通过对安塞纸坊沟流域14块不同弃耕年限的草地土壤理化性质的研究表明:随着弃耕地植被的恢复,土壤容重降低、孔隙度增大、质地改善;土壤有机质含量、CEC、全氮含量、全钾含量、水解氮及速效钾含量逐步提高,土壤盐分含量、土壤pH值有逐步降低的趋势,说明随着植被的恢复,土壤理化性质在不断优化.另外植被生物量与土壤有机质、CEC、全钾、速效钾、全氮及水解氮均呈极显著正相关,与土壤pH值与土壤容重呈极显著负相关,说明土壤与植被具有互动效应.

退耕地草地植被恢复与重建的理论是目前我国进行“退耕还草”、“天然草地保护”和“退牧还草”等工程的重要科技支撑，是我国进行草原地区生态环境治理与改善的理论基础和实践保障。文章主要涉及弃耕地草地植被恢复与重建的理论基础及实践措施，详细论述了弃耕地草地植被恢复过程中自然恢复的演替过程、土壤种子库的重要作用、土壤有机质的变化规律、草地植被盖度的变化规律，并根据草地生态系统理论，采取一些促进植被快速恢复的措施，如采用人工配置的植物群落组合代替自然恢复的缓慢演替过程，采用除草剂、灌溉、施肥及耕作等措施；综述比较了众多学者对弃耕地研究的成果，对于不同类型弃耕地草地植被的恢复与重建具有指导意义。

Abandoned cultivation succession is an important succession pattern.It can provide guidance for restoration projects.Abandoned cultivation succession is an advancing succession.It takes a very long time to restore an ecological system to a sustainable equilibrium one,which depends on inherent law of succession.Appropriate human intervention could change and shorten the succession process greatly.Research on abandoned cultivation succession was the basis for restoration ecology,which is established and developed with the research on abandoned cultivation succession.

弃耕演替是一种重要的演替模式,可以为生态恢复规划提供指导。弃耕演替为进展演替,但要恢复为稳定的生态系统可能会经历很长一段时间。这是由演替本身的规律决定的。适当的人为干预可能会改变这种状况,并使演替进程大大缩短。对弃耕演替的研究是恢复生态学兴起的原始策动力,恢复生态学是在对弃耕演替的研究中形成并获得发展的。弃耕演替研究隶属于恢复生态学,是恢复生态学涵盖的一个重要领域。

As one of the key topics of landscape ecology, the relationship between landscape pattern and ecological processes has been paid much attention recently, in particular on the relationship of land use structure and ecological processes, such as soil moisture dynamics, soil nutrient change and soil erosion. In this paper, the key issues of land use structure and ecological processes are discussed.

本文从土地利用与土壤水分、土地利用与土壤养分、土地利用与水土流失3个方面系统讨论了土地利用结构与生态过程研究的现状和特征,指出:1)土地利用结构对土壤水分的影响涉及生态系统、坡面、小流域和区域等系列尺度,土地利用的分布及景观特点影响土壤水分的时空变异;2)土地利用对土壤养分的影响表现在土地利用的镶嵌格局影响土壤养分的分布和迁移,土地利用的变化可以引起土壤养分的变化;3)土地利用与水土流失关系密切,土地利用的改变能够减少或增加径流和土壤侵蚀.尺度不同,土地利用与水土流失的机制也不尽相同.土地利用结构与生态过程的研究,还需要注重大尺度和多尺度上的综合研究.

The changes occurred in composition and structure of plant communities in Zhifanggou watershed at Loess Gully region of China, constitutes major objective for the present study. The ground data was collected through field surveys during 1981, 1988 and 2001 respectively to analyze the significant relationships existing between plant composition, structure and their changes. Based on statistical analysis, the following conclusions could be made such as considerable increase in number of species (7%～73%), cove...

在 1 98 1、1 988和 2 0 0 1年 3个时期调查数据的基础上 ,对纸坊沟流域恢复生态系统中的植物群落的组成和结构进行了对比研究。结果表明 :对于中度退化生态系统 ,短期封禁就能使草本群落得到明显恢复。主要表现在植物种类的增加、植被盖度的提高和生物量的提高 ,其增加幅度分别为 7%～ 73%、81 %～ 1 67%和 61 %～ 1 38%。伴随着植被恢复 ,植被保持水土功能增强。流域土壤侵蚀从封禁前的极强度侵蚀 ( 1 0 0 0 0～1 40 0 0 t/( km2·a) )减小到轻度侵蚀 ( 1 2 1 0 .2 t/( km2·a) )。中期封禁过程中群落盖度、生物量继续增加 ,水土保持功能进一步提高 ,但和短期封禁恢复相比 ,提高幅度较小 ,群落盖度和生物量分别增加了 3%～1 8%、- 4%～ 8%。随着植被水土保持功能的加强 ,土壤表层养分也逐渐提高。中期封禁后群落结构和短期封禁相比发生较大变化 ,其中天然草本群落中发生了优势种更替现象 ,但天然灌木群落和人工乔灌群落优势种变化不大或无变化 ;群落垂直结构变化表现为 :草本群落结构变化最大 ,人工乔木林次之 ,但灌丛结构变化相对较小。封禁消除了致使植被退化的影响因子后，促进了群落内物种的正常生长和繁殖，从而使群落生态功能得到恢复；群落生态功能的恢复使群落生境得到改善，从而又促进了植被的进一步恢复。在此相互作用下，群落开始向当地顶极群落发展。此外，组建的群落结构变化系数作为一个衡量群落垂直结构变化状况的指标是合适的，该指标综合考虑群落在垂直结构上不同层的变化情况，能较好的反映群落结构的变化情况。

