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1.
In this study we investigated the effect of different land use options (wildlife versus livestock) on species richness of plants and reptiles in the protected Kgalagadi Transfrontier Park (KTP) versus adjacent non-protected farmland within the same savanna habitat type (Aoub dune veld) in the southern Kalahari, South Africa. Our results show that both plant and reptile species richness as well as plant cover and reptile abundance was significantly higher in the protected KTP than in the non-protected farmland. The higher proportion of shrub but lower proportions of perennial grass cover, herb cover, and herb species richness in the farmland can be explained by higher stocking rates and the differences in feeding behaviour between native wild ungulates (e.g. Antidorcas marsupialis, Oryx gazella) and livestock (mainly sheep). The reptile’s prey availability and microhabitats (perennial grass tussocks and rodent burrows) for thermoregulation and protection against predators were significantly lower in the farmland. To conclude, our results clearly show that long term effects of different land use options (wildlife in protected KTP versus extensive livestock production in the non-protected farmland) even within the same habitat type have led to significant changes in vegetation composition, availability of microhabitat structures and in the reptile community. 相似文献
2.
Invasive species pose global biological and economic challenges. Over the past four decades, Prosopis taxa have emerged as a major invader of the arid and semi-arid regions of the world. Prosopis juliflora, one of the highly invasive Prosopis species, is dominantly present in the Afar region of Ethiopia and continues to spread into the surrounding areas. The objective of this study was to aid the mapping, utilization, and management of the invasive P. juliflora in Afar, by employing participatory research techniques. We assessed the introduction history, impacts, uses, and control strategies of invasive P. juliflora by interviewing 108 pastoralists and agro-pastoralists. In addition, we used Participatory Mapping (PM), Geographic Information Systems (GIS), Global Positioning System (GPS), and remote sensing technologies and approaches to map sites invaded by P. juliflora. Sketch maps were produced by men, women, pastoralist and agro-pastoralist groups. Experts aggregated, scaled and reproduced the sketch maps with support from the Afar communities. We provided GPS and GIS trainings to selected community members who assisted us in collecting the GPS locations of more than 70 key features and landmarks. The sketch maps were digitized and geo-referenced by experts using the 70 GPS records as control points. Geo-referenced community maps were superimposed on pan-sharpened Landsat 8 satellite images and presented to the communities for verification. We overlaid the verified community maps on ancillary land-cover layers, and detected the land-cover classes that were most affected by P. juliflora invasion. Despite its uses as source of fire wood, charcoal, and animal fodder, the species has adverse impacts on native species and livestock resources. Afar communities mapped P. juliflora infestations, particularly those that occurred near their villages, using high and moderate density classes. The two highly invaded land-cover categories were dense grassland, and exposed sand & soils. Participants collaborated in creating the produced maps, suggesting that participatory research approaches are another tool for early detection of invasive species and guiding fine-scale management strategies. 相似文献
3.
A comparative ethnobotanical study was carried out in two rural communities in northwest Patagonia. The methodology involved semi structured interviews and free listing, through which richness and use patterns of fuel species were registered, as well as socioeconomic factors and alternative fuel sources such as liquefied petroleum gas (LPG) and animal dung. Firewood was found to be a subsistence resource, complemented with the purchase of other firewood resources and the use of alternative fuels. A total of 21 species were registered, of which 18 were native species and 3 exotic; 12 fuel species were used by both communities. The species with highest use consensus were Berberis microphylla (michay), Lycium sp. (montenegro) and Senecio subulatus (romerillo) in the Laguna Blanca community, and Salix sp. (sauce) and S. subulatus in Comallo. Collection is mainly carried out on foot. Whereas the inhabitants of Laguna Blanca cover large distances in order to collect native woods, in Comallo this is made easier by the use of prunings from urban tree planting, obtained closer to dwellings. This is an interesting result since the recycling of biological products to supplement firewood, together with forestation practices, could contribute to the resilience processes of inhabitants of these arid, hostile environments. We propose that the use of multiple fuel resources could be an indicator of ecological–social resilience processes. 相似文献
4.
