导　　师： 张健;杨万勤

学科专业： I0702

授予学位： 博士

作　　者： ;

机构地区： 四川农业大学

摘　　要： 高山林线特殊的结构、功能及对气候变化的高度敏感性,已成为全球气候变化适应与减缓研究的关键区域,有关林线对全球变暖和人类活动干扰的响应是全球变化生态学研究的热点。气候变化和人类干扰是影响生物多样性的两个重要因素。本研究结合这两个因素,以川西米亚罗林区鹧鸪山自然形成的林线交错带和人为干扰形成的林草交错带为研究对象,采用野外调查与室内分析相结合、常规分析与分子生物学技术相结合的研究方法,对两个高山交错带的地上植物与地下生物多样性进行了同步研究,分析了不同驱动机制下的植物多样性、土壤动物多样性和土壤微生物多样性的分布格局,地下生物多样性与植物多样性的相互作用关系,以及不同生物群落物种组成、多样性与环境因子的相关性。研究结果对于了解高山林草交错带地上／地下生物多样性的关系和生态学过程有重要意义,对高山林草交错带的管理和林线的生态学研究提供了重要的科学依据。主要研究结果如下： /(1/)高山林线交错带和林草交错带共记录植物物种221种,分属48科,124属,其中木本植物42种,草本植物179种。从植物科的分布区类型划分,所调查的大部分植物属于北温带型和世界广布型,其中,禾本科、菊科、毛茛科、蔷薇科、玄参科、蓼科、虎耳草科、龙胆科、伞形科、忍冬科这十大科的植物是高山林线交错带和林草交错带的优势种,且大部分科的植物都属于极地一高山属的成分。 交错带木本植物丰富度和多样性低于草本植物。林线交错带则随海拔升高物种数呈上升再下降的偏锋分布格局。林草交错带随放牧干扰强度的减小植物丰富度逐渐降低。两个交错带物种丰富度都在疏灌处达到峰值,HAS的物种数最多88种,VAS为79种。两个交错带木本植物丰富度都呈钟形曲线,林线交错带中间的密灌达到峰值,林草交错带在疏灌达到峰值。林线交错带草本植物物种丰富度的分布随海拔升高先上升后下降,在疏灌处达到峰值,呈偏锋分布格局,而草本多样性指数H’与D的变化趋势类似U型分布,林线和树线的草本多样性低于草甸和针叶林。林草交错带草本丰富度随干扰强度的增加直线上升,草本的种类在草甸达到峰值,但草本植物多样性和均匀度却是密灌最高,呈单峰分布规律。 由于两个交错带都有类似的景观分布,从高山草甸过渡至针叶林,两个交错带木本植物和草本植物科属种的变化趋势基本一致。群落木本植物优势种由蔷薇科、杜鹃花科、杨柳科、忍冬科过渡到松科、桦木科、茶藨子科等,但林线交错带缺少红桦、糙皮桦等阔叶树种。群落草本植物优势种由菊科、龙胆科、禾本科过渡到玄参科、柳叶菜科、毛茛科,最后再到蕨类植物、五加科、莎草科等。虽然两个交错带的形成机制不同,但不同交错带之间也有相似的物种组成,同一交错带相邻植被之间、不同交错带相近植被类型之间植物群落的相似度较高。交错带草甸的物种组成与其它群落的物种组成差别最大。从β多样性来看,林线交错带针叶林到林线的过渡最明显；从树线到密灌丛草本植物的过渡最明显,林草交错带从密灌丛到阔叶林木本植物过渡最明显,从疏灌丛到密灌丛草本植物的过渡最明显。 两个交错带中物种数量最多的4个功能群是落叶木本植物、基生叶阔叶杂草、半基生叶型阔叶杂草与茎叶型阔叶杂草。随海拔上升,林线交错带茎叶型阔叶杂草、基生阔叶杂草、半基生叶阔叶杂草和丛生禾草的物种数量呈先增加后降低的趋势。植物功能群多样性在林线达到峰值,在树线达到低谷,针叶林内植物功能群的均匀度最高。林草交错带随放牧强度的增大阔叶类杂草和丛生禾草的数量增加,林草交错带PFTs的多样性和均匀度随干扰强度的增大逐渐降低。 /(2/)川西高山两类交错带3类体型土壤动物中,大型土壤动物个体数最小,种类最多；小型湿生动物数量最大,类群数最少。两类交错带拥有相同的类群共103类。线虫纲是唯一的优势类群,占总个体密度的80/%以上,线蚓科、真缓步纲、猛水蚤目及等节跳科为常见类群,其余126类土壤动物为稀有类群。 蜱螨目和弹尾目在不同季节不同交错带的分布有较大差异。林线交错带的和林草交错带的A／C值总体趋势符合寒带的特征。随海拔梯度的上升,林线交错带A／C值先上升后降低,其中林线的A／C值最大。在干扰梯度下,林草交错带的A／C值随干扰强度降低逐步增大。说明螨类可以作为林线环境急剧变化的生境指示种来预测环境和气候变化,秋季是螨类活动最频繁的季节。 林线与林草交错带的大、中、小型的土壤动物个体密度与类群数都具有明显的表聚性。林线苔藓层的土壤动物个体密度大、类群数十分丰富,是土壤动物理想的生存场所。两类交错带土壤层的土壤动物类群数分布表现为单峰型。林线交错带土壤动物多样性和均匀度随海拔升高呈降低趋势,优势度变化趋势相反;林草交错带土壤动物多样性和均匀度随干扰梯度减弱呈现略有下降然后逐步上升的趋势。夏季土壤动物多样性高于春季和秋季,DG指数值能更好的体现高密度和高类群数下交错带土壤动物群落结构与多样性的变化程度。 Wilson-Shmida多样性指数表明高山草甸与其他群落的土壤动物替代程度较大。不同植被类型的生态系统之间土壤动物群落的类群组成存在较大差异,而相同或相近的植被类型的生态系统间土壤动物类群组成相似。大型土壤动物生物量中,蚯蚓的生物量占据绝对主要地位,其次为马陆类等。林线交错带大型土壤动物平均生物量要高于林草交错带。不同季节大型土壤动物生物量差异明显。林线交错带大型土壤动物生物量与海拔呈负相关,林草交错带土壤动物群落结构随干扰强度减弱发生了明显变化。处于受严重干扰的草甸,其土壤动物密度、类群、生物量都处于最低水平；而类群数最大出现在中度干扰的灌木林；大型土壤动物生物量最大出现在受轻微干扰的阔叶林；密度最大出现在几乎未受干扰的针叶林。可见土壤动物个体密度、类群、生物量以及群落结构的变化与放牧干扰存在明显的关系。 /(3/)高山林线交错带和林草交错带土壤微生物区系组成中,土壤细菌数量最多,占绝对优势,放线菌数次之,真菌数量最少,占不到微生物总数的0.1/%。交错带不同的植被类型的土壤微生物数量差异显著。林线交错带和林草交错带可培养土壤微生物数量在密灌最高,在空间分布上交错带中间达到峰值。林线交错带疏灌或密灌的土壤微生物量最大,针叶林内最小,表现出偏锋分布趋势,土壤微生物数量和SMBC秋季达到峰值。林草交错带土壤微生物生物量在秋季和春季呈单峰分布趋势,而夏季土壤微生物生物量草甸最大,秋季SMBC最高,SMBN的季节变化趋势不明显。林线交错带土壤微生物多样性与微生物生物量和可培养微生物数量之间存在相互作用的正效应。土壤真菌多样性与细菌多样性、SMBC、SMBN和可培养土壤细菌、真菌、放线菌数量都呈正相关,两个交错带的SMBC和SMBN呈正相关,其中林线交错带SMBC和SMBN的相关性极显著。土壤微生物生物量与可培养微生物数量之间都呈正相关。 根据DGGE图谱反映出土壤细菌多样性高于真菌多样性,真菌多样性的变幅大于细菌。两个交错带土壤细菌多样性具有一定的共性,即草甸土壤细菌多样性变幅最大,细菌群落多样性具有显著的季节变化,而针叶林内有较稳定的小生境,土壤细菌的变幅最小,说明细菌对外界的因素十分敏感。与土壤微生物量的季节变化不同,林草交错带土壤细菌多样性的变化趋势为春季>秋季>夏季。