Strategies to combat desertification for the twenty-first century in China

SUMMARY

During the past half century, China has experienced increasingly severe land degradation, soil erosion, and desert expansion. Desertification is affecting one third of China's total territory and the annual accelerating rate of desertification spread is as high as 2460 km² in China. In 1996, China developed a National Action Programme to Combat Desertification (NAP), which is aimed to apply new legal measures and technical approaches to slow down desertification processes and achieve a long-term goal — control desertification and alleviate poverty through continuous efforts to fight against desertification, stabilize mobile dunes, revegetate degraded rangeland and control soil erosion in arid, semi-arid, and dry sub-humid areas. The long-term and integrated strategies of China's NAP result in encouragement of social participation, legal institutional guarantees, policy making, and establishment of demonstrations/pilot projects to combat desertification at both national and provincial level.     

荒漠草原典型植物群落枯落物生态水文功能

在退化荒漠草原生态系统恢复过程中,枯落物是联系植被和土壤物质循环与能量流动的重要中间环节,且发挥着重要的生态水文功能。通过调查荒漠草原5种典型植物群落（蒙古冰草群落、甘草群落、赖草群落、杂类草群落和沙蒿群落）枯落物蓄积量、持水性能、对降雨的截留和对土壤水分蒸发的抑制作用,分析了荒漠草原不同植被类型枯落物的生态水文功能。结果表明：枯落物蓄积量和最大持水量均为蒙古冰草群落〉甘草群落〉赖草群落〉杂类草群落〉沙蒿群落;5种群落枯落物层对降雨的截留量在3.36～5.27 mm,截留率在3.40%～6.82%,枯落物对降雨的截留量与降雨量呈正相关,而降雨量与截留率呈负相关,且枯落物对降雨的截留具有显著的季节变化规律。在不同枯落物覆盖下,枯落物对土壤的抑制效应也存在显著差异,0.5~2 cm覆盖厚度比不盖枯落物土壤水分蒸发减少了19.25%～76.82%,枯落物层减少土壤水分蒸发效应随枯落物层厚度增大而增加。枯落物的蓄积与覆盖对土壤水分的运移和蓄存产生明显的生物学作用,已经成为荒漠草原最重要的生态过程之一。     

Association between plant species diversity and edaphic factors in the lower reaches of the Heihe River,northwestern China

The lower reaches of the Heihe River, in northwestern China, is characterised by unique local edaphic conditions that have influenced the development of local desert riparian forests. This study examines the variations in spatial variation patterns to reveal the relationships between plant species diversity and soil moisture/salinity/texture gradients at different soil depths, providing insights into the management and restoration of vegetation in ecosystems in the study area. The species–environmental relationships are investigated by redundancy analysis based on the plant species diversity matrix and the edaphic gradient matrix. A survey of 61 sampling plots identified 37 plant species in the study area. The distribution pattern of the plant species diversity are mainly affected by soil moisture, soil salinity, and soil texture at different soil depths. These edaphic factors are able to explain 98.47% of the total variation in the analysed vegetation dataset. Soil moisture, salinity, and texture content vary in terms of both the soil depths and the vegetation types in the study area. The plant community Class IV, xeric shrub, has the lowest soil water content among different vegetation types. The surface soil salinity differs for different plants and follows the order: Sophora alopecurides?>?Tamarix chinensis?>?Populus euphratica.     

宁夏新垦区昆虫群落生态演替及有害种预警系统研究

以宁夏中宁县长山头、大战场（荒漠半荒漠）、灵武市狼皮子梁（沙漠）、青铜峡市渠口农场（草原化荒漠）３类垦前环境及其垦后不同耕作年限（１－１５ａ）农田昆虫群落演替进行了系统调查与研究，事理鉴定出昆虫１１目７９科２０４种，按其分布和种群动态变化划分为原生性种类、共生性种类、继生性种类和迁入性种类４个生态型类群。在此基础上研究了不同目、不同营养型类群和不同生态型类群昆虫多样性变化及时间系列演替，发现随着荒     

