秦岭华北落叶松人工林群落结构和物种多样性研究

秦岭植被在水平地带上有逐渐的过渡性，在海拔梯度上形成明显的垂直带谱，对研究我国南北部植被分异特征具有重要意义。同时，该区森林又是重要的水源涵养林，在水土保持、气候调节、水质净化、减灾抗洪以及游憩娱乐、丰富人民生活等诸多方面发挥着巨大作用。由于气候等自然因素和人为因素等的影响，天然植被破坏严重，人工林的面积不断扩大，人工林生态系统在秦岭地区发挥着越来越大的作用。但由于人工植被树种结构单一，与天然植被差异较大而导致其群落内物质循环缓慢、土壤肥力退化、林地生产力水平降低，出现不同程度的衰退现象。因此，对该区人工林植被的研究具有非常重要的理论和实际价值。华北落叶松(Larix principis-rupprechtii)为松科落叶松属落叶乔木，属阳性树种，性极耐寒;对土壤的适应性强，喜深厚湿润而排水良好的酸性或中性土壤:我国特产，产于河北、山西，辽宁、内蒙古、山东、陕西、甘肃、宁夏、北京、新疆等省有引种栽培;生长快，材质优良，用途大，对不良气候的抵抗力较强，并有保土、防风的效能，可作分布区内以及黄河流域高山地区及辽河上游高山地区的森林更新和荒山造林树种。陕西省自1958年先后在黄龙、秦岭等林区进行华北落叶松引种试验和造林，截至1986年在秦岭山区造林面积已达0.3×10~4 hm~2:华北落叶松在秦岭林区初期生长良好，而近年来生长势明显下降。本研究采用样方法在野外调查了秦岭平河梁地区3个样地30个样方的资料，应用方差分析和多重比较等统计方法，对秦岭华北落叶松人工林群落的结构及物种多样性进行了分析研究，并与秦岭油松(Pinus tabulaeformis)人工林群落的结构和物种多样性进行比较分析，得到以下结论:1.在秦岭山地华北落叶松人工林群落3个样地中共记录到植物89种，隶属于42科39属。各样地垂直结构层次分明，划分为乔木层、灌木层和草本层。植物种类草本层＞灌木层＞乔木层。乔木层组成上较为单一，大多为纯林，林中的油松等一般为抚育时补种;灌木层重要值最大的物种是蔷薇科的悬钩子(Rubus)，草本层为莎草科的苔草(Carex lanceolata)，构成了以华北落叶松为建群种、悬钩子和苔草为优势种的群落。各样地之间各层的胸径、盖度和高度等指标有差异或者有显著差异。华北落叶松在径级上趋向于正态分布，在年龄上分布于几个不同的年龄段，主要为中龄林，相同年龄的华北落叶松胸径差异较大。2.通过对华北落叶松人工林群落物种多样性分析可知，由于生境条件和人为干扰程度的不同，各样地物种多样性存在着一定的差异。从物种α多样性分层分析来看，该区华北落叶松群落人工林下灌木层和草本层物种多样性指数、优势度指数、丰富度指数和均匀度指数都表现出草本层＞灌木层的特点。对3个样地灌木层和草本层的四种α多样性指数进行方差分析和多重比较，发现灌木层:3个样地的优势度指数和多样性指数差异显著，丰富度指数和均匀度指数差异不显著;草本层:3个样地丰富度指数有显著差异，多样性指数、优势度指数和均匀度指数差异不显著。灌木层优势度指数，样地3和样地2差异显著，样地3和样地1差异显著，样地1和样地2差异不显著，这是因为样地3灌木层优势种数目多且盖度大，所以其优势度较小。β多样性揭示出该区不同样地群落组成存在差异。3.华北落叶松人工林群落与油松人工林群落相比，华北落叶松人工林群落乔木层树种单一，几乎为由华北落叶松组成的纯林;油松人工林群落的乔木层由于树种丰富、高度不同，又可以划分3个不同的亚层。华北落叶松人工林群落乔木层的平均高度、盖度和胸径，灌木层平均高度和盖度，草本层盖度与油松人工林群落相比都有极其显著的差异。两种人工林群落在物种组成上不同:秦岭华北落叶松人工林群落中有植物42科83属89种，是以华北落叶松为建群种，灌草主要优势种植物分别是悬钩子和苔草:油松人工林群落中有植物73科104属125种，灌草主要优势种植物为分别为白檀(Symplocos paniculata)和荚果蕨(Mattencciastrathiopteri)。对两种人工林群落垂直各层的密度比较，两种人工林乔木层密度没有显著差异，但灌木层和草本层密度差异显著。物种多样性方面，华北落叶松人工林样地的多样性指数、优势度指数、丰富度指数和均匀度指数都表现出草本层＞灌木层＞乔木层的特点;油松人工林多样性指数、丰富度指数、均匀度指数和优势度指数均呈现为灌木层＞草本层＞乔木层的相同变化趋势。乔木层、灌木层和草本层的均匀度指数均为油松人工林＞华北落叶松人工林;灌木层优势度指数、多样性指数油松人工林＞华北落叶松人工林，草本层相反;灌木层丰富度指数华北落叶松人工林＞油松人工林，草本层相反。

