兰州大学机构库 >生态学院
人为干扰对青藏高原东北部紫果云杉林群落多样性和土壤种子库影响的研究
Alternative TitleStudy on Effects of Human Disturbance on Community Diversity and Soil Seed Bank of Picea purpurea Forests on the Northeastern Qinghai-Tibetan Plateau
曹家豪
Subtype博士
Thesis Advisor赵志刚
2023-09-02
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name理学博士
Degree Discipline生态学
Keyword青藏高原 Qinghai-Tibetan plateau 紫果云杉 Picea purpurea 人为干扰 human disturbance 生物多样性 biodiversity 土壤种子库 soil seed bank
Abstract

       森林是地球上最重要的生态系统之一,为人类社会提供广泛而重要的生态系统服务。近年来,人为干扰对森林生态系统的影响倍受关注,有研究表明人为干扰是导致全球森林生态系统结构改变以及生物多样性丧失最重要的驱动因子之一。因此,厘清森林生态系统的群落结构并阐明其如何响应人为干扰,已成为当前生态学研究关注的热点问题之一。青藏高原亚高山林区生态环境脆弱且独特,在我国生物多样性保护、生态安全屏障构建和生态文明建设等重大战略目标实现中具有重要意义。然而,与全球热带和亚热带区域相比,针对人为干扰对青藏高原亚高山森林生态系统群落多样性影响的研究仍相对薄弱,关于森林土壤种子库在应对人为干扰过程中所发挥的作用更是鲜有报道。         本文聚焦青藏高原东北部的亚高山地区,利用林冠郁闭度与5个指标(距离最近村庄距离、2 公里范围内牲畜数量和人口数量、采样点保护的年数和停止采伐的年数)主成分分析(principal component analysis, PCA)相互印证的方法对43个(30 × 20 m)紫果云杉(Picea purpurea)林样地进行了不同人为干扰程度(轻度、中度和重度)的划分并做了调查。研究了紫果云杉林植物的生长状况、物种组成和群落结构,深入解析了人为干扰对紫果云杉林植物的生长状况、乔木、灌木和草本植物群落的不同维度多样性(物种多样性、系统发育多样性和功能多样性)以及土壤种子库的影响模式,探究了不同人为干扰背景下气候、生境和土壤等环境因素变化对紫果云杉植物群落多样性格局及土壤种子库的相对贡献与调控机制。主要结果摘要如下:

(1)青藏高原东北部紫果云杉林群落主要由胸径在15 ~ 20 cm之间的幼龄乔木组成(90 %以上的乔木胸高断面积低于20 cm),90 %以上灌木的地径低于4 cm。经鉴定共发现木本植物52种,隶属于18科28属,含我国特有种25种。其中乔木有9种,优势物种除紫果云杉外,还有云杉(Picea asperata)、冷杉(Abies fabri)和祁连圆柏(Sabina przewalskii);灌木11科22属43种;草本植物共计48科105属151种,含我国特有种50种,其中,甘肃贝母(Fritillaria przewalskii)、波密斑叶兰(Goodyera bomiensis)和细辛(Asarum sieboldii)3个物种被世界自然保护联盟列为易危种。

(2)人为干扰改变了木本群落植物生长状况、物种组成、丰富度和系统发育多样性。重度干扰减少了高大乔木的数量和比例,降低了灌木的个体大小。干扰没有改变乔木层植物群落物种组成,但显著改变了灌木层植物群落物种组成,中度和重度干扰下灌木层中的华帚菊(Pertya sinensis)和瑞香(Daphne odora)增多。相比轻度和重度干扰,中度干扰水平下的木本植物具有最高的物种丰富度和系统发育多样性。

(3)草本植物层是森林植物群落的主要组成部分,占总森林群落物种组成的74 %。草本植物物种丰富度和系统发育多样性对人为干扰的响应与木本植物相似,均在中度干扰水平下达到最大,分别受到光的可利用性和土壤有机质的影响。人为干扰对草本植物群落功能多样性的影响与纬度有关,即纬度和干扰程度的交互作用可显著改变草本植物群落的功能多样性:在中度干扰下,草本植物群落功能多样性会随着纬度的上升而升高,在轻度干扰下,草本植物群落的功能多样性则会随着纬度的上升而下降,这一变化主要是由温度和资源限制(例如,速效氮)共同导致的。

(4)人为干扰对土壤种子库丰富度和密度的影响不显著,这一结果与地上植物群落的响应不同,表明种子库对于人为干扰和气候变化的响应有滞后性,通过“储存效应”有利于维持物种的多样性。而土壤种子库密度会随着年平均降水的增加而增加,同时受到土壤和凋落物性质的驱动,意味着气候变化(例如干旱)会降低土壤种子库在维持群落稳定过程中的作用。

      本研究涵盖了植物群落生态学的多个角度:从植被的分层方面,考虑了乔、灌、草三层植被;从多样性方面,包含了基于物种多样性、功能多样性和系统发育多样性等不同维度,还关注了有着“隐秘”植物多样性之称的土壤种子库。草本植物尽管个体较小,但它们是针叶林群落多样性的重要贡献者,受人为干扰的影响较强,因此在保护森林生态系统的多样性时应当充分考虑草本植物这一容易被忽视的植物类群。

