期:2021-08-11 出版日期:2021-12-20 发布日期:2021-09-18
  • 通讯作者: 陈立欣
  • 作者简介:*(myclover17@126.com)
  • 基金资助:
    国家自然科学基金(41977149)

Responses of short-term water use efficiency to environmental factors in typical trees and shrubs of the loess area in West Shanxi, China

HAN Lu1,2, YANG Fei1,2, WU Ying-Ming1,2, NIU Yun-Ming1,2, ZENG Yi-Ming1,2, CHEN Li-Xin1,2,*()   

  1. 1College of Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China
    2National Station for Forest Ecosystem Research in Jixian County, Ji Xian, Shanxi 042200, China
  • Received:2021-06-09 Accepted:2021-08-11 Online:2021-12-20 Published:2021-09-18
  • Contact: CHEN Li-Xin
  • Supported by:
    National Natural Science Foundation of China(41977149)

摘要:

为明确晋西黄土区植物的水分利用规律及对半干旱区的适应策略, 提高黄土地区植被建设效益, 该研究对该地区典型乔灌木短期水分利用效率随环境因子的变化进行了探究。以典型乔木油松(Pinus tabuliformis)、刺槐(Robinia pseudoacacia)及其林下灌木黄刺玫(Rosa xanthina)、杠柳(Periploca sepium)为研究对象, 测定叶片可溶性糖稳定碳同位素比值(δ13Cleaf)与枝条渗出液稳定碳同位素比值(δ13Cbranch), 使用δ13Cleaf推导计算7-10月叶片尺度下植物短期水分利用效率(WUEleaf)变化趋势, 使用δ13Cbranch明确植物光合作用后分馏情况, 确定半干旱区植物在生长季的水分变化规律对环境因子变化的响应。结果表明: (1) 7-10月4种植物δ13Cleaf总体呈现降低趋势, δ13Cbranch呈现先升高后降低趋势。δ13Cleaf在种间和生活型中均存在差异。具体表现为: 灌木>乔木, 常绿乔木(油松) >落叶乔木(刺槐)。研究过程中未发现明显的碳同位素在光合作用后发生分馏的情况。(2) 4种植物WUEleaf在7-8月保持稳定, 9-10月逐渐升高。21.5 ℃、0.9 kPa、52.4%分别为WUEleaf随温度(Ta)、饱和水汽压差(VPD)、相对湿度(RH)变化的突变点, 突变点之后4种植物WUEleaf均表现出稳定的变化趋势, 不再随TaVPDRH升高而降低。(3) WUEleafTaRHVPD之间存在显著负相关关系, Ta通过非气孔因素, 即酶的作用改变光合速率, 引起WUEleaf变化。RHVPD等水分因子则通过改变气孔开度, 影响蒸腾, 进而改变WUEleaf。随着土壤含水量(SWC)的升高, WUEleaf呈现先升高后降低的趋势。油松林和刺槐林在SWC分别达到15%-18%、13%-14%时, WUEleaf达到最高值。经过混合线性模型(LMM)分析得到, 油松和刺槐WUEleaf主导环境因子分别为RHVPD, 黄刺玫和杠柳WUEleaf主导环境因子均为Ta。该研究得到了黄土地区典型乔灌木生长季水分利用效率变化的规律和主要环境影响因子, 明确了黄土地区植物对气候因子变化的适应机制。

关键词: 水分利用效率, 稳定碳同位素, 可溶性糖, 黄土地区, 混合线性模型

Abstract:

Aims We studied changes in the short-term water use efficiency with environmental factors in typical trees and shrubs of the loess area in West Shanxi. Our objective was to determine the patterns of water use and adaptive strategies in plants of this region, aiming for improving the efficiency of vegetation establishment in the loess area.

Methods Two typical trees, Pinus tabuliformis and Robinia pseudoacacia, and two typical understory shrubs, Rosa xanthina and Periploca sepium, were investigated in this study. Measurements were made on the stable carbon isotope of soluble sugars in leaves (δ13Cleaf) and phloem in branches (δ13Cbranch). δ13Cleaf was used to calculated the trend of short-term water use efficiency (WUEleaf) at the leaf level. δ13Cbranch was used to determine the carbon fractionation from photosynthesis. We compared the difference in WUEleaf between species and determined the responses of WUEleaf to changes in environmental factors.

Important findings From July through to October in the year of investigation, the δ13Cleafshowed an overall decreasing trend in the four species, whilst δ13Cbranch displayed a temporal pattern of “up and down”. δ13Cleaf differed among the species and between life forms, in the order of shrubs > trees, and Pinus tabuliformis (an evergreen tree) > Robinia pseudoacacia (a deciduous tree). The WUEleaf values remained stable from July to August in the four species, and then gradually increased from September to October. Abrupt changes in the WUEleafvalue occurred at 21.5 °C with temperature (Ta), 0.9 kPa with vapor pressure deficit (VPD), and 52.4% with relative humidity (RH), respectively. Following the abrupt changes, the WUEleaf value remained steady with further increases in Ta, VPD,and RH in the four species. There were significantly negative correlations between the WUEleaf value and Ta, RH, and VPD. Ta altered the photosynthetic rate by non-stomatal factors, specifically through the effects on enzymes, causing changes in the WUEleaf value. The water factor affects transpiration by controlling stomatal opening, and then changes the WUEleaf value. With increases in soil water content (SWC), the value of WUEleaf showed a trend of an initial increase and then decreases. The WUEleaf reached peak value at 15%-18% of SWC in the Pinus tabuliformis stands and 13%-14% in the Robinia pseudoacacia stands. The dominant environmental factors influencing WUEleaf also differed among species. Linear mixed model (LMM) analysis identified RH as the dominant environmental factor on Pinus tabuliformis, and VPD on Robinia pseudoacacia, respectively; Ta was identified as the dominant environmental factor on both Periploca sepium and Rosa xanthina. This study provides quantitative analysis of water use ability of typical trees and shrubs in the loess area, the internal water consumption mechanism in the growing season, and the major controlling environmental factors, which provides a theoretical basis for the vegetation configuration in this region.

Key words: water use efficiency, stable carbon isotope, soluble sugar, the loess area, linear mixed model