相似性分析表明,交错带土壤真菌种类的相似度普遍低于细菌相似度。交错带相邻的样地间土壤细菌和真菌相似程度更高,植被类型差异较大的样地土壤细菌和真菌相似程度较低。 林线交错带和林草交错带主要有4个大纲的细菌种类：变形菌门/(Proteobacteria/)的α、β及γ类群、拟杆纲门/(Bacteroidetes/)、酸杆菌门/(Acidobacteria/)、疣微菌门/(Verrucomicrobia/),其中变形细菌占绝对优势。大部分序列在遗传关系上相近于分离自亚高山森林和草甸土壤、青藏高原草甸土壤、东祁连山高寒草地和喜马拉雅山系的冰川土壤等适冷生境的菌株。 /(4/)高山林线/(草/)交错带生态系统的地上和地下部分是一个相互联系的整体,土壤生物与地上植物之间存在着密切的联系和动态的相互作用。两个交错带土壤动物类群数与草本植物丰富度都呈负相关。中小型土壤动物作为重要的取食者进而调节土壤微生物的群落结构和生物量。土壤微生物与土壤动物之间是一个相互消长的关系。林线交错带土壤细菌多样性与中小型土壤动物类群数呈负相关,林草交错带土壤细菌多样性与大中小型土壤动物类群数呈负相关。两个交错带内土壤真菌多样性与大型土壤动物类群数呈正相关,说明大型土壤动物通过改善土壤结构而提高了土壤真菌多样性。林线交错带土壤动物和微生物与地上植物多样性的相关性更加明显,如真菌与木本的丰富度为显著正相关性,小型土壤动物与草本的丰富度为显著负相关性。由于由于两个交错带的形成机制不同,放牧干扰使林草交错带植物多样性与土壤生物多样性的关系变的更加复杂,导致土壤动物和微生物与植物多样性的关系很难以单一的相关性加以解释,可能是多种因素共同作用的结果。 川西高山林线生长季节10cm土壤平均温度为6.40℃,接近全球林线分布的10cm土壤平均温度。DCCA排序能较好地表达植物群落的物种组成与环境相互作用的综合生态梯度。林线交错带草本植物的丰富度和木本植物的多样性指数与环境因子有显著的相关性。其中,林线交错带的海拔、土壤pH值、SOC、TN、TP、AN、AK、草本生物量、苔藓和枯落物储量显著影响草本植物的丰富度和多样性；SOC、TN、TP、AN、草本生物量、苔藓和枯落物储量显著影响木本植物的多样性。木本植物的丰富度和草本植物的优势度、均匀度与环境因子相关性不显著。林草交错带植物多样性与环境因子的关系不如林线交错带与环境因子的相关性明显。只有土壤pH值、草本生物量、苔藓和枯落物储量显著影响草本植物的丰富度,其余因子与草本植物多样性和木本植物的多样性相关性不显著。 植物功能群与环境因子的CCA分析表明,海拔、土壤类型、pH值、地被物储量和土壤养分状况是影响林线交错带植物功能群分布分异的主要环境因子。土壤类型、放牧干扰、草本生物量、地被物储量是影响林草交错带植物功能群分布分异的主要环境因子。丛生禾草、茎生叶型阔叶杂草适合在草甸和疏灌生存,蕨类适合在阴湿的地被物较厚的环境中生存。 CCA分析表明,同一优势类群的土壤动物在两个交错带都选择相似的适宜生存环境。林线交错带中小型土壤动物和大型土壤动物步甲科、石蜈蚣目、皿蛛科、球体蛛科主要集中分布在地被物较厚且环境条件阴湿的针叶林及林线,大型土壤动物类群如正蚓目、蚁科、乌叶蝉科、金龟甲科幼虫、叶蜂科幼虫喜温暖、草本生物量大的高山草甸及灌丛。林草交错带中小型土壤动物和大型土壤中动物优势类群带马陆目、步甲科、石蜈蚣目、地蜈蚣目、大蚊科幼虫、皿蛛科、球体蛛科主要集中分布在地被物较厚且潮湿的针叶林和阔叶林。大型土壤中动物类群正蚓目、蚁科、乌叶蝉科、金龟甲科幼虫、隐翅甲科、瘿蚊科幼虫在放牧干扰、草本生物量大的草甸及灌丛中分布较多。林草交错带绝大部分土壤动物个体数夏季高于秋冬季。 春夏秋三个季度交错带土壤细菌和真菌组成与环境因子的CCA分析表明,土壤温度对土壤细菌组成及分布影响最大,在春季和夏季都表现出显著影响；其次,春季土壤TP、AN的影响显著,秋季土壤水分的影响显著,夏季土壤TK的影响显著。土壤pH值对土壤真菌组成及分布影响最大,春夏秋三个季节都有显著影响。SMBC和海拔的影响其次,夏季和秋季表现显著,土壤温度春季影响较大,土壤水分夏季影响明显。 影响林线交错带土壤微生物群落结构的因素主要有土壤pH值、有机质、全氮和速效K,土壤温度对细菌多样性和可培养真菌数量的影响很大,土壤水分与土壤微生物的相关性很小。相比林线交错带,影响林草交错带土壤微生物的关键土壤因子很少,只有土壤有机碳和全氮对林草交错带土壤微生物的作用明显。综合来看,相比自然状态下的林线交错带,林草交错带受到的干扰程度较大,干扰通过改变群落内的环境条件、植物物种组成和多样性等,进而影响土壤动物和微生物群落结构和功能,使生态因子与植物多样性、土壤动物和微生物多样性的关系更加复杂。 Alpine timberline has become the key areas of research in climate change adaptation and mitigation as its special structure, function and high sensitivity to the climate change, the timberline response to global warming and human activities on global change is a hot research. Climate change and human interference are two important factors affect biodiversity. The research combined two factors, studied of natural timberline and forest-grassland ecotone by grazing of ZheGu Mountain in western Sichuan with the field investigation and laboratory analysis as well as molecular biology methods, analyzed the distribution patterns of above-and belowground biodiversity include plant diversity, soil fauna and soil microbial diversity simultaneously under different driving mechanisms, interaction between plant diversity and soil organism diversity as well as biodiversity related to the environmental factors. The results were important for the understanding of the relationship between