A 2-year experiment was carried out in the Loess Plateau to better understand vegetation succession of arable old land after being abandoned in Loess hilly region. Based on 2 kinds of ways, one was quantitative classification using system clustering, the other was abandoned year. Again with the overall understood of 25 sample plots research, the result showed that: from 1 to 6 years, annual weeds community →annual weeds + tuft grass community →annual weeds + perennial herbage community or rhizome grass →from 7 to 16 years, perennial herbage community →perennial grass+ undershrub community →from 17 to 42 years, rhizome tuft grass + undershrub community or undershrub + perennial grass community →undershrub community or perennial grass + tuft grass community. The representative communities were: Artemisia scoparia Waldstet. et kit community or A.scoparia Waldstet. et kit + Stipa bungeana Trin. community → A.scoparia Waldstet. et kit + Artemisia sacrorum Leded. community (or Agropyron cristatum(L.)Gaertn community) →Artemisia sacrorum Leded. community → A.scarorum Ledeb. + Lespedeza var.dahurica (Laxm.)Schindl community → Bothriochloa ischaemum (L.)Keng + Artemisia sacrorum Leded. community Or Lespedeza var.dahurica (Laxm.)Schindl+ Artemisia sacrorum Leded. community or Artemisia sacrorum Leded .+ Poa sphondylodes Trin.et Bge community. In order to restore the degraded environment in the arid zone, it was important to know how to collocate kinds of pastures with wild grasses. There is a new way: first, based on the result of the investigation into succession, all kinds of wild grasses were arranged in order of their important values, 1～35th herbage was warranted that being able to yield more quantity production than from 36 to the last grass according with the model of important value, this character was the most important not only for the ecological benefit but also for the economic effectiveness; second, according as the result of palatability experiment, 23 kinds of pastures were selected from the 1～35th grasses to be analyzed their chemical nutrient composition, then, they were graded excellent, fine, good and inferior by the score that gained appraisal by chemical nutrient composition in accordance with the pasture’s quality standard; third, these kinds of pasture community’s ecological benefit was analyzed, then, they were graded excellent, fine, good and inferior too; ultimately, over efficacy of 23 kinds of herbage community was ascertained. To summarize: 23 kinds of pastures were classified into 3 groups according to their site quality of locality in the community in the succession process. One was constructive or dominant species in the period of succession process, but in the other times there were not these herbages, such as Sophora vicifolia Hance, Phragmitas communis Trin; Two was subdominant or companion species in the whole period of succession process, such as Gueldenstaedtia multiflora Bunge, Potentilla bifurca L .; Three was those grasses that transform their site quality of locality in the community in the succession process from constructive or dominant species into subdominant or companion species, or reverse, for example Lespedeza var. dahurica (Laxm.)Schindl, Bothriochloa ischaemum(L.)Keng. Besides, chemical nutrient compositions of these pastures have shown much variation, so, we should be attach importance to this phenomenon. When these conclusions being have applied, it appears important to repair vegetation based on the community structure in the succession process of different abandoned lands, the different pastures that should have overwhelming chemical nutrient composition will be selected from the grasses in the corresponding nature communities.

用系统聚类、撂荒年限两种方法对陕北黄土高原丘陵区撂荒演替序列进行分析，结果基本一致：1～6a,1年生杂草类群落→1年生杂草类＋丛生禾草群落→1年生杂草类＋根茎禾草群落或多年生草本群落→7～16a,多年生草本群落→多年生草本＋小灌木群落→17～42a：根茎丛生型禾草＋小灌木群落或小灌木＋多年生草本群落→小灌木群落或多年生草本＋丛生禾草群落，代表性群落依次为猪毛蒿( Artemisia scoparia  Waldstet. et kit)群落或猪毛蒿＋长芒草( Stipa bungeana Trin .)群落→猪毛蒿＋铁杆蒿( Artemisia sacrorum  Leded.)群落或冰草( Agropyron cristatum (L.)Gaertn)群落→铁杆蒿群落→铁杆蒿＋达乌里胡枝子( Lespedeza  var. dahurica  (Laxm.)Schindl)群落→白羊草( Bothriochloa ischaemum (L.)Keng)＋达乌里胡枝子群落或达乌里胡枝子＋铁杆蒿群落或铁杆蒿＋硬质早熟禾( Poa sphondylodes  Trin.et Bge)群落。在此基础之上，提出将各物种在演替过程中重要值之和按大小排序，对前35位草种经适口性试验初步筛选后进行以粗蛋白、粗纤维等为指标的化学成分及以有效植被盖度为指标的生态效益的分析、评价，并依据两种评价结果对陕北黄土高原主要乡土牧草进行了综合评定，得出黄土高原23种乡土牧草具备较高的改良潜质，分为4类，主要归属于豆科(Leguminosae)、禾本科(Gramineae)、菊科(Compositae)等，并进一步探讨了黄土高原人工草场改良过程中不同荒地上草种的合理搭配。

