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陕北水蚀风蚀交错带沙柳和柠条叶光合作用对降雨改变的响应

陈丽茹1,李秧秧2*   

  1. 1西北农林科技大学林学院, 陕西杨凌 712100;2西北农林科技大学水土保持研究所, 陕西杨凌 712100)
  • 出版日期:2019-10-10 发布日期:2019-10-10

Responses of leaf photosynthesis in Salix psammophila and Caragana korshinskii to precipitation alteration in the water wind erosion crisscross region of northern Shaanxi Province.

CHEN Li-ru1, LI Yang-yang2*   

  1. (1College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China; 2Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China).
  • Online:2019-10-10 Published:2019-10-10

摘要: 为揭示黄土高原水蚀风蚀交错带分布广泛的两种灌木沙柳和柠条叶光合作用对降雨改变的响应机制,采用模拟降雨操纵试验(对照、降雨增加45%和减少50%),研究了降雨改变第3年两种灌木叶水分关系、光合能力、叶形态结构和养分含量的变化。结果表明:沙柳旱季和雨季不同处理间黎明前叶水势无显著差异,旱季正午叶水势对增水和干旱均有显著响应;柠条黎明前和正午叶水势对干旱有显著响应,而对增水无显著响应;沙柳旱季最大光合速率(Amax)、柠条旱季和雨季的Amax对增水和干旱均有显著响应;增水导致沙柳旱季Amax增加的原因主要是叶生物化学性质改善,而干旱降低沙柳旱季Amax的主要原因是CO2扩散的限制;增水导致柠条旱季光合增加的主要原因是气孔限制的减少,而雨季则与气孔限制及生化限制的减少均有关;干旱导致柠条旱季和雨季光合降低的主要原因是细胞生化限制的增加;两种灌木比叶质量、叶氮及磷含量对增水和干旱均无显著响应,表明降水改变导致的光合能力变化与叶形态结构和叶养分含量改变关系不大。研究结果可为全球气候变化背景下两种灌木的适应性评价和水碳循环模拟提供参考。

关键词: 长江口, 棘头梅童鱼, 适宜度指数, 相关性分析

Abstract: To understand the responses of photosynthesis in Salix psammophila and Caragana korshinskii, two shrub species commonly distributed in the water and wind erosion crisscross region on the Loess Plateau, to precipitation alteration, a manipulated precipitation experiment (control, water addition by 45%, and water reduction by 50%) was conducted. Leaf water relation, photosynthetic capacity, leaf morphological structure and nutrient concentration were measured after three years precipitation manipulation. For Salix, there was no difference of predawn leaf water potential among treatments during both dry and wet season, while midday leaf water potential showed significant responses to both water  addition and reduction during the dry season. For Caragana, both predawn and midday leaf water potential significantly decreased by water reduction, and showed no response to water addition. The light-saturated photosynthetic rate (Amax) in Salix during the dry season and Caragana during both dry and wet  changed for the treatments of water addition and reduction. The enhanced Amax in Salixby water addition during dry season was attributed to improved biochemical properties, while the decreased Amax in Salix during dry season was mainly related to increased CO2 diffusion limitation. For Caragana, the increasedAmax by water increase during the dry season was attributed to decreased stomatal limitation, and to decreased CO2 diffusion limitation and biochemical limitation during the wet season, respectively. The decreased Amax of Caraganaby water reduction during both seasons was related to increased biochemical limitation. Specific leaf mass, N and P contents of both species did not respond to water addition and reduction, indicating that the variation of Amax by water availability was not related to leaf structure and nutrient limitation. These results provide reference for evaluating the adaptability of both shrub species and modeling water and carbon cycling under future climate change.

Key words: Yangtze estuary, Collichthys lucidus, suitability index, correlation analysis.