Soil water deficit and vegetation restoration in the refuse dumps of the Heidaigou open-pit coal mine, Inner Mongolia, China

The sustainability of ecosystem restoration of refuse dumps in open-pit coal mines depends on plant species selection, their configuration, and the optimal usage of water resources. This study is based on field experiments in the northern refuse dump of the Heidaigou open-pit coal mine in Inner Mongolia of China established in 1995. Eight plant configurations, including trees, shrubs, grasses, and their combinations, as well as the adjacent community of natural vegetation, were selected. The succession of the revegetated plants, soil water storage, the spatiotemporal distribution of plant water deficits degree and its compensation degree were also studied. Results indicated that the vegetation cover (shrubs and herbaceous cover), richness, abundance, soil nutrients (soil organic matter, N and P), and biological soil crust coverage on the soil surface are significantly influenced by the vegetation configurations. The average soil water storage values in the shrub+grass and grass communities throughout the growing season are 208.69 mm and 206.55 mm, which are the closest to that of in the natural vegetation community (215.87 mm). Plant water deficits degree in the grass and shrub+grass communities were the lowest, but the degrees of water deficit compensation in these configuration were larger than those of the other vegetation configurations. Differences in plant water deficit degree and water compensation among the different configurations were significant (P<0.05). Plant water deficit degrees were predominantly minimal on the surface, increased with increasing soil depth, and remained stable at 80 cm soil depth. The soil moisture compensation in the natural vegetation, shrub+grass, and grass communities changed at 10%, while that in other vegetation communities changed between 20% and 40%. Overall, we conclude that the shrub+grass and grass configuration modes are the optimal vegetation restoration models in terms of ecohydrology for future ecological engineering projects.     

黄土高原西部荒漠草原植被恢复的土壤水分管理研究

针对兰州地区荒漠草原带具有代表性的三种地带性植被：草本植被短花针茅、灌木植被珍珠猪毛菜、荒漠锦鸡儿,对其0~2.0 m的土壤含水量进行了比较,同时对草本和灌木植被的根系进行了测定。结果表明：天然植被对土壤含水量的影响在1 m以上。随着土壤深度的不断加深,土壤含水量呈减少趋势而后趋于稳定。短花针茅区1 m以上含水量比珍珠猪毛菜和荒漠锦鸡区平均高1.08和1.21个百分点;1 m以下土壤含水量变化情况是:珍珠猪毛菜区最高,荒漠锦鸡儿区最低。本文在分析了兰州地区荒漠草原区土壤水分动态的基础上,提出了这一地区植被恢复的对策。     

河西走廊荒漠绿洲过渡带封育对土壤和植被的影响

在河西走廊荒漠绿洲过渡带,封育天然植被是植被群落恢复、防止绿洲沙漠化的有效措施。以流动沙丘作为对照(0年),对封育5年和15年的半固沙和固定沙丘植被群落以及土壤进行调查取样和分析。结果表明:随着封育年限增加,天然固沙植被群落生物多样性增加,灌木层和草本层植物密度、盖度和生物量都显著增加,灌木层盖度从10%增加到40%,草本层以一年生草本植物为主,物种从5种增加到8种,生物量从1 g·m^-2增加到13 g·m^-2。随着天然植被盖度增加,土壤表层沙土细粒化明显,沙土中黏粉粒含量显著增加,土壤质地由粗质沙粒向细质沙粒转变;随着沙土中黏粉粒成分的增加,沙土有机质、全氮、全磷含量也增加,灌丛下土壤养分含量高于灌丛间,“沃岛效应”明显。同时,在灌丛下表层土壤出现明显的盐分集聚现象,其中SO₄^2-、K⁺、Na⁺含量分别增加了6、3、17倍。在降水100 mm左右的荒漠绿洲过渡带,封育可以显著恢复固沙植被群落和提高沙土质地和养分。     

Linking landscape and species: Effect of shrubs on patch preference of beetles in arid and semi-arid ecosystems