above-and belowground diversity and ecological processes in alpine forest-grassland ecotone, which provide the important scientific basis for the research of timberline and management of forest-grassland ecotone. The major findings are as follows: /(1/) 221 species of plants were recorded belonging to 48 families,124 genera, which 42 species of woody plants and 179 species of herbs in timberline ecotone and forest-grassland ecotone. From the distribution of plant families, the majority species were northern temperate plant type and the world wide distribution type. Gramineae, Compositae, Ranunculaceae, Rosaceae, Scrophulariaceae, Polygonaceae, Saxifragaceae, Gentianaceae, Apiaceae, Caprifoliaceae were the dominant species of ten families in alpine timberline ecotone and forest-grassland ecotone, and most of the families belong to the ingredients of polar-alpine. Richness and diversity of woody plants were lower than herbaceous plants in ecotone. Plant abundance decreased with grazing intensity decreasing in forest-grassland ecotone.The number of species with elevation rasing show partial front patterns in timberline ecotone. The species richness in shrub reached its peak in ecotone. HAS had 88 species while VAS had 79 spcecies. Abundance of woody plants of two ecotone were tested with bell-shaped curve, which maximum species were in VAT and HAS. Plant diversity in herb layer increased with the elevation and then decreased in timberline ecotone, reached its peak in the shrub, showed a partial distribution pattern front, while the herb diversity index H'with a similar trend of D as U-distribution, herbal diversity of meadow and conifer forest were lower than timberline and treeline. Herb richness with increasing disturbance intensity soared and reaches its peak in the meadow in forest-grassland ecotone, but the herb diversity and evenness were showed single peak distribution. Since the two ecotone have similar landscape interlaced with the distribution of the transition from alpine meadow to the coniferous forest, the families of woody and herbaceous species plants were in consistent with the trend in two ecotone. Woody dominant species were from the Rosaceae, Ericaceae, Salicaceae, Caprifoliaceae transition to the Pinaceae, Betulaceae, Ribes, etc., but lack of hardwood species such as Betula albo-sinensis, Betula utilis in timberline ecotone. Herb dominant species were from Gentianaceae, Gramineae transition to Scrophulariaceae, Onagraceae, Ranunculaceae, and finally then ferns, Araliaceae, sedge, etc.. Two ecotone also had similar species composition although the formation mechanism were different, plant communities had high degree of similarity between adjacent vegetation in the same ecotone and similar vegetation in the different ecotone. Plant species composition in alpine meadow were most different with other communities. From the view ofβdiversity, the most obvious transitions of woody plants were from VPCF to VTi and from HAT to HBF. The