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1.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2):77-84
Because of its species-rich hay meadows and old pollards that are traditionally managed, Ulvund in Myrkdalen, Voss, is one of 14 areas in Hordaland county that are considered to be of special interest for cultural landscape conservation. The spatial patterns of species richness were investigated in hay meadows at Ulvund. Two main types of vegetation were recognised in managed meadows. Unfertilised and species-rich areas with a rather short field layer were situated in the steep parts of the meadows. Fertilised and species-poor areas with a high field layer were situated on flat or gently sloping areas. This spatial pattern is recognised in other west Norwegian hay meadows as well and is very likely linked to historical differences in land management; the flatter areas were formerly used as heavily fertilised permanent tilled fields for grain production, while the steep areas were used for hay production. As the conservation value largely lies in small, localized parts of the farms, conservation management actions can also be localized and thus feasible under modern conditions. 相似文献
2.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(2):65-73
In a sloping hay meadow, situated on phyllitic soils in the fjord region of western Norway, shade from solitary trees in the lower meadow and from high tree cover on the upper slopes has reduced the number of indicators of traditional management, which include vulnerable hay-meadow species. However, the number of additional species, for example, forest species, was higher in shade from solitary trees than in the open; the areas under the crowns may have functioned as refuges for forest species in former days, when wooded hay meadows, comprising small woodlots, solitary trees and shrubs, were widespread in the region. Indicators of traditional management were more frequent in dry plots than in moist plots, but most species in this group occurred in moist plots too. To keep the habitat area for these species as large as possible and at the same time restore the former well-managed tree-layer of the meadow, the removal of large Fraxinus excelsior and Alnus incana specimens from the upper slopes and reduction of the crowns of solitary Taxus baccata and Prunus domesticus on the lower slopes is recommended. 相似文献
3.
XU Lijun SHEN Beibei NIE Yingying XIN Xiaoping GAO Wa LI Da WANG Di YAN Ruirui CHEN Baorui 《资源与生态学报(英文版)》2019,10(2):163-173
Natural hay pastures in semi-arid pastoral areas produce the highest yields of hay in northern China. However, long-term continuous hay harvesting with no rest interval has resulted in severe degradation across widespread areas of these natural hay pastures. In addition, no clear data exist on the spatial distribution or degree of degradation occurring in natural hay pastures primarily because a nationally unified and normative evaluation standard is lacking. In view of the above problems, we employed an analytic hierarchy process to carry out screening and accuracy validation of evaluation indicators for natural hay pastures in north China grasslands (temperate meadow steppes, temperate steppes, mountain meadows, and lowland meadows). Our study identified seven easily measured indicators that reflect the state of natural hay pastures (average height, aboveground biomass, coverage, proportion of medium grasses, litter biomass, proportion of degradation-indicative plants, and proportion of bare spots and saline-alkali spots). A five-level scoring method was employed to delineate the threshold range for these indicators, The results of this study show that this method effectively solved the technical bottleneck for graded evaluation of degradation in natural hay pastures. This provides a theoretical basis for the scientific assessment of natural hay pasture degradation as well as important technical support for sustainable use of natural hay pastures and livestock production. 相似文献
4.
腾格里沙漠人工固沙植被区浅层土壤水分对降水和生物结皮的响应 总被引：2，自引：1，他引：1
选择腾格里沙漠东南缘人工植被区3种典型的地表覆被类型（藓类结皮、藻类结皮和流沙）土壤为对象,选取发生在7月和9月的两次降水事件,研究浅层土壤（3、5、10 cm）水分入渗与再分布过程。结果表明：浅表层3 cm深度土壤水分在降雨初期均表现为跳跃式增加,而在降雨中后期由于土壤剖面不同深度水势梯度减小,降水入渗速率降低,土壤水分仅呈现小幅波动。在两次降水事件中,藓类结皮和藻类结皮对降水入渗的阻碍作用比较显著,入渗速率表现为沙土 > 藻类结皮 > 藓类结皮;从水分再分布看,生物土壤结皮的存在致使水分再分配过程表现出明显的浅层化;降水过程结束后,结皮促进水分的蒸发损失,从而减少植被可利用水分含量。人工固沙植被区广泛发育的生物土壤结皮对降水入渗与再分布过程以及土壤水量平衡具有重要影响。 相似文献
5.