The vegetation of the Qinling Mountains shows gradual transitional characteristics along the horizontal zonation, and forms distinct vertical vegetation belts along the elevation gradient, which is of great significance for studying the vegetation differentiation characteristics between the northern and southern parts of China. Meanwhile, the forests in this region are also important water conservation forests, playing a huge role in soil and water conservation, climate regulation, water purification, disaster reduction and flood control, as well as recreational entertainment and enriching people's lives. Affected by natural factors such as climate and human activities, natural vegetation has been severely damaged, and the area of plantation forests has been continuously expanding. The plantation forest ecosystems are playing an increasingly important role in the Qinling Mountains. However, due to the single tree species structure of artificial vegetation and the large difference from natural vegetation, the material circulation in its community is slow, soil fertility degenerates, and forestland productivity decreases, leading to varying degrees of decline. Therefore, research on the artificial forest vegetation in this region has extremely important theoretical and practical value.

*Larix principis-rupprechtii* (family Pinaceae, genus *Larix*) is a deciduous arbor species, which is a heliophilous tree with extremely high cold tolerance. It has strong adaptability to soil, and prefers deep, moist, well-drained acidic or neutral soils. It is a native species of China, originally distributed in Hebei and Shanxi, and introduced and cultivated in Liaoning, Inner Mongolia, Shandong, Shaanxi, Gansu, Ningxia, Beijing, Xinjiang and other provinces/municipalities. It features fast growth, excellent wood quality, wide applications, strong resistance to adverse climates, as well as soil and wind conservation functions. It can be used as a tree species for forest regeneration and afforestation of barren mountains in its distribution area, as well as in alpine regions of the Yellow River Basin and the upper reaches of the Liaohe River.

Since 1958, Shaanxi Province has carried out introduction trials and afforestation of *Larix principis-rupprechtii* in forest regions such as Huanglong and the Qinling Mountains. By 1986, the afforestation area in the Qinling Mountains had reached 0.3×10^4 hm². The initial growth of *Larix principis-rupprechtii* in the Qinling forest region was good, but its growth vigor has declined significantly in recent years.

This study used the quadrat method to conduct field investigations on data from 30 quadrats in 3 sampling plots in the Pingheliang area of the Qinling Mountains. Using statistical methods such as analysis of variance and multiple comparisons, we analyzed and studied the community structure and species diversity of the *Larix principis-rupprechtii* plantation forest in the Qinling Mountains, and compared them with the community structure and species diversity of the *Pinus tabulaeformis* plantation forest in the Qinling Mountains. The following conclusions were obtained:

1. A total of 89 plant species belonging to 42 families and 39 genera were recorded in the 3 sampling plots of the *Larix principis-rupprechtii* plantation community in the Qinling Mountains. The vertical structure of each sampling plot is clearly stratified, divided into tree layer, shrub layer and herb layer. The number of plant species follows the order: herb layer > shrub layer > tree layer. The tree layer is relatively single in composition, mostly pure stands, and species such as *Pinus tabulaeformis* in the forest are generally replanted during tending. The species with the highest importance value in the shrub layer is *Rubus* (Rosaceae), and the dominant species in the herb layer is *Carex lanceolata* (Cyperaceae), forming a community with *Larix principis-rupprechtii* as the constructive species, and *Rubus* and *Carex lanceolata* as the dominant species. There are differences or significant differences in indicators such as diameter at breast height (DBH), coverage and height of each layer among different sampling plots. The DBH classes of *Larix principis-rupprechtii* tend to follow a normal distribution, and the age distribution spans several different age groups, mainly middle-aged forests, with large differences in DBH among *Larix principis-rupprechtii* of the same age.

