毛竹比叶质量时空变化及对截雨干旱的响应

Seasonal and Canopy Variation of Leaf Mass Per Area for Phyllostachys edulis Leaves and its Response to Drought Stress

[目的]定量分析毛竹叶片比叶质量随生长季节、冠层部位和竹龄的变化及其对截雨干旱的响应,为全球气候变化下毛竹人工林可持续高效经营提供理论依据。[方法]以毛竹为研究对象,通过人工截雨干旱试验,对毛竹叶片比叶质量时空特性进行测定分析。[结果](1)截雨干旱与自然生长下,毛竹叶片比叶质量存在显著季节差异和年龄差异;不同生长季节,毛竹叶片比叶质量均随竹龄增加而增加;各龄竹比叶质量随生长季节的变化趋势均为春季>冬季>秋季>夏季。(2)截雨干旱与自然生长下,各龄竹比叶质量冠层差异不显著;自然生长下,比叶质量随冠层高度的垂直变化在不同生长季节均为冠层上部>冠层中部>冠层下部;截雨干旱下,比叶质量随冠层高度的变化因生长季节变化而不同。(3)截雨干旱下,各龄竹不同季节的比叶质量均高于自然生长下的比叶质量。干旱缓解了各冠层比叶质量的季节差异。截雨干旱与自然生长间比叶质量差异显著性受竹龄影响。(4)不同处理下各季节毛竹叶片比叶质量与土壤含水量、竹龄呈线性正相关。[结论]毛竹属于低比叶质量物种,生长季节显著影响其比叶质量变化;与光照相比,土壤水分条件对毛竹比叶质量产生重要影响。

[Objective]To quantitatively analyze the seasonal change of leaf mass per area(LMA)along canopy height for different aged moso bamboo(Phyllostachys edulis)in natural and drought stress growth environment,and to clarify the response characteristics of LMA to the throughfall exclusion for drought stress,aiming at providing references for sustainable and efficient management of Ph.edulis plantations under the global climate background.[Method]The spatial and temporal dynamic change of LMA is detected for moso bamboo under two different treatments with rain shelter or not.[Result](1)Regardless of throughfall exclusion or not,the LMA increased with the age of bamboo during different growing seasons,and the seasonal change trend from maximum to minimum was spring,winter,autumn and then summer in turn.There were significant differences of LMA among different seasons and treatments for the same age of bamboo(P<0.05),regardless of throughfall exclusion or not.(2)Regardless of throughfall exclusion or not,the differences of LMA were not significant among canopy for various ages of bamboo,while it was significant among seasons within the same canopy.In natural growth condition,the LMA of each season increased along with the canopy height and its vertical change showed the trend of the upper canopy>middle canopy>lower canopy successively,and the value of each canopy decreased at first and then increased as the growing season.There was significant difference among different seasons(P<0.01)for LMA of different ages of bamboo,while there was no significant difference among different canopy layers under throughfall exclusion.(3)Under the drought stress,the annual average value and each individual value of the LMA were all higher than the control in every season.The drought stress relieved seasonal difference of LMA in various canopy.The seasonal change of the LMA within the same canopy was also affected by age of bamboo.(4)With or without drought stress,there was linear positive correlation between the LMA and soil water content in each season,but the correlation under drought stress was lower than that of the control.The positive correlation between LMA and ages of bamboo under drought stress was higher than that of the control.[Conclusion]It is concluded that moso bamboo belongs to the species with lower LMA,and the growth season has significant effect on the change of LMA.Compared with the light,the soil moisture condition has more important influence on the LMA of the moso bamboo.