Agricultural intensification has led to the extreme simplification of agricultural landscapes. The subsequent impoverishment of farmland plant communities can drive dramatic changes in the associated food webs of agricultural systems, with potential implications for vertebrate pest management. Weeds may provide alternative food sources for damaging species and thus contribute to reducing their damage, which is particularly desirable if the species is a valuable resource in its own right. Wild rabbits (Oryctolagus cuniculus) are a game species of great conservation value in the Iberian Peninsula that cause frequent damage to crops. Here we describe the dynamics of non-crop plant communities over an annual cycle in a semiarid Mediterranean agro-ecosystem, and discuss the potential linkages and implications for rabbit damage management. Overall, the availability of alternative food for rabbits was very low, especially in the most extensive habitat types, i.e. olive groves and vineyards. The seasonal pattern in plant productivity, which coincides with the phenology of rabbits in Mediterranean areas was only detectable in the less intensively managed habitat types. Scarce natural vegetation remnants retained the highest richness, diversity and plant cover, potentially acting as a refuge for both, plants and rabbits. Our results indicate that intensive management practices, through reducing alternative food sources for rabbits, are likely to promote conflict between hunters, farmers and conservationists in semiarid agro-ecosystems of Southern Spain. 相似文献
6.
Abundance and diversity of fungi in relation to chemical changes in arctic moss profiles 总被引：1，自引：1，他引：0
Mosses are a dominant component of high-arctic terrestrial ecosystems, yet little is known regarding the abundance and diversity of fungi associated with these abundant plants. We investigated vertical patterns of abundance and diversity of fungi and their relationship with chemical properties within profiles of Hylocomium splendens and Racomitrium lanuginosum collected in the Oobloyah Bay area on Ellesmere Island, Canada. The moss profiles were divided into 6 (H. splendens) and 5 (R. lanuginosum) layers according to the color and texture, and hyphal length, fungal assemblages, and contents of organic chemical components (acid-unhydrolyzable residues, total carbohydrates, extractives) and nutrients (N, P, K, Ca, Mg) were measured. Total hyphal length was greatest at the middle layers of H. splendens and at the deepest layers of R. lanuginosum and was significantly affected by moss species and nutrient contents. A total of 18 and 19 fungal taxa was isolated from the profiles of H. splendens and R. lanuginosum, respectively, with 11 taxa being common to both moss species. Moss species significantly affected the species distribution of fungi. Individual fungal taxa showed patterns of vertical distribution within the moss profiles. The contents of acid-unhydrolyzable residues and nutrients increased and the content of total carbohydrates decreased down the profile, which was attributable to the ability of fungi to decompose carbohydrates selectively and to immobilize nutrients in decomposed moss residues. 相似文献
7.
轮牧传统衰退:滇西北藏区亚高山草地退化的人文因素 总被引：1，自引：1，他引：1
滇西北藏区亚高山草地退化是个有目共睹的现实,有自然的原因也有人文的原因。以实地调查为基础,从藏民生计出发的研究发现,滇西北藏族的畜牧生产特点是6～9月位于3800m以上的高山草甸地带,11月至翌年3月位于3200m左右的亚高山草甸地带,属于轮牧作业;轮牧传统适应了气候和植物生长的季节性变化,有效地维持草地生产和传统围栏农业。轮牧传统的衰退,使牲畜集中在亚高山草甸地带,导致了草地退化。充分挖掘和尊重民族传统知识有助于退化草地恢复。 相似文献
8.
Eleven species of tardigrades in South Georgia, of which two are new to science, were found in samples collected at fifteen localities. The highest number of species was found in moss from a scree field. Twenty species of tardigrades are presently known from South Georgia, but the island remains insufficiently investigated. The species composition is similar to that of southern South America. The high number of cosmopolitan species makes the geographical distribution pattern of the South Georgian tardigrades more similar to that of macrolichens than to that of insects and vascular plants. 相似文献
9.
