不同放牧强度与土壤异质性对植物空间格局的影响

NWIPB OpenIR

	不同放牧强度与土壤异质性对植物空间格局的影响
	王文颖
学位类型	硕士
导师	周立
	1998
学位授予单位	中国科学院西北高原生物研究所
学位授予地点	中国科学院西北高原生物研究所
学位专业	生态学
关键词	放牧强度空间格局异质性
摘要	本项实验旨在通过采用样条取样系统，分形分析方法对高寒草甸草场不同放牧强度及其土壤异质性对植物空间格局影响的研究，探讨不同放牧强度改变植被结构特征的内在起因，优势种植物和土壤因子的空间异质性及其植物空间格局与土壤因子之间的相互关系。研究结果表明：1. 不同放牧组植物群落组成及其多度的差异较大。杂类草多度随放牧强度的减轻而减少，A、C、E、CK组依次为65.88%、52.07%、50.08%、45.14%。禾草类的多度随放牧强度的减轻而增大，A、C、E、CK组依次为10.75%、17.50%、19.59%、23.74%。经相关性分析表明：杂类草的多度与放牧强度呈显著正相关（P < 0.05）。禾草类的多度与放牧强度呈显著负相关（P < 0.05）。2. 各放牧组总盖度的变化趋势基本相似，从返青期开始盖度逐渐增大，到8月底达到最大。但是，在不同放牧强度下各植物类群盖度的季节矩异较大。经多元方差分析表明：A 组种盖度的季节差异不明显（P > 0.05），C组、E组、CK组种盖度的季节差异显著（P < 0.05）。3. 不同放牧强度下，物种数依次为E 组>CK 组>C 组>A 组；多样性指数依次为A 组>C 组>E组>CK 组；均匀度指数依次为A 组>C 组>CK 组>E 组。经相关性检验表明：多样性指数与均匀度指数呈极度显著的正相关（P < 0.01），多样性指数与物种丰富度指数呈显著正相关（P < 0.05）。4. 不同放牧强度下植物群落种一多度分布呈典型对数正态分布模型，其数学表达式为：S(R) = S_0EXP(-a~2R~2)。但是，各放牧强度组的分布格局具明显差异。5. 重牧组（A组）优势种在小尺度上的格局不明显，几乎都在较大尺度70-160cm或>160cm尺度上的异质性程度发生显著变化。金露梅在分析尺度内不存在尺度依赖特征，即不具有空间相关性。6. 中牧组（C）优势种的尺度依赖特征明显，但其异质性规律发生显著变化的尺度差异较大：一般在30-110cm尺度上出现格局，如高山唐松草在30cm尺度上，矮嵩草在50cm尺度上，金露梅在110cm尺度上出现格局。7. 轻牧组（E）优势种在较小尺度上的空间依赖性较强，一般在30-70cm尺度上出现格局，如垂穗披碱草在30cm尺度上，兰石草、金露梅在40cm尺度上，异针茅在60cm尺充上首次出现格局。此外，象兰石草、矮火绒草在小尺度上聚块形成较大尺度上的镶嵌性聚块，反映出分布格局的层次性。8. 对照组（CK）优势种也是在小尺度上的空间依赖性较强，各个种的异质性发生显著变化的尺度均在30-70cm尺度上，如矮火绒草、垂穗披碱草在30cm尺度上，异针茅、紫羊茅在60cm尺度上出现格局。9. 各放牧强度组的土壤因子表现了较强的异质性，而且在不同放牧强度下有机质，速效氮，速效磷的分布格局有所不同：重牧组在较大尺度显示格局，轻牧组、对照组在小尺度显示格局，与植物空间格局的分布趋势相似。但是，不同放牧强度下全氮，全磷的格局变化不明显。10. 植被排序轴得分与土壤因子的多元回归分析结果表明：对照组（CK）土壤因子与植物分布格局相关性强，且有机质，速效氮，速效磷均为影响该组植物分布重要因子（P < 0.05），而各放牧组（A组，C组，E组）土壤因子与植被分布的相关性弱。重牧组相对重要的因子是有机质，速效氮，中牧组相对重要的因子是有机质，速效氮，速效磷，而轻牧组相对重要的因子是速效磷。但在各放牧组，全氮、全磷与植物的分布格局没有明显的相关性。11. 总之，干扰（如放牧）及土壤因子分布的有规则性均会导致植物分布的空间异质性，并且不同的干扰程度对植物的空间分布可产物不同的影响。另外，植被上存在的异质性反映了土壤因子的分布特征。
其他摘要	The purpose of this study was to test the relationships of different grazing intensities and soil heterogeneity to plant spatial pattern in Alpine meadow and explain the internal cause of the characters of vegetation structure changed by grazing. The spatial heterogeneity of dominant species and soil factors were estimated by transect sampling system and fractal analysis method. The relationship between plant patterns and soil factors was analyzed by stepwise multiple regression. The result showed: 1. The compositions of dominant species and abundance under different grazing intensities were significantly different. The abundance of forb decreased with the decrease of stocking intensity, and that were 65.88%, 52.07%, 50.08% and 45.16% in the A, C, E, CK groups respectively. The abundance of grass increased with the decrease of stocking intensity, and that were 10.75%, 17.50%, 19.59% and 23.74% in the A, C, E, CK groups respectively. The change of abundance of forb was significantly positive correlated with grazing intensity (P < 0.05), while that of grass was significantly negative correlated with grazing intensity (p < 0.05). 2. During the growing season (6-10 mouth), vegetation cover changed in a predictable manner in every grazing plot, increasing from initial growth and was highest in August. But the different growth forms (forb, grass, shrub et al.) in different grazing plots were significant difference among the growing season. Multivariate analysis of variance (MANOVA) for differences in cover for all growth forms among sampling periods wasn't significant in A plot (F = 2.48 df = 4,16 P > 0.05), and was significant in C, E, CK groups (P < 0.05). 3. The order of average richness indices was E>CK>C>A, and that of evenness indices was A>C>CK>E, and that of diversity indices was A>C>E>CK. Diversity indices were significantly positive correlated with evenness indices (P < 0.01) and richness indices (P < 0.05). 