most obvious transition of herbaceous plant were from VTr to VAS and from HAS to HAT. The maximum species of four functional group were deciduous woody plants, basal forbs, semi-basal forbs, erect leafy forbs in two ecotone. Basal forbs, semi-basal forbs and erect leafy forbs and bunch grass species were first increased and then decreased as elevation rising.Plant functional group diversity reached its peak in timberline and reached bottom in the treeline, evenness of plant functional groups were highest in the coniferous forest.Species of broadleaf weeds and bunch grasses increase with grassing intensity increased, the diversity and evenness of PFTs increased with disturbance intensity decreased. /(2/) Macro soil fauna was with minimum number and most species; while micro soil fauna was maximum number and least groups in three size categories, which 103 groups were same in two ecotones. Nematoda is the only dominant group, accounting for more than 80/% of individual density, Enchytraeidae, Eutardigrada, Harpacticoida, Isotomidae were the common groups, and the remaining 126 were the rare groups. The distribution of Acarina and Collembola were different in seasons and ecotones. The characteristics of A//C values were consistent with cold zone climates from the overall trends. A//C values first increased and then decreased in timberline ecotone with rasing altitude, while in forest-grassland ecotone A//C value increased gradually with decreasing disturbance intensity. That show the mite can be habitat indicator species to predict the environment and climate change, and fall was the most active season for mite. Soil fauna density and the number of individuals had obvious surface accumulation, moss layer was the ideal living place for soil faunas. fauna groups in soil layers showed a single peak in two ecotones. Soil fauna diversity index H' and evenness index E showed gradual reduction with altitude rising in timberline ecotone, dominance index D showed the opposite trend; soil fauna diversity index H' and evenness index E showed a slight decrease and then gradually upward trend with the disturbance gradient reducing. DG index can better reflect the structure and diversity of soil faunas under high density and abundant groups. Wilson-Shmida diversity index showed that soil fauna alternatives were higher in alpine meadow with the rest of communities. The group composition of soil faunas were quite different between different vegetations while in similar between the same or similar types of vegetation ecosystems. Earthworm biomass occupies the main position in macro-fauna biomass, followed by Malaysia in two ecotones. Average biomass of soil macrofauna in timberline ecotone was higher than forest-grassland ecotone. Soil macrofauna biomass significantly different in seasons and was negatively correlated with elevation in timberline ecotone. And soil fauna community structure has changed significantly with reduced grassing intensity. the soil fauna