To understand the relationship between plant community succession and soil nutrient dynamics is crucial in intervening vegetation succession.This paper reported the results from a study carried out in a forest-steppe zone on the Loess Plateau,with emphasis on the vegetation characteristics and soil nutrient dynamics during vegetation restoration on abandoned farmlands of this area.The results showed that under zonal habitat conditions,natural vegetation succession would turn toward the original vegetation communities,but the expected shrub or trees communities didn't occur after 40～50 years,and Stipa bungeana,Artemisia sacrorum,Bothriochloa ischaemun,Stipa grandis and Lespedeza davurica communities were still the widely distributed communities.Vegetation restoration had a significant effect on soil nutrient dynamics.In general,soil nutrient contents increased with restoration time,and extremely significant changes occurred in soil organic matter,total N,available N,and available K( P P P >0.05).Moreover,the changes were also found in soil profile.Statistical analysis showed that from surface layer(0～20 cm)to deeper layer(to 60 cm),extremely significant changes occurred in soil organic matter,total N,available N,available K and available P( P P P <0.001),but didn't show correlation with soil total P and available P.

研究了黄土高原森林草原区退耕地植被自然恢复过程与土壤养分变化.结果表明,在显域生境下,植被自然演替过程虽然趋向于该区原有植物群落类型,但经过40～0年的时间,仍未形成灌丛或稀树等群落,分布较多的仍是长芒草、铁杆蒿、白羊草、大针茅和达乌里胡枝子等群落类型.从植被恢复时间对土壤养分变化的影响来看,除全P外( P ＞0.0),有机质、全N、速效氮、速效钾的变化极显著( P ＜0.001),速效磷变化较显著(0.0＜ P ＜0.01),并随植被恢复时间的延长而呈增加趋势.除恢复时间外,养分含量变化也随土壤剖面深度而变化,其中除全P含量变化较显著外( P ＜0.0),其余各养分含量变化都达极显著水平( P ＜0.001).土壤养分变化具有明显的表聚性.相关分析表明,土壤有机质、全N、有效氮与速效钾相互间相关极显著( P ＜0.001),而与全P与速效磷相关性不明显( P ＞0.0),全P与速效磷二者相关性也不明显( P ＞0.0).

The Detrended Correspondence Analysis (DCA) was employed to analyze the trend and direction ofplant community succession of abandoned loess land. Seven species diversity indices were used to study thechanges in species richness , species evenness and diversity in the succession. With the development of succession , species richness increased significantly , species evenness decreased slightly and diversity went up.

用DCA排序研究了黄土丘陵区撂荒地上植物群落演替的趋势和方向，用6种多样性指数分析了物种丰富度、均匀度和综合多样性在演替过程中的变化。随着演替的进展，物种丰富性显著增高，均匀性逐渐降低，综合多样性逐渐升高。

The characteristics of plant communities on abandoned land in different years were surveyed in agricultural cross bedding in the south edge of Otindag sandy land. The results showed that there were four stages in the whole succession of abandoned land, including annual weeds stage, overgrowth grass stage, perennial root grass stage and perennial overgrowth grass stage; changes of total over ground biomass and the abandoned time was not a linear dependence relation, and with increasing of time, the proportion of perennial grass over ground biomass in the total over ground biomass increased too. By comparing the characteristics of plant communities in different pasture disturbances, another result was gained that abandoned land shouldn't be made use in the first two stages, but appropriate use was allowed in the last two succession stages. Along with increasing years of abandoned plant, as long as surface soil is not destroyed, the land would have a progressive succession and reach the partial climax community, and then would cause regressive succession under pasture disturbance.

以浑善达克沙地南缘农牧交错带不同年限弃耕地为对象,研究了不同年限弃耕地植物群落特征。结果表明:弃耕地的植被演替一般经历4个阶段:1年生杂草阶段、丛生小禾草阶段、多年生根茎禾草阶段和多年生丛生禾草阶段;地上生物量的变化与弃耕年限不是单一的直线关系,且随弃耕年限的增加,多年生植物的地上生物量占地上总生物量的百分比逐渐增大。对不同放牧干扰下弃耕地植被群落特征进行了研究,结果表明:在弃耕地植被演替的第1、2阶段不宜利用,但在弃耕地植被演替的第3、4阶段,可以进行适度利用;随着弃耕年限的增加,只要不对地表土壤进行破坏,弃耕地都会发生进展演替,并达到一个偏顶级群落,然后又会在放牧干扰下,发生逆行演替。

Impact factors and relationships between plant biodiversity and biomass of different communities of desert steppe in an unmodified condition were determined using biodiversity indices, soil physical and chemical factors and assessment of aboveground and underground biomass. The results showed that species richness and diversity varied similarly in different communities. Exponential relationships between aboveground biomass and underground biomass showed that the desert steppe community displayed allometric growth patterns. The response of community richness to aboveground biomass was unimodal, while that to underground biomass was linear. Underground biomass was positively correlated with surface litter. Soil moisture, soil organic carbon, total nitrogen and available nutrients also contributed to underground biomass while soil moisture and soil organic carbon greatly contributed to aboveground biomass. Soil microbial biomass, soil carbon and nitrogen had a significant influence on community diversity indices.