4. The distribution models of species-abundance in different grazing plots conform to lognormal distribution: S(R) = S_0EXP(-a~2R~2). But distribution patterns were different significantly. 5. In the intensive grazing plot, the evidence for consistent small-scale pattern of the dominant species was not strong. The scale that the heterogeneity arised change were almost at 70-160cm or above 160cm. Some species such as Leontopodium nanum display pattern at 20cm, but these patterns were not consistent through the season and showed pattern greater than 160cm in July and August. Potentilla fruticosa had no scale-dependance properties. 6. In the moderately grazed plot, the scale dependent properties of dominant species were strong, but the strong changing scales (infection points) of analyzed species were very different. This ranged from pattern at 30cm for Thalictrum alpinum and at 50cm for Kobresia humilis to a peak at 110cm for Potentila frustcosa. In a word, the pattern of the dominant species in the moderately grazed plot was more varied than in the intensively grazed plot. 7. In the lightly grazed plot, the scale dependent properties of the dominant species showed strong variation at small-scale. For example Potentilla frustcisa, Stipa aliena, Lancea tibetica showed pattern at small scale of 40, 60, 40cm respectively. In addition, Lancea tibetica and Leontopodium nanum exhibited mosaic lump and reflected levels of the pattern distribution. 8. In the ungrazed plot, the small scale dependence were strong too. All the species analysed showed pattern at scale between 30cm and 70cm. Leontopodium nanum, Elymus nutans exhibited scale-dependence when observing scale < 30cm, Festuca ovina, and Stiple aliena were at <60cm. 9. The soil factors in different grazing plots showed strong heterogeneity. The distribution patterns of organic matter, available N, and available P had discrepancy under different grazing intensities and those of total N and total P was more stable. 10. The results of multiple linear regression of vegetation ordination stand scores on soil variables showed: the correspondence between the plant pattern of distribution and the soil factors was strong in the ungrazed plot, while those was weak in the heavily, moderately and lightly grazed plots. The important factors for plant dristribution were organic matter, available N, available P in the ungrazed plot. Organic matter and available N had a relationship with the vegetation axes in the intensively grazed plot. In the moderately grazed plot, organic matter, available N, available P had a relationship to the vegetation distribution. Additionally, Available P had a clear relationship with the vegetation axes in the lightly grazing plot. But the correspondence of total N, total P with plant distribution was very weak in every plot. 11. In a word, the disturbance and the irregularities of the soil factors' distribution all led to spatial heterogeneity of plant distribution. The effects of plant spatial pattern to different disturbance level were different. The heterogeneity that aeisted in the vegetation reflected the properties of soil factors distribution too.
页数	51
语种	中文
文献类型	学位论文
条目标识符	http://210.75.249.4/handle/363003/3370
专题	中国科学院西北高原生物研究所
推荐引用方式 GB/T 7714	王文颖. 不同放牧强度与土壤异质性对植物空间格局的影响[D]. 中国科学院西北高原生物研究所. 中国科学院西北高原生物研究所,1998.

条目包含的文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
N98147.pdf（1799KB）			开放获取	--	请求全文