density, group, biomass was the lowest in the meadow subject to serious interference, the largest groups were in HAT with moderate disturbance, soil macrofauna biomass was highest in HBF and soil fauna density was highest in almost undisturbed HPCF. Can see thereby, soil fauna density, group, biomass and community structure had obvious relationship with grazing interference. Soil bacterial count was dominated of soil microorganisms, followed by actinomycetes count and fungi count was at least, account for less than 0.1/% of the total number in two ecotones. The quantity of soil microorganism was significantly different in vegetation types. Culturable soil microorganism count were highest in VAT and HAT. Soil microbial biomass were highest in VAS and VAT, while lowest in VPCF, the spatial distribution showing a single peak trend, soil microorganism count and soil microbial biomass were highest in the fall, soil microbial biomass reached peak in summer and autumn of forest-grassland ecotone, while SMBC and SMBN were highest in the meadow, SMBC were highest in fall but seasonal trends of SMBN were not obvious. Soil microbial diversity and microbial biomass as well as culturable soil microorganism count interaction has the positive effect. Bacterial diversity, SMBC, SMBN, soil bacteria, fungi, actinomycetes count were tested positive correlation with fungal diversity. SMBC and SMBN were in positive correlation of two ecotones and the correlation was highly significant in forest-grassland ecotone. Also soil microbial biomass was positively correlated with culturable soil microorganism count. According to DGGE patterns reflected the diversity of soil bacteria higer than fungal diversity, fungal diversity were more amplitude than bacteria. Diversity of soil bacterial share some common characteristics in two ecotones, meadow soil bacterial diversity had significant seasonal variation while coniferous forests were more stable niche, while the percentage changes in soil bacteria were minimum, indicating bacteria sensitive to external factors. Seasonal changes of soil bacteria diversity showed spring> autumn> summer. Similarity analysis showed that the fungal species similarity was generally lower than soil bacteria similarity. Soil bacteria and fungi between adjacent plots had higher degree of similarity, while with greater difference in different vegetation samples. There were four main groups of bacteria in timberline ecotone and forest-grassland ecotone:α,βandγgroups of Proteobacteria, Bacteroidetes, Acidobacteria, Verrucomicrobia, of which Proteobacteria were predominant of bacteria diversity. Most similar sequences in the genetic relationships were similar with cold-adapted strains isolated from habitats of subalpine forests and meadow soil, meadow soil in Qinghai-Tibet Plateau, the East Qilian Mountains alpine meadows and glaciers in the Himalayas series soil. Ecosystems above and below ground was an inter-connected and inter-dependent whole. There