毛竹向撂荒地扩展过程中叶功能性状变化

【目的】探索毛竹林扩展过程中叶片的适应特性和生存对策,为合理调控毛竹林的扩展提供依据。【方法】以毛竹-撂荒地扩展界面为对象,比较了不同扩展阶段毛竹比叶面积(SLA)、叶干物质含量(LDMC)及叶片主要养分元素及计量比等叶功能性状。【结果】(1)随着毛竹的扩展,SLA呈先上升后降低的趋势,扩展前期、中期和后期的SLA值分别为1.80、2.16和1.83 m~2/kg。(2)不同年龄毛竹不同时期的LDMC的变化趋势不同,Ⅰ度竹LDMC随着毛竹扩展呈降低的趋势;Ⅱ和Ⅲ度竹LDMC呈升高的趋势。(3)随着毛竹的扩展,叶碳含量(LC)、叶氮含量(LN)、碳氮比(C/N)的变化差异不明显,叶磷含量(LP)呈降低的趋势,分别为1.70、1.53和1.15 g/kg;碳磷比(C/P)呈升高的趋势,分别为264.06、292.33、392.03;氮磷比(N/P)呈升高的趋势,分别为12.70、13.62和17.16。【结论】随着毛竹向撂荒地扩展,SLA先升后降,Ⅰ度竹LDMC降低,Ⅱ和Ⅲ度竹LDMC升高,LP降低,C/P和N/P升高,毛竹主要叶功能性状随着环境的变化发生了适应性改变。毛竹通过降低SLA和N/P,增加LP含量来适应扩展前期剧烈变化的环境条件。随着毛竹的扩展和林分环境的形成,毛竹叶N/P增加,生长由受N制约变化为受P元素制约。Ⅰ、Ⅱ、Ⅲ度毛竹LDMC随着毛竹扩展的变化规律不同,使毛竹能够在扩展过程中更好地保有资源,具有"集团"优势,能更灵活地利用资源。

Leaf functional traits of moso bamboo during its expansion into abandoned land

Objective]Elucidate differences in leaf functional traits of moso bamboo along a gradient of moso bamboo ex?pansion into abandoned land.Method] We compared the leaf functional traits of moso bamboo at different stages of ex?pansion, and explored the adaptability and survival strategy during expansion. Result]The specific leaf area ( SLA) was highest (2.16 m2/kg) during the middle stage of expansion. The second highest SLA (1. 83 m2/kg) was recorded during the final stage of expansion, whereas the lowest SLA (1.80 m2/kg) was recorded during the initial stage of ex?pansion. The leaf dry matter content ( LDMC) was different in different stages of expansion for moso bamboo of different age. LDMC of one?year?old moso bamboo decreased with moso bamboo expansion, whereas the LDMC of three and five years old moso was increased. There was no significant difference with regards the leaf carbon content ( LC) , leaf nitro?gen content ( LN) and C/N during the different stages of moso bamboo expansion. There was a significant decrease in leaf phosphorus content (LP) with expansion:1.70 g/kg in the initial stage, 1. 53 g/kg in the middle stage, and 1.15 g/kg in the final stage. There was a significant increase in C/P and N/P with expansion:C/P was 264.06, 292.33 and 392.03, and N/P was 12.70, 13.62 and 17.16, in the initial, middle and final stages, respectively. Conclusion]That the main leaf functional traits of moso bamboo changed during the course of its expansion into abandoned land, and that there was a trade?off among the leaf functional traits with this expansion. moso bamboo adapts to the disturbed environ?mental conditions during the initial stage of expansion by decreasing SLA and N/P , and increasing LP . The N/P of moso bamboo increased with its expansion when the forest environment was formed, and the growth of moso bamboo was changed from the N constraints to P constraints. Moreover, the results may reveal that moso bamboo has an obvious ad?vantage in competition because of its uneven age structure and the fact that different?aged bamboo has different trends in leaf functional traits during its expansion.