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水蚀风蚀交错带植被恢复 对土壤质量的影响与植物生理生态适应性
白文娟
Subtype博士
2010-05
Degree Grantor中国科学院研究生院
Place of Conferral北京
Keyword黄土高原水蚀风蚀交错带 植被恢复 土壤种子库 土壤质量 水分生理生态 光合生理生态
Abstract

黄土高原水蚀风蚀交错带生态环境脆弱,土壤侵蚀严重,是黄河粗泥沙的主要来源
区。合理的植被恢复措施对于该区退化生态系统的恢复与重建具有重要的意义。本研究
以该区不同生境的植物—土壤系统为研究对象,采用野外调查和室内分析相结合的方
法,研究了植被恢复过程中地上植被特征和土壤种子库特征,阐明了植被恢复对土壤质
量的影响,分析了植物水分和光合生理生态适应性。本论文取得如下主要结论:
(1)阐明了植被恢复过程中地上植被物种组成和多样性变化。地上植被以菊科、
禾本科和豆科植物为主,共占物种总数的76%。从生活型来看,主要以多年生草本植物
为主,占物种总数的64%。植被演替过程可分为三个阶段:演替初期(1-3a)主要以猪
毛蒿、猪毛菜等一年生植物为主;接着草木樨状黄耆成为群落的主要物种,糙隐子草、
达乌里胡枝子等为主要的伴生物种;15a 以后群落优势种更替为长芒草,而后随着植被
演替过程的进行,长芒草群落的建群种地位一直没有发生变化。丰富度指数随恢复年限
的增加其变化趋势不很明显,Shannon-wiener 指数和均匀度指数均随恢复年限的增加呈
现一定的上升趋势,而生态优势度却呈现下降的趋势。说明随着植被演替进展,群落的
组成结构趋向均匀和稳定。
(2)研究了土壤种子库特征及其对植被恢复的影响。土壤种子库密度范围为105~
6 301 粒·m-2,平均密度为2 095±448 粒·m-2 ;土壤种子库具有明显的垂直分布格局,0-5
cm 土层种子库密度大于5-10 cm,且占土壤种子库总密度的72%。土壤种子库主要以猪
毛蒿、画眉草等演替早期的物种为主,占土壤种子库总密度的62.18%(分别为41.37%
和20.81%),而演替后期物种即目标种却较缺乏。土壤种子库和地上植被的物种数目接
近,但其物种种类和功能群组成有一定的差异。二者的相似性总体上较低,其相似性系
数变化于0~0.667。土壤种子库的物种多样性指数随恢复年限的变化趋势与地上植被的
相似。上述结果表明,土壤种子库在植被演替前期具有重要的作用,但是在演替后期贡献较小。土壤种子库在植被恢复中的潜力较小,植被恢复还需要适度的人为干预。
(3)阐明了退耕地植被演替对土壤质量的影响。>0.25 mm 团聚体破坏率随恢复年
限的增加呈下降趋势;>0.25 mm 水稳性团聚体含量和平均质量直径(MWD)均随恢复
年限的增加呈上升趋势。这说明了植被恢复过程中,土壤结构稳定性有所增强。0-200 cm
和200-500 cm 土层平均土壤含水量随恢复年限的增加呈现先减少而后又有所增加的趋
势。在500 cm 土壤水分剖面内,随土层深度的变化土壤含水量具有较大的波动。随着
恢复年限的增加,土壤有机质、全氮、碱解氮和速效磷含量表现出先减少后增加的非正
“U”型变化;且它们随土层深度的增加而减少。土壤真菌、细菌和放线菌数量与土壤化
学性质随恢复年限增加的变化规律相似。退耕地微生物区系以细菌类群占绝对优势,占
微生物总数的70%以上,其次为放线菌,真菌数量最少。不同恢复年限的蔗糖酶、脲酶
和碱性磷酸酶活性的变化趋势也与土壤化学性质相似。过氧化氢酶活性随恢复年限增加
的变化规律不明显。
(4)比较了不同植被类型间土壤质量因子的差异。农地和柠条林地的土壤结构和
稳定性较好。0-500 cm 土层土壤含水量平均值基本都小于10%,其排序为:农地(10.53%)
>柠条灌木地(9.46%)>退耕地(8.31%)>油松林地(8.21%)>小叶杨疏林地(4.50%)
>沙蒿地(3.97%)≈刺槐林地(3.95%)。不同植被类型的土壤养分含量、酶活性和微生
物数量基本上均表现为刺槐和农地较高,柠条和小叶杨疏林较低。
(5)通过敏感性分析、主成分分析和相关分析确立了土壤质量评价最小数据集,
定量评价了植被恢复对土壤质量的影响。土壤质量评价指标最小数据集为有机质、速效
磷、蔗糖酶和真菌,其能够反映综合评价指标的信息,评价结果具有较好的代表性。土
壤质量综合评价表明,随着恢复年限的增加,土壤质量综合指数表现为演替的前15a 呈
现下降趋势,15a 后开始呈现增加的趋势,即表现出非正“U”型变化。就不同植被类
型而言,研究区土壤质量的排序为:刺槐林地>农地>退耕草地>油松林地>沙蒿地>柠条
灌木地>小叶杨疏林地,这在一定程度上反映了人工培肥土壤的有效作用。总体而言,
研究区土壤质量仍属于较低水平。
(6)分析了植物水分生理生态适应性。叶片渗透势的变化范围为-1.9 MPa(苦菜)~
-4.3 MPa(恢复年限为40a 退耕地的长芒草)。70%的物种集中在-4.0~-3.0 MPa 范围内。
就生活型而言,一年生草本植物的渗透势显著大于灌木、乔木和多年生草本(P<0.05),
而多年生植物间渗透势值的差异较小,其排序为灌木(-3.483MPa)<乔木(-3.384MPa)
<多年生草本植物(-3.287Mpa)<一年生草本植物(-2.469MPa)。这说明多年生植物可
能比一年生草本植物从土壤环境中吸收水分的能力强。叶片渗透势和叶片含水量随恢复年限的增加呈显著的下降趋势。这在一定程度上表明拥有较低渗透势的植物在植被演替
的物种竞争中具有一定的优势,植被演替后期物种对研究区干旱环境具有较强适应性。
长芒草、达乌里胡枝子和草木樨状黄耆的叶片渗透势随恢复年限的增加也均呈现显著下
降趋势,这种种间差异是由植物的表型可塑性引起的,反映了物种对环境的适应。
(7)分析了植物光合生理生态适应性。不同生境植物的光合特征和叶片结构特征的
种间差异较大,这可能是植物长期适应生态环境的结果,同时也与其本身固有的遗传特
性有关。在物种水平上,最大光合速率(Pmax)、光合氮素利用效率(PNUE)和比叶面
积(SLA)随恢复年限的增加呈显著下降趋势,而水分利用效率(WUE)、叶氮含量(Nmass)
与恢复年限相关关系不显著。在群落水平上,除SLA 与恢复年限的相关性不显著以外,
其它指标皆与物种水平的变化趋势一致。研究区物种的Pmax 与WUE、PNUE、Nmass 呈
显著正相关(P <0.05),而与SLA 的相关关系不显著。PNUE 与WUE、SLA 呈显著正
相关(P <0.001),而与Nmass 的相关性不显著;物种的Nmass 与SLA 呈显著正相关(P
<0.001)。同其它地区相比,研究区物种的Pmax、PNUE 和SLA 较低。具有较低Pmax、
PNUE 和SLA 的物种可能更适宜研究区土壤贫瘠的生境。

Other Abstract

Ecological environment is fragile in water-wind erosion region where soil erosion is