Linking individual behavior to spatial population processes, may clarify the complex link between species distribution and landscape properties. We asked how shrubs affect beetles in drylands and tested if we could explain distribution patterns of beetles by individual response to shrub landscape. We studied patch preference of ground-dwelling beetles segregated in a two-phase mosaic landscape, composed of shrub-covered and open patches and hypothesized that species richness and abundance are higher under shrubs due to the ameliorated microclimatic conditions and greater food resources. Pitfall trapping showed that shrub patches were preferred in shrub poor ecosystem because there was more food available under shrubs and cooler temperatures. However, similar conditions resulted in shrub preference only in an arid ecosystem, whereas in a semi-arid ecosystem, with high cover of shrubs, we found more beetles in the open patches. Observations in beetle movement patterns explained the contradicting effects of shrub patches in the two ecosystems. Beetle movement was affected by shrubs’ shading suggesting dependency on shrub structure rather than speciesdependency. Integrating analysis of beetle distribution in the population level with analysis of individual movement provides a robust framework for linking landscape properties to species behavior and distribution in a patchy landscape.     

干旱半干旱区草原灌丛化的原因及影响-争议与进展

灌丛化作为全球干旱半干旱区草原普遍发生的现象,其定义为草原生态系统中灌木/木本的生物量、密度、盖度的增加以及草本的生物量、密度、盖度的减少。草原灌丛化是气候变化和人类活动多种因素综合作用的结果。过度放牧被认为是引发草原灌丛化的主要原因之一。最新的研究结果表明过度放牧并不能导致草原灌丛化,但过度放牧后实施休牧却改变了草本与灌木的种间作用,有可能导致灌木的扩张。灌木入侵草原长期以来被认为是草原的退化,结论来源于干旱区土壤沙化的情形,在沙化的灌木林中,土壤碳库被局限于灌木株丛及其周边,使草原的碳截留和储存降低。但最近的全球性集成研究表明草原中灌木覆盖率盖度增加对生态系统可以产生积极作用,灌木可以增加土壤水分的下渗,有利于生态系统的水分储存和和养分的转化(如加强氮的矿化过程)。草原灌丛化对生态系统结构和功能影响存在景观尺度和斑块尺度上的差异。进一步研究适应灌丛化过程的管理机制,综合不断变化的气候条件因素和地域因素,采取合理的草原管理策略,对于全球草原区生产具有极其重要的意义。     

巴丹吉林沙漠周边植被特征和物种多样性

通过对巴丹吉林沙漠周边地区的野外调查,以重要值为测度指标,计算物种多样性指数、均匀度指数和优势度指数,对巴丹吉林沙漠周边地区荒漠植物群落物种多样性进行分析。结果表明:(1)该区域共计植物37种,各区域重要值大于0.1的物种中,灌木和半灌木占优势;(2)8个区域的Shannon-Wiener指数、Simpson指数、丰富度指数和优势度指数差异显著,区域5(北部)和7(西部)因含有单物种群落,Shannon-Wiener指数和Simpson指数显著低于其他区域;(3)荒漠植物群落结构层次中,8个区域的灌木层片每个多样性指数均没有显著性差异,草本层片在8个区域中多样性水平差异显著,由于荒漠区植被物种稀少、数量少,灌木层和草本层并未表现出显著差异;(4)巴丹吉林沙漠物种多样性水平较低,生态系统脆弱,对巴丹吉林沙漠周边地区生态系统重建时应该关注各种生态型植被的恢复重建。     

地表径流对荒漠灌丛生境土壤水分空间特征的影响

土壤水分是干旱区多尺度生态水文过程的关键影响因素和驱动因子,其时空格局是生态、水文、气象、地形等自然过程研究的重要参数。笔者研究了降水径流事件后3种不同灌丛个体尺度土壤水分空间异质性特征,结果表明,珍珠灌丛个体尺度土壤水分空间分布特征表现为灌丛边缘>灌丛内部>灌丛间裸地,驼绒藜灌丛表现为灌丛内部>灌丛边缘>灌丛间裸地,而狭叶锦鸡儿灌丛不同微生境土壤水分差异不显著。珍珠和驼绒藜灌丛同一微生境土壤水分存在坡位梯度,珍珠灌丛3个微生境土壤水分均表现为上坡位大于下坡位,而驼绒藜灌丛边缘表现为上坡位小于下坡位,其他两个微生境无明显规律;狭叶锦鸡儿灌丛土壤水分无明显的坡位梯度。3种灌丛不同微生境土壤含水量随土层深度增加的变化不明显。这说明在降水径流事件中,不同斑块的反应差异引起了地表径流的形成以及随之发生的资源再分配,从而导致了景观内土壤水分的空间异质性。     

Long-term impact of agricultural practices on biological soil crusts and their hydrological processes in a semiarid landscape