通过测定生物多样性各指标、地上-地下生物量、枯落物量、土壤理化因子以及土壤微生物量碳氮,研究了自然状态下荒漠草原6种群落生物多样性与生物量的关系及其影响因子。结果表明:荒漠草原不同群落丰富度、均匀度与多样性指数变化趋势一致;地上生物量与地下生物量呈指数关系,表明荒漠草原群落呈异速生长模式;生物多样性与地上生物量呈单峰曲线,与地下生物量呈线性关系,初步表明荒漠草原不同群落地上部分种间作用、资源利用程度基本一致,生物多样性抑制了地上生物量,但并没有抑制其地下生物量;地表枯落物与地下生物量呈极显著的线性相关关系( P <0.01),初步表明了地下生物量更加依赖于地表枯落物。相关分析表明,荒漠草原生物多样性指数和生物量影响因子存在明显差异,自然条件下土壤含水量、有机碳、全氮以及有效养分对地下生物量贡献较大,土壤含水量和有机碳对地上生物量贡献较大,土壤微生物量碳和氮对群落多样性指数贡献较大。

Due to serious soil and water loss, the ecosystem on the Loess Plateau is in a seriously degraded status. Discussion about the tendency of plant diversity change during the natural recovery process of vegetation in the studied area is very important both in theory and in practice. The studied area is located at Ziwuling in Fuxian county, Shaanxi province, China, at 109°11′E and 36°05′N. The climate is semi-arid in warm temperate zone with mean annual precipitation of 576.7mm and mean temperature of 9℃. It i...

黄土高原地区由于强烈的水土流失生态系统处于极度退化的状态 ,探讨该地区植被自然恢复演替过程中植物多样性的变化规律 ,对于指导该地区的人工植被建设具有重要的理论价值与实际意义。以时空互代的方法初步研究了黄土高原子午岭弃耕地植被自然恢复演替过程中植物多样性的变化。结果表明 ,在近 15 0 a的植被恢复演替过程中调查样方内共出现高等植物 12 8种 ,分属于 4 7科 113属 ,累计出现的科、属、种数 (y)随着演替时间 (t)的延长呈对数函数变化 :y =a L n(t) +b,而且在植被恢复的前期增加速度较快 ,有 6 0 %的科属种在前 30 a出现。杠柳 (Periploca sepium)与茶条槭 (Acer ginnala)是植被恢复演替过程中出现最早而且持续时间最长的木本植物 ,具有较宽的生态位 ,建议作为该地区人工造林树种考虑。在植被恢复演替过程中草本层与灌木层物种丰富度指数 (Gleason指数与 Margalef指数 )、多样性指数 (Shannon- Wiener指数 )以及 Pielou均匀度指数的变化均表现为抛物线函数变化规律 :y =at2 +bt+c。在不同的群落层次植物多样性的变化是不同步的,草木层、灌木层与乔木层植物多样性达到最大的时间依次为70~80a、90~100a与100a以上。森林群落植物多样性在空间上的变化顺序为：草木层>灌木层>乔木层。

Vegetation recovery and reconstruction is the key of ecosystem restoration in the North Loess Plateau.With the Liudaogou catchment of Shenmu County,Shaanxi Province as test area,this paper studied the dynamics of the plant diversity of artificial alfalfa ( Medicago sativa ) grassland during its degradation process.The results showed that the degradation process of the grassland could be divided into three stages, i.e .,artificial alfalfa grassland stage (1～6 yrs),transitional stage from artificial to natural grassland (6～10 yrs),and secondary natural grassland stage dominated by Stipa bungeana (>10 yrs).In the whole degradation process from 1-to 30-yrs,32 species belonging to 13 families and 28 genera were found,of which,90% appeared in the initial 6-yrs.The dynamics of accumulatively appeared family,genus,and species in the vegetation succession process were well described by logarithmic function.During the process of community succession,the species richness (Gleason index and Margalef index),plant diversity (Shannon-Wiener index),and Pielou evenness index were changed with a similar tendency, i.e .,increased more rapidly at the first stage,and the climax phase appeared in the second stage.The plant diversity and evenness decreased slightly,and gradually became stable later.Planting alfalfa could markedly accelerate the natural vegetation succession process in the forest-steppe ecotone of Loess Plateau,mainly due to the intensive soil water consumption of artificial grassland,which accelerated the process of soil aridification.To develop artificial grasslands in the Loess Plateau is an optimal joint between accelerating natural vegetation recovery and increasing farmers'income by stockbreeding,and is also a favorable paradigm both for the ecological and for the economic benefits in the eco-environmental construction in West China.

以陕西省神木县六道沟小流域为研究区域,探讨了黄土高原北部紫花苜蓿人工草地退化过程中植物多样性的变化.结果表明,在黄土高原北部森林草原气候区,紫花苜蓿人工草地的退化演替过程可以划分为3个阶段:紫花苜蓿草地阶段(1～6年)、人工草地向天然草地演替的过渡阶段(6～10年)与长芒草次生天然草地阶段(10年以上).在1～30年的演替过程中,调查样方内共出现高等植物32种,分属于13科28属,其中90%以上出现在前6年.植被演替过程中累积出现的植物科属种数的动态变化可以用对数函数进行较好地描述.在群落演替过程中,物种丰富度指数、多样性指数和Pielou均匀度指数的变化趋势基本一致,在演替前期(第1个阶段)增加较快,在第2个阶段(过渡阶段)达到最高,然后有所降低并渐趋稳定.种植紫花苜蓿可显著地加快植被的自然演替进程,这与人工草地水分消耗强烈加速了土壤的旱化过程密切相关.发展人工草地是黄土高原北部加速天然植被恢复与发展畜牧业、增加农民收入的有机结合点,是西部生态环境建设中生态效益与经济效益兼顾的良好范式.

