Effects Of Shade On Leaf Traits And Photosynthetic Characteristics Of 5 Species From Different Functional Groups

This dissertation selected typical nature secondary bushes community as testing ground in Lin’an,Zhejiang province.Pioneer species Liquidambar formosana and accompanied species Schima superba replanted in this stand,with dominant species Quercus glandulifera,random species Llex chimensis,successional stage climax species Castanopiss sclerophylla growing naturally in the wild were chosen as experimental materials.To simulate light environment under the forest standard(open,gap,under),three levels of shade(separately the shade of 0%、50%、70%)were set to study the effects of different light conditions on leaf characteriatics 、 chlorophyll fluorescence index and photosynthetic index.What’s more,an analysis of subordination function was used to make a comprehensive assessment of the adaptability to the low light conditions,and it could be a reference that shading as a kind of human disturbance way to promote trees growing.The management methods about how to deal with these 5 different functional groups species in the secondary bushes community recovery process were also put forward.The experimental results showed that:1.In the shading environment,Liquidambar formosana、Schima superba、Quercus glandulifera 、 Llex chimensis 、 Castanopiss sclerophylla could absorb light maximally through reducing blade thickness,expanding specific leaf area,increasing chlorophyll content,and it also reduced respiration rate to accumulate C.The ability of replanted species Liquidambar formosana and Schima superba to capture light through expanding leaf area were stronger than that of natural growth species Quercus glandulifera 、 Llex chimensis and Castanopiss sclerophylla,but Castanopiss sclerophylla would grow better than Quercus glandulifera、Llex chimensis in the low light,which had a strong capacity to capture more light through the change of leaf morphology responsing to shade.In natural light enviorment,Quercus glandulifera and Llex chimensis could be defined as sun plants and Liquidambar formosana 、 Schima superba and Castanopiss sclerophylla had some characteristics as similar as shading-tolerant plants according to the chlorophyll a/b values.All of five species could absorb more blue light in the shading environment through changing the leaves characteristics.Chlorophyll a/b values of Liquidambar formosana 、Schima superba and Castanopiss sclerophylla in shading were smaller than 2.3 showed that these three species had a strong shade tolerant ability,Schima superba was biggest,and then Castanopiss sclerophylla 、 Liquidambar formosana.If chlorophyll content as a single index was chosen to assess the ability to survive in the shading environment,the relationship appeared as Schima superba>Castanopiss sclerophylla>Liquidambar formosana>Quercus glandulifera>Llex chimensis.2.Shading decreased Fv/Fm of Liquidambar formosana 、 Quercus glandulifera and Llex chimensis,which meant the maximum ability for photosynthesis decresed,and shading brought the negative effects on these three species.Especially for Liquidambar formosana,Fv/Fm values in 50% shading and 70% shading were only 0.733,0.723 separately,growth was blocked,Liquidambar formosana suitable to live in high light environment.Schima superb and Castanopiss sclerophylla had a strong ability for maximum photosynthsis in all light environments(with Fv/Fm>0.75),and they became stronger in the shading conditions.So the light amplitude suitable for Schima superba and Castanopiss sclerophylla was wider,shading could promote their growth.3.In the shading environment,Liquidambar formosana,Quercus glandulifera and Llex chimensis could capture more light energy,but the proption of light enegy used to photosynthetic electron transfer decreased,much more light was used to generate heat.In the terms of Schima superba and Castanopiss sclerophylla,shading could increase the proportion of light used in the photochemical process,improved photosynthesis,decreased the light energy used for heat.Therefore,Liquidambar formosana、Quercus glandulifer and Llex chimensis suited to live in the high light density conditions.Castanopiss sclerophylla was weak to use higher light intensity,and the ability to use low light was strong,so it could take advantage of lower light intensity for photosynthesis in the community.It showed that this species was suitable to live in the low light environment,and proper shading could maximally increase net photosynthetic rate.The light range suitable for Schima superba survival was wider,and its adaptability was strong.4.The analysis of subordination function showed that Schima superba had the strongest shading-tolerant ability,and then came by Castanopiss sclerophylla,Liquidambar formosana,Quercus glandulifera and Llex chimensis were suitable to survive in strong light conditions.5.Liquidambar formosana was suitable to live in the high light environment,and the light range suitable for Schima superba was wider,therefore,Liquidambar formosana was much more suitable to be planted in the open or cutting blank than Schima superba.In the process of transformating coniferous forest to broad-leaved forest,planting Schimasuperba was much more appropriate after thinning needle-leaved trees.6.In the secondary shrub tansformation process,Quercus glandulifera and Llex chimensis with good growth condition and straight trunk could be chosen as sample trees with the focus on cultivating,cutting sprouts and tending for them so that they could grow rapidly in the community to become the dominat trees.7.Castanopiss sclerophylla was successional stage climax species with shade tolerant ability.If they were set sahding in the early successional stage so that they could grow up and it might push the climax species into the community ahead of time,and this process would be beneficial for vegetation recovery.Therefore,in the feasible conditions,setting shading for Castanopiss sclerophylla in the secondary bush community was beneficial for its growth,and then promoted the succession.