2. Through the analysis of species diversity of the *Larix principis-rupprechtii* plantation community, it can be seen that due to differences in habitat conditions and the degree of human disturbance, there are certain differences in species diversity among different sampling plots. From the stratified analysis of species alpha diversity, the species diversity index, dominance index, richness index and evenness index of the shrub layer and herb layer under the *Larix principis-rupprechtii* community in this region all show the pattern: herb layer > shrub layer. We conducted analysis of variance and multiple comparisons on the four alpha diversity indices of the shrub layer and herb layer in the 3 sampling plots, and found that for the shrub layer: the dominance index and diversity index of the 3 plots have significant differences, while the richness index and evenness index have no significant difference; for the herb layer: the richness index of the 3 plots has significant differences, while the diversity index, dominance index and evenness index have no significant difference. For the dominance index of the shrub layer, there are significant differences between Plot 3 and Plot 2, and between Plot 3 and Plot 1, while there is no significant difference between Plot 1 and Plot 2. This is because Plot 3 has more dominant species and higher coverage in the shrub layer, so its dominance degree is lower. Beta diversity reveals that there are differences in community composition among different sampling plots in this region.

3. Compared with the *Pinus tabulaeformis* plantation community, the tree layer of the *Larix principis-rupprechtii* plantation community has a single tree species composition, almost being a pure stand composed of *Larix principis-rupprechtii*. The tree layer of the *Pinus tabulaeformis* plantation community can be divided into 3 different sub-layers due to abundant tree species and different heights. The average height, coverage and DBH of the tree layer, the average height and coverage of the shrub layer, and the coverage of the herb layer of the *Larix principis-rupprechtii* plantation community all have extremely significant differences compared with those of the *Pinus tabulaeformis* plantation community. The two plantation communities differ in species composition: the *Larix principis-rupprechtii* plantation community in the Qinling Mountains has 89 plant species belonging to 42 families and 83 genera, with *Larix principis-rupprechtii* as the constructive species, and the main dominant shrub and herb species are *Rubus* and *Carex lanceolata* respectively; the *Pinus tabulaeformis* plantation community has 125 plant species belonging to 73 families and 104 genera, with the main dominant shrub and herb species being *Symplocos paniculata* and *Matteuccia struthiopteris* respectively. Comparing the density of each vertical layer of the two plantation communities, there is no significant difference in the tree layer density between the two plantations, but there are significant differences in the density of the shrub layer and herb layer. In terms of species diversity, the diversity index, dominance index, richness index and evenness index of the *Larix principis-rupprechtii* plantation plots all show the pattern: herb layer > shrub layer > tree layer; the diversity index, richness index, evenness index and dominance index of the *Pinus tabulaeformis* plantation all show the same trend: shrub layer > herb layer > tree layer. The evenness indices of the tree layer, shrub layer and herb layer are all higher in the *Pinus tabulaeformis* plantation than in the *Larix principis-rupprechtii* plantation; the dominance index and diversity index of the shrub layer are higher in the *Pinus tabulaeformis* plantation than in the *Larix principis-rupprechtii* plantation, while the opposite is true for the herb layer; the richness index of the shrub layer is higher in the *Larix principis-rupprechtii* plantation than in the *Pinus tabulaeformis* plantation, while the opposite is true for the herb layer.

搜集汇总

背景与挑战

背景概述

该数据集研究了秦岭地区华北落叶松人工林的群落结构和物种多样性，通过野外调查和统计分析，揭示了其植物种类组成、垂直结构特征以及多样性指数分布。研究还比较了华北落叶松与油松人工林在结构和多样性上的差异，为人工林生态管理提供了科学依据。