The natural landscapes of semiarid areas worldwide comprise a series of scattered patches of shrubs within a matrix of biologically crusted soils (BSC). As BSCs are considered ecosystem engineers the relationships between the BSC and the shrub patches determine system functioning. The objective of our study was to investigate long-term effects of agricultural practices on biological soil crusts and their influence on hydrological aspects of a semiarid ecosystem. During 1991, we experimentally simulated five of the area's agricultural practices; 1) Scraping – the topsoil was removed to a depth of 2 cm, 2) Spraying – phototrophic organisms were chemically killed with herbicide, 3) Mowing – perennial vegetation was cut and spread to simulate grazing practices, 4) Car track – a heavy roller was used to simulate car-tracks, 5) Control – undisturbed natural plots. Sixteen years later, in 2007, these agricultural practices were found to have a long-term effect on the crusted soil surface and the related soil-surface properties. Mowing and car-track treatments led to decreased overland runoff and increased hydraulic conductivity, whereas scraping and spraying treatments led to increased overland runoff production and decreased hydraulic conductivity. We conclude that the practices had a long-term residual impact on BSC succession and related soil surface properties, which affected the hydrological processes and system functioning.     

Plant Area Index and microclimate underneath shrub species from a Chilean semiarid community

In drylands, environmental conditions under shrub canopy differ from those found in open sites. We should expect that microclimate conditions under shrubs with distinct canopy architecture should also be different. Plant Area Index (PAI) of the three most abundant shrubs species (Porlieria chilensis, Adesmia bedwellii and Proustia cuneifolia) in Bosque Fray Jorge National Park, north-central Chile was measured using a Plant Canopy Analyzer. During two years (2004-2005), we recorded the Relative Humidity and Air Temperature underneath and away from the canopy of the shrubs.The three shrub species showed significant differences in PAI. Microclimate at 30 cm and 2 m above the soil in the open conditions were drier and warmer than underneath shrub canopies. Vegetation patches generate moderate microclimate conditions.Canopy structure can buffer climatic variability, contributing to high herbaceous productivity as well as shrub recruitment. Reflecting shrub architecture and observed PAI values, the lowest microclimate variations were observed under the canopies of P. chilensis, followed by P. cuneifolia and finally A. bedwellii. We bring a novel approach quantifying the Plant Area Index instead of the Plant cover and using a low cost method that integrates the distribution of leaves and may be derived from remote sensing products.     

荒漠化草原植被斑块分布对地表径流、侵蚀及养分流失的影响

地表径流是干旱区水、养分和土壤物质迁移和再分配的主要途径之一,它在很大程度上受植被格局的影响。研究了腾格里沙漠东南缘生物土壤结皮斑块和灌丛斑块镶嵌分布的植被格局对地表径流、侵蚀及其驱动下的资源再分配的影响。结果表明,植被斑块对地表径流和侵蚀产物起着拦截作用,能显著减少资源的流失。生物土壤结皮斑块和植被斑块之间存在资源(径流、侵蚀产物及养分等)再分配的源-汇关系。模拟降雨条件下,含有灌丛斑块和生物土壤结皮斑块的样方出现表面积水和径流需要的时间均显著大于只含生物土壤结皮斑块的样方;含两类斑块的样方出现径流需要的降雨量显著大于只含生物土壤结皮斑块的样方。在模拟降水和自然降水条件下,生物土壤结皮斑块产生的径流、侵蚀产物、有机质、氮及溶解养分中均大量被位于下坡向的灌丛斑块截获;灌丛斑块土壤水分入渗深度显著大于结皮斑块。灌丛斑块对生物土壤结皮斑块产生的地表径流、侵蚀产物及其携带的资源的捕获能显著减少资源流失,有效地防止荒漠化的进一步发生发展。     