was a close connection and dynamic interaction between soil organisms and plants aboveground. Soil fauna groups were negatively correlated with herbaceous plants richness. Soil meso- and micro-fauna was the important regulator of feeding microbial community structure and biomass. There was a mutual relationship between growth and decline between microbial and soil fauna. Such as negatively related between soil bacteria diversity and soil meso and micro-fauna groups in timberline ecotone while negatively related between soil bacteria diversity and soil macro, meso and microfauna groups in forest-grassland ecotone. There was positively correlated between soil fungal diversity and macrofauna groups, which indicate soil macro-fauna improve fungi diversity by improving the structure of soil. The relevance of soil fauna and microorganisms with plant diversity aboveground was more obvious in timberline ecotone, such as significant positive correlation of fungi and woody richness, significantly negatively correlated between soil microfauna and herb richness. As the formation mechanism of two ecotones were different, the relationship of plant diversity and soil biodiversity became more complex in forest-grassland ecotone as a result of grazing,leading to the relationship more complex between plant diversity and soil fauna and microorganisms that difficult to explain with single correlation, there may be the result of many factors. Average temperature of growing season in 10cm soil layer was 6.40℃in timberline, which close to the average soil temperature of global timberline. DCCA can better express the species composition of plant communities and ecological gradient of environment interaction. Herb richness and woody diversity had significant correlation with environmental factors in timberline ecotone, the elevation, soil pH value, SOC, TN, TP, AN, AK, herbaceous biomass, moss and litter reserves significantly affect the richness and diversity of herbaceous plants; SOC, TN, TP,AN, herbaceous biomass, moss and litter storage significantly affected the diversity of woody plants. Richness of woody plants or dominance and evenness of herbaceous plants were not significant associated with environmental factors. Relationship between plant diversity and environmental factors was less obviously than that of timberline ecotone. Only soil pH, herbaceous biomass, moss and litter reserves significantly affect the richness of herbaceous plants, the remaining factors were not significant correlation with herb species diversity and woody plants diversity. CCA analysis of plant functional groups and environmental factors showed that altitude, soil type, pH, ground cover reserves and soil nutrient were the main environmental factors affect the distribution of plant functional group differentiation in timberline ecotone; while soil type, grazing, herbage biomass and ground cover reserves were the main environmental factors affect the distribution of plant functional group