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黄土丘陵沟壑区植被自然更新 的 种源 限制因素 研究
王 宁
Subtype博士
Thesis Advisor焦菊英
2013-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword物种库 土壤种子库 幼苗库 营养繁殖 土壤侵蚀 植被更新
Abstract

黄土丘陵区是我国水土流失与生态系统退化最为严重的地区之一,也是生态环境
建设的重点与难点区域。植被恢复是该区水土流失治理与生态安全的根本途径。但是,
该区长期的植被恢复建设效果不佳,人工植被物种单一,保存率低。而植被自然恢复
因其适应性与稳定性受到关注,于是提出通过植被自然恢复来控制水土流失,改善生
态环境。然而,该区是否具有足够的种源及有效的繁殖体来保障植被自然更新与恢复
尚不清楚。所以,本文选择延河流域为研究区域,通过对区域物种库、典型小流域不
同立地条件的土壤种子库、幼苗库及营养繁殖体库研究的基础上,从种源、扩散、幼
苗建植等方面分析该区植被更新的限制因素,主要研究结果如下:
1. 区域物种库具有 209 种植物,分属于 45 种群落类型,包含了黄土丘陵沟壑区
退耕地植被恢复演替不同阶段的群落类型,如退耕恢复初期的猪毛蒿、赖草群落,进
一步发展的长芒草、达乌里胡枝子群落,较高阶段的茭蒿、铁杆蒿、白羊草群落;沟
坡残留灌草丛群落,如狼牙刺、虎榛子、丁香、黄刺玫、荆条、小叶锦鸡儿、杠柳、
酸枣等群落;乔木林群落,如辽东栎、侧柏、小叶杨群落。这些群落的分布环境包含
了峁顶,阴阳梁峁坡、沟坡等生境类型,证明区域物种库能够为研究区不同地形、不
同土壤侵蚀程度生境的植被恢复提供种源。
2. 土壤种子库特征随立地条件及地上植被类型发生变化,平均密度变化在
1188~22560 seed/m 2 之间,且主要分布于表层土壤中;虽然种子有随土壤侵蚀而流失
迁移的现象,但土壤侵蚀没有造成土壤种子库的显著降低。土壤种子库中共有 91 个
物种,退耕地植被恢复演替过程中的主要物种在种子库中分布广泛,并多具有持久土
壤种子库,能够为侵蚀干扰环境中的幼苗建植提供保障。
3. 幼苗的时空变化主要受到土壤水分有效性的影响,随着雨季水热条件的改善,
幼苗密度和物种丰富度均有显著的增加;而且坡面上有利于水分保存的微生境能够增
加种子萌发与幼苗存活。幼苗调查中共记录 91 个物种,其中退耕地植被恢复演替过
程中的主要物种在土壤种子库、幼苗库与地上植被中对应出现,说明这些物种能够在
自然条件下萌发、建植,并实现植被在侵蚀环境中的自然更新与演替。4. 物种库中有 24 种多年生禾草、40 种多年生草本物种具有营养繁殖能力,而多
数乔木、灌木物种具有萌生能力。植被恢复演替过程中的主要营养繁殖物种具有较强
的营养繁殖能力,营养繁殖体芽库密度要远远高于对应物种的土壤种子库密度及幼苗
密度。营养繁殖物种更能适应存在土壤侵蚀的环境,表现为随着坡度的增加营养繁殖
物种在群落中的重要值显著增加,而依靠种子繁殖的物种重要值逐渐降低。
5. 在退耕地自然恢复过程中,早期物种具有生产大量易于传播的小种子的特性,
能够形成高密度土壤种子库,以幼苗库优势迅速占领生境;演替较高阶段的主要建群
种、伴生种亦能生产大量易于传播的种子,具有一定数量的土壤种子库,能够在适宜
条件实现幼苗萌发与建植,并且大多主要物种具有营养繁殖能力,有利于在侵蚀干扰
条件下利用营养繁殖方式维持并扩展种群。所以,退耕地植被恢复过程中的主要物种
不受种源和扩散限制。而沟坡残存灌乔物种,一般零散分布于地势较低的沟坡,再加
上其种子重量较大、产量较小,在缺乏有效传播媒介的情况下,长距离传播受到限制。
可见,这些沟坡残存灌乔物种在种源和种子扩散上均受到一定的限制。
6. 研究区退耕地植被恢复演替过程中的主要草本、半灌木物种基本不受种源与
扩散限制,能够在退耕后较短的时间恢复到典型的蒿草群落;但沟坡残存乔、灌木物
种由于种源和扩散的限制,其恢复缓慢。因此,在植被恢复建设过程中应加大乡土乔、
灌木物种扩散、建植、生长限制因素的研究,以加快该区植被恢复演替进程,改善植
被结构,提高群落的水土保持与生态功能。
关键词:物种库;土壤种子库;幼苗库;营养繁殖;土壤侵蚀;植被更新