荒漠灌丛降雨再分配对土壤pH值的影响

对腾格里沙漠东南缘沙坡头地区1989年建植人工植被区优势固沙灌木柠条（Caragana korshinskii）和半灌木油蒿（Artemisia ordosica）树干茎流及穿透雨的pH值,以及灌丛基部、灌丛下和灌丛外裸地0～10 cm和10～20 cm剖面深度土壤pH值分别进行测定,并与大气降雨pH值进行比较,以探讨荒漠灌丛降雨再分配对土壤pH值空间变异的影响。结果表明:大气降雨pH值最高,穿透雨pH值次之,树干茎流pH值最低,三者之间具有显著差异（p<0.05）。灌丛外裸地土壤pH值最高,灌丛下次之,树干基部最低。总体而言,0～10 cm剖面深度土壤pH值小于其下方10～20 cm剖面深度土壤pH值。柠条灌丛产生的树干茎流对土壤的酸化作用强于油蒿灌丛。树干茎流和穿透雨的酸化作用是导致土壤pH值从灌丛间裸地到灌丛基部方向上降低的一个重要原因。     

黄土高原半干旱区天然锦鸡儿灌丛对土壤水分的影响

本文选择黄土高原半干旱区定西地区的一种地带性植被,天然甘蒙锦鸡儿灌丛,将其0～99m深的土壤水分含量与人工柠条锦鸡儿灌丛、人工杏树林、天然草地、放牧荒坡和农地的土壤水分含量进行了比较。结果发现,天然锦鸡儿灌丛在1m以下土壤各层的水分含量均高于人工柠条灌丛和人工杏树林,而与放牧荒坡和农地的土壤湿度接近,略低于农地。天然锦鸡儿灌丛4m以上土层的土壤湿度还明显高于天然草地;天然锦鸡儿灌丛形成的难效—无效水层深度在2m土层以上,而人工柠条灌丛形成的难效无效水层则深达56m,人工杏树林42m,天然草地、放牧荒坡分别为36m和33m,农地1m。     

Grazing effects on patchy dryland vegetation in northern Patagonia

In this study the spatial patterns and dynamics of vegetation patches along a grazing gradient in the steppe ofLarrea divaricataandStipaspp. in NE Patagonia (Argentina) are described. A general effect of grazing is the reduction of total plant cover resulting from the decrease in cover of perennial grasses (Stipa speciosa, Poa ligularis, Stipa tenuis) and some tall shrubs (Chuquiraga hystrix, Bougainvillea spinosa, Lycium chilense). Dwarf shrubs (Nassauvia fueguianaandJunellia seriphioides) increase their cover under medium and/or high grazing pressures. Plant species are spatially grouped into patches which alternate with areas of bare soil. Eleven types of vegetation patch differing in the dominant plant functional type or species, floristic richness and size were identified with different relative frequency along the grazing gradient. Based on these results, it is postulated that grazing forces the replacement of large patches dominated by tall shrubs with high species richness, byLarrea divaricatapatches or small dwarf shrub patches with low species richness and the extinction of grass patches. This results from: (1) disruption of local balances of species deletions and additions; (2) fragmentation of large patches; and (3) formation of new vegetation patches. These changes lead to differing plant spatial organization and heterogeneity along the grazing gradient which may be described by characteristic arrays of vegetation patches.     

Spatial and temporal variability of soil properties under Caragana microphylla shrubs in the northwestern Shanxi Loess Plateau, China

Shrub-induced spatial and temporal heterogeneity of soil properties is common in arid and semiarid ecosystems, and it facilitates the development of plant species diversity. We selected 5-, 10-, 20-, 30-, and 40-year-old Caragana microphylla shrubs in the Shanxi Loess Plateau to evaluate the spatial and temporal heterogeneity of soil properties under and outside the shrub canopy. In addition, the presence of adventitious plant species was investigated to assess the development of herbaceous species diversity. Soil samples were collected from two depths (0-5 cm and 5-10 cm). The establishment and development of shrubs promoted temporal variation, improved soil texture, enhanced soil organic matter (SOM), total nitrogen (TN), and cation exchange capacity (CEC), and decreased pH, bulk density (BD), and soil water content (SWC). The results further confirmed that SOM, TN, and CEC were significantly higher at the center than at the outside of the shrub canopies (P < 0.05) and were higher at the 0-5 cm depth than at the 5-10 cm depth. Moreover, the differences in SOM, TN, and CEC from the center to the outside of shrub canopies were greater under 30- and 40-year-old shrubs than under 10- and 5-year-old shrubs. Furthermore, the spatiotemporal heterogeneity of the soil properties facilitated the development of herbaceous species diversity.     