干旱区绿洲灌漠土Cu、Zn和Pb的吸附解吸特征

土壤重金属吸附解吸是影响土壤系统中重金属移动性和归宿的主要过程,影响重金属的生物有效性以及重金属在食物链中的传递等.配制一系列不同浓度的重金属,灌漠土对重金属溶液进行吸附实验24 h以达到平衡,再用硝酸铵和乙酸铵进行解吸实验24 h以达到平衡.利用热力学吸附平衡法,对西北干旱区绿洲灌漠土重金属Cu、Ni和Pb的吸附解吸行为进行序批实验研究.实验结果表明:(1)灰漠土在常温下对铜、锌和铅重金属离子的吸附等温线符合Freundlich型吸附模式,灰漠土对重金属铜、锌和铅的吸附能力由强到弱的顺序为:铅,铜,锌.(2)硝酸铵和乙酸铵解吸重金属的量与灰漠土吸附重金属量呈现出线性正相关,乙酸铵解吸重金属的量比硝酸铵解吸重金属的量大,两种解吸剂对铜、锌和铅重金属离子的解吸能力由大到小的顺序都为:铜,锌,铅,说明了一般外源的铜、锌和铅进入土壤以后,铜和锌可能比铅容易向四周转移.(3)硝酸铵和乙酸铵的解吸率呈谷形曲线,开始时硝酸铵和乙酸铵解吸重金属量的百分比随灰漠土吸附重金属量的增加而减小,在吸附量达到某一特定值时,解吸率随吸附量的增加而增加.灰漠土对铜、锌和铅的吸附作用以专性吸附为主,被灰漠土吸附的铜、锌和铅重金属离子较难解吸.     

沙尘天气多发区民勤县发现多例非职业性尘肺病

为了调查非职业性尘肺在我国沙尘天气多发区的发病情况,采用多阶段随机抽样方法随机抽取沙尘天气多发区甘肃省民勤县6个乡镇从未接触过职业性沙尘的1500名18岁以上的农民为调查对象,对其中自觉呼吸系统不适的480人进行了胸透,其中81人进行了X光拍片,分析非职业性尘肺病的发生.分析结果表明,有8例非职业性尘肺患者.如果假设在所调查的未进行X光拍片的农民中无人患有非职业性尘肺病(实际上漏检的可能性是存在的),其患病率也高达5.33‰,表明长期暴露于沙尘天气可引发非职业性尘肺,且发病率高,症状严重,对当地农民的健康影响很大.对此,应引起高度重视.由此结论:长年暴露于沙尘天气可导致非职业性尘肺病的发生.论文建议,将这种因常年暴露于沙尘天气而引起的非职业性尘肺病定名为"沙漠尘肺"(简称:沙漠肺)。     

不同干扰下阿拉善荒漠啮齿动物群落格局的变动特征

干扰广泛被认为是影响物种多样性变化的最主要的因素。近年来,物种多样性对干扰的响应是生态学家关注和研究的热点问题之一。2002-2011年,在内蒙古阿拉善荒漠区对人为不同利用（干扰）方式形成的禁牧、轮牧、过牧和开垦4种不同区域中,通过对啮齿动物群落的物种数、物种总捕获率、Shannon-Wiener多样性指数和Pielou均匀性指数等4个变量的时间序列资料的比较,分析了这些变量的年间变动特点及在不同干扰条件下的变动规律,并对不同干扰区各变量的趋势进行分析,探讨啮齿动物群落对不同干扰过程的响应。结果表明：4个变量的最高值均出现在受中等干扰的轮牧区中,物种总捕获率2003年出现了各区的第1个高峰,总捕获率分别为过牧区10.75%、轮牧区19.60%、禁牧区11.20%、开垦区10.55%;2008年出现第2个高峰,4个区物种总捕获率均达到了各区的最高峰,捕获率分别为过牧区29.60%、轮牧区34.15%、禁牧区14.20%、开垦区27.10%。过牧区与轮牧区群落物种总捕获率、Shannon-Wiener指数和Pielou均匀性指数显著相关（p〈0.05）,变动规律相似。过牧区与轮牧区、禁牧区与过牧区、轮牧区与禁牧区之间的物种总捕获率呈极显著正相关（p〈0.01）。过牧区与轮牧区相似度较高（I=0.8568）;过牧区Shannon-Wiener指数表现为有显著的下降趋势（Y=-0.142 lnt＋1.487,F=6.320,p＜0.05）,表明随着过牧时间的积累,对生境的干扰逐步加重,啮齿动物群落的多样性会逐渐降低。     

