摘要
【目的】旨在通过模拟毛竹扩张过程中产生的关键环境变化(林下遮阴与土壤养分的改变),探究其对濒危植物华木莲幼苗形态生长、养分吸收以及光合生理特性的影响机制。【方法】基于毛竹扩张会形成高郁闭林冠以及改变土壤养分环境的生态过程,试验通过设置不同遮阴和施肥处理进行模拟。共设置7个处理组合:以全光照不施肥(L0N0)模拟毛竹扩张前的原生环境,作为试验的基础对照;全光照施肥(L0N1)、50%遮阴施肥(L1N1)、50%遮阴不施肥(L1N0)、75%遮阴施肥(L2N1)、75%遮阴不施肥(L2N0)用于模拟不同扩张程度下的光照与土壤养分条件的变化;同时,以竹林生境作为现实对照,反映扩张后的实际环境状况,比较分析各处理下华木莲幼苗在生长、光合生理和养分吸收等方面的差异。【结果】(1)遮阴显著抑制华木莲株高与地径生长(P<0.001),而施肥效应不显著(P>0.05),且二者无交互作用,竹林组对生长的抑制作用与75%遮阴组相近。(2)华木莲净光合速率随遮阴的加剧而下降,遮阴会显著降低最大光合速率(P_(max))、暗呼吸速率(Rd)、光饱和点(LSP)和光补偿点(LCP),而施肥仅能提升最大光合速率(P_(max)),且两者对Rd和LCP存在显著交互作用。(3)充足光照有利于提高气孔导度、蒸腾速率和水分利用效率,降低胞间CO_(2)浓度,从而增强光合作用,而遮阴显著抑制了这些光响应参数,导致光合作用和水分利用效率下降。(4)竹林组的N含量与全光照不施肥组差异不显著,但显著低于其他处理(P<0.05),同时竹林组的N∶P最低(11.67)且显著低于其他处理组(P<0.05),这表明在竹林生境下氮素是限制华木莲幼苗更新的关键因素。【结论】毛竹扩张通过光限制和氮素竞争对华木莲幼苗光合作用与生长产生抑制,是加剧其濒危的关键因素,建议对竹林进行疏伐增加林窗透光,同时采取定向补充氮肥等干预措施以保证华木莲的正常更新。
[Objective]By simulating key environmental changes,specifically understory shading and soil nutrient alterations,that occur during the expansion of moso bamboo,this study aims to clarify the mechanisms by which these changes affect morphological growth,nutrient absorption,and photosynthetic physiological characteristics in seedlings of the endangered plant species Sinomanglietia glauca.[Method]Based on the ecological process wherein the expansion of moso bamboo leads to the formation of a highly closed canopy and altered soil nutrient conditions,this study employed an experimental simulation using different shading and fertilization treatments.A total of seven treatment combinations were established:full light without fertilization(L0N0)was used to simulate the original environment prior to bamboo expansion,serving as the baseline control;full light with fertilization(L0N1),50%shading with fertilization(L1N1),50%shading without fertilization(L1N0),75%shading with fertilization(L2N1),and 75%shading without fertilization(L2N0)were implemented to simulate varying light and soil nutrient conditions under different degrees of bamboo expansion.At the same time,bamboo forest habitat was used as a realistic control,reflecting the actual environmental conditions after expansion.The differences in growth,photosynthetic physiology,and nutrient absorption of Sinomanglietia glauca seedlings under various treatments were compared and analyzed.[Result](1)Shading significantly inhibited the growth of plant height and ground diameter(P<0.001),but the effect of fertilization was not significant(P>0.05),and there was no interaction between them.The inhibition effect of bamboo forest group on growth was similar to that of 75%shading group.(2)The net photosynthetic rate of Sinomanglietia glauca decreased with the increase of shading.Shading significantly reduced the maximum photosynthetic rate(P_(max)),dark respiration rate(Rd),light saturation point(LSP)and light compensation point(LCP),while fertilization only increased the maximum photosynthetic rate(P_(max)),and there was a significant interaction between the two on Rd and LCP.(3)Sufficient light was beneficial to improve stomatal conductance,transpiration rate and water use efficiency,reduce intercellular CO_(2) concentration,and thus enhance photosynthesis,while shading significantly inhibited these light response parameters,leading to the decline of photosynthesis and water use efficiency.(4)There was no significant difference in N content between the bamboo forest group and the full sunlight non fertilization group,but it was significantly lower than other treatments(P<0.05).At the same time,the N∶P ratio of the bamboo forest group was the lowest(11.67)and significantly lower than other treatment groups(P<0.05),which showed that nitrogen was the key factor limiting the regeneration of Sinomanglietia glauca seedlings in the bamboo forest habitat.[Conclusion]The inhibition of photosynthesis and growth of Sinomanglietia glauca seedlings by light limitation and nitrogen competition during the expansion of Phyllostachys edulis is the key factor to aggravate its endangerment.To mitigate these effects,it is recommended to implement forest management interventions such as selective thinning of bamboo stands to improve light penetration through the creation of canopy gaps.Concurrently,targeted fertilization strategies,particularly nitrogen supplementation,should be applied to alleviate nutrient competition and support the natural regeneration process of Sinomanglietia glauca populations.
作者
郑崇龙
陈昕
欧阳园兰
张智华
张振炜
宋庆妮
刘骏
肖智勇
杨清培
ZHENG Chonglong;CHEN Xin;OUYANG Yuanlan;ZHANG Zhihua;ZHANG Zhenwei;SONG Qingni;LIU Jun;XIAO Zhiyong;YANG Qingpei(Jiangxi Provincial Key Laboratory of Breeding and Efficient Utilization of Native Tree Species,Jiangxi Agricultural University,Nanchang 330045,China;Nanchang Business College,Jiangxi Agricultural University,Nanchang 330045,China;Jiangxi Guanshan National Nature Reserve Management Bureau,Yichun,Jiangxi 336300,China;Yichun Academy of Sciences,Jiangxi Province,Yichun,Jiangxi 330600,China)
出处
《江西农业大学学报》
2026年第1期120-130,共11页
Acta Agriculturae Universitatis Jiangxiensis
基金
国家自然科学基金项目(3226130542)
国家重点研发计划项目(2024YFF130740005)。
关键词
华木莲
濒危植物
遮阴
施肥
光合生理
毛竹扩张
Sinomanglietia glauca
endangered plants
shading
fertilization
photosynthetic physiology
moso bamboo expansion