very serious. And this region is the main source of the coarse sediments of the Yellow River.
Sound vegetation restoration measures are of importance to the vegetation restoration of
degraded ecosystem in the study area. Vegetation-soil systems in different habitats were
studied using the field survey and laboratory experiment. In detail, characteristics of standing
vegetation and soil seed bank during vegetation restoration were identified. The effects of
vegetation restoration on soil quality and water and photosynthesis physio-ecological
adaptability were clarified. These results are helpful to reveal the interactional mechanism
between vegetation and soil quality and provide theoretical basis for vegetation restoration
and reconstruction in water-wind erosion region on the Loess Plateau. The main conclusions
are as follows:
(1) Species composition and species diversity of communities during vegetation
restoration were clarified. Standing vegetation was dominated by Compositae, Gramineae and
Leguminocae species, which accounted for 76% of total species numbers. For life forms,
perennial hebaceous plants were dominant, which occupied 64% of total species numbers.
Vegetation succession process was classified three stages.The dominant species were annuals
of Artemisia scoparia and Salsola ruthenica in the.first stage; Astragalus melitoloides in the
second stage; Stipa bungeana in the three stages (after 15a). And the role of Stipa bungeana as
constructive species remanined unchanged with vegetation succession after 15a. There was no
obvious tendency in richness index. Shannon-wiener and evenness index increased, while
ecological dominance declined with increased years. The results indicated that species
composition of community becomed even and stable along with vegetation succession.  (2) Characteristic of soil seed bank and its effect on vegetation restoration were studied.
The results showed that density of soil seed bank ranged from 105 to 6 301 seeds m-2 with an
average of 2 095±448 seeds m-2. Soil seed bank had vertical distribution pattern that seed
density at 0-5 cm depth (accounting for 72%) was greater than that at 5-10 cm depth. The
seed bank was mainly composed of early successional species such as Artemisia scoparia and
Eragrostis pilosa and their dentities accounted for 72% of total density (41.37% and 20.81%,
respectively). Species of the later successional stages (i.e. target species) were absent.
Similarity between seed bank and standing vegetation was low in the whole. Their Sorensen
similarity coefficient ranges from 0 to 0.667. The tendency of diversity with increased years
was consistent with the standing vegetation. The results suggested that seed bank plays an
important role on vegetation in the early succession stage, while contributes little in the later
succession stages. Potential for vegetation restoration from soil seed banks is limited and it is
recommended to employ morderate human intervention to accelerate succession.
