Environmental Controls of Diurnal and Seasonal Variations in the Stem Radius of Platycladus orientalis in Northern China
Environmental Controls of Diurnal and Seasonal Variations in the Stem Radius of Platycladus orientalis in Northern China
复制标题
中国北方侧柏茎半径日变化和季节变化的环境控制
DOI：
10.3390/f10090784
复制
发表时间：
2019-09-01
期刊：
影响因子：
2.9
通讯作者：
Ding, Xinyuan
中科院分区：
文献类型：
--
作者：
Dong, Manyu;Wang, Bingqin;Ding, Xinyuan
对全年短时间尺度的茎径向变化进行精细分辨率研究，可以深入了解年际内的茎动态，提高我们对气候对树木生理和生长过程影响的认识。利用2013年9月至2014年12月采集的高分辨率点树枝计数据，研究了侧柏（Platycladus orientalis, Linn.）树干径向日变化规律和季节变化规律，以及生长季节环境因子与树干径向日变化的关系。在温暖季节和寒冷季节观察到两种截然不同的日循环模式。0°C的日平均气温是一个关键阈值，它与茎的日循环模式的季节变化有关，表明气温对茎的日循环有重要影响。东洋茎半径的年变化可分为春季补水期、夏季生长期、秋季停滞期和冬季收缩期四个不同时期。这些周期反映了树木水分状况的季节性变化，在春季和冬季尤为明显。在生长季节，东方杉的最大日收缩量（MDS）与气温（Ta）呈正相关，与土壤含水量（SWC）和降水量(P)负相关。蒸汽压差（VPD）在低于或高于0.8 kPa时也表现出基于阈值的MDS控制。日径向变化（DRC）与Ta和VPD呈负相关，而与相对空气湿度（RH）和p呈正相关。这些结果表明，上述环境因子通过影响树木的水分有效性与树木水分状况相关，进而影响树干的日变化指标，包括MDS和DRC。
Fine-resolution studies of stem radial variation over short timescales throughout the year can provide insight into intra-annual stem dynamics and improve our understanding of climate impacts on tree physiology and growth processes. Using data from high-resolution point dendrometers collected from Platycladus orientalis (Linn.) trees between September 2013 and December 2014, this study investigated the daily and seasonal patterns of stem radial variation in addition to the relationships between daily stem radial variation and environmental factors over the growing season. Two contrasting daily cycle patterns were observed for warm and cold seasons. A daily mean air temperature of 0 °C was a critical threshold that was related to seasonal shifts in stem diurnal cycle patterns, indicating that air temperature critically influences diurnal stem cycles. The annual variation in P. orientalis stem radius variation can be divided into four distinct periods including (1) spring rehydration, (2) the summer growing season, (3) autumn stagnation, and (4) winter contraction. These periods reflect seasonal changes in tree water status that are especially pronounced in spring and winter. During the growing season, the maximum daily shrinkage (MDS) of P. orientalis was positively correlated with air temperature (Ta) and negatively correlated with soil water content (SWC) and precipitation (P). The vapor pressure deficit (VPD) also exhibited a threshold-based control on MDS at values below or above 0.8 kPa. Daily radial changes (DRC) were negatively correlated with Ta and VPD but positively correlated with relative air humidity (RH) and P. These results suggest that the above environmental factors are associated with tree water status via their influence on moisture availability to trees, which in turn affects the metrics of daily stem variation including MDS and DRC.