河北塞罕坝樟子松径向生长动态变化及其与气象因子的关系

树木是森林生态系统的基本组成, 其生长受气象因子的影响, 基于此, 该研究通过监测樟子松(Pinus sylvestris var. mongolica)的径向生长, 研究樟子松生长日动态规律、季节动态规律及其与气象因子的关系, 探讨河北塞罕坝地区樟子松森林生态系统对气候变化的响应机制。此外, 以往研究树木生长大多数基于树轮年代学, 缺少短期树木径向生长动态的研究。该研究利用径向生长记录仪监测河北塞罕坝机械林场内樟子松连续3年(2016-2018)的树干径向动态变化。结果表明: 由于树干的水分吸收与蒸腾作用, 樟子松树干径向昼夜变化呈现季节性规律, 可划分为4个阶段: 春季萌动期、夏季生长期、秋冬交替期和冬季休眠期。塞罕坝樟子松树干径向生长开始于每年4月初; 4月初至5月中旬为水分恢复阶段; 5月中旬至7月中旬为快速生长阶段; 7月中旬至10月中旬为缓慢生长阶段; 10月中、下旬生长趋于停止, 并有树干径向收缩现象。以一天为时间尺度, 在快速生长阶段(5月初至7月中旬)樟子松径向生长主要受空气温度的影响; 缓慢生长阶段(7月中旬至10月下旬)降水量、空气温度均影响樟子松径向生长。以15天为时间尺度, 温度对樟子松径向生长的影响显著。结果显示樟子松的生长动态规律及其影响因子, 为未来樟子松生理研究提供参考时间节点, 同时在极端低温与干旱的情况下, 为半干旱地区樟子松的生长状态提供参考依据。

Stem radial growth dynamics of Pinus sylvestris var. mongolica and their relationship with meteorological factor in Saihanba,Hebei, China

Aims Trees are the basic components of forest ecosystems, and their growth is affected by meteorological factors. It is important to explore the response mechanism of forest ecosystems in this region to climate change if radial growth dynamics of dominant tree species and their relationship with meteorological factors are determined. Furthermore, previous studies on tree growth were mostly based on tree-ring chronology, whereas short- term studies on the stem radial growth dynamics of trees are scare. Therefore, this study aims to investigate the daily and seasonal dynamics of radial growth in Pinus sylvestris var. mongolica and its relationship with meteorological factors.Methods In this study, dendrometer increment sensor was used to monitor the stem radial dynamic changes of P. sylvestris var. mongolica for three years from 2016 to 2018 in the Saihanba, Hebei Province, China.Important findings Due to the water absorption and transpiration of the stems, the diurnal variation of the stem radial can be divided into four periods: spring germination period; summer growth period; autumn-winter alternating period; winter dormant period. Stem radial growth begins at early April in each year during water recovery from early April to mid-May. The fast-growing stage occurred from mid-May to mid-July. From mid-July to mid-October, trees entered a slow-growing stage. The radial growth tended to stop during mid- and late-October. Temperature was the main meteorological factor influencing the stem radial growth. On the time scale of one day, the stem radial growth was mainly affected by temperature during the rapid growth stage, but by rainfall and air temperature during slow growing stage. On the time scale of 15 days, only temperature had a significant effect on the stem radial growth. Under the conditions of extreme low temperature and drought, our results provide important reference for the growth status of P. sylvestris var. mongolica in semi-arid areas.