(3) Impact of vegetation succession of abandoned croplands on soil quality was
clarified.The results showed that content of >0.25 mm soil water stable aggregate and MWD
increased, while destruction rate of >0.25 mm soil water stable aggregate decreased with
increased years, suggesting that soil structure stability increase during vegetation restoration.
Soil water content at 0-200 cm and 200-500 cm depth showed the trend of a decrease at the
inital stage but then an increase. Soil water content distribution in the 500 cm soil profile
showed a great fluctuation. Soil organic matter, total N, available N and available P
demonstrated a trend of a drease at the initial stage but then an increase, i.e. partially “U”
shape. They decreased with increasing depth in the soil profile. The trend of quantity of fungi,
bacteria and actinomyces with increased years was similar to the soil chemical properties. Soil
microflora in abandoned croplands was maily composed of bacteria accounting for more than
70% followed by actinomyces and fungi. The trends of soil invertase, urease and alkaline
phosphates with increased years were consistent with the soil chemical properties. But soil
catalase had no obvious trend with them.
(4) Soil quality factors of different vegetation types were compared. The results showed
that soil structure and stability of cropland and Caragana korshinskii land were better than
other types. The mean soil water contents of different vegetation types were less than 10% at
0-500cm depth. They were ranked as follows: cropland (10.53%) > Caragana korshinskii  land (9.46%) > abandoned cropland (8.31%) > Pinus tabulaeformis forestland (8.21%) >
Populus simonii forestland (4.50%) > Artemisia desertorum land (3.97%) ≈ Robinia
pseudoacacia forestland (3.95%). The soil nutrients, enzyme activities and microorganisms of
Robinia pseudoacacia forestland and cropland were higher, while those of Caragana
korshinskii land and Populus simonii forestland were lower in the whole.
(5) A Minimum Data Set (MDS) for soil quality assessment was established by the
methods of sensitivity analysis, principal components analysis and correlation analysis.
Effects of succession stages and different vegetation types on soil quality were quantitatively
evaluated based on integrated indictors and MDS. The results showed that MDS included soil
organic matter content, available phosphorus, invertase activity and fungi. Established MDS
could reflect the information of integrated indicators and results of assessment were of better
representative. The trend of integrated fertility index (IFI) changes was partially “U” shape,
namely, showing a decrease in 15 years following abandonment, but an increase after 15 years.
Considering different vegetation types, the values of IFI ranked in the order: Robinia
pseudoacacia forestland>cropland>abandoned farmland>Pinus tabulaeformis
forestland>Artemisia desertorum land>Caragana korshinskii land>Populus simonii forestland.
This reflected human activity could improve soil quality to some extent. Conclusively, soil
quality level in the study area was low.
(6) Plant water physio-ecological adaptability was analyzed. The results show that the
values of leaf osmotic potential (ψs) ranged from -1.9 MPa in Sonchus oleraceus to -4.3 MPa
in Stipa bungeana in the 40-year abandoned croplands; 70% of all species fell in the range
from -4.0 MPa to -3.0 MPa. Considering life forms, annual herbs had significantly higher ψs
than trees, shrubs and perennial herbs (P<0.05), while ψs differed little for trees, shrubs and
perennial herbs. The trend of ψs variation among lifeforms was shrubs (-3.483MPa) (-3.384MPa) perennial woody plants could have a superior capacity to extract water by root system from
dry soil environment than annual herbs. Leaf osmotic potentials and water contents
demonstrated a significant tendency to decrease as years passed from the leaving the
croplands, especially in Stipa bungeana, Lespedeza davurica, and Astragalus melitoloides.
The results implied that species with low ψs in the later succession stages would have
substantial advantages to survive the xeric habits. And plant species had evolved adaptive  plasticity in response to varying environmental conditions during vegetation succession.
(7) Plant photosynthesis physio-ecological adaptability was analyzed. The results
showed that large inter-species differences existed in all habitats, probably reflecting the
adaptation of species to the environment and strong influence of their genetic nature. At the
species level, the maximum photosynthesis rate (Pmax), photosynthetic nitrogen use efficiency
(PNUE), and specific leaf area (SLA) showed significant decreasing trends as time elapsed
since abandonment, while water use efficiency (WUE) and nitrogen content (Nmass) were not
significantly correlated to years elapsed since abandonment. At the community level, the
trends were consistent with those at the species level except for SLA. Among the plant species
in the studied area, Pmax, while not correlated with SLA, was significantly positively
correlated with the WUE、PNUE and Nmass(P<0.05); the PNUE, while not correlated with
Nmass, was significantly positively correlated with the WUE and SLA(P<0.001); and the Nmass
was significantly positively related to SLA (P<0.001). Compared with other studies in other
regions, the species in the study area had lower Pmax、PNUE and SLA. Those lower values
may be a result of the plant species adapting to infertile soil and harsh habitats of the study
area.

Language中文
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8860
Collection水保所知识产出(1956---)
Recommended Citation
GB/T 7714
白文娟. 水蚀风蚀交错带植被恢复 对土壤质量的影响与植物生理生态适应性[D]. 北京. 中国科学院研究生院,2010.
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