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人类活动影响下科尔沁沙地沙漠化动态的敏感性分析及灰色预测 总被引:19,自引:2,他引:19
利用90年代1◊25万和1◊50万的TM遥感影像及GIS获得的数据,结合该区70、80年代遥感调查数据,分析了科尔沁地区6个县的土地覆盖类型和潜在沙漠化动态及敏感因子。结果表明,1980~1990年该区的沙化面积从53%扩大到70%,林地下降10.7%,草地增加8.38%,主要为低覆盖草地。由于10年来人口密度增加了10人·km-2,耕地平均增加了7%,人口增加和活动是土地覆盖变化的敏感性因子。分析该区沙漠化的自然因素表明气候变化导致沙漠化的正逆过程,人类活动是近代该区沙漠化加剧的直接原因。灰色预测表明该地区2000年以后人口增加,而沙漠化呈增加和减少两种趋势. 相似文献
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菌根及其在荒漠化土地恢复中的应用 总被引:28,自引:2,他引:28
对菌根的作用及其荒漠化对其影响,以及菌根在荒漠化土地恢复中的应用进行了探讨,指出菌根不仅能够促进植物个体养分的吸收,提高植物光合作用,增强植物抗旱、抗盐性,而且能够调节群落内植物间的关系、群落的演替轨道及其生物多样性、耕作、灌溉、过度放牧和开矿等诱发土地荒漠化过程的人类活动直接影响菌根的建立和生存,采用外来菌引入及原来残存菌培育,在恢复区建立丛状菌根植物,菌木化菌根造林及开矿土地管理中表土的存贮等方式都会有力地促进恢复地菌根的建立,并可缩短恢复周期。 相似文献
4.
Assessing the spatial variability of ecosystem structure and functioning is an important step towards developing monitoring systems to detect changes in ecosystem attributes that could be linked to desertification processes in drylands. Methods based on ground-collected soil and plant indicators are being increasingly used for this aim, but they have limitations regarding the extent of the area that can be measured using them. Approaches based on remote sensing data can successfully assess large areas, but it is largely unknown how the different indices that can be derived from such data relate to ground-based indicators of ecosystem health. We tested whether we can predict ecosystem structure and functioning, as measured with a field methodology based on indicators of ecosystem functioning (the landscape function analysis, LFA), over a large area using spectral vegetation indices (VIs), and evaluated which VIs are the best predictors of these ecosystem attributes. For doing this, we assessed the relationship between vegetation attributes (cover and species richness), LFA indices (stability, infiltration and nutrient cycling) and nine VIs obtained from satellite images of the MODIS sensor in 194 sites located across the Patagonian steppe. We found that NDVI was the VI best predictor of ecosystem attributes. This VI showed a significant positive linear relationship with both vegetation basal cover (R2 = 0.39) and plant species richness (R2 = 0.31). NDVI was also significantly and linearly related to the infiltration and nutrient cycling indices (R2 = 0.36 and 0.49, respectively), but the relationship with the stability index was weak (R2 = 0.13). Our results indicate that VIs obtained from MODIS, and NDVI in particular, are a suitable tool for estimate the spatial variability of functional and structural ecosystem attributes in the Patagonian steppe at the regional scale. 相似文献
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《Fungal Ecology》2019
Arbuscular mycorrhizal fungi (AMF) are related to plant community dynamics and ecosystem functioning. Overgrazing can negatively affect plant performance, and consequently unbalance the association with AMF. We studied the grazing effect on AMF colonization for preferred (Bromus pictus and Poa ligularis) and unpreferred grasses (Pappostipa speciosa and Pappostipa humilis) by sheep in the Patagonian steppe. For each species, AMF colonization in ungrazed, moderate and intense grazing sites was quantified. In ungrazed areas, B. pictus showed the highest extent of AMF colonization. Mycorrhizal colonization was higher during the active season, and largely reduced by intense grazing conditions. The decrease of AMF colonization was maximal for the most preferred species, but also significant for the unpreferred species. Our results suggest that overgrazing could reduce mycorrhizal benefits for the plant by reduction of AMF colonization, which can be a good indicator of ecosystem functioning, eventually revealing an increasing degree of environmental degradation. 相似文献
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Vegetation restoration by seasonal exclosure in the Kerqin Sandy Land,Inner Mongolia 总被引:11,自引:0,他引:11
Katoh Kazuhiro Takeuchi Kazuhiko Jiang Deming Nan Yinhao Kou Zhenwu 《Plant Ecology》1998,139(2):133-144
Grazing control has been reported to be effective for the control of desertification in semi-arid regions. However, economic reasons often make complete inhibition of grazing (complete exclosure) difficult to carry out. Grazing control has been applied to the Kerqin Sandy Lands, Inner Mongolia, China, by means of seasonal exclosure, whereby grazing is allowed from November to April. The harvesting of hay is also allowed once during September - October. The aim of the reported study was to evaluate the effectiveness of this seasonal exclosure on vegetation restoration. Species compositional data were obtained from 356 quadrats and ordinated by Detrended Correspondence Analysis (DCA). Ordination indicated that landform was the most important factor influencing the species composition of the vegetation. Regardless of landform and type of grazing control, however, vegetation coverage, vegetation height and species richness were higher at sites where grazing had been controlled, than at sites lacking any control. Perennial species were dominant at the former while annual species were dominant at the latter. Both shrub and tree species were quite rare at the sites where seasonal exclosure had been carried out. It is concluded that seasonal exclosure is sufficient to restore and maintain grassland vegetation in and around the study area. When shrubby or tree vegetation is needed for reasons such as fixing sands or preventing sand dune remobilization, complete exclosure is recommended. 相似文献
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科尔沁沙地沙漠化过程中的物种多样性 总被引:59,自引:8,他引:59