以黑河中游人工绿洲边缘天然草地及其转变的人工梭梭灌木林（21 a）、人工杨树林（28 a）、人工樟子松林（33 a）和农田（开垦27 a和100 a）为研究对象,基于6种研究样地中小型土壤动物群落的调查数据,采用多变量排序和通径分析等方法,研究了土地利用/覆被变化与管理措施对中小型土壤动物群落及其主要类群演变的耦合效应。主要结果是:①将天然草地转变为未实施管理措施的人工梭梭灌木林后并未引起土壤动物群落组成、数量和物种多样性的显著变化,而转变为实施管理措施的杨树和樟子松人工林及农田后,导致了土壤动物群落组成、数量和物种多样性的变异,证实了土地覆被变化对中小型土壤动物群落的作用及其效应受管理措施的强烈调控。②土壤动物群落的演变过程受土地覆被变化与灌溉和施肥管理的共同影响,其中灌溉的贡献率最大,是关键驱动因子。③不同土壤动物类群对土地覆被变化和管理耦合作用的响应不同。灌溉对跳虫、甲螨和革螨的个体数量和物种丰富度的直接影响和总效应最大;施肥对辐螨的个体数量和物种丰富度的直接影响和总效应最大;灌溉和施肥对稀有类群的个体数量和物种丰富度的直接影响和总效应均较大,具同等重要的作用。结论是,土地覆被变化与管理耦合作用通过改变土壤水文和生态环境条件驱动了中小型土壤动物群落的演变过程。 相似文献
10.
腾格里沙漠固定沙丘结皮层藓类植物的生态功能及与土壤环境因子的关系 总被引：32，自引：14，他引：18
通过1998-2001年的野外调查,沙坡头地区固定沙丘结皮层藓类植物共3科、11属、24种,新发现 8 个本地区新记录种。人工固定沙丘仅分布有7种藓类,而自然固定沙丘包括了所有的 24 种藓类,具有较高的物种多样性,构成了复杂的苔藓植物群落。沿坡向随高度的上升,藓类植物的盖度减少,而藻类植物的盖度却有上升的趋势。自然固定沙丘藓类植物盖度明显小于围封的人工固定沙丘。人工固定沙丘随着固定年限的增加,藓类植物的生物量明显增高,不同种类藓类植物的生物量明显不同,综合盖度因素,真藓拥有该地区最大的生物量。不同类型、不同种类的藓类植物结皮厚度和株高之间都存在显著的相关性(P < 0.01)。不同固定沙丘藓类结皮土壤的总盐量、阴、阳离子总量都明显高于藻结皮和流沙,苔藓结皮中苔藓植物体内Mg/Ca率在0.50~0.98之间,结皮土壤Ca2+含量明显高于其他3种离子,Na+、K+离子含量较少。苔藓植物生物量与土壤磷、土壤有机质呈明显正相关(P < 0.05),土壤pH值与土壤磷含量和苔藓植物生物量呈显著负相关(P 分别为 < 0.01 和 < 0.05),表明高的 pH值显著影响土壤磷含量和植物生物量。藓类结皮土壤中的有机质、全磷、全氮、速磷、速氮含量显著高于藻结皮的含量,尤其是有机质含量,藓类结皮都超过了1%的水平,在有机质含量普遍低于1%的沙区,对维持沙丘的稳定,促进维管植物的定居和繁殖起着极其重要的作用。 相似文献
11.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(4):192-206
Centuries of seasonal farming in the Norwegian mountains led to a decrease in forested areas, a lowering of the alpine tree- and forest lines, and an increase in grassland coverage in the subalpine zone. Since the mid-19th century seasonal farming has declined significantly. In the sub-alpine belt, this has resulted in woodland succession on former hay meadows and open grasslands and heathlands. In contrast, vegetation changes caused by seasonal farming and its decline in alpine environments may be comparatively subtle because of unsuitable conditions for tree growth. The study examines vegetation changes in a former mountain summer farming area in the alpine zone of Western Norway using data on present and previous vegetation and old photographs. On curtilages high levels of defoliation, trampling and nutrient accumulation resulted in grass- and herb-dominated vegetation that differs significantly from that of surrounding areas. This curtilage-specific vegetation is persistent and occurs even at locations that have been grazed with only low intensity for several decades. Local concentrations of nutrients are probably a key factor that maintains the grass-dominated vegetation and strongly delays or even prevents regrowth of shrub heath. 相似文献
12.