differentiation in forest-grassland ecotone. Bunchgrass and erect leafy forbs suited to survive in the meadow and shrub while ferns was suitable for survive in the environment of damp and thick ground cover. CCA analysis showed that soil fauna of same dominant groups chose to live in similar suitable environment. Soil microfauna and mesofauna as well as macrofauna such as Carabidae, Lithobiomorpha, Linyphiidae, Theridiosomatidae mainly concentrated in thick and damp environmental conditions of coniferous forest and timberline. soil macrofauna such as Lumbricomorpha, Formicidae, Penthimiinae, Scarabaeidate, Tentherdinidate perfered to live in alpine meadow and scrubs of timberline ecotone. Soil microfauna and mesofauna as well as macrofauna such as Polydesmida, Carabidae, Lithobiomorpha, Geophilomorpha, Tipulidate, Linyphiidae, Theridiosomatidae mainly concentrated in thick and damp environmental conditions of coniferous forest and broadleaf forest. soil macrofauna such as Lumbricomorpha, Formicidae, Penthimiinae, Scarabaeidate, Staphilinidae, Cecidomyiidae perfered to live in alpine meadow and scrubs with grazing interference of forest-grassland ecotone. CCA analysis of species composition of soil bacteria and fungi with environmental factors in spring, summer and autumn showed that soil temperature had the most important effects on composition and distribution of soil bacteria, which influence significantly in spring and summer; secondly, soil TP and AN affected significantly in spring, soil moisture affected significantly in fall, soil TK affected significantly in summer. Soil pH had the most important effects on composition and distribution of soil fungi, which influence significantly in spring, summer and autumn; SMBC and the elevation were in secondly that affect significantly in the summer and fall, soil temperature influenced more in the spring and soil moisture influenced apparently in the summer. Correlation analysis indicated that soil pH, organic matter, total N and available K were main factors influence soil microbial community, soil temperature had much influence on bacterial diversity and culturable fungi count, connection between soil moisture and soil microorganisms was weak. Compared to timberline ecotone, there were little key soil factors effect soil microorganisms in forest-grassland ecotone, only the soil organic carbon and nitrogen affected significantly. On the whole, degree of interference in forest-grassland ecotone was greater compared to the natural state of the timberline ecotone, thereby interference affected the structure and function of soil fauna and microbial communities by changing environmental conditions and plant species composition and diversity within community, which lead to more complex relationship between ecological factors and plant diversity as well as soil fauna diversity and soil microbial diversity.

关 键 词： 高山林线交错带 林草交错带 植物多样性 土壤动物多样性 土壤微生物多样性 环境因子 相关性

分 类 号： [X14 S71]

领　　域： [环境科学与工程] [农业科学]