【作者】 汤爱仪；

【导师】 陶建平；

【作者基本信息】 西南大学 ， 生态学， 2008， 硕士

【摘要】 本论文以亚热带常绿阔叶林演替序列上不同地位的物种为研究对象，选择3种自然环境（旷地、常绿阔叶林林窗和常绿阔叶林林下）并比较3种环境的主要环境因子，从生长特征、光合特征、解剖特征方面研究幼苗对3种光环境的适应，得到以下结论：（1）研究发现由于受到林冠结构（空隙度、平均叶面积指数及平均叶倾角）的影响，旷地有效光辐射高于林窗和林下，旷地的相对湿度、气温日变化比林窗和林下变动大。3种环境的有效光辐射、气温和相对湿度的季节变化趋势一致，均表现出夏季值最高。不同环境中环境因子的变化幅度在夏季表现最为明显。（2）在旷地、林窗和林下3种自然光环境下，通过比较亚热带常绿阔叶林演替前期种四川大头茶（Gordonia acuminate（Pritz．）H．T.Chang）和后期种薄果猴欢喜（Sloanea leptocarpa Diels）的幼苗生长、生物量和光合色素含量，探讨不同生态习性亚热带常绿阔叶树种幼苗对光环境的适应。结果表明：1)在旷地环境，两种幼苗具有低的SSL、Chl_M、Chl_A、Car_M和高的Car／Chl以适应高光环境。与四川大头茶相比，薄果猴欢喜具有高的SMR、Car／Chl和低的SSL、LMR（p<0．05）：2)在林下环境，两种幼苗具有高的SLA、LAR、Chl_M、Chl_A、Car_M和低的Chl a／b以适应低光环境。与四川大头茶相比，薄果猴欢喜具有更高的SLA、LAR、Chl_M、Chl_A、Car_M和低的Chl a／b（p<0．05）。总之，前期种四川大头茶适应旷地光环境的能力略强于后期种薄果猴欢喜，但适应林下的能力较差。（3）研究了生长于旷地、林窗和林下环境的亚热带常绿阔叶林演替前期树种灯台树（Cornuscontroversa Hemsl.）和香樟（Cinnamomum camphora（L．）Presl）、中间种大果杜英（Elaeocarpusduclowxii Gagnep．）及演替后期种薯豆（Elaeocarpus japonicus Sieb．et Zucc）和栲树（Castanopsisfargwsii Franch．）幼苗的稳态光合特征和荧光参数对光强的响应。结果表明：灯台树和香樟具有高水平的ETR、NPQ、P_max和Rd，在3种光环境下均没有发生光抑制，相反，大果杜英、薯豆和栲树具有较低水平的ETR、NPQ和P_max，在旷地环境发生长期的光抑制现象。超过一定光强范围后，生长在林下环境的灯台树、香樟和大果杜英，比在旷地和林窗环境受到更大的光抑制（低的ΔF／Fm’值），可能是它们在林下生长具有较小的P_max、Rd、q_P、ETR和NPQ，而薯豆和栲树幼苗生长在三种环境下的q_P、ETR和NPQ差异不显著，即使施以相同光强，生长在林下的幼苗也与旷地和林窗发生的短期光抑制。结果表明幼苗在高光环境下是否会发生光抑制，与它本身具有的P_max、Rd、q_P、ETR和NPQ综合特征水平有关。（4）研究了生长于旷地、林窗和林下环境的亚热带常绿阔叶林前期树种川灰木（Symplocossetchuanensis Brand）、中间种大果杜英及演替后期种薯豆和栲树幼苗的生态解剖及可塑性特征。结果表明：在旷地环境下，4种幼苗表现出较高的气孔密度、气孔指数、叶厚、栅栏组织、栅栏／海绵组织、S_c、S_mec或S_c／S_mec值。在林下环境，4种幼苗具有较小的上表皮、叶厚和较大的海绵组织值。比较4种幼苗解剖可塑性，发现川灰木和大果杜英的大部分的解剖特征（气孔长度、保卫细胞长度、上表皮、上角质层、栅栏组织、栅栏组织／海绵组织、S_c指标）的可塑性指数显著高于薯豆和栲树（p＜0．05），且总体可塑性指数表现为川灰木（0．825）＞大果杜英（0．753）＞薯豆（0．597）＞栲树（0．583）。结果表明，常绿阔叶林演替前期种和中间演替种的可塑性比演替后期种大，这一定程度上解释了它们在常绿阔叶林演替中的地位。从本实验的综合结果中发现，一般演替前期种比演替后期种更适应于开阔的林窗环境，相反，后者更适应于郁闭的林下环境。更多还原