研究结果表明,大通县退耕还林不同配置模式下群落物种多样性指数与丰富度、均匀度呈显著正相关,与优势度呈显著负相关.群落物种多样性指数排序,在浅山区为模式C(青杨+枸杞)＞模式D(中国沙棘)＞模式B(紫花苜蓿)＞模式A(川赤芍)＞模式E(柠条),多样性指数分别为5.3091、5.089 4、4.657 3、4.081 6、3.410 5;在高山区为模式H(白桦+青海云杉)＞模式J(青杨+中国沙棘)＞模式G(华北落叶松)＞模式F(青海云杉)＞模式K(青海云杉+中国沙棘),多样性指数分别为5.228 9、5.071 7、4.699 2、2.780 9、2.646 2,群落乔、灌、草3层结构物种多样性指数呈现出草本层＞灌木层＞乔木层的规律,在优势度方面,草本层在森林中的作用远不及乔木层.

The species richness, evenness and species diversity of plant communities in Dinghushan Nature Reserve were investigated. The species richness index, species diversity index and the evenness index were compared for different vegetation types. The indices increased with the plant community succession, but the indices of mature forest were not the highest. Generally, the species richness order was that the shrub layer>herb layer>tree layer, the diversity index order is that the shrub layer>tree layer>herb lay...

根据鼎湖山自然保护区 1 6个植物群落的样地调查资料 ,从种丰富度和不同类型的物种多样性指数、均匀度与植被类型、人为干扰程度、演替阶段等方面的关系进行了分析。本区植被类型的多样性指数、均匀度指数变化反映了其结构复杂程度、生境的差异。物种丰富度和多样性随着人为干扰程度的增强而降低。群落内各层的物种丰富度的大小的顺序为“灌木层 >草本层 >乔木层”,而群落多样性指数的大小顺序为“灌木层 >乔木层 >草本层”。群落多样性随群落演替发展而增高 ,但最稳定群落的多样性不是最高。物种重要值和株数作为测度指标计算群落多样性所得结果相近 ,与用覆盖度(冠幅面积 )作为测度指标计算的结果相差较远。 Shannon-Wiener指数在样地达到一定面积后趋于稳定 ,Simpson指数较之 Shannon-Wiener指数对样地面积更敏感。

Land use change is the results of interactions between physical factors and human activities, and it also leads to changes of soil nutrient. Taking Quzhou county of Hebei province as a case study, this paper analyzed the changes of land use types and the corresponding changes of soil fertilities from 1980 to 1999. The results are as follows: The convert order of land use type is from grassland to farmland, from farmland to irrigable land, from irrigable land to vegetable land; the change extent of organic matter, total-N, and available-P content is different among different land use types in 1980 and 1999, the order of content change in different land use types is irrigable land > farmland > grassland, but the range is from 2% to 18%; the order of content change in different land use types in 1999 is vegetable land > irrigable land > farmland, but the range is 18%-690%; and the change extent of organic matter, total-N and available-P content is different among different land use types from 1980 to 1999, the order of content change in different land use types is vegetable land > irrigable land > farmland > grassland.

以河北省曲周县为集约化农区的分析样区，通过对1980年、1999年土地利用类型变化和2期不同用地类型的土壤养分变化进行分析。结果表明：曲周县1980~1999年之间的土地利用类型以水浇地、旱地、菜地、园地、林地等农业用地类型为主，1980年农业用地类型占土地总面积的77.47%，1999年的农业利用类型占土地总面积的77.43%；但是土地利用类型也存在着转化，转化的顺序为荒草地向旱地、水浇地、菜地方向转化，旱地向水浇地、菜地方向转化；1980年土壤养分含量在不同用地类型间的变化顺序为水浇地>旱地>荒草地，差异幅度在2%～18%之间，1999年土壤养分含量在不同用地类型间的变化顺序为菜地>水浇地>旱地，差异幅度在18%～690%之间；2期对比分析表明，土壤养分含量除速效钾外不仅在相同用地类型之间增加幅度大，而且在转化后地用地类型之间也存在明显差异；土壤有机质、全氮、速效磷含量在不同土地利用类型中的变化顺序为菜地>水浇地>旱地>荒草地，速效钾含量变化的顺序为旱地>荒草地>菜地>水浇地。

Soil quality improvement plays an important role in sustaining global biosphere.This paper studied the changes of soil quality after 25 years' land use and vegetation restoration at the Anjiapo catchment of western Loess Plateau.The analyses of soil characteristics of wasteland,almond land,farmland,pineland,shrub land and fallow land showed that different land use and vegetation restoration had different effects on soil integrated fertility index.Soil organic matter content was increased due to planting shrubs and forests.Both vegetation restoration and fallow could improve soil quality.Cultivation practice could decrease soil nutrient levels,and cropland soil was degraded.Shrub soil formed “fertile island” in the semi-arid region.Fallow could improve soil fertility to some extent.Human activities and vegetation restoration could affect soil nutrient contents after land use pattern was changed.With the launch out into the “Grand development of Western China”,“Grain for Green Project” and ecological restoration,both shrub planting and fallow(natural restoration)should be the optional choices to restore soil fertility,as they could decrease soil erosion and improve soil condition at catchment scale,especially in the hilly and gully loess area.Integrative control of small catchment may be the best way for the sustainable development of the semi-arid hilly area of Loess Plateau.

