洪水漫溢对林窗微环境时空差异的影响——以塔里木河中游荒漠河岸林为例

林窗是森林生态系统中普遍存在的干扰形式。探究洪水漫溢对林窗内部微环境时空异质性的影响，对揭示荒漠河岸林物种多样性变化及其更新特征具有重要意义。在塔里木河中游非洪水和洪水漫溢区各选取一个大小相似的林窗样地，并使用便携式气象监测仪对林窗内不同方位的空气温湿度进行监测，对比分析不同水淹条件下林窗内微环境的时空分布差异，为深入探索荒漠河岸林植被更新机制奠定基础。结果表明：（1）非洪水漫溢区和洪水漫溢区林窗内空气温度均呈现先上升后下降的变化趋势，空气湿度均呈现先下降后上升的变化趋势，且同一个样地中温度与湿度之间存在明显的负相关关系，而洪水漫溢改变了森林微环境，使林窗内湿度升高，温度下降。（2）非洪水漫溢区和洪水漫溢区林窗内不同方位温度分布差异较小，洪水漫溢对温度变化影响不大；两个样地林窗内湿度变化过程较为复杂，差异明显，洪水漫溢区湿度变化梯度更为密集。（3）非洪水漫溢区和洪水漫溢区林窗内温度差界限明显，西南方向温度差较小，中心位置温度差最大，洪水漫溢并未改变不同方位温度变化趋势；湿度差以中心偏北方向较大，其中非洪水漫溢区湿度差在西北方向较小，而洪水漫溢区湿度差最小值出现在西南方向。研究结果表示荒漠河岸林林窗微环境时空差异具有干旱区独特性，同时阐明了林窗微环境对洪水漫溢的响应，为深入研究林窗干扰对荒漠河岸林更新与演替提供了科学依据。

Spatiotemporal variation of forest gaps microenvironment under flooding: an example of desert riparian forest in the middle reaches of the Tarim River

Forest gap is a common form of disturbance in forest ecosystems. Exploring the effect of flooding on the spatial and temporal heterogeneity of the microenvironment within forest gaps is important to reveal the changes of species diversity and their renewal characteristics in desert riparian forests. In this study, a sample plot of forest gaps of similar size was selected in each of the non-flooded areas and flooded areas in the middle reaches of the Tarim River. The air temperature and humidity in different directions within the forest gaps were monitored using a portable meteorological monitor. The spatial and temporal distribution differences of the microenvironment within the forest gaps under different flooding conditions were compared and analyzed to lay the foundation for an in-depth exploration of the vegetation regeneration mechanism of desert riparian forests. The results showed that:(1) the air temperature in the forest gaps of both non-flooded and flooded areas presented a trend which increases at first and then decreases; the air humidity showed an opposite trend which decreases at first and then increases. There was an obviously negative correlation between temperature and humidity in the same sample plot, while the flooding changed the forest microenvironment, increasing humidity and lowering the temperature in the forest gaps. (2) The difference in temperature distribution between the non-flooded areas and the flooded areas of the forest gaps in different directions was small, and the flooded areas had little effect on the temperature change. The process of humidity change within the forest gaps of the two sample sites was more complicated and the difference was obvious, and the gradient of humidity change was more intensive in the flooded areas. (3) The temperature difference boundaries between the non-flooded and flooded areas were obvious. The temperature difference was smaller in the south-west direction and the largest in the center. Flooding did not change the temperature trend in different directions. The humidity gap was larger in the north of the center, with the non-flooded areas having a smaller humidity gap in the northwest, while the smallest humidity gap in the flooded areas appeared in the southwest. The results show that the spatial and temporal variation in the microenvironment of forest gaps in desert riparian forests is specific to arid zones, and also elucidate the responses of forest gap microenvironments to flooding. This provides a scientific basis for an in-depth study of forest gap disturbance on the renewal and succession of desert riparian forests.