河西走廊中部荒漠植被的生态学研究

根据对河西走廊中部荒漠植被的调查，对荒漠植被进行了分类及生态学描述，重点讨论了荒漠植被对改善河西走廊中部农村生态环境的作用，提出了保护和利用荒漠植被的措施及改善生态环境的途径。     

Can Extractive Reserves Save the Rain Forest? An Ecological and Socioeconomic Comparison of Nontimber Forest Product Extraction Systems in Petén,Guatemala, and West Kalimantan,Indonesia

We compare existing nontimber forest product extraction systems in Petén, Guatemala, and West Kalimantan, Indonesia, to identify key ecological, socioeconomic, and political factors in the design and implementation of extractive reserves. Ecological parameters include the spatial and temporal availability of harvested products and the sustainability of harvesting practices from both a population and an ecosystem perspective. Socioeconomic and political factors include the presence or absence of well-defined resource tenure rights, physical and social infrastructure, markets, and alternative land uses. We conclude that although extractive reserves can play a significant role in preserving tropical forests as a part of a broader land-use spectrum, their effectiveness is highly dependent on prevailing local ecological, socioeconomic, and political conditions. Ultimately, extractive reserves should be regarded as one component of an overall approach to the problem of tropical deforestation.     

Changes in desert steppe soil culturable bacteria from northwestern China and correlation with physicochemical parameters

Seasonal variations effects on desert steppe soil culturable bacteria in northwestern China and physicochemical parameters were investigated. Soil temperature ranged from 5.37 to 23.73 °C. Moisture content varied from 3.22% to 7.62%. The pH was between 7.98 and 8.72. Soil nutrients were altered in different seasons. Total potassium (K) remained the same, but available K levels ranged from 101.29 to 227.55 mg/kg. The culturable bacterial counts in January, April, July and October were 0.13 × 10⁷, 4.09 × 10⁷, 5.33 × 10⁷ and 1.8 × 10⁷ colony forming units (cfu)/g, respectively. Bacterial populations were most abundant in surface layers and declined with increase of soil depth. Seventy-two bacterial strains were isolated and classified according to 27 genera of 5 phyla groups: Firmicutes, Actinobacteria, Alphaproteobacteria, Gammaproteobacteria and Bacteroidates. The bacterial diversities varied according to seasons. In spring, only Firmicutes and Actinobacteria were isolated. In summer, Firmicutes, Actinobacteria and Bacteroidetes were detected with Firmicutes the dominant species. In autumn and winter, Firmicutes, Actinobacteria, α-Proteobacteria and γ-Proteobacteria predominated. Our results indicated that climatic variations, vegetation coverage and soil physicochemical parameters are critical factors for maintaining culturable bacterial populations and diversity in the desert steppe. Soil moisture content and temperature exerted marked influence on bacterial quantities and diversities.     