Mountaintop removal mining is a dominant driver of land use/land cover changes in the Appalachian Region of the eastern United States and is expected to increase in scale in the coming decades. While several studies quantify land use/land cover changes attributed to traditional surface mining and at regional scales, no studies we are aware of focus specifically on mountaintop removal/valley fill mining practices at the watershed scale. Further, despite its scale and extent, its impact on runoff, particularly at larger spatial scales (103 km2), is poorly understood due to the complex relationships between climate, land use, and hydrology. To explore the impacts of this practice at broader scales, we estimated land use/land cover changes using Landsat 5 TM imagery over five periods between 1994 and 2010; used a simple rainfall–runoff model to estimate hydrologic response time; and conducted non-parametric trend analyses on annual hydrologic metrics (streamflow, Q/P, response time) for the Big Coal River watershed located in the southern West Virginia coalfields. No statistically significant trends were detected in any of the timeseries. The lack of detectable trends and correlations between land use changes and hydrology at the basin scale are not entirely unexpected due to the history and mosaic of land cover changes that span timescales larger than our study period. Further interannual variation likely overwhelms our ability to detect potential changes using monotonic trend analysis at the annual time scale, particularly in light of strong streamflow seasonality. Future studies therefore should include different methods of change detection applied to different timescales to more appropriately account seasonal and interannual variations. Until the significance of this practice on water resources (quality and quality) are understood, efforts to reduce the environmental problems associated with mountaintop mining will be difficult to achieve. 相似文献
13.
14.
The influence of elevation, shrub species, and biological soil crust on fertile islands in the Mojave Desert, USA 总被引：4，自引：1，他引：4
We quantified soil nutrients and biological crust cover (bryophytes and lichens) under the canopies of three species of Mojave Desert shrubs and in interspaces between shrubs at three elevations to determine the effects of shrub species, soil crust, and elevation on islands of soil fertility. Means of pH, organic matter, total Kjeldahl nitrogen, nitrogen mineralization, and gravimetric soil moisture are significantly greater in soils under Ambrosia dumosa (Gray) Payne, Larrea tridentata Cov., and Coleogyne ramosissima Torr. than soils from adjacent interspace microhabitats. Although soil moisture and soil organic matter increase by a factor of 1.5 from the low elevation to the high elevation site, the ratio of shrub to interspace concentrations, or the difference in mean soil variables between shrubs and interspaces, is effectively constant and independent of elevation. Total bryophyte and lichen cover is relatively low (24.5%), however, there are 11 species of bryophytes and two species of lichens distributed across three elevations with the highest species richness and cover at the low-elevation site. Bryophyte and lichen cover is correlated with silt but is not related, consistently, to soil nutrients. Overall, the balance of processes controlling spatial aggregation of soil nutrients under shrubs is remarkably insensitive to potential differences in organic inputs among elevations, shrub species, and soil crust surfaces. 相似文献
15.
2006年开始在库布齐沙漠选择4种藓类植物进行人工培养促进结皮层形成实验,发现人工结皮层中藓类成活率、盖度与土壤基质、降雨量、小生境和藓类植物的生长和繁殖特性密切相关。双色真藓（Bryum dichotomum）成活率和盖度最高,密度与盖度相关,可形成大面积藓类结皮层。单位面积内土生对齿藓（Didymodon vinealis）密度最大,对结皮层的稳定具有重要作用。在培养初期藓类植物生长和繁殖速度较快的原因是消耗繁殖体内营养的结果,以后稳定在一个水平上不会出现生长的高峰期。本项研究为人工培养藓类植物促进结皮层的形成提供了实验依据,并为深入探讨生物结皮层的形成和维持机制提供基础科学资料。 相似文献
16.