土壤质量的维护和提高是全球生物圈可持续发展的重要因素之一.对黄土丘陵小流域持续利用25年后的荒草地、山杏林地、农地、油松林地、灌木林地和撂荒地土壤性状的研究结果表明,不同土地利用方式和植被恢复类型对土壤质量有很大影响;植被恢复重建和农地撂荒将增加土壤有机质含量,提高土壤质量;粗放的农业耕作措施将降低土壤质量并引起土壤退化;灌丛有明显的肥力岛屿作用;撂荒在一定程度上可以培肥土壤.随着“西部大开发”、“退耕还林还草”和生态重建工程的开展,在半干旱黄土丘陵沟壑区,建植灌木、种植牧草、农地撂荒和自然恢复是较好的生态重建和植被恢复方式.

土壤有机碳是陆地生态系统的重要碳库之一,增加土壤中碳的储量对于减缓全球变暖的趋势具有重要意义。通过野外样品采集及室内分析,比较了退耕1年,3年,5年,7年,10年,15年和25年7个不同年限撂荒地的土壤有机碳及其活性的变化。结果表明:耕地撂荒后,表层土壤有机碳及活性有机碳的含量随着退耕年限的增长呈增加趋势;土壤中的腐殖质以胡敏素为主,占总有机碳含量的70%～80%;深度在40cm以上的表土,腐殖酸总量及各组分含量都随着撂荒年限的增长呈递增趋势。说明耕地撂荒后,土壤中有机碳的含量明显增高,对增加土壤中有机碳的储量具有积极的意义;同时植被恢复后也减少了土壤中有机碳的流失。

探讨了松嫩平原植物群落演替与土壤肥力的关系.结果表明:不同演替群落阶段,其土壤的化学性质和肥力存在一定差异,由于土壤化学性质不同,使群落镶嵌分布,组成植被的复合体.随着植被的退化演替,群落的盖度、高度下降,种类组成趋势于简单化,生物量减少,土壤盐碱化程度加重,土壤肥力下降,出现次生盐碱植物群落.群落的生物量度与土壤、含盐量、咸化度呈负相关,与土壤腐殖质和全氮含量呈正相关.

By the method of substituting temporal serial with spatial serial, and taking five abandoned cultivated lands with different ages (1, 4, 9, 12, and 20 years) in desert steppe region as test objects, this paper studied the change characteristics of plant community biomass and soil nutrients during vegetation succession. With the increasing abandoned years, the plant community aboveground biomass on the abandoned lands increased after an initial decrease, whereas the total nitrogen, total phosphorus, organic carbon contents, and carbon density in 0-60 cm soil layer increased first, decreased then, and increased again, with the maximum values of soil total nitrogen and phosphorus contents appeared on the abandoned lands with the ages 4 and 20 years. During vegetation succession, the effects of soil total nitrogen and organic carbon on plant community biomass were greater than those of soil total phosphorus and soil bulk density.

采用空间变化代替时间变化的方法，以荒漠草原区不同年限(1、4、9、12和20年)弃耕地为对象，研究弃耕演替过程中植物群落生物量与土壤养分的变化特征.结果表明： 随弃耕年限的增加，弃耕地植物群落地上生物量呈先减少后增加的趋势，0～60 cm土层的土壤全氮、全磷和有机碳含量及碳密度均呈先增大后减小再增大的趋势，4年和20年弃耕地的土壤全氮、全磷含量达到峰值.弃耕演替过程中土壤全氮和有机碳含量对植物群落生物量的影响大于土壤容重和土壤全磷.

为了探讨我国亚热带红壤丘陵区不同利用方式下土壤有机碳(SOC)和土壤微生物生物量碳(MB-C)含量的特征,在湖南省桃源县选取典型样区,通过密集取样,分析了红壤丘陵景观单元内水田、旱地、林地、果园4种典型利用方式下表层土壤(0～20 cm)SOC和MB-C含量.结果表明,典型红壤丘陵景观单元中SOC含量高低的顺序为水田(16.0 g·kg-1)＞旱地(11.2 g·kg-1)＞果园(9.5 g·kg-1)＞林地(8.4g·kg-1),MB-C含量则为水田(830 mg·kg-1)＞旱地(361 mg·kg-1)＞林地(200mg·kg-1)＞果园(186 mg·kg-1),且在不同利用方式下SOC与MB-C均呈极显著正相关(P＜0.01),说明本研究区内各土地利用类型的土壤MB-C含量变化可以敏感地指示SOC的动态.研究结果还表明,将我国亚热带红壤丘陵林地开垦为果园或耕地后,表层土壤SOC含量不可能降低.

C/N比值在湖泊沉积物研究中广泛用于反映有机质的来源;在冰缘冻土区、热带和地中海地区主要用于指示有机质的分解程度.然而,有关C/N比值在中国黄土沉积中指示意义的研究目前讨论的较少.选取位于干旱一半干旱区的黄土高原中部西峰和洛川竖井剖面为研究对象,对该区末次间冰期以来土壤有机碳及全氮的时间分布规律进行了初步研究,结果表明研究剖面磁化率、TOC和TN含量及C/N比值的垂直分布趋势一致,古土壤层的TOC和TN含量及C/N比值相对黄土层偏高,而TN含量值在整个序列均在0.03%～0.05%的低值范围,波动很小.因此,初步认为C/N比值在中国黄土高原地区主要响应上覆植被TOC输入的多少,即C/N比值在干旱一半干旱的黄土沉积序列更多地指示上覆植物生物量的大小.

