【作者】 李强；

【导师】 欧晓昆； 张志明；

【作者基本信息】 云南大学 ， 生态学， 2019， 硕士

【摘要】 林窗作为森林群落中一种重要的干扰方式,对林下物种构成有着重要的影响。开展林窗空间格局及其特征指数与林下植物多样性关系研究对探讨不同的林窗特征指数对林下植物生长情况有重要意义,有助于进一步了解群落动态,在物种多样性保护方面也具有指导作用。本研究在西双版纳热带森林地区随机选取了4块大小为1 ha的样地作为研究区,其中含3块大小为1 ha的热带雨林样地,1块大小为1 ha的季风常绿阔叶林样地。采用轻小型六旋翼无人机搭载Sony ILCE-A7r可见光传感器,分别获取各个样地的高清数字影像,结合数字表面高程模型以及各个样地的地形数据用以确定各样区的林窗分布格局,并进一步提取出各林窗的景观格局指数。结合地面样方基础调查数据,对各样地各林窗下植物多样性情况进行统计调查,旨在分析1)西双版纳州热带森林林窗空间格局特征;2)西双版纳州热带森林林窗下植物组成是否会受林窗影响而不同于林下;3)西双版纳热带森林林窗空间格局对林下植物多样性的影响情况。研究表明:(1)西双版纳热带森林中,4个样地内林窗面积分布均表现出小林窗数目多、大林窗数目少但面积总和大的负指数分布格局;就整体林窗空间格局来看,该地热带森林中热带雨林样地林窗平均最小邻近距离(ENN)均大于10,相比之下该地季风常绿阔叶林样地(DPZ)平均最小邻近距离较小。此外,相对于3个热带雨林样地(44、CC、SK)内林窗,季风常绿阔叶林样地DPZ林窗比之呈较聚集分布的空间格局。林窗形状复杂性方面,3个热带雨林样地形状复杂性程度多在1.6—3之间分布,平均形状指数为2.47,季风常绿阔叶林形状复杂性程度多在1.5—2.6之间分布,平均形状指数为2.19,西双版纳热带森林中热带雨林的林窗形状较该地季风常绿阔叶林更复杂。其原因可能与样地所处森林类型的不同而导致不同的林窗形成方式有关。(2)植物多样性特征上,首先西双版纳热带森林4个样地林窗下与样地内相比均表现出林窗下植物物种数量占比少,种类占比多的格局;其次各样地林窗下重要值前10的物种与各样地内重要值前10的物种基本一致,表现出大多数林窗都会朝着现有样地顶极格局进行恢复;再次,林窗下植物多样性特征皆表现出林窗下植物特征配置与林下一致的结果,但林窗下所包含的植物种数较多,也即说明林窗的形成所带来的影响有利于林下更多物种的共存,增加了林窗下植物多样性但并没有完全改变森林群落中植物的组成比例。(3)在植物多样性计算的3个指数中,物种丰富度对林窗空间特征与其林下植物多样性之间有很直观的响应。林窗的面积与物种丰富度之间呈极显著正相关关系(P<0.01)。就3个热带雨林样地来看,林窗面积与物种丰富度呈现极显著正相关关系(P<0.01,R2=0.6),关系曲线呈对数形式增长;林窗平均形状复杂性指数(MSI)与林窗下多样性指数之间呈显著正相关关系(P<0.05)。西双版纳热带森林林窗空间格局的改变如面积、形状复杂性的增加,有利于提高林下植物的多样性。且在该地热带雨林中,在面积小的林窗下,林下植物多样性主要受限于林窗面积的影响,此时林窗形状复杂性对林下植物多样性的影响较小。但在林窗面积大到一定程度时,其林下植物多样性受林窗面积因子的影响减弱,林窗形状复杂性对其的影响较之更为强烈,林下植物多样性主要受两者的共同影响。综上,研究表明,在西双版纳热带森林中:1)就3个热带雨林样地和一个季风常绿阔叶林样地林窗空间格局来看,相对于季风常绿阔叶林样地,3个热带雨林样地的ENN值更大,也即林窗分布较季风常绿阔叶林样地更为分散。其原因可能与样地所处地水热条件、微生物活动与冠层优势树种组成有关;2)就林窗下植物多样性特征来看,4个热带森林样地中,林窗下重要值前10的物种基本与样地内重要值前10的物种基本一致,各样地林窗皆趋于向各自所处样地顶极群落发展恢复。林窗下植物组成配置与林下一致,但其多样性高于林下,说明林窗的形成所带来的影响有利于林下植物多样性的提高,但不影响林窗下植物的组成比列;3)就林窗空间格局与林下植物多样性关系来看,林窗空间格局特征指数如林窗形状复杂性指数、林窗面积都与林下植物多样性情况呈显著正相关关系。在面积小的林窗下,较之林窗形状复杂性因子,林窗面积大小对林下植物多样性情况影响更显著;在面积大到一定程度后,相对于面积因子,林窗形状复杂性指数对林下植物多样性情况影响更剧烈。原因可能与地形(如坡度、海拔)、林窗闭合方式等有关。通过此次研究进一步加深了对西双版纳州热带雨林林窗空间格局及其与林下植物多样性关系的理解,能够为日后类似研究起一定的支撑和借鉴作用。更多还原

