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601.
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
602.
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
603.
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
604.
Mingliang Liu Hanqin Tian Guangsheng Chen Wei Ren Chi Zhang Jiyuan Liu 《Journal of the American Water Resources Association》2008,44(5):1193-1207
Abstract: China has experienced a rapid land‐use/cover change (LUCC) during the 20th Century, and this process is expected to continue in the future. How LUCC has affected water resources across China, however, remains uncertain due to the complexity of LUCC‐water interactions. In this study, we used an integrated Dynamic Land Ecosystem Model (DLEM) in conjunction with spatial data of LUCC to estimate the LUCC effects on the magnitude, spatial and temporal variations of evapotranspiration (ET), runoff, and water yield across China. Through comparisons of DLEM results with other model simulations, field observations, and river discharge data, we found that DLEM model can adequately catch the spatial and seasonal patterns of hydrological processes. Our simulation results demonstrate that LUCC led to substantial changes in ET, runoff, and water yield in most of the China’s river basins during the 20th Century. The temporal and spatial patterns varied significantly across China. The largest change occurred during the second half century when almost all of the river basins had a decreasing trend in ET and an increasing trend in water yield and runoff, in contrast to the inclinations of ET and declinations of water yield in major river basins, such as Pearl river basin, Yangtze river basin, and Yellow river basin during the first half century. The increased water yield and runoff indicated alleviated water deficiency in China in the late 20th Century, but the increased peak flow might make the runoff difficult to be held by reservoirs. The continuously increasing ET and decreasing water yield in Continental river basin, Southwest river basin, and Songhua and Liaohe river basin implied regional water deficiency. Our study in China indicates that deforestation averagely increased ET by 138 mm/year but decreased water yield by the same amount and that reforestation averagely decreased ET by 422 mm/year since most of deforested land was converted to paddy land or irrigated cropland. In China, cropland‐related land transformation is the dominant anthropogenic force affecting water resources during the 20th Century. On national average, cropland expansion was estimated to increase ET by 182 mm/year while cropland abandonment decreased ET by 379 mm/year. Our simulation results indicate that urban sprawl generally decreased ET and increased water yield. Cropland managements (fertilization and irrigation) significantly increased ET by 98 mm/year. To better understand LUCC effects on China’s water resources, it is needed to take into account the interactions of LUCC with other environmental changes such as climate and atmospheric composition. 相似文献
605.
The United Nations Convention to Combat Desertification (UNCCD) has lacked an efficient mechanism to access scientific knowledge since entering into force in 1996. In 2011 it decided to convene an Ad Hoc Working Group on Scientific Advice (AGSA) and gave it a unique challenge: to design a new mechanism for science-policy communication based on the best available scientific evidence. This paper outlines the innovative ‘modular mechanism’ which the AGSA proposed to the UNCCD in September 2013, and how it was designed. Framed by the boundary organization model, and an understanding of the emergence of a new multi-scalar and polycentric style of governing, the modular mechanism consists of three modules: a Science-Policy Interface (SPI); an international self-governing and self-organizing Independent Non-Governmental Group of Scientists; and Regional Science and Technology Hubs in each UNCCD region. Now that the UNCCD has established the SPI, it is up to the worldwide scientific community to take the lead in establishing the other two modules. Science-policy communication in other UN environmental conventions could benefit from three generic principles corresponding to the innovations in the three modules—joint management of science-policy interfaces by policy makers and scientists; the production of synthetic assessments of scientific knowledge by autonomous and accountable groups of scientists; and multi-scalar and multi-directional synthesis and reporting of knowledge. 相似文献
606.
Impact of land use and land cover changes on the ambient temperature in a middle scale city, Takamatsu, in Southwest Japan 总被引:1,自引:0,他引:1
Atsuko Nonomura Mutsuko Kitahara Takuro Masuda 《Journal of environmental management》2009,90(11):3297-3304
There is a lack of information on urban heat island impact on the thermal environment due to low populated urban sprawl, although densely populated urban sprawl impact has been identified by several researchers. The Takamatsu area has recently developed in a low populated urban sprawl style without any increase in population. This paper examined the impact of a low populated urban sprawl on the thermal environment through an analysis of the last 30 years data set and investigated the contribution of vegetation fraction and population density to the temperature trend. As a consequence, it was shown that one of the most significant causative factors of temperature increase is an expansion of non-vegetated area even without population growth. This result implied that vegetated zones should be maintained in urban areas in order to realize sustainable urbanization. 相似文献
607.
利用TM遥感影像数据,运用ENVI及GIS技术,提取典型喀斯特城区(白云区)2002~2013年的土地利用覆盖类型,并反演出地表温度,从而进一步分析探讨土地利用变化对地表温度的影响。贵阳市白云区是贵阳市重点工业区和新2型工业集中分布区,在2002~2013年土地利用变化明显,特别是城区建设用地增加显著,从35.11增加到71.81 km,并占用了大量耕地和灌疏林。白云区土地利用类型的变化引起地表温度的改变,尤其是建设用地的扩张对地表温度影响较大。对地表温度与NDVI关系进行分析,结果表明不同土地类型的地表温度与NDVI相关程度不同。 相似文献
608.
Carbon farming policies aim to contribute to climate change mitigation, but their success strongly depends on whether landholders actually adopt desired practices or participate in offered programs. The Australian Government’s Carbon Farming Initiative and Emissions Reduction Fund policies were designed to incentivise the adoption of carbon farming practices. Although these policies have been active since December 2011, farmer engagement has been limited, and net emissions reductions low as a result. We surveyed broad-acre farmers in the Western Australian wheatbelt to explore their drivers and barriers to adopting carbon farming practices and participating in carbon farming policy programs. Drivers of adoption included knowledge and perception of co-benefits (for yield, productivity, and the environment), knowing another adopter, and believing that changes to farm management are an appropriate method to reduce Australia’s greenhouse gas emissions. Barriers to adoption included lack of information, uncertainty and costs. The key barrier to participation was policy and political uncertainty. The determinants of adoption and participation that we identify in our study offer important insights into how to best ensure the success of Australia’s land sector-based climate change policies. We conclude that, to increase landholder engagement, the co-benefits and climate change benefits of carbon farming practices must be actively promoted, and additional information is needed about the costs associated with adoption. Information diffusion is best achieved if it actively leverages landholder social networks. Finally, our results indicate that landholder buy-in to carbon farming could be greatly enhanced by achieving more continuity in Australian climate change policies and politics. 相似文献
609.
Oasis land-use change and its environmental impact in Jinta Oasis, arid northwestern China 总被引:3,自引:0,他引:3
Land use change resulted in land degradation is a focus of research on global environmental changes and plays a significant
role in the stability and economic development of oases in arid regions of China. Jinta Oasis, a typical oasis of temperate
arid zone in northwestern China, was investigated to assess land-use change dynamics during 1988–2003 with the aid of satellite
remote sensing and GIS, and to explore the interaction between these changes and oasis environment. Six land-use types were
identified, namely: cropland, forestland, grassland, water, urban or built-up land, and barren land. The results indicate
that cropland, urban/built-up land, and barren land increase greatly by 30.03, 13.35, and 15.52 km2, respectively; but grassland and forestland areas decrease rapidly by 58.06, and 1.76 km2, respectively. These results also show that obvious widespread changes in land-use occur within the whole oasis over the
study period and result in severe problems of environmental degradation (i.e. land desertification, decline of groundwater,
and vegetation degeneracy). 相似文献
610.