Other Abstract

Forests are one of the most important ecosystems on Earth, providing a wide range of important ecosystem services to human society. The impact of human disturbances on forest ecosystems has been received much more attention in recent years, with studies showing that human disturbances are one of the most important drivers leading to changes in the structure of forest ecosystems and loss of biodiversity worldwide. Therefore, clarifying the community structure of forest ecosystems and elucidating how they respond to human disturbances has become one of the hot issues in current ecological research. The subalpine forest areas on the Qinghai-Tibetan Plateau is fragile and unique, and is of great significance in the realization of China's major strategic goals, such as the protection of biodiversity, the construction of an ecological security barrier and the building of an ecological civilization. However, compared with the global tropical and subtropical regions, the research on the effects of human disturbances on the community diversity of subalpine forest ecosystems on the Qinghai-Tibetan Plateau is still relatively weak,and the role played by forest soil seed bank in response to human disturbances has rarely reported.

Focusing on the subalpine region in the northeastern part of the Qinghai-Tibetan Plateau, 43 (30 × 20 m) Picea purpurea forest samples with different levels of anthropogenic disturbances (mild, moderate, and severe) were classified and investigated by using measured canopy closure and five indicators (distance to nearest village, number of livestock and population within 2 km, the number of years of protection and of cessation logging of sampling site) of principal component analysis (PCA) to corroborate each other. We studied the growth status, species composition and community structure of the plants in the P. purpurea forest, analyzed in depth the influence of human disturbance on the growth status of the plants in the P. purpurea forest, the diversity of tree, shrub and herbaceous plant communities in different dimensions (species diversity, phylogenetic diversity, and functional diversity), and the soil seed bank, and explored the relative contribution of the changes in the environmental factors such as climate, habitat, and soil to the diversity pattern of the P. purpurea forest and the soil seed bank and their regulatory mechanisms under different backgrounds of human disturbances. The main results are summarized below:

(1) The P. purpurea forest community in the northeastern part of the Qinghai-Tibetan Plateau mainly consists of young trees with diameter at breast height ranging from 15 to 20 cm (more than 90 % of the tree basal area of less than 20 cm ), and more than 90 % of the shrubs have a ground diameter of less than 4 cm. A total of 52 species of woody plants were identified, belonging to 18 families and 28 genera, including 25 endemic species in China. Among them, there are 9 species of trees, and the dominant species, in addition to the P. purpurea, are Picea asperata, Abies fabri and Sabina przewalskii; Shrubs 11 families, 22 genera, 43 species; The total number of herbaceous plants is 48 families, 105 genera and 151 species, including 50 endemic species in China, among which three species, Fritillaria przewalskii, Goodyera bomiensis and Asarum sieboldii, are classified by International Union for Conservation of Nature (IUCN) as endangered species.

(2) Human disturbance altered the plant growth, species composition, richness and phylogenetic diversity of woody communities. Severe disturbance reduced the number and proportion of tall trees and reduced the individual size of shrubs. Disturbance did not change the species composition of the plant community in the tree layer, but significantly changed the species composition of the plant community in the shrub layer, with moderate and severe disturbance increasing the abundance of Pertya sinensis and Daphne odora in the shrub layer. Woody plants at moderate disturbance levels had the highest species richness and phylogenetic diversity compared to mild and severe disturbance.

(3) The herbaceous layer is the main component of the forest plant community, accounting for 74 % of the species composition of the total forest community. The response of species richness and phylogenetic diversity of herbaceous plants to human disturbance was similar to that of woody plants, both reaching a maximum at moderate disturbance levels, influenced by light availability and soil organic matter,respectively. The effect of human disturbance on the functional diversity of herbaceous communities was latitude-dependent, i.e. the interaction of latitude and disturbance level could significantly alter the functional diversity of herbaceous communities: The functional diversity of herbaceous communities increased with increasing latitude under moderate disturbance and decreased with increasing latitude under mild disturbance, and this change was mainly caused by a combination of temperature and resource limitation (e.g., available nitrogen).

(4) The non-significant effect of human disturbance on soil seed bank richness and density, which is different from the response of above-ground plant communities, suggests that the seed bank have a lag in response to human disturbance and climate change, and contribute to the maintenance of species diversity through a "storage effect". In contrast, soil seed bank density increased with mean annual precipitation and was driven by soil and litter properties, implying that climate change (e.g., drought) would reduce the potential of soil seed bank to maintain community stability.

This study covers several perspectives of plant community ecology: for vegetation stratification, three layers of vegetation are considered: trees, shrubs and herbs; for biodiversity, different dimensions based on species diversity, functional diversity and phylogenetic diversity are included, and the soil seed bank, which is known as the “hidden” plant diversity, is also considered. Despite their small size, herbaceous plants are the important contributors to coniferous forest community diversity and are strongly influenced by human disturbances, therefore, herbaceous plants, an easily neglected plant group, should be fully considered when conserving the diversity of forest ecosystems.

MOST Discipline Catalogue理学 - 生态学
URL查看原文
Language中文
Other Code262010_120190905031
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/538345
Collection生态学院
Affiliation
兰州大学生态学院
Recommended Citation
GB/T 7714
曹家豪. 人为干扰对青藏高原东北部紫果云杉林群落多样性和土壤种子库影响的研究[D]. 兰州. 兰州大学,2023.
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