Wind Characteristics of Mesquite Streets in the Northern Chihuahuan Desert, New Mexico, USA

Past research has shown that the most important areas for active sand movement in the northern part of the Chihuahuan Desert are mesquite-dominated desert ecosystems possessing sandy soil texture. The most active sand movement in the mesquite-dominated ecosystems has been shown to take place on elongated bare soil patches referred to as “streets”. Aerodynamic properties of mesquite streets eroded by wind should be included in explaining how mesquite streets are more emissive sand sources than surrounding desert land. To understand the effects of wind properties, we measured them at two flat mesquite sites having highly similar soil textures but very different configurations of mesquite. The differences in wind properties at the two sites were caused by differences of size, orientation, and porosity of the mesquite, along with the presence of mesquite coppice dunes (sand dunes stabilized by mesquites growing in the dune and on its surface) found only at one of the two sites. Wind direction, u_* (friction velocity), z₀ (aerodynamic roughness height) and D (zero plane displacement height) were estimated for 15-m tower and 3-m mast data. These aerodynamic data allowed us to distinguish five categories with differing potentials for sediment transport. Sediment transport for the five categories varied from unrestricted, free transport to virtually no transport caused by vegetation protection from wind forces. In addition, “steering” of winds below the level of the tops of mesquite bushes and coppice dunes allowed longer parallel wind durations and increased wind erosion for streets that aligned roughly SW–NE. U.S. Government right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged.     

宁夏荒漠草原恢复演替过程中物种多样性与生产力的变化

荒漠草原一直是生态学者关注的焦点。文章以宁夏灵武的荒漠草原区为研究对象,对围栏条件下退化群落的物种多样性、生产力和群落演替及其生态机制进行探讨,为荒漠草原的植被恢复和重建提供理论基础。结果表明:群落生产力除受物种多样性的影响外,也受物种本身特征和环境资源的影响。在荒漠草原中功能群盖度与群落初级生产力无显著的相关关系。荒漠植物群落物种多样性指数在时间尺度上的变化表现为随着围栏时间的延续逐渐增加,而生态优势度变化趋势则相反。在不同年份年降水量直接影响植物群落物种数的多少、丰富度和生产力。     

桂西南喀斯特区域群落主要环境因子及稳定性对飞机草入侵的影响

为揭示桂西南喀斯特区域群落主要环境因子及稳定性对飞机草（Eupatorium odoratum）入侵的影响,本文通过对群落生存状况、土壤环境因子的调查分析,研究群落的稳定性特征,探讨不同植物群落对外来入侵种飞机草生长扩散的影响。结果发现：植物群落内本地种盖度、群落高度等与飞机草的盖度和多度呈极显著的负相关关系,说明本地种的生长能对飞机草的入侵产生显著影响,其中光因子可能是影响飞机草生长的主导因子和限制因子;本地物种多样性对飞机草的盖度和多度影响也较显著,说明本地种多样性能有效抵御飞机草入侵;人为干扰对飞机草的盖度和多度则呈极显著的正相关关系,说明干扰能促进飞机草的入侵;土壤速效氮含量、土壤含水量、有机质含量和与飞机草的盖度和多度的关系均呈显著负相关关系,可能是由于群落内肥水充裕程度与调节飞机草生长的主导因子光水平呈负相关关系造成的。群落的稳定性与飞机草的盖度和多度呈极显著的相关关系,说明稳定性较高的群落更能有效的抵御飞机草的入侵,稳定性较低的群落更容易受到飞机草的入侵。     

湖南省宁乡县巷子口—沩山荒漠化治理研究

巷子口—沩山地处我国南方红壤丘陵地区。由于长期过度砍伐和陡坡开垦等不合理人为活动的影响，加上降雨多且暴雨集中、丘陵地形和花岗岩母质的自然条件，这里由水蚀导致的荒漠化一度比较严重，１９８２年以来，采取封禁与造林相结合恢复植被、多途径解决农村能源问题、坡耕地退耕还林、广泛开展宣传、加强机构建设、落实政策、加强监督等措施，开展了荒漠化治理，取得了显著的生态和经济效益。     

