Comparing primary and secondary growth of co-occurring deciduous and evergreen conifers in an alpine habitat
Comparing primary and secondary growth of co-occurring deciduous and evergreen conifers in an alpine habitat
复制标题
比较高山生境中同时发生的落叶和常绿针叶树的初生和次生生长
作者：
Zhang Yiping;Jiang Yuan;Wen Yan;Ding Xinyuan;Wang Biao;Xu Junliang
对共生物种的原生和次生生长的调查将有助于评估物种的生理适应性和预测林分结构动态。为探讨华北落叶松原生林与次生林生长的相关性和协调性，对共生林华北落叶松的叶片物候、新梢伸长和茎生长进行了动态监测。和白云杉（Picea meyeri）。et wils. 2014年生长季节，在高山栖息地芦芽山（中国中北部）。我们测量了芽的发育顶枝每周三天的直接观察和一年内干木质部形成每周的时间间隔，微芯法。三个器官的发病顺序为针叶、枝、茎，无种间差异。落叶松的针叶出现比树干生长早一个月，而云杉的针叶出现比树干生长早一周。针叶的生长期最短，其次是地上部和茎。初级生长的时间（即，两种植物的次生生长（开始、结束和最大生长速率）是不同步的，但次生生长与最大生长速率发生的日期是同步的，这可能表明两种植物对资源的竞争。与落叶松不同，云杉不同器官的生长高峰交错，这可能有效地缓解树木对资源的内部竞争。土壤温度与两树种的地上部和茎部生长均呈正相关，而气温和土壤含水量仅与落叶松的针叶生长呈正相关。因此，可以推断，云杉可能会胜过落叶松在寒冷的高山树线网站，由于其高适应性，以获取和分配资源。这些结果提供了深入了解初级和次级生长之间的潜在生理相关性，并允许更好地预测未来气候变化对森林生态系统生产力的影响。
Investigations on primary and secondary growth in co-occurring species will aid in assessment of the physiological adaptation of species and the prediction of forest stand structure dynamics. To explore the correlation and coordination between primary and secondary growth, we monitored the leaf phenology, shoot elongation, and stem growth of co-occurring Larix principis-rupprechtii Mayr. and Picea meyeri Rehd. et Wils. in an alpine habitat, Luya Mountain (North-Central China), during the growing season of 2014. We measured bud development on terminal branches three days per week by direct observations and intra-annual stem xylem formation at weekly intervals by the microcores method. The onset sequence of three organs was the needle, shoot, and stem, without species-specific differences. Needles appeared one month earlier than stem growth in larch, while it was only one week earlier in spruce. The duration of needle growth was the shortest, followed by the shoot and stem. The timing of primary growth (i.e., onset, end, and maximum growth rate) between the two species was asynchronous, but secondary growth was synchronic with the same date of the maximum growth rate occurrence, potentially indicating species competition for resources. Unlike larch, spruce staggered growth peaks among different organs, which may effectively mitigate trees’ internal competition for resources. Soil temperature was positively correlated with both shoot and stem growth in the two species, whereas air temperature and soil water content were positively correlated with needle growth only in larch. Therefore, it can be inferred that the spruce will probably outcompete the larch at cold alpine treeline sites due to its high adaptability to acquiring and allocating resources. These results provide insight into the potential physiological correlation between primary and secondary growth and allow better prediction of future climate change effects on forest ecosystem productivity.