对内蒙古科尔沁地区沙漠化过程中物种多样性的变化特征进行了分析 ,依据植物种在各类型沙漠化土地的出现频率和不同沙漠化阶段各生活型植物种的组成 ,探讨了沙漠化过程中植物种绝灭和定居特点 .物种多样性指数分析表明 ,沙漠化过程是一个物种多样性衰减的过程 ,沙漠化首先导致特有种的绝灭 ,其次为稀有种和普通种 .从植物的生活型来看 ,多年生草本和灌木类植物受沙漠化影响最大 ,而 1年生草本和半灌木类植物可存活于沙漠化过程各个阶段 .在沙漠化过程中植物种的绝灭速率大于定居速率 . 相似文献
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R.J. Harper A.C. Beck P. Ritson M.J. Hill C.D. Mitchell D.J. Barrett K.R.J. Smettem S.S. Mann 《Ecological Engineering》2007,29(4):329-341
The current agricultural systems of broad areas of Australia are unsustainable, with large projected increases in salinization, decreases in water quality, wind erosion, and losses of biodiversity. It is well known that these problems can be partially resolved by farmland reforestation; however, a major issue is financing the scale of activity required. The international response to global warming, the United Nations Framework Convention on Climate Change and its Kyoto Protocol, includes provisions that enable greenhouse sinks (sequestration of carbon in soils and vegetation) to be used by parties to fulfil their obligations. The Kyoto Protocol also allows for trading in emission reductions, and this opens the possibility that investment in carbon sinks may help underwrite broader natural resource management objectives. This paper examines the possibilities for improved land management in Western Australia arising from the development of carbon sinks by considering: (a) the likelihood of a carbon market developing and the likely depth of that market as a result of current national and international policies, (b) the data available to provide estimates on different types of sinks, and (c) the likely benefits of wide-scale sink investment.It was estimated that the total amount of carbon that could be sequestered by reforesting 16.8 Mha of cleared farmland is 2200 Mt CO2-e, and between 290 and 1170 Mt CO2-e by destocking 94.8 Mha of rangelands. There were insufficient data to produce estimates of sequestration following changes in tillage practice in cropping systems or the revegetation of already salinized land. We conclude that carbon sinks are only likely to become profitable as a broad-scale stand-alone enterprise when carbon prices reach AUD$15/t CO2-e, with this threshold value varying with carbon yield and project costs. Below this price, their value can be significant as an adjunct to reforestation schemes that are aimed at providing other products (wood, pulp, bioenergy) and land and water conservation benefits. Irrespective of this, carbon sinks provide an opportunity to both sequester carbon in a least-cost fashion and improve soil and watershed management. 相似文献
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Carbon isotopes reveal soil organic matter dynamics following arid land shrub expansion 总被引:1,自引:0,他引:1
Over the past century, overgrazing and drought in New Mexico’s Jornada Basin has promoted the replacement of native black
grama (Bouteloua eriopoda Torr.) grass communities by shrubs, primarily mesquite (Prosopis glandulosa Torr.). We investigated the effects of shrub expansion on the distribution, origin, turnover, and quality of light (LFC) and
heavy (HFC) soil organic matter (SOM) fractions using δ13C natural abundance to partition SOM into C4 (grass) and C3 (shrub) sources. Soil organic matter beneath grasses and mesquite was isotopically distinct from associated plant litter,
providing evidence of both recent shrub expansion and Holocene plant community changes. Our δ13C analyses indicated that SOM derived from mesquite was greatest beneath shrub canopies, but extended at least 3 m beyond
canopy margins, similar to the distribution of fine roots. Specific 14C activities of LFC indicated that root litter is an important source of SOM at depth. Comparison of turnover rates for surface
LFC pools in grass (7 or 40 years) and mesquite (11 or 28 years) soils and for HFC pools by soil depth (∼150–280 years), suggest
that mesquite may enhance soil C storage relative to grasses. We conclude that the replacement of semiarid grasslands by woody
shrubs will effect changes in root biomass, litter production, and SOM cycling that influence nutrient availability and long-term
soil C sequestration at the ecosystem level.
Received: 17 May 1996 / Accepted: 12 November 1996 相似文献
10.
Eun-Shik Kim Dong Kyun Park Xueyong Zhao Sun Kee Hong Kang Suk Koh Min Hwan Suh Young Sun Kim 《Ecological Research》2006,21(6):907-911
Asian dusts, yellow sand, or dust and sand storms (DSS) in Asian continent are the end products of desertification, which
became a regional environmental problem being aggravated by time. It is closely related to an issue of sustainability in the
region. As the desertification is caused not only by natural factors, such as the climate change, strong wind, and low precipitation,
but also by rapidly increasing human activities, such as overgrazing, misuse of water resources, and irrational land use,
it is urgent to make efforts to combat desertification in Asian continent including China. In this regard, it is necessary
to consider socio-economic aspects as well as ecological aspects and, consequently, the project for the construction of a
Demonstration Model Village for eco-environmental rehabilitation should be paid to a special attention. The authors deal with
this regional issue in consideration of three Es, which are represented by ecology, economy, and environment in providing
the perspectives in sound approach to the issue. As an approach to the issue of Asian dusts and desertification in Asian continent,
this Eco-Village study provides one way forward. 相似文献