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551.
In this study we quantified land cover changes in the arid region of Yulin City, Northwest China between 1985 and 2000 using
remote sensing and GIS in conjunction with landscape modeling. Land covers were mapped into 20 categories from multitemporal
Landsat TM images. Five landscape indices were calculated from these maps at the land cover patches level. It was found that
fallow land decreased by 125,148 ha while grassland and woodland increased by 107,975 and 17,157 ha, respectively. Landscape
heterogeneity, dominance and fractal dimension changed little during the 15-year period while landscape became more fragmented,
with an index rising from 0.56 to 0.58. The major factors responsible for these changes are identified as the change in the
government policy on preserving the environment, continued growth in mining, and urbanization. 相似文献
552.
Lussier SM da Silva SN Charpentier M Heltshe JF Cormier SM Klemm DJ Chintala M Jayaraman S 《Environmental monitoring and assessment》2008,139(1-3):119-136
Watershed land use in suburban areas can affect stream biota through degradation of instream habitat, water quality, and riparian vegetation. By monitoring stream biotic communities in various geographic regions, we can better understand and conserve our watershed ecosystems. The objective of this study was to examine the relationship between watershed land use and the integrity of benthic invertebrate communities in eight streams that were assessed over a 3-year period (2001-2003). Sites were selected from coastal Rhode Island watersheds along a residential land-use gradient (4-59%). Using the rapid bioassessment protocol, we collected biological, physicochemical, habitat, and nutrient data from wadeable stream reaches and compared metrics of structure and integrity. Principal component analyses showed significant negative correlation of indicators for stream physicochemical, habitat, and instream biodiversity with increasing residential land use (RLU) in the watershed. The physicochemical variables that were most responsive to percent RLU were conductivity, instream habitat, nitrate, and dissolved inorganic nitrogen (DIN). The positive correlation of DIN with percent RLU indicated an anthropogenic source of pollution affecting the streams. The biotic composition of the streams shifted from sensitive to insensitive taxa as percent RLU increased; the most responsive biological variables were percent Ephemeroptera, percent Scrapers, percent Insects, and the Hilsenhoff biotic index. These data show the importance of land management and conservation at the watershed scale to sustaining the biotic integrity of coastal stream ecosystems. 相似文献
553.
Woli KP Hayakawa A Kuramochi K Hatano R 《Environmental monitoring and assessment》2008,137(1-3):251-260
River water quality was evaluated with respect to eutrophication and land use during spring snowmelt and summer base flow
periods in Abashiri (mixed cropland-livestock farming) and Okoppe (grassland-based dairy cattle farming), eastern Hokkaido,
Japan. Water from rivers and tributaries was sampled during snowmelt and summer base flow periods in 2005, and river flow
was measured. Total N (TN), NO3–N, and Si concentrations were determined using standard methods. Total catchment and upland areas for each sampling site
were determined with ArcGIS hydrology modeling software and 1:25,000-scale digital topographic maps. Specific discharge was
significantly higher during snowmelt than during base flow. In both areas, TN concentrations increased, whereas Si concentrations
decreased, with increased specific discharge, and were significantly higher during snowmelt. The Si:TN mole ratio decreased
to below or close to the threshold value for eutrophication (2.7) in one-third of sites during snowmelt. River NO3–N concentrations during base flow were significantly and positively correlated with the proportion of upland fields in the
catchment in both the Abashiri (r = 0.88, P < 0.001) and Okoppe (r = 0.43, P < 0.01) areas. However, the regression slope, defined as the impact factor (IF) of water quality, was much higher in Abashiri
(0.025) than in Okoppe (0.0094). The correlations were also significantly positive during snowmelt in both areas, but IF was
four to eight times higher during snowmelt than during base flow. Higher discharge of N from upland fields and grasslands
during snowmelt and the resulting eutrophication in estuaries suggest that nutrient discharge during snowmelt should be taken
into account when assessing and monitoring the annual loss of nutrients from agricultural fields. 相似文献
554.