【Abstract】 Forest gaps,as an important mode of disturbance in forest communities,has an important impact on the composition of understory species.The research on the relationship between the spatial pattern of forest canopy gap and its characteristic index and the diversity of understory plants is of great significance to explore the different forest canopy gap characteristics index for the growth of understory plants,which will further help understand the dynamics community and also act like a guiding role in protecting the species diversity.In this study,there were 4 research plots were randomly selected,which included three tropical rainforests and one monsoon evergreen broad leaved forest that were one hectare in the Xishuangbanna tropical rain forest.The light and small six-rotor UAVs were used to mount the Sony ILCE-A7r visible light sensor to obtain high-definition digital images of each plot.The digital surface elevation model and the topographic data of each plot are used to determine the distribution type of the forest canopy gap in each plot,and further extract the landscape pattern index of each forest canopy gap.Based on the basic survey data of surface quadrangle,a statistical survey was conducted on the plant diversity under different forest canopy gap in different areas,aiming to analyze:1)The characteristics of spatial pattern of forest canopy gap in tropical rain forest of Xishuangbanna prefecture;2)Whether the plant composition under the tropical forest in xishuangbanna prefecture is affected by the forest canopy gap that is different from plant composition under the forest;3)The influence from the spatial pattern of the tropical forest canopy gap affected the undergrowth plant diversity in xishuangbanna.Research shows that:(1)In the tropical forest of Xishuangbanna,the area distribution of forest canopy gap in the four sample plots all showed a negative exponential distribution pattern with a large number of small forest canopy gap and a small number of large forest canopy gap but a large total area;For spatial pattern of overall forest canopy gap,tropical rain forest sample canopy gap mean euclidean near-neighbor distance(ENN)are more than 10,compared with evergreen broad-leaved forest sample plots(DPZ)mean euclidean near-neighbor distance to the youngest,outside,relative to the three tropical rain forest sample plots(44,CC,SK)in forest gap,evergreen broad-leaved forest sample plots DPZ forest gap than in the distribution pattern of space.Forest canopy gap shape complexity,more than three tropical rain forests to shape complexity degree between 1.6-3 distribution,the average shape complexity index was 2.47,evergreen broad-leaved forest shape complexity degree distribution between 1.5 to 2.6,the average shape index was 2.19,tropical rain forest in Xishuangbanna tropical forest canopy gap shape more complex than the area evergreen broad-leaved forest.(2)In terms of plant diversity characteristics,first of all,four sample forest canopy gaps of xishuangbanna tropical forest,the number of plant species in the forest canopy gap was less than that in the same forest canopy gap,while the number of single species was more than that in the same forest canopy gap.Secondly,the species with the top 10 important values under various forest canopy gap are almost consistent with the species with the top 10 important values under various forest canopy gap,which shows that most forest canopy gap will recover towards the existing pattern of the same climax.Again,characteristics of plant diversity under forest canopy gap are shown that plant characteristics under the forest canopy gap is as same as plant configuration under the forest,but below the canopy gap contains many plant species,which shows that the effects of forest canopy gap formation were beneficial to the improvement of the understory plant diversity,but it didn’t change the composition of the understory.(3)Among the three indexes calculated for plant diversity,species richness has an intuitive response between the spatial characteristics of forest canopy gap and the plant diversity under forest.There was a highly significant positive correlation between forest canopy gap area and species richness(P<0.001).In terms of the three tropical rain forest samples,the forest canopy gap area and species richness showed a highly significant positive correlation(P<0.01,R2 = 0.6),and the relationship curve showed a logarithmic growth.There was a significant positive correlation between the mean shape complexity index(MSI)and the diversity index under the canopy(P<0.05).The change of the spatial pattern of the tropical forest canopy gap in Xishuangbanna,such as the increase of the area and shape complexity,is conducive to improving the diversity of the understory plants.Moreover,in the tropical rain forest of this region,under the small forest canopy gap,the plant diversity under the forest is mainly limited by the influence of the forest canopy gap area,and the influence of the shape complexity of the forest canopy gap on the plant diversity under the forest is small.However,when the forest canopy gap area is large to a certain extent,the plant diversity under the forest is weakened by the factor of the forest canopy gap area,and the influence of the shape complexity of the forest canopy gap on the plant diversity under the forest is stronger than that under the factor of the forest canopy gap area,and the plant diversity under the forest is mainly affected by the two factors.To sum up,the research shows that in Xishuangbanna tropical forest:1)in terms of spatial pattern of forest canopy gap of three tropical rainforest plots and one evergreen broad-leaved forest plot,compared with that of evergreen broad-leaved forest plot,ENN value of three tropical rainforest plots is larger and forest canopy gap distribution is more dispersed than that of evergreen broad-leaved forest plot.The reason may be related to the ground water and heat condition,microbial activity and the composition of dominant tree species in the canopy;2)In terms of the characteristics of plant diversity under the forest canopy gap,the species with the top 10 important values under the forest canopy gap in the four tropical forest samples are almost consistent with the species with the top 10 important values within the sample,and all kinds of forest canopy gap tend to develop and recover towards the climax communities of the sample.The composition and configuration of plants under the forest canopy gap are consistent with plant composition under the forest,but their diversity is higher than that under the forest,it means the influence from the formation of the forest canopy gap is beneficial to the improvement of the diversity of plants under the forest,and this influence is in a small range and has little impact on the whole forest community;3)In terms of the relationship between the spatial pattern of forest canopy gap and the diversity of undergrowth plants,the characteristics indexes of the spatial pattern of forest canopy gap,such as the shape complexity index of forest canopy gap and the area of forest canopy gap,are significantly positively correlated with the diversity of undergrowth plants.Compared with the shape complexity factor of the forest canopy gap,the area of the forest canopy gap has a more significant effect on the plant diversity under the small forest canopy gap.When the area is large to a certain extent,compared with the area factor,the shape complexity index of forest canopy gap has a more dramatic impact on the diversity of understory plants.The reasons may be related to topography(such as slope,altitude)and closing mode of forest canopy gap.This study further deepened the understanding of the spatial pattern of the forest canopy gap in Xishuangbanna tropical rain forest and its relationship with the diversity of undergrowth plants,which can provide certain support and reference for similar studies in the future.更多还原