An Integrated Approach to the Ecology and Management of Plant Invasions

Plant invasions are a serious threat to natural and managed ecosystems worldwide. The number of species involved and the extent of existing invasions renders the problem virtually intractable, and it is likely to worsen as more species are introduced to new habitats and more existing invaders move into a phase of rapid spread. We contend that current research and management approaches are inadequate to tackle the problem. The current focus is mostly on the characteristics and control of individual invading species. Much can be gained, however, by considering other important components of the invasion problem. Patterns of weed spread indicate that many species have a long lag phase following introduction before they spread explosively. Early detection and treatment of invasions before explosive spread occurs will prevent many future problems. Similarly, a focus on the invaded ecosystem and its management, rather than on the invader, is likely to be more effective. Identification of the causal factors enhancing ecosystem invasibility should lead to more-effective integrated control programs. An assessment of the value of particular sites and their degree of disturbance would allow the setting of management priorities for protection and control. Socioeconomic factors frequently play a larger part than ecological factors in plant invasions. Changes in human activities in terms of plant introduction and use, land use, and timing of control measures are all required before the plant invasion problem can be tackled adequately. Dealing with plant invasions is an urgent task that will require difficult decisions about land use and management priorities. These decisions have to be made if we want to conserve biodiversity worldwide.     

Assessment of traditional rights,local interference and natural resource management in Kedarnath Wildlife Sanctuary

An assessment of human interference in Kedarnath Wildlife Sanctuary (KWLS) showed huge dependence of local communities on forest fringes. KWLS is under active consideration as a national park because of its unique flora and fauna. Studies have evidenced habitat destruction and successional changes in the area because of ongoing unsustainable harvesting and logging. The present study provides an integrated approach towards evaluating resource extraction and management of the sanctuary. The study was based on in-depth semi-structured interviews and group discussions with local inhabitants of six villages and with forest officials. In addition, regeneration patterns and vegetation analysis was conducted in three land tenurial systems: community forest (CF), reserve forest (RF) and protected forest (PF). Key issues identified were wildlife offences, encroachment, pressure from unsustainable harvesting of resources and lack of livelihood opportunities. Ecological studies showed continuous change in regeneration patterns in forest patches/stands. The local survey stressed managing sanctuary fringes considering the village economy, social issues and resource requirements, and enhancing on-farm resource production to reduce pressure on forests. Forest personnel demanded more training on encroachment and poaching, these being major threats to biodiversity and bio-resources. Supporting and providing better livelihood opportunities is a viable option for minimizing pressure and managing biodiversity of the area through active community participation. This study generated useful outcomes and strategies for advancing policies to reduce pressure and overcome management constraints in the sanctuary.     

Woody encroachment decreases diversity across North American grasslands and savannas

Woody encroachment is a widespread and acute phenomenon affecting grasslands and savannas worldwide. We performed a meta-analysis of 29 studies from 13 different grassland/savanna communities in North America to determine the consequences of woody encroachment on plant species richness. In all 13 communities, species richness declined with woody plant encroachment (average decline = 45%). Species richness declined more in communities with higher precipitation (r2 = 0.81) and where encroachment was associated with a greater change in annual net primary productivity (ANPP; r2 = 0.69). Based on the strong positive correlation between precipitation and ANPP following encroachment (r2 = 0.87), we hypothesize that these relationships occur because water-limited woody plants experience a greater physiological and demographic release as precipitation increases. The observed relationship between species richness and ANPP provides support for the theoretical expectation that a trade-off occurs between richness and productivity in herbaceous communities. We conclude that woody plant encroachment leads to significant declines in species richness in North American grassland/savanna communities.     