The purpose of this research was to provide the theoretical basis for grassland management and restoration for degraded land in Yellow River Source.The plant species diversity,biomass and soil nutrition were studied among alpine meadow communities( Kobresia pygmaea meadow alpine meadow, K.tibetica swamp alpine meadow and Salix oritrepha shrub alpine meadow) in Maqin connty,Qinghai province of China.Results show that Shannon-wienner index,abundance index,evenness index and Simpson index are all presented with the same patterns in three communities.They are ranked as Salix oritrepha shrub meadow> Kobresia pygmaea meadow> K.tibetica swamp meadow.There is significant difference in biomass between three communities.Total biomass of above-ground and under-ground in these treatments are ranked as K.tibetica swamp meadow> Salix oritrepha shrub meadow> K.pygmaea meadow( P K.tibetica swamp meadow are significantly higher than the other two alpine meadows.Soil nutrition content is decreased,and pH valve increased with soil depth increasing for K.pygmaea meadow and Salix oritrepha shrub meadow,while K.tibetica swamp meadow shows an opposite trend.

为了给黄河源区原生草地植被的科学管理及退化草地的治理提供理论依据,对青海省玛沁县藏嵩草( Kobresia tibetica )沼泽化草甸,山生柳( Salix oritrepha )灌丛草甸及小嵩草( Kobresia pygmaea )草甸物种多样性、生物量及土壤养分状况进行比较研究。结果表明:不同植被类型植物群落多样性指数、物种丰富度指数、均匀度指数、生态优势度指数均为山生柳灌丛草甸>小嵩草草甸>藏嵩草沼泽化草甸。各群落生物量差异明显,地上、地下总生物量均为藏嵩草沼泽化草甸>山生柳灌丛草甸>小嵩草草甸( P <0.05)。藏嵩草沼泽化草甸土壤养分含量最高。小嵩草草甸和山生柳灌丛草甸各土壤层养分含量随土壤深度的增加呈下降趋势,pH值呈上升趋势,而藏嵩草沼泽化草甸却表现出相反的趋势,即随土壤深度的增加各层养分含量呈上升趋势,pH值呈下降趋势。

In order to provide some basic foundation with revegetation, we need to deepen our understanding on the interactive effects of vegetation and soil. In this article, aboveground biomass, soil nutrition and moisture of 36 old-fields with different abandonment ages (from 2 to 45 years after abandonment), aboveground biomass of 4 typical old-fields, and growth characteristics of 7 predominant old-field species were measured. Changing pace, trend and relationship of community aboveground biomass and soil nutrition during secondary succession were evaluated; effects of soil nutrition on community aboveground biomass were analyzed using multianalysis and pathway analysis, and effects of aboveground biomass on soil nutrition were further discussed. The results show that: (1) Soil nutrition, including organic matter, total nitrogen, total phosphorus, total potassium, nitrate nitrogen, ammonium nitrogen, and active phosphorus, active potassium have the same changing pace and trends as the aboveground biomass does in the process of secondary succession, both decreased in earlier abandonment stage of succession, then increased subsequently. (2) If offered from the correlation of soil nutrients and abandonment ages, effects of vegetation on 0-20 cm organic matter, active phosphorus, 0-20 cm and 20-40 cm nitrate nitrogen nutrition are significant, while deduced from the correlation of soil nutrition and aboveground biomass, no significant effects were observed. Hereinbefore, aboveground biomass account for only a part of vegetation-soil nutrition effects. The effects of biomass to organic matter, total nitrogen, total phosphorous, total potassium, nitrate nitrogen, active potassium and phosphorous are positive, ammonium nitrogen is negative. (3) Abandonment ages, total nitrogen, total potassium, active potassium and soil moisture fluctuation have direct positive effects on the aboveground biomass of old-field communities, abandonment and soil moisture fluctuation have more lager effects. Each ingredient of soil nutrition has relative small effect, among them total nitrogen have larger effects than total and active potassium. The changes of aboveground biomass of old-field communities during succession are caused mainly by the changes of coverage and ecological characteristics of community species (the relatively larger direct effects of abandonment ages), and secondly by the soil moisture fluctuation (the relative smaller indirect effect of abandonment ages through soil moisture). (4) As a dependent variable, underground biomass approach power function of soil depth, declines in deeper layer. The root shoot ration of community tends to increase in later succession stages, later sere species also have increasing tendency. These will influence the accumulation of biomass and decomposition of organic matter, and the vegetation-soil effects may be different.

