基于生长测量仪监测的亚热带地区马尾松多时间尺度径向变化及其与环境因子的关系

树干径向变化的多尺度研究提供了树木生长及其和环境因子关系的详细信息，有助于准确评估全球气候变化背景下森林生态系统碳汇变异。以往树干径向变化研究主要集中在温带和热带地区，且大多数研究方法基于时间分辨率较粗的树木年轮法，然而缺少亚热带地区高时间分辨率树干径向变化的研究。利用树干径向变化记录仪连续监测亚热带地区马尾松13个月的树干径向变化动态，探索不同时间尺度树干径向变化规律及与环境因子的关系。结果表明：（1）在日尺度，马尾松径向变化模式为白天收缩夜晚膨胀，秋冬季节夜晚膨胀没有春夏季明显。（2）在季节尺度，马尾松树干径向变化可分为4个时期，其中3-8月是主要生长月份，4月是累计生长量最大的月份。（3）在日尺度上，相对湿度和饱和水汽压亏缺是调节马尾松径向变化主要环境因素；在季节尺度上，土壤温度对树干径向变化的影响大于空气温度，降水量与相对湿度等水分因素对树干径向生长的促进作用在生长季中后期更为明显。研究结果有助于深入理解亚热带季风气候区树干径向变化及其对环境变化的响应，为气候变化背景下亚热带地区的植树造林设计和森林可持续管理提供依据。

Dendrometer-derived radial variations of Pinus Massoniana at multiple time scales and its response to environmental factors in subtropical region

The research on the radial variations of forest trunks provides us with more details of forest trunks growth and its relationships with various environmental factors, which enables us to accurately assess how forest ecosystem productivity responds to climate change to quantify the dynamics of forest ecosystem in the future. Previous studies on tree radial growth in China mainly focused on temperate and tropical regions, which were based on coarse temporal resolutions-tree annual rings method. However, there is a lack of studies on radial variations of forest trunks based on high temporal resolution. Therefore, in this study, dendrometer was used to continuously monitor the tree-radial dynamics of Masson''s pines in the subtropical regions for 13 months to explore the patterns of tree-radial growth and its response to environmental factors at different time scales. The results showed that:(1) on the diurnal scale, the radial variation of the Masson''s pine appeared it contracted during the day and expanded at night. Meanwhile, the expansion of radial at night in autumn and winter was less obvious than in spring and summer. (2) On the seasonal scale, the radial growth of Masson''s pine could be divided into four periods(start growth season, rapid growth season,slow growth season and shrinkage season). March-August was the main growth period, and April was the period with the largest cumulative growth. (3) On the daily scale, the relative humidity and water vapor pressure deficit were the main climatic factors to regulate radial variations of Masson pine; on the seasonal scale, soil temperature had a greater influence on trunks'' radial variation than that of air temperature. The effects of soil temperature on the trunks'' radial variation were different among periods. In the start growth season and the slow growth period, there was a positive and negative correlation between soil temperature and trunks'' radial variation, respectively, but in the rapid growth season, no correlation between soil temperature and trunks'' radial variation can be found. However, the correlation of water conditions gradually increased over time, and the promoting effect of water factors such as precipitation and relative humidity on the radial growth of trunk was more obvious in the middle and late growing season. The results can help us further understand the radical changes in tree trunks and their response to the environmental changes in subtropical monsoon climate regions. These efforts will provide a basis for reforestation design and sustainable forest management in subtropical regions against the background of climate change.