The effect of land cover change, from natural to anthropogenic, on physical geography conditions has been studied in Kayisdagi
Mountain. Land degradation is the most important environmental issue involved in this study. Most forms of land degradation
are natural processes accelerated by human activity. Land degradation is a human induced or natural process that negatively
affects the ability of land to function effectively within an ecosystem. Environmental degradation from human pressure and
land use has become a major problem in the study area because of high population growth, urbanization rate, and the associated
rapid depletion of natural resources. When studying the cost of land degradation, it is not possible to ignore the role of
urbanization. In particular, a major cause of deforestation is conversion to urban land. The paper reviews the principles
of current remote sensing techniques considered particularly suitable for monitoring Kayisdagi Mountain and its surrounding
land cover changes and their effects on physical geography conditions. In addition, this paper addresses the problem of how
spatially explicit information about degradation processes in the study area rangelands can be derived from different time
series of satellite data. The monitoring approach comprises the time period between 1990 and 2005. Satellite remote sensing
techniques have proven to be cost effective in widespread land cover changes. Physical geography and particularly natural
geomorphologic processes like erosion, mass movement, physical weathering, and chemical weathering features etc. have faced
significant unnatural variation. 相似文献
555.
Monitoring the impacts of urbanization and industrialization on the agricultural land and environment of the Torbali, Izmir region, Turkey 总被引:1,自引:0,他引:1
The aim of this research is to determine agricultural land loss and environmental pollution caused by industrialization and
urban sprawl using the Geographical Information System (GIS) and Remote Sensing technique (RS). Remotely sensed data is the
most powerful tool for monitoring land use changes and GIS is the best way to store and reproduce various kinds of integrated
data. Considering the rapid increase of population the loss of fertile agricultural soils is a very dangerous situation for
the future of the country. Thus, people are living in the cities in (with adverse) conditions of insufficient drinking water,
infrastructure problems, inadequate landscape and many unsolved (extreme) environmental problems. During the last 36 years,
unplanned urbanization and industrialization have led to the use of agricultural areas for non-agricultural purposes in the
Torbali (Izmir) region, which has the most fertile soils of the Aegean Region. Within this study, a database was created on
the parameters of land loss and environmental pollution by means of field observation, interpretation of satellite images
(ASTER), aerial photos(1/25.000 scale), topographic map ,soil map, and 1/5.000 scale cadastral map. Results of previous researches
and the archives of Torbali municipality were used as ancillary data. In the research, urbanization and industrialization
of the town was studied by (using) GIS and RS between 1965 and 2001. Since 1965, 4.742.357 m2 agricultural land, mostly of first and second land use capability classes, has been lost due to unplanned urban and industrial
developments. Urbanization and industrialization involved an area of which 58% was being used as irrigated lands, 25 % rain
feed (rain fed lands)and 17 % for olive growing. 相似文献
556.
Fang L Bai Z Wei S Yanfen H Zongming W Kaishan S Dianwei L Zhiming L 《Environmental monitoring and assessment》2008,136(1-3):379-390
This paper investigates the sandy desertification change between 1986 and 2000 in the western Jilin province, North China.
Land use and land cover data were obtained from Landsat TM data by using a supervised classification approach. We summarized
the total area of desertified land by each county, as well as the area for each of the four categories of desertified land.
The changes of different types of land use and land cover between 1986 and 2000 were calculated and analyzed. Taking Tongyu
and Qianan as examples, both human and natural driving forces of the sandy desertification were analyzed. Our analyses indicate
that the material sources and windy, warm and dry climate are the immanent causes of potential land desertification, while
the irrational human activities, such as deforestation, reclaiming and grazing in the grassland, are the external causes of
potential land desertification. However, rational human activities, such as planting trees and restoring grassland can reverse
the land desertification process. Furthermore, the countermeasures and suggestions for the sustainable development in ecotone
between agriculture and animal husbandry in North China are put forward. 相似文献
557.