湿地价值及其有关问题探讨 总被引：9，自引：2，他引：7
当前,全球湿地正处于退化和丧失的威胁之中,其中一个主要原因是对湿地价值认识的不足。通过对湿地价值的来源、基本特征、有关利益群体及不同生态尺度下湿地价值的差异等有关问题的探讨,以期为湿地的保护与管理提供科学依据。 相似文献
5.
Joseph E. Mbaiwa Barbara N. Ngwenya Donald L. Kgathi 《Singapore journal of tropical geography》2008,29(2):155-172
This paper reviews how state policy and regulatory instruments, including protected area alienations and concessions, have altered or denied the access to land and natural livelihood resources of the indigenous Basarwa and minority subsistence-oriented communities in the Okavango Delta (OD) in Botswana. Drawing on field research and guided by a sustainable rural livelihoods framework, the paper provides an overview of key institutional interventions – in particular the setting up of the Moremi Game Reserve, Wildlife Conservation Policy, Tourism Policy, Agricultural Development Policy and the erection of veterinary fences – that have served to privilege a foreign-owned and dominated commercialized wildlife and nature tourism sector and the export-oriented beef industry in the OD. The officially sanctioned barriers to customary and usufructory rights and access, and the non-recognition of historically embedded traditional land uses have decimated already marginalized resource-based subsistence livelihoods, and precipitated intergroup conflicts over preferential rights and access to resources and opportunities, notably wildlife, non-timber veld products, agriculture and community-based tourism schemes. Such outcomes, moreover, will have consequences for the longer-term sustainability of the OD both as a socioeconomic resource base and as a natural ecosystem. 相似文献
6.
Biological invasions are a major threat for natural ecosystems. Deserts are characterized by their scarce, highly variable rainfall and thus considerably susceptible to invasions, especially by annual plants that can quickly capitalize sporadic rainfall events. In this study we evaluated the potential of an invasive winter-annual species native to the Mediterranean region (Schismus barbatus) to invade a summer-rainfall desert in the Central-Northern Monte Phytogeographical Province, Argentina, where the native annual flora is mainly composed of summer species. We recorded the number of germinated seeds from soil samples collected in four seasons (during one year) coinciding with four important life-stages of Schismus (pre-germination, post-germination I and II and post-dispersal), and contrasted our results with data obtained from the literature. Almost 33,000 Schismus seeds were estimated to germinate per m2, and about 90% percent of them germinated from samples collected in the pre-germination stage. Compared to deserts in USA and Australia, where Schismus has been a successful invader, the density of germinated seeds we observed was especially high even though the amount of rainfall for the vegetative period of Schismus was considerable lower. Our results suggest that S. barbatus has a great invasive potential in the Central-Northern Monte. The low number of annual plant populations that are able to compete for highly variable cool-season rains may be a key feature determining the invasibility of these deserts during the winter. 相似文献
7.
中国资源型城市经济发展效率评析 总被引：4，自引：0，他引：4
从城市经济运行的角度,运用数据包络分析方法(DEA模型),对2007年我国75个地级资源型城市的经济发展规模效益进行了定量评价,揭示出我国资源型城市经济发展效率在空间分布、资源类别上的差异,分析了影响资源型城市经济发展效率的原因,并就如何提高资源型城市经济发展效益,促进其持续发展提出了相应建议. 相似文献
8.