Other Abstract

The hilly-gullied region of the Loess Plateau is well known due to the serious soil
erosion and ecosystem degradation. It is also the key region needing much hard work to
restore ecological environments. The vegetation is the key factor to control soil erosion and
restore the degraded environments. However, the efficiency of vegetation restoration was
not entirely satisfactory due to the simple planted species and high mortality rate.
Compared with an artificial plant community, a natural vegetation community has a higher
potential for adaptability and stability; thus, natural vegetation rehabilitation has been
proposed to control soil erosion in the Loess Plateau region. But, as an ecological stress,
the soil erosion can influence the process of vegetation development including
post-dispersal movement of seeds, establishment of seedlings, growth and reproduction of
plant. However, in the study region with serious soil erosion, it is still not clear whether
enough species and propagule persist in this field for the vegetation natural recruitment and
restoration. Thus, the regional species pool was studied in the Yanhe watershed. The soil
seed bank, seedling bank and the vegetative propagation were studied in a typical small
watershed with different vegetation and erosion intensities. And then the limiting factor of
the vegetation recruitment was analyzed on the basis of the species sources, seed dispersal
and seedling establishment. The main results as follows:
1. In the regional species pool, 209 species were recorded and belonged to 45 types of
communities which includes the communities during the different successional stages on
abandoned land, such as Artemisia scoparia, Leymus secalinus communities in the early
stage, followed by Stipa bungeana, Lespedeza davurica communities and Artemisia
giraldii, Artemisia gmelinii, Bothriochloa ischcemum communities in the later restoration
stage; the remnant communities on the gully slope, such as Sophora davidii , Ostryopsis
davidiana, Syringa oblate, Rosa xanthina, Vitex negundo var. heterophylla, Caragana  microphylla, Periploca sepium, Ziziphus jujuba communities; and tree communities, such
as Quercus wutaishanica, Platycladus orientals, Populus simonii communities. The
distribution habitats of these communities include the hilly top, sunny and shady hilly
slope and gully slope. In the regional species pool, the dominant constructive species and
companion species have a wide distribution and can provide seed sources for natural
revegetation on the abandoned land with different soil erosion conditions.
2. Characteristics of the soil seed bank changed with the ecological environments and
standing vegetation. The average soil seed bank density varied from 1188~22560 seed/m 2 .
The soil seed bank mainly distributed in the top soil, but there was no significant seed loss
with the soil erosion intensity increasing. 91 species were recorded in the soil seed bank,
and the dominant abandoned successional species distributed widely. Most of the dominant
species had persistent soil seed bank which can enhance their recolonization in the eroded
environments.
3. Soil water validity was the main factor influence the seedling changing in space
and time. The density and species richness of seedling both had significant increase with
the improvement of soil water and temperature in the rain season. On the slope, the
microsite where more soil water can be retained could enhance the seed germination and
seedling survival. 91 species were recorded in the seedling bank and 57 of these species
coexisted in the soil seed bank, seedling bank and standing vegetation. This result
suggested that these species can germinate and establish under the natural conditions, and
the vegetation can be recruited and succession in the eroded environments.
4. In the species pool, 24 perennial grasses and 40 perennial herbs have the ability of
vegetative propagation. And many of the wood species have the ability of sprouting. The
main clone species had high density of bud bank. The density of bud bank was higher than
the density of soil seed bank and seedling bank of the corresponding species. The
vegetative reproduction (versus sexual) is the most effective mechanism for species to
colonize and resist on such erosive degraded areas. The important value of the vegetative
reproduction species increased with the slope angle increasing.
5. During the abandoned land restoration, the early successional species always can
produce large number of seeds with small size and form high density soil seed bank which
can recolonization quickly by the seedling press. The following species also can produce
large number of seeds which dispersal distance and persist in the soil seed bank. As the
same time, most of the dominant species can survival and spread under the harsh habitats
by vegetative reproduction. These results indicated that these species were not limited by
seeds sources and dispersal. Due to fragment landform the remnant wood species distributed on the gully slope with low frequency. The seed dispersal faces the stress of soil
erosion and gravity when they dispersed from the lower position (gully slope) to higher
position (hilly slope). Furthermore, the wood species always produce big seeds which can
not disperse distance without help. Thus the recolonization of these wood species was
limited by the seeds sources and dispersal.
6. In the study region, the main herb and subshrub species can recolonize the
abandoned slope land within decades and form typical steppe community without limit in
seeds sources and dispersal. But the woody species recolonize slowly due to the limit of
seeds sources and dispersal. These results suggested that more studies should be done to
find out the limiting factor in seed dispersal, seedling establishment and growth of the
native woody species in order to enhance their restoration on the abandoned slope land
which can improve the vegetation structure and enhance the ability of control soil erosion
and ecological function.
Key Words: species pool; soil seed bank; seedling bank; vegetative propagation; soil
erosion; vegetation recruitment 

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8977
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
王 宁. 黄土丘陵沟壑区植被自然更新 的 种源 限制因素 研究[D]. 北京. 中国科学院研究生院,2013.
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