晋西黄土区刺槐林典型植物蒸腾特征及其环境响应

Transpiration Characteristics and Environmental Response of Typical Plants in Robinia pseudoacacia Forest in Loess Area of Western Shanxi Province

[目的]揭示晋西黄土区刺槐林典型植物(乔木、灌木、草本)的蒸腾耗水规律,以期明确该区刺槐人工林蒸腾耗水的主导环境因子。[方法]利用Li-6400XT便携式光合仪对植物的蒸腾过程进行测定,并同步收集土壤水分及气象因子数据,分析了刺槐林典型植物蒸腾特征及其环境响应。[结果](1)7月,刺槐(乔木)和高羊茅(草本)的蒸腾速率日变化特征呈现双峰曲线规律,杠柳(灌木)蒸腾速率日变化特征为单峰曲线;9月3种植物蒸腾速率的日变化特征均呈单峰曲线的趋势。(2)研究期间0—20 cm土层的平均土壤体积含水率在9.37%~18.09%,坡上的平均土壤含水量为12.16%,坡下的平均土壤含水量为15.41%。坡上刺槐和杠柳的蒸腾速率对土壤含水量的响应大于坡下,而高羊茅的蒸腾速率对土壤含水量的响应在坡上小于坡下。(3)在坡上,光合有效辐射是驱动植物蒸腾的主导气象因子;在坡下,刺槐、杠柳和高羊茅蒸腾的主导气象因子分别为空气相对湿度、光合有效辐射和大气CO_(2)浓度。(4)在整个研究期间建立逐步回归拟合,刺槐和杠柳建立的方程可以更准确地模拟蒸腾速率,而高羊茅效果不理想。[结论]在晋西黄土区,不同植物蒸腾特征差异明显,且各植物影响蒸腾特征的环境因子因坡位而异,在植被建设过程中应综合考虑坡位以及环境因子的作用。

[Objective]The aims of this study are to reveal the transpiration and water consumption pattern of typical plants(trees,shrubs,herbs)in Robinia pseudoacacia forests in the loess area of western Shanxi,and to clarify the dominant environmental factors of transpiration water consumption in Robinia pseudoacacia plantation forests in this area.[Methods]Li-6400XT portable photosynthesizer was used to measure the transpiration process of the plants,and the data of soil moisture and meteorological factors were synchronously collected to analyze the characteristics of the transpiration of typical plants in Robinia pseudoacacia forests and their environmental responses.[Results](1)In July,the diurnal variation characteristics of transpiration rate of Robinia pseudoacacia and Festuca elata showed bimodal curves,and the diurnal variation characteristics of transpiration rate of Periploca sepium showed unimodal curves.The diurnal variation characteristics of transpiration rate of the three plants in September showed a unimodal curve,and there was an obvious change pattern.(2)The average soil volume water content of 0—20 cm soil layer during the study period was between 9.37% and 18.09%,and the average soil moisture contents were 12.16% on the upslope and 15.43% on the downslope.The response of the transpiration rate of Robinia pseudoacacia and Periploca sepium to soil water content on the upslope was greater than that on the downslope,while the transpiration rate of Festuca elata on the upslope was less responsive to soil water content than that on the downslope.(3)On the upslope,photosynthetically effective radiation was the dominant factor driving transpiration of forest stands.On the downslope,the dominant factor of each vegetation was different.The dominant factor of Robinia pseudoacacia was air relative humidity.The dominant factor of Periploca sepium was photosynthetically effective radiation.The dominant factor of Festuca elata was atmospheric CO_(2) concentration.(4)During the entire research period,a stepwise regression fitting was established.The stepwise regression equations established for Robinia pseudoacacia and Periploca sepium could more accurately simulate transpiration rate,while the effect of Festuca elata was not ideal.[Conclusion]In the loess area of western Shanxi,the transpiration characteristics of different plants differ significantly,and the environmental factors affecting the transpiration characteristics of each plant vary according to the slope position,so the role of slope position as well as environmental factors should be considered comprehensively in the process of vegetation construction.