Throughout the western United States, the invasive annual grass, medusahead (Taeniatherum caput-medusae L. Nevski), is rapidly invading grasslands once dominated by native perennial grasses, such as bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) A). It is also invading grasslands dominated by less undesirable invasive annual grasses, especially cheatgrass (Bromus tectorum L.). Understanding medusahead growth dynamics relative to native perennial grasses and cheatgrass is central to predicting and managing medusahead invasion. We hypothesized that medusahead would have a higher relative growth rate (RGR), a longer period of growth, and as a consequence, more total biomass at the end of the growing season than the native perennial grass and cheatgrass. In 2008 (dry conditions), 250 seeds and in 2009 (wet conditions), 250 and 100 seeds of each species were sown in 1 m2 plots with 5 replicates. Shoots were harvested on 3-25 day intervals throughout the growing season. The native perennial grass had more biomass and higher RGR than medusahead in the dry year, but the relationship was reversed in the wet year. Precipitation in 2008 was well-below average and this level of drought is very infrequent based on historical weather data. Medusahead had a longer period of growth and more total biomass than cheatgrass for both years. We expect that medusahead will continue to invade both native perennial and less undesirable invasive annual grasslands because of its higher RGR and extended period of growth. 相似文献
9.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(1):20-30
Gjellan, A. 1975. Protection of bird wildlife. Norsk geogr. Tidsskr. 29, 21–38. Plans for establishing bird wildlife nature reserves and areas where bird wildlife can be protected are discussed. Areas already established for this purpose are mentioned, as are other important areas worthy of protection. An attempt is made to evaluate the criteria for the selection of such important areas in the future. A classification is made of the areas in question, such as wetlands and other biotope types in forest and mountain localities. The main criterion is that the area should satisfy at least one important life function, such as breeding, foraging and resting (primarily of migrating birds), moulting, and wintering. The man-made threat towards the maintenance of these natural areas for the preservation of bird wildlife must be controlled, and the resources available for conservation must be well argued by public and private nature conservation organizations and institutions. 相似文献
10.
Wild rice (Zizania spp. L.) is a North American native grain with spiritual and dietary significance to many native people. Wild rice is also an important aquatic plant that provides critical habitat to wetland and aquatic wildlife. Past distribution of wild rice in North America is poorly understood, largely because of the limited taxonomic resolution of Poaceae pollen. A novel technique for detecting diagnostic Zizania silica phytoliths allows unambiguous identification of this taxon in lake sediments. We need to better understand modern depositional patterns of phytoliths in lake sediments, however, before attempting detailed paleoreconstructions. We analyzed distributions of diagnostic Zizania and other Poaceae phytoliths in modern sediments from three lakes with variable percent cover of wild rice and a non-wild rice control lake in central Minnesota. Absolute counts of phytoliths per gram sediment were achieved using an exotic diatom marker. Non-Zizania short-cell phytoliths, i.e. phytoliths from wetland grasses Phragmites australis and Muhlenbergia glomerata, dominate the assemblages in all lakes. Most Poaceae short-cell phytoliths appear to be derived locally, with little evidence for regional inheritance from eolian or alluvial processes. Because of anatomical differences in decay of plant debris and other taphonomic issues, Zizania inflorescence rondel phytoliths were most abundant, with morphotypes from other parts rarely encountered. Even in sediments under the densest wild rice stands, Zizania phytoliths contributed a maximum of 9 % to total Poaceae phytolith abundance. Lake morphology also affects the depositional pattern of phytoliths in modern sediments, so coring locations should be considered carefully. At least 500 phytoliths should be counted to detect a sufficient number of wild rice phytolith morphotypes. Diagnostic Zizania phytoliths are a reliable tool for wild rice detection in paleolake sediments. 相似文献
11.
农业资源可持续利用模式及案例分析——以冀中南平原为例 总被引：6，自引：2，他引：4
如何实现农业资源的可持续利用依然是目前农业可持续发展研究的重点与难点。本文选择冀中南平原为研究区域,以农业资源利用方式与地域单元的耦合为切入点界定了农业资源可持续利用模式的概念与内涵,并通过分析模式5要素,即农业自然资源特征、农业主导产业(品)、农业产业链(产-加-销)、农民组织化程度和农村经济发展水平之间的关系,探讨了农业资源可持续利用模式的作用过程,构建了农业资源可持续利用模式的三级层次结构体系。在此方法框架的指导下,本文选取冀中南平原的曲周、藁城、馆陶三个典型县,具体剖析了第三级模式的基本运作状况,总结了农业资源可持续利用模式的应用前景。 相似文献
12.