Tourism is Nepal's largest industry, giving people in rural areas an alternative to subsistence farming. Tourism can have an impact on the forest cover of a region as trees provide firewood for cooking and heating and timber for building accommodation. In 1986 the Annapurna Conservation Area Project was established to ensure that tourism was managed more sustainably, which includes minimising its impact on the forest cover. This study assesses the impacts of tourism on the forest cover in the Annapurna region by comparing Landsat images from 1999 to 2011. This was achieved through spectral classification of different land cover and by assessing the change in forest cover in relation to increasing distances from tourism villages. A major problem with remote sensing in mountainous regions such as Nepal is shadow caused by the relief. This issue was addressed by only assessing areas which were free from shadow, which in effect meant a sample was used rather than the whole study region. The results indicate that there has been an 8 percent reduction in overall forest extent, but this change varies by region. In the northern, drier regions there has been a net increase in forest cover, while in the southern regions there has been a net reduction in forests. The influence of tourism facilities on forest is also variable. Around each of the tourism villages sampled there was a general trend of forest removal decreasing as the distance from each village increased, which indicates tourism does have a negative impact on forests. However, there was an opposite trend in the northern villages that were well inside the conservation area. 相似文献
17.
南极地区冰雪消失对全球大气环流和气候影响的数值模拟 总被引：1，自引：0，他引：1
本文利用全球大气环流模式通过数值模拟研究了北半球夏季南极地区冰雪覆盖的消失对大气环流和全球气候影响的过程。结果表明南极冰雪消失不仅影响南半球大气环流异常,而且通过引起热带环流异常如增强东亚季风环流和减弱Walker环流等引起北半球大气环流和我国夏季气候的异常。南极冰雪覆盖的消失将给全球气候带来严重后果。文中也对南极冰雪气候效应的动力学机制进行了讨论。 相似文献
18.
古尔班通古特沙漠南缘苔藓结皮中可培养真菌的多样性 总被引：2，自引：2，他引：0
为了解古尔班通古特沙漠南缘苔藓结皮中可培养真菌的多样性,运用稀释平板法和基于ITS-rDNA基因序列的系统发育分析,将得到的基因序列与NCBI数据库GenBank中的序列进行相似性比较并构建系统发育树。结果显示,从古尔班通古特沙漠南缘苔藓结皮中共分离得到24株菌落形态各异的真菌,分属于11属21种,绝大多数属于子囊菌亚门和半知菌亚门。其中,青霉属（Penicillium）和链格孢属（Alternaria）为优势菌群,茎点霉属（Phoma）、曲霉菌属（Aspergillus）、镰刀孢菌属（Fusarium）为常见属;有些种类的真菌具有耐热及特殊产酶活性。 相似文献
19.
Rebecca Grey-Ross Colleen T. Downs Kevin Kirkman 《Applied geography (Sevenoaks, England)》2009,29(3):371-376
Increasing transformation and fragmentation of rural landscapes for economic reasons is causing concern to conservationists worldwide. With this trend likely to continue, perhaps conservation agencies and development corporations need to co-operate and plan housing developments that are environmentally and ecologically sustainable and can serve as refuges for endangered species. In KwaZulu-Natal, South Africa, grasslands are particularly threatened by land transformation for housing developments. A case study is presented of a housing development, Wedgewood Estate in KwaZulu-Natal that has been developed and managed for conserving grassland habitat and associated species, particularly the endangered oribi (Ourebia ourebi). Feedback from the Estate's managers about the development and ecological impact were obtained. Wedgewood is an example of the viability of housing estates as refuges for endangered species and shows that the density and placement of housing and management of the natural habitat are important. It emphasizes the need for reviewing the types and amount of housing development, management of natural habitat, and the rules and regulations they put in place to assure the integrity of the conservancy is preserved. This case study also shows the potential of such ecologically sensitive housing developments as sources of surplus game for translocation, especially in the case of endangered species such as oribi. 相似文献
20.
塔里木河下游荒漠化过程土壤种子库特征 总被引：4，自引：0，他引：4
沿塔里木河下游荒漠河岸林,选择了荒漠化程度依次加重的5个断面,进行了土壤种子库野外萌发试验。结果表明:①在中度荒漠化区土壤种子库的物种相对丰富(11种),密度较高(892.6粒\5m-2);随着荒漠化程度的加剧,土壤种子库物种丰富度、总密度以及多样性指数呈现出明显下降的趋势;②与重度荒漠化区和中度荒漠化区相比,极度荒漠化区土壤种子库中的多年生草本和灌木密度占总密度的百分比有所增加,一年生草本百分比明显降低;③不同荒漠化程度对种子库密度的垂直分布影响不大,70%以上的种子集中在土壤表层0～2 cm深度。综合来看,随着荒漠化程度的加剧,土壤种子库的恢复潜力有所下降。 相似文献