中国北方山地针叶林生长的时空分异及其对水热条件的响应

This research project in proposing will take the mountain ranges covered with a special vertical zone of temperate mountane conifer forests from northeast to far west in Northern China, including Changbai Mountain, Greater Khingan Mountain, Lüliang Mountain, Helan Mountain, Qilian Mountain, Tianshan Mountain, and Altai Mountain, as the target study areas, and conduct an intergrated study on the growth rhythms and phenological growing features of trees in those forests. The techniques of treering analysis, micro-coring, dendrometer and dynamic monitoring on tree’s growth within sampling plots, and methods as derivation of forests’ phenology by inversion of vegetaion indeces from remotely sensed data, multi-variate analyses, time series analysis and growth model builiding and simulation will be used in the research processes to clarify the phytogeographic rules patterned both spatially and temporally behind the growth rhythms and growing features, and to reveal the responses of the forests’ growth to clmatic factors, particularly the influential temperature and precipitation regimes..Based on the dynamic tree growth data measured by above-mentioned methods and techniques at annual intervals, the research will, on the one hand, conduct a series of quantitative analyses on the features of forests’ growth patterns, their horizontal and vertical differentiations, as well as their temperal variations. On the other hand, the research will conduct certain analyses on the trees’ radial growth rhythms and their spatial differentiation patterns within a year, based on the dynamic tree growth data measured at monthly, daily, and semi-hourly intervals. The research will try to make clear the responses of growth patterns in those conifer forests to temperature and precipitation regimes, and to reveal the rules of territorial differentiation in light of bio-climatic relationships reflected by variations of cornifer forest growth under oscillated climatic conditions..The unique feature and scientific novelties in this research are, to integrate the geographic, ecological and biological theories and methods to explore the influential and decicive microscopic-ecological mechanisms driving the macroscopic phytogeographic rules, and to reveal the diversified spatial-temporal responses of the montane conifer forests in their growth process on temperature and precipitation regimes. The research findings will be conducive to enriching the fundemental theories in phytogeography, and promoting the forecast accuracy on the dynamics of montane conifer forests and the evaluation of the ecosystem services they provide.

选择中国北方山地（包括长白山、大兴安岭、吕梁山、贺兰山、祁连山、天山、阿尔泰山）区针叶林为研究对象，采用树木年轮分析、微树芯技术、茎干径向生长监测技术、生长动态样地调查、遥感植被指数反演、多元统计分析和时间序列分析等方法和技术手段开展研究。.一方面以年际生长动态变化数据为基础，定量分析森林生长特征、生长的水平和垂直空间变化规律、时间变化规律等；另一方面以年内生长动态变化数据为依据，研究径向生长的年内节律及其空间分异特征。从多种时间和空间尺度，认识针叶林生长对水热条件的响应及其地域分异特征。.项目的创新与特色在于将地理学、生态学和生物学理论与方法相结合，探索驱动地理学宏观规律的生态学微观机理，揭示山地针叶林生长过程对水热条件响应的时空多样性。研究结果将丰富植物地理学理论，并有助于提高预测山地针叶森林生态系统动态及其所提供的生态系统服务的能力。

茎干径向生长监测技术、遥感植被指数反演、多元统计分析和时间序列分析等方法，研究针叶林优势树种生长对水热条件响应的时空分异特征。主要结论如下：.从1960年到2010s年代以来，项目研究的寒温性针叶林样地序列中，采用轮宽指数为代表的生长变化以无明显趋势占比最高，其次是下降趋势，上升趋势仅在一些山地的局部地段有表现，三种变化类型分别占75.3%、14%和10.7%。生长趋势在大多数的山地没有表现出沿海拔产生分异；从生长-水热响应关系看，东部和西部存在显著差别，造成这种差别的气候驱动因子是降水，在地理分异规律上则表现为随经度和海拔变化产生分异；生长-水热响应关系的纬向差异，表现在以大兴安岭及其向南延伸的山地这一区域中。这些结论表明，近半世纪以来普遍存在的气温升高过程，对我国北方山地针叶林的不利影响有限。.以高时间分辨率径向生长数据为基础，确定了云杉茎干的主要生长季节在5-6月，且径向生长的开始时间比针叶和小枝的开始时间早大约1周，而结束期晚于针叶和小枝。研究还发现，不仅径向生长启动时间表现出明显的垂直变化规律，而且生长速率也表现出随海拔梯度的变化，海拔每上升200m，生长速率提高约7%。此外，茎干的日变化模式在生长季和冬季存在明显差异，项目提出了基于正弦波函数的两种不同模式的定量识别方法。这些结果从树木径向生长过程方面，揭示了生长-水热关系地理格局形成的部分微观机制。.径向生长年际变化与NDVI年际变化之间的关系，在东北大兴安岭地区表现得相对一致。树轮宽指数与5月份NDVI之间的相关系数普遍为正值，且相关显著性达到0.05水平的像元数超过40%。在西部地区山地，树轮宽度指数与生长季NDVI的相关系数具有随海拔升高逐渐由正转负的趋势，但相关显著性达到0.05水平的样点均表现为正相关，且主要位于低海拔地带。