Many arid basins in western North America are likely to experience future changes in precipitation timing and amount. Where shallow water tables occur, plant acquisition of groundwater and soil water may be influenced by growing season precipitation. We conducted a rainfall manipulation experiment to investigate responses of four common native plant species to ambient, increased, and decreased summer monsoon rainfall. We measured plant xylem pressure potentials (Ψ) and stable oxygen isotope signatures (δ18O) to assess effects of altered precipitation on plant water relations and water acquisition patterns. Reduced rainfall decreased Ψ more in the grasses Sporobolus airoides and Distichlis spicata than the more deeply rooted shrubs Sarcobatus vermiculatus and Ericameria nauseosa. E. nauseosa had little response to natural or experimental differences in available soil water. Plant xylem water δ18O indicated that S. airoides and D. spicata are almost entirely dependent on rain-recharged soil water, while E. nauseosa is almost entirely groundwater-dependent. Sarcobatus vermiculatus used groundwater during dry periods, but utilized precipitation from soil layers after large rainfall events. Persistent changes in precipitation patterns could cause shifts in plant community composition that may alter basin-scale groundwater consumption by native plants, affecting water availability for human and ecosystem uses. 相似文献
13.
湿地生态系统的服务功益及可持续利用 总被引：33，自引：5，他引：28
湿地生态系统作为独特的生态系统类型多样,在地球上广泛分布。湿地生态系统在改善环境、调洪蓄洪、为人类提供各种资源等方面,具有调节气候和水文的生态服务功益、保护水禽迁徙和繁育的生态服务功益、丰富的生物多样性、降解和富集污染物的环境服务功益、物质生产服务功益和旅游服务功益等。鉴于目前湿地生态系统服务功益的片面理解和不合理利用问题,对湿地生态系统服务功益的可持续利用现状进行了分析,提出了湿地生态系统服务功益可持续利用的科学对策,包括全面认识和发挥湿地生态系统的生态和环境服务功益;正确处理直接和间接服务功益的关系,提高湿地生态系统的利用效率;寻求实现湿地生态系统综合经济服务功益的最佳开发模式。 相似文献
14.
15.
生态足迹模型在我国土地可持续利用评价中的应用及启示 总被引：7，自引：0，他引：7
近年来,我国土地资源的不合理利用给生态环境带来了诸多负面影响,这使开展土地可持续利用评价研究成为当务之急,而科学发展观和新一轮土地利用总体规划修编工作的开展,为土地可持续利用评价研究提出了新的要求。生态足迹模型是目前可持续发展评价领域的研究热点,为土地可持续利用评价提供了重要途径。该文分析生态足迹模型在我国土地可持续利用评价中的研究现状,指出研究中主要存在评价精度较低、研究内容不全、应用方法单一等不足,并从研究尺度、研究精度、研究内容、研究方法和对土地利用相关政策启示等角度,提出需进一步改进的方向和建议。 相似文献
16.
Identifying the problem regions and regional problems, and thus improving regional policies, are crucial for the sustainable development of various economic entities. The coordinated development of industrialization, informatization, urbanization and agricultural modernization（hereinafter referred to as ＂Sihua＂） is not only a practical need but an important strategic direction of integrating urban-rural development and regional development in recent China, and it also provides a significant perspective for identifying problem regions and regional problems so as to improve the regional policies. This study mainly aims to： firstly, establish a comprehensive evaluation index system so as to explore the spatial pattern of coordinated development of Sihua in China at prefecture level; secondly, to develop an evaluation criteria system to identify the problem regions and regional problems from the perspective of coordinated development of Sihua. This paper comes first in the scientific community to evaluate the coordinated development state of Sihua in China at prefecture level and identify the problem regions and regional problems from the perspective of Sihua development by quantitative analysis. This study may benefit the improvement of regional policies and thus contribute to the sustainable socio-economic development of China. 相似文献
17.