Jonathan Davies 《Natural resources forum》2008,32(3):175-184
Sustainable development for Africa's mobile pastoralists is slowly becoming a reality. Success depends to a large extent on understanding the dynamics of drylands environments, accepting the logic of customary mobile livestock keeping, and enabling effective governance. Appropriate investment in pastoralism requires a clear understanding of the values that are attached to it and innovative approaches to marketing of the goods and services that emanate from the system. To make development truly sustainable it is imperative that the environmental services of pastoralism are recognised, rewarded and promoted. Constraints to sustainable pastoral development include low and misdirected public and private investment, weak security of resource rights, low human capital, weak pastoral voice and poor governance. Successful and sustainable development is observed in pastoral regions where customary governance has been legitimized, resource rights secured and economic development of the pastoral sector, as opposed to transformation of livestock keeping, has prevailed. This article presents state‐of‐the‐art knowledge on sustainable pastoralism, gathered through the GEF/UNDP/IUCN World Initiative for Sustainable Pastoralism (WISP), with data and case studies taken from three recently published WISP reports: “Global Economic Review of Pastoralism”, “Pastoralism as Conservation in the Horn of Africa”, and “Policy Impacts on Pastoral Environments”. 相似文献
558.
Morris J Bailey AP Lawson CS Leeds-Harrison PB Alsop D Vivash R 《Journal of environmental management》2008,88(2):372-381
In many river floodplains in the UK, there has been a long history of flood defence, land reclamation and water regime management for farming. In recent years, however, changing European and national policies with respect to farming, environment and flood management are encouraging a re-appraisal of land use in rural areas. In particular, there is scope to develop, through the use of appropriate promotional mechanisms, washland areas, which will simultaneously accommodate winter inundation, support extensive farming methods, deliver environmental benefits, and do this in a way which can underpin the rural economy. This paper explores the likely economic impacts of the development of flood storage and washland creation. In doing so, consideration is given to feasibility of this type of development, the environmental implications for a variety of habitats and species, and the financial and institutional mechanisms required to achieve implementation. 相似文献
559.
Australian reporting requirements for native vegetation require improved spatial and temporal information on the anthropogenic
effects on vegetation. This includes better linkage of information on vegetation type (e.g., native vegetation association),
extent and change, vegetation condition, or modification. The Vegetation Assets, States and Transitions (VAST) framework is
presented as a means for ordering vegetation by degree of anthropogenic modification as a series of condition states, from
a residual or base-line condition through to total removal. The VAST framework facilitates mapping and accounting for change
and trends in the status and condition of vegetation. The framework makes clear the links between land management and vegetation
condition states, provides a mechanism for describing the consequences of land management practices on vegetation condition,
and contributes to an understanding of resilience. VAST is a simple communication and reporting tool designed to assist in
describing and accounting for anthropogenic modification of vegetation. A benchmark is identified for each vegetation association.
Benchmarks are based on structure, composition, and current regenerative capacity. This article describes the application
of the VAST framework as a consistent national framework to translate and compile existing mapped information on the modification
of native vegetation. We discuss the correspondence between these compiled VAST datasets at national and regional scales and
describe their relevance for natural resource policy and planning. 相似文献
560.
The potential impacts of land use on large woody debris (LWD) were examined in Sourdough Creek Watershed, a rapidly growing
area encompassing Bozeman, Montana, USA. We identified six land classes within a 250 m buffer extending on either side of
Sourdough Creek and assessed aquatic habitat and geomorphologic variables within each class. All LWD pieces were counted,
and we examined 14 other variables, including undercut bank, sinuosity, and substrate composition. LWD numbers were generally
low and ranged from 0 to 8.2 pieces per 50 m of stream. Linear regression showed that LWD increased with distance from headwaters,
riparian forest width, and sinuosity in four of the six land classes. Statistically significant differences between land classes
for many aquatic habitat and geomorphologic variables indicated the impacts of different land uses on stream structure. We
also found that practices such as active wood removal played a key role in LWD abundance. This finding suggests that managers
should prioritize public education and outreach concerning the importance of in-stream wood, especially in mixed-use watersheds
where wood is removed for either aesthetic reasons or to prevent stream flooding. 相似文献