文献类型：期刊文献

中文题名：增加光照对林下樟树苗木的影响及作用机理

英文题名：Effects and action mechanisms of increased light availability to understory Cinnamomum camphora seedlings

作者：蔡继醇[1,2,3] 李兆佳[1,3] 周光益[1,3] 赵厚本[1,3] 王旭[1,3] 邱治军[1,3] 吴仲民[1,3]

第一作者：蔡继醇

机构：[1]中国林业科学研究院热带林业研究所,广东广州510520;[2]南京林业大学,江苏南京210037;[3]南岭北江源森林生态系统国家定位观测研究站,广东广州510520

年份：2024

卷号：44

期号：7

起止页码：36-46

中文期刊名：中南林业科技大学学报

外文期刊名：Journal of Central South University of Forestry & Technology

收录：CSTPCD;;北大核心:【北大核心2023】；CSCD:【CSCD2023_2024】；

基金：国家自然科学基金项目(31770664);广东省林业科技创新项目(2019KJCX026);中央级科研院所基本业务费重点项目(CAFYBB2019SZ003)。

语种：中文

中文关键词：光照;樟树;光合作用;比叶面积;叶绿素

外文关键词：light;Cinnamomum camphora;photosynthesis;specific leaf area;chlorophyll

分类号：S792.23

摘要：【目的】揭示增加光照对林下樟树苗木生长的影响,促进退化天然次生林的更新,【方法】选择中上层植物种为常绿阔叶树和苦竹的退化天然次生林,采用伐除苦竹后补植樟树苗木的方法研究增加光照对樟树苗木存活和生长的影响,并通过遮阴试验研究樟树幼苗对光照强度的生理适应机制。【结果】伐除苦竹对林下樟树苗木存活和生长有明显影响,林冠开度由2.36%±0.46%(对照林分)提高到11.37%±0.87%(伐除苦竹林分)时,樟树苗木存活率由16.67%提高到63.89%,地径生长量由0.5 cm提高到0.9 cm,树高生长量由0.16 m提高到0.63 m。在30%~50%遮阴条件下,樟树幼苗高生长显著高于对照(未遮阴)和其他处理的植株,遮阴70%~90%时与对照之间的差异不显著;30%~70%遮阴处理下的叶片数量显著高于对照和90%遮阴处理;叶面积和叶片厚度随着遮阴程度增加而下降,而比叶面积的变化趋势则相反;随着遮阴程度的增加,叶片含水量增加并呈台阶式变化,70%~90%遮阴下的叶片含水量显著高于光照更强的处理。遮阴使樟树幼苗叶片叶绿素a和b含量上升,但遮阴强度达到90%时叶片叶绿素a和b含量出现下降;遮阴强度达到70%及以上时,叶绿素a/b比值低于其他处理。随着遮阴程度上升,樟树幼苗最大净光合速率和表观量子效率均逐渐下降,光补偿点和暗呼吸速率整体呈下降趋势,但有例外(遮阴70%),光饱和点范围为800~1 200 μmol·m^(-2)·s^(-1),且没有明显变化规律。【结论】在苦竹扩张严重的退化天然次生常绿阔叶林中,伐除苦竹增加林地光照可提高樟树苗木的存活率和生长,有利于林分的更新和提质增效。轻度和中度遮阴条件下,樟树幼苗可通过减少对叶片的投入、降低最大净光合能力及提高叶绿素含量等策略来适应光照限制的生境;强度遮阴将严重抑制樟树幼苗的生长,从控制试验结果看,70%遮阴率是限制樟树幼苗生长的光照强度阈值。
【Objective】This paper aims to reveal the effects of increased light on the growth of understory Cinnamomum camphora seedlings and to facilitate the regeneration of degraded natural secondary forest.【Method】The survival and growth of C.camphora seedlings were investigated with and without removing the Pleioblastus amarus in a degraded natural evergreen broad-leaf forest,and the physiological adaptation mechanisms of C.camphora seedlings to light intensity was also studied in a shade experiment.【Result】Theremoval of P.amarus had a significant effect on the survival and growth of the C.camphora seedlings under the forest.The survival of C.camphora seedlings increased from 16.67% to 63.89% when canopy openness increased from 2.36%±0.46% (control stand) to 11.37%±0.87% (P.amarus removed),and the growth of ground diameter (from 0.5 to 0.9 cm) and seedling height (from 0.16 to 0.63 m)increased as well.Under 30%-50% shading,the height growth of C.camphora seedlings was significantly higher than that in other treatments,while no significant difference was observed between 70%-90% shading and control.The number of leaves under 30%-70% shade treatments was significantly higher than that under control and 90% shade treatment.The area and thickness of leaves decreased with the increased shading,but the trend of specific leaf area was opposite.The leaf water content also increased with increased shading.And it changed in a stepped manner that it was significantly higher under 70%-90% shading than in other treatments with higher light availability.The contents of chlorophyll a and b in leaves of C.camphora seedlings generally increased under shading,but decreased when the shading intensity reached 90%.The chlorophyll a/b ratio was lower than other treatments when the shading intensity reached 70% and above.The maximum net photosynthetic rate and apparent quantum yield of C.camphora seedlings decreased gradually,and the light compensation point and dark respiration rate showed a downward trend,with some exceptions (70% shade).The light saturation point range was about 800-1 200 μmol·m^(-2)·s^(-1)without obvious trend.【Conclusion】In the degraded secondary evergreen broad-leaved forest with severe expansion of P.amarus,increased light availability by removing bamboo improve the survival and growth of C.camphora seedlings,which is conducive to the regeneration,quality and efficiency of the stands.Under mild and moderate shading,C.camphora seedlings are capable of adapting to light-restricted habitats by reducing investment to leaf structure,reducing maximum net photosynthetic capacity and increasing chlorophyll content.And intense shading will seriously inhibit the growth of C.camphora seedlings.According to the shading experiment,70% shading is the threshold of light availability limiting the growth of C.camphora seedlings.