县域经济发展与资源环境协调问题研究--以河南省为例 总被引：3，自引：0，他引：3
县域经济作为一个相对独立的区域经济,在制定发展战略、寻求经济增长的途径时,必须处理好可持续发展资源、环境的关系问题。文章从资源环境对县域经济可持续发展的制约和要求入手,对河南域这个特殊的经济发展单元进行了研究,提出了相应建议。 相似文献
18.
Aloe L., is the largest genus in the Asphodelaceae, a family of succulent-leaved, petaloid monocots, geographically restricted to the Old World. Aloes exhibit remarkable morphological variability and range in size from dwarf species only a few centimetres tall, to tree aloes reaching heights of up to 20 m. Aloes form a striking and important component of many arid and semi-arid African landscapes. Most Aloe species occur in arid savanna, which is widespread over subtropical southern and eastern Africa. In southern Africa, aloes receive considerable interest from both scientists and succulent plant enthusiasts. World-renowned for their medicinal properties, aloes are used in numerous natural products traded in the health and cosmetic industries. There is a wealth of popular literature on the genus, as well as various scientific publications, although these have tended to focus on aloe pollination biology and medicinal use. Knowledge on aloe ecology is vital for the management and conservation of wild populations as well as the arid and semi-arid lands in which they occur. Sound ecological understanding of the genus is also important for making decisions regarding sustainable utilization, as well as predictions relating to possible threats posed by climate change. Furthermore, by better understanding the genus, its utility in practical applications such as ecosystem restoration can be explored further. Hence, this review provides a synthesis of a wide range of available information on several aspects of aloe ecology, and highlights important opportunities for future research. The key aspects covered include aloe distribution, ecophysiology, functional role in the ecosystem, population dynamics, fire tolerance, resprouting, pollination ecology, seed biology, economic botany and conservation. 相似文献
19.
Fire in shrub-dominated portions of the Great Basin, largely fueled by non-native annuals such as Bromus tectorum, has become an important structuring force altering vegetation composition and soil characteristics. The extent to which fire affects native species in drier portions of the Great Basin, termed salt desert, is poorly documented. We conducted a survey of grazed salt desert habitat in northwestern Nevada 5 years after wildfires burned 650,000 ha, with the goal of investigating community response to fire and factors correlating with post-fire recovery. We found that recruitment of a dominant shrub, Artemisia spinescens, is severely restricted following fire: it occurred in only 2 of the 24 burned sites. The co-dominant shrub, Atriplex confertifolia, occurred in most burned sites although on average its percent cover was one-third lower than adjacent unburned sites. Biotic soil crust cover was four times lower, and non-native species cover 5 times higher, in burned sites compared to unburned. Ordination analyses confirmed differences among plant communities in burned versus unburned sites, with environmental variables soil conductivity, plant litter, soil potassium (K+) and pH explaining 38% of the variance in community composition. However, we found no environmental predictors of recovery for native species in burned sites. Future recruitment is likely to be further limited, as fire frequency in the salt desert is expected to increase with invasion by non-native annual grasses and with global climate change. 相似文献
20.
Creosote bushes (Larrea tridentata) form islands of fertility that influence annual plant abundances in desert ecosystems, and the distribution of native and non-native annuals with respect to creosote may differ. We established plots on the north and south facing sides of L. tridentata in the Mojave and Sonoran Deserts within four different microhabitats spanning from under the shrub canopy into the open. We counted native and non-native annuals twice during the winter growing season to determine the effects of L. tridentata on the spatial distribution of native and non-native annuals. In both deserts, annual plant abundances were higher on the north side of L. tridentata and in open areas. Native annuals in the Mojave were most abundant near the edge of the shrub canopy, whereas native annuals in the Sonoran were most abundant in open areas. The effects of L. tridentata fertility islands on annual abundances were not consistent between the two deserts we studied. Our study emphasizes the importance of research on native and non-native annuals in multiple regions before generalizations can be made about the effects of L. tridentata on annual plant abundances in desert scrub ecosystems. 相似文献