Establishment patterns in a secondary tree line ecotone

On semi-open pre-alpine fen pastures Alder encroachment creates a dynamic mosaic of grassland and woodland, which is rich in ecotones from fen to Carr. The structural diversity in colonisation patterns of Alder on fens suggests a dependency on multiple environmental drivers. Unidirectional progressive ecotone development provides an opportunity to address a current deficit in understanding successional patterns, i.e. process-pattern relationships in a multiple factor regime.We developed an individual-based model of Alder establishment on fen grassland to investigate the dependency of encroachment patterns upon seed production, dispersal distances and safe site availability. The purpose of the model is to provide a causal understanding of establishment patterns of Alder. In the model, all life processes of Alder individuals were parameterised with field data. This allowed us to strictly perform bottom-up simulations and successfully check plausibility by comparing simulated establishment patterns of cohorts with observed ecotone structures.Simulation results show that establishment patterns strongly depend on environmental drivers. Spatial progression of Alder encroachment and width of ecotones, respectively, mainly depend on wind speed during seed dispersal. Dense establishment of Alder leading to community change from fen grassland to Carr, requires windows of opportunity, which are defined by the rare coincidence of widespread dispersal, high seed production and favorable establishment conditions. Life-history traits of Alder (mast year cycle, high seed weight, weak establishment in fen) spatially and temporarily constrain the encroachment process. The structural diversity of long-term encroachment patterns is explained by the event-driven character of encroachment.Modelling individual establishment pathways of seedlings starting from germination revealed an endogenous stochasticity in establishment patterns emerging from low seed densities in the tail of the dispersal function. We conclude an inherent stochastic structure of dispersal-limited tree line ecotones, which limits reconstruction of processes from patterns.In order to describe long-term successional patterns of Alder encroachment at landscape scale, we propose the combination of two concepts: deterministic “patch-movement” of Alder woodland driven by continuous ecotone migration together with rare and stochastic “infiltration” of single Alder trees into open fen grasslands. Conservation management can control predictable “patch-movement” by cutting off maturing saplings around existing Alder woods. But the preservation of the actual large proportion of open grassland in fen pastures from infiltrating Alder seedlings and from the subsequent shift of the pasture to a densely wooded state would require mowing additionally to extensive grazing.     

Social Capital in Biodiversity Conservation and Management

Abstract:  The knowledge and values of local communities are now being acknowledged as valuable for biodiversity conservation. Relationships of trust, reciprocity and exchange, common rules, norms and sanctions, and connectedness in groups are what make up social capital, which is a necessary resource for shaping individual action to achieve positive biodiversity outcomes. Agricultural and rural conservation programs address biodiversity at three levels: agrobiodiversity on farms, nearby nature in landscapes, and protected areas. Recent initiatives that have sought to build social capital have shown that rural people can improve their understanding of biodiversity and agroecological relationships at the same time as they develop new social rules, norms, and institutions. This process of social learning helps new ideas to spread and can lead to positive biodiversity outcomes over large areas. New ideas spread more rapidly where there is high social capital. There remain many practical and policy difficulties, however, not least regarding the need to invest in social capital formation and the many unresolved questions of how the state views communities empowered to make their own decisions. Nonetheless, attention to the value of social relations, in the form of trust, reciprocal arrangements, locally developed rules, norms and sanctions, and emergent institutions, has clearly been shown to deliver a biodiversity dividend in many contexts. This suggests a need to blend both the biological and social elements of conservation.     

宁夏东北部典型荒漠草原植物群落与土壤养分特征

以宁夏东北部荒漠草原为研究区,采用野外样方调查、采样和室内植物鉴定、土壤样品测定等方法,探析研究区内植物群落物种组成与土壤养分特征,以及植物多样性指数与土壤养分的相关关系,以期为中国荒漠治理、生物资源保护与可持续性利用提供依据。结果显示:(1)研究区植物共86种,隶属61属21科,其中禾本科(18种)、豆科(16种)、菊科(13种)和藜科(11种)植物占总物种数的67.44%;(2)研究区土壤总体上呈碱性,pH值平均为8.81,全氮、全磷、有机质的质量分数(0-10 cm土层)分别为0.07-0.54、0.16-0.51、0.51-6.24 g·kg^-1;(3)研究区植物多样性指数中的Margalef丰富度指数和Shannon-Wiener多样性指数与土壤pH值呈显著负相关,与其他土壤养分的相关关系未达到显著水平,其他植物多样性指数与土壤养分的关系均未达到显著水平。研究表明,宁夏东北部荒漠草原植物种类少,禾本科、豆科植物优势明显,土壤养分条件差,土壤全氮、全磷、有机质对植物多样性指数的影响不大。