为了明确植被演替过程中植被与土壤的互动效应，为植被恢复提供依据。根据陕北黄土丘陵区36块不同年限（时间尺度为2～45a）的撂荒样地地上生物量、土壤养分和水分的测定结果，及4块典型撂荒群落样地地上/地下生物量，7种撂荒群落主要植物生长特性的测定，分析了撂荒演替过程中群落生物量与土壤养分的变化过程、趋势及其相互关系，进而探讨了撂荒演替过程中群落生物量对土壤养分的作用效应，并利用多元回归和通径分析法分析了土壤养分对群落生物量的作用。结果表明：（1）除速效磷外，撂荒演替过程中群落地上生物量和土壤有机质、全氮、全磷、全钾、NO 3 -N、NH 4 -N和速效钾都呈先减少后增加的趋势，步调基本一致。（2）从撂荒年限与土壤养分的相关性来看，0～20cm土壤有机质含量、速效磷含量和0～20、20～40cm 土壤层NO 3 -N含量与撂荒年限相关显著，说明演替过程中有机质、速效磷和NO 3 -N有较为明显的植被土壤效应，而其它土壤养分与撂荒年限相关不显著，不能排除演替初始条件和植物暂时固定的影响；从群落生物量与土壤养分的相关性来看，群落生物量对土壤有机质、全氮、磷、钾、NO 3 -N、速效钾和速效磷含量具有正效应，而对NH 4 -N具有负效应，但都不显著。（3）通径分析说明撂荒年限、土壤全氮、全钾、速效钾和土壤水分变异量对生物量表现为正的直接作用，其中以撂荒年限和土壤水分波动量作用较大，土壤养分对群落地上生物量的作用以土壤全氮最大，全钾和速效钾影响较小；演替过程中群落地上生物量的变化主要是由于植被盖度和群落组成种的生态学特性造成的（撂荒年限较大的直接作用），其次是由于撂荒演替过程中土壤水分的波动造成的（撂荒年限通过土壤水分的间接负作用）。（4）随着土层深度的加深植物根系生物量呈幂函数递减过程，演替后期群落根冠比有增加的趋势，演替后期序列种根冠比和根长也有增加的趋势，这些在一定程度上会影响到生物量积累和有机质分解等，进而会影响到植被土壤效应。

探讨了松嫩平原植物群落演替与土壤肥力的关系.结果表明:不同演替群落阶段,其土壤的化学性质和肥力存在一定差异,由于土壤化学性质不同,使群落镶嵌分布,组成植被的复合体.随着植被的退化演替,群落的盖度、高度下降,种类组成趋势于简单化,生物量减少,土壤盐碱化程度加重,土壤肥力下降,出现次生盐碱植物群落.群落的生物量度与土壤、含盐量、咸化度呈负相关,与土壤腐殖质和全氮含量呈正相关.

Carbon cycle process in ecosystem can be influenced by land use change. After implementing the project of farmlands converted to woodland and grassland in China, a large volume of farmland have been changed into woodland and grassland. In order to study the change of carbon emissions after the abandoned project, soil respirations of alfalfa field (converted from farmland) grassland, and farmland were measured in the loess hilly region of south Ningxia. The results indicated that soil temperature was strongly correlated with soil respiration, and the influence of soil moisture on soil respiration was limited. Average values of soil respiration on the alfalfa field, farmland and grassland were 1.60, 1.03 and 0.85 μmol·m-2·s-1, respectively. The soil respiration of alfalfa field, compared with farmland and grassland, were 55.3% and 88.2% higher. Annual CO2 emissions of alfalfa field, farmland and the grassland were 1461.96, 940.66 and 777.36 g·m-2·a-1,respectively. We concluded that after 9 years of farmland converted into alfalfa field, soil organic carbon decreased and soil respiration increased. The contributions of increasing carbon sink in the stage of farmland converted to grassland were not good as expected.

土地利用的变化会影响到生态系统碳循环过程。中国退耕还林还草工程实施后，大量农田转变为林地和草地。为了摸清退耕后土壤碳排放的变化，在宁夏黄土丘陵区，对退耕苜蓿(Medicago sativa)地、农田和天然草地的土壤呼吸进行了测定。结果表明，土壤温度和土壤呼吸相关性较强，土壤水分和土壤呼吸没有显著相关性；苜蓿地、农田、天然草地的年均土壤呼吸值分别为1.60、1.03和0.85 μmol·m-2·s-1，苜蓿地土壤呼吸比农田高出55.3%，比天然草地高出88.2%;年CO2排放量分别为1 461.96、940.66和777.36 g·m-2·a-1。农田转化为苜蓿地9年后，土壤CO2排放量增加、有机碳含量下降。在黄土丘陵区退耕还草初级阶段，生态恢复措施对固碳增汇的贡献有限。

对典型黄土丘陵区的延安、安塞和吴旗不同退耕年份植被特征、土壤水分和养分的调查和测定,研究了退耕地植被与土壤水分和养分随时间变异及其互动效应规律.结果表明,退耕初期土壤有较高的水分和养分,在较高的土壤水分和养分支持下,植被指数呈增长趋势,随着耕作施肥活动的停止和植被恢复对土壤水分和养分的消耗,使土壤水分和养分含量降低,土壤水分和养分的变异幅度也较大;从变化趋势看,植被指数和土壤贮水量变化呈相反趋势,植被指数与土壤水分之间的关系比其与土壤养分之间的关系更加密切,表明土壤水分对植被恢复和植被群落演替的作用更加显著;在退耕初期,土壤水分和养分对植被恢复和群落演替的作用要大于植被恢复和群落演替对土壤水分和养分的作用,随着植被群落演替的进行,植被对环境的适应能力不断增强,它们之间的作用关系不断改变,这种相互作用使植被群落以自己的方式改变着土壤水分和养分,并使自己逐步达到稳定.