毛乌素沙地东南部人工植被演替研究

毛乌素沙地东南部人工植被的演替过程大致可分为如下几个阶段：天然稀疏草本阶段人工灌木林阶段—人工灌木、天然半灌木、天然草本阶段—天然草本优势阶段。     

古尔班通古特沙漠纵向沙垄植被空间异质性

在古尔班通古特沙漠南部纵向沙垄上按5 m×10 m的网格测度植被样方100个,采集浅层风沙土样品184件。调查发现,乔灌木层片和草本层片的分布及相互关系明显受沙垄地形影响,并且在干旱环境下种群间的竞争和空间上的互补使两层片生态优势度具有显著的相关性。地统计分析结果显示,纵向沙垄上植被空间异质性表现为木本层片的物种多样性呈斑块状分布,草本层片物种多样性呈现平行沙垄的带状结构和斑块结构叠加的特点,而植被盖度则在垂直沙垄走向的方向上具有强烈的梯度性变化。和沙垄土壤理化性质空间格局特征相对比,植被盖度及物种多样性与风沙土浅层含水量在自相关空间（变程）及空间异质性程度上比较接近。这是纵向沙垄小生态系统中草本植物和浅层土壤水分耦合关系在空间上的反映,也是木本植物对水分和土壤资源在小尺度（m）上竞争及中小尺度（10～100 m）上互补的结果。     

云南元谋干热河谷造林区植被生长与土壤渗透性的关系

通过云南元谋干热河谷造林区林分生物量及生产力指标与双环入渗试验的土壤入渗性能指标的相关分析，发现乔木生长与土壤渗透性具有显著正相关关系(P＜0.01)，地表枯枝落叶量与土壤渗透性的相关关系也较密切(P＜0.05)，而灌草生长与土壤渗透性无显著相关。研究指出，改善土壤入渗性能的措施，如沿等高线开深沟种植、禁止放牧践踏、保护地表枯枝落叶等均对林木生长有积极的影响。     

生态水文阈值在中国沙区人工植被生态系统管理中的意义

中国北方风沙区是全球沙漠化发展和生态退化最为严重的地区之一。利用植被固沙是遏制沙化土地扩张和生态重建与恢复的主要途径,但人工植被的稳定维持是可持续性风沙治理所长期面临的挑战。作为人工植被生态系统管理的依据,对生态水文阈值的认识及界定具有重要的理论和实践意义。本文以固沙植被中人工种植的灌木和乔木（仅限东部沙区）的盖度与深层土壤水分含量互馈互调作用的长期变化为依据,基于对中国不同气候带沙区典型人工植被系统生态和水文过程的模拟,通过建立生态水文模型初步界定了不同沙区适宜于人工植被生态系统管理的生态水文阈值,对现有沙区固沙植被的生态系统管理和未来风沙区植被建设具有一定的借鉴意义。     

中国北方几种灌丛群落表土花粉与植被关系研究

中国北方20个典型灌丛群落主要花粉类型的百分比与植被盖度关系表明:除蒿及沙棘外,其它灌丛群落中,优势植物种的花粉百分比多低于20%。灌木花粉对植被的指示性研究表明:皂荚花粉为适中代表性类型,对植被指示明显。苦豆子、霸王柴、荆条、四合木、锦鸡儿、鼠李、绣线菊、虎榛子、榛、白刺、柽柳、柳等为低代表性类型(R值低于0.3),对植被有一定的指示意义;沙棘、蒿属、藜科花粉为超代表性类型(R值高于1或O值高于0.5),对植被也只有一定的指示意义。虎耳草科、豆科花粉对植被指示意义不明显。     

The role of facilitation in seedling recruitment and survival patterns, in the Strandveld Succulent Karoo, South Africa

Several studies in arid ecosystems have demonstrated that seedling establishment and survival were greater underneath the canopies of shrubs than in the open spaces between shrubs. These results led to the formulation of the hypothesis that seedling recruitment and survival were dependent on the shelter provided by shrub species (nurse-plant hypothesis). Seedling emergence and survival beneath and between the canopies of selected perennial shrub species were investigated at five localities in the Strandveld Succulent Karoo, each dominated by a different shrub species. Seedling emergence and survival were also examined at three localities dominated by annual species. In general, species richness and seedling densities were significantly higher in open areas than underneath shrubs, while seedling survival percentages did not differ significantly between microsites. Therefore, no evidence could be found to support the hypothesis that seedling recruitment and survival were facilitated by the presence of shrub species. Although most species will be able to establish in the absence of shrubs, the presence of woody species may have other advantages when restoring vegetation in mined areas.