【Abstract】 To explore the light adaptation characteristics and related ecophysiological mechanism ofseedlings,this paper studied:1)The comparison on the canopy structure and light characteristicsamong three light regimes （Open land,Gap and Understory）.2)The growth,photosynthetic and leafanatomical responses of several seedlings growing in three light regimes.The results were asfollowing:（1） Because of the canopy structure （Gap fraction,LAI,MTA）,the photosynthetically available radiation in Open land was higher than that in Gap and Understory.The daily variance of thetemperature and relative humidity in Open land were greater than that in Gap and Understory.The seasonal variation trend of the photosynthetically available radiation,air temperature and relativehumidity in three different light regimes were consistent that the value of them was highest in summer.The variance of environment factors was greatest in summer.（2） It was studied that the adaptation to the different light regimes of seedlings of two species,one of which was Gordonia acuminate （Pritz.）H.T.Chang （early-successional species）and another was Sloanea leptocarpa Diels （late-successional species）in subtropical evengreen broad-leaved forest by comparing their growth characteristics,biomass and pigment contents in different lightregimes.The results showed that:1)The two species in this study could adapt to the high growthlight regimes （Open land）with low value of specific stem length （SSL）,chlorophyll contents（Chll_M,Chl_A）,Car_M,and high value of carrotenoid/chlorophyll （Car/Chl）.Compared with G.acuminate,S.leptocarpa had higher values of stem mass ratio （SMR）,carrotenoid/chlorophyll （Car/Chl）,and lower values of specific stem length （SSL）,leaf mass ratio （LMR）in Open land（p<0.05）.2)In Understory,the two species had low values of specific leaf area （SLA）,leaf arearatio（LAR）,chlorophyll contents （Chll_M,Chl_A）and Car_M,and high value of Chlorophyll a/ b （Chla/b）to adapt to the high light intensity.Compared with G.acuminate,S.leptocarpa had highervalues of SLA,LAR,Chl_M,Chl_A)Car_M,and lower values of Chlorophyll a/b （Chl a/b）（p<0.05）.Allof the results presented above indicated that G.acuminate could adapt better to Open land but did worse to Understory compared with S.leptocarpa.Their abilities to adapt to light regimes mightexplain their successional status in subtropical evengreen broad-leaved forest.（3） The response of the photosynthetic characteristic and fluorescence parameter were studied in seedlings of five tropical rainforest tree species.Cornus controversa Hemsl.and Cinnamomum camphora （L.）Presl were pioneer and early successional species,Elaeocarpus duclowxii Gagnep.was intermediate-tolerant and mid-successional species,Elaeocarpus japonicus Sieb.et Zucc andCastanopsis fargwsii Franch.were shad-tolerant and late-succesional species.The results showedthat:C.controversa and C.camphora were higher in ETR,NPQ,P_max and Rd,and there were nophotoinhibition in three light regimes.In reverse,C.controversa and C.camphora,E.duclowxii,E.japonicus and C.fargwsii were lower in ETR,NPQ and P_max,and there was photoinhabition for longtime in Open land.Exceeding some extent of light intensity,the C.controversa,C.camphora,and E.duclowxi growing in Understory had greater photoinhabition than that growing in Open land or Gap,because they had low values of P_max,Rd,q_P,ETR and NPQ;however there were no significant differences in q_P、ETR and NPQ of E.japonicus and C.fargwsii,even if growing in the Understorywith the same light intensity they had shorter time photoinhabition than that growing in Open land orGap.We concluded that whether the seedlings might happen photoinhabition or not was related tothe integrating characteristics of P_max,Rd,q_P,ETR and NPQ.（4） The ecological anatomy characteristics and phenotypic plasticities were studied in seedlings of four tropical rainforest tree species.Symplocos setchuanensis Brand was early-successionalspecies,E.duclowxii was mid-successional species,E.japonicus and C.fargwsii werelate-successional species.All of them acclimated to different light regimes （Open land,Gap andUnderstory）.The results showed that the four species had higher values of Stomatal density （SD）,Stomatal index （SI）,Leaf thickness （LT）,Thickness of palisade tissue （TPL）,Thickness of palisadetissue/Thickness of spongy tissue （TPL/TST）,S_c,S_mec and S_c/S_mec in Open land.However,the valuesof Thickness of upper epidermis,Leaf thickness （LT）,Thickness of spongy tissue （TST）were lower in four seedlings in the Understory.And it was showed that most of the indexes （SL,GCL,TUE,CTUB,TPL,TPL/TST,S_c）of S.setchuanensi and E.duclowxii were singnificant higher thanthat of E.japonicus and C.fargwsii.And the general Plasticity Index showed:S.setchuanensi （0.825）>E.duclowxii （0.753）>E.japonicus （0.597）>C.fargwsii （0.583）.All of the results presented above indicate that the PI in early-successional and mid-successional species were higher in that oflate-successional species.Their abilities to acclimate light regimes might explain their successional status in subtropical evengreen broad-leaved forest.All of the results presented above indicate that early-successional and mid-successional species acclimated better to high light regimes but did worse to the understory compared withlate-successional species.更多还原