Spatial and temporal relationships between precipitation and ANPP of four types of grasslands in northern China

Precipitation is considered to be the primary resource limiting terrestrial biological activity in water-limited regions. Its overriding effect on the production of grassland is complex. In this paper, field data of 48 sites （including temperate meadow steppe, temperate steppe, temperate desert steppe and alpine meadow） were gathered from 31 published papers and monographs to analyze the relationship between above-ground net primary productivity （ANPP） and precipitation by the method of regression analysis. The results indicated that there was a great difference between spatial pattern and temporal pattern by which precipitation influenced grassland ANPP. Mean annual precipitation （MAP） was the main factor determining spatial distribution of grassland ANPP （r^2 = 0.61, P 〈 0.01）; while temporally, no significant relationship was found between the variance of AN PP and inter-annual precipitation for the four types of grassland. However, after dividing annual preeipitation into monthly value and taking time lag effect into account, the study found significant relationships between ANPP and precipitation. For the temperate meadow steppe, the key variable determining inter-annual change of ANPP was last August-May precipitation （r^2 = 0.47, P = 0.01）; for the temperate steppe, the key variable was July precipitation （r^2 = 0.36, P = 0.02）; for the temperate desert steppe, the key variable was April-June precipitation （r^2 = 0.51, P 〈 0.01）; for the alpine meadow, the key variable was last September-May precipitation （r^2 = 0.29, P 〈 0.05）. In comparison with analogous research, the study demonstrated that the key factor determining inter-annual changes of grassland ANPP was the cumulative precipitation in certain periods of that year or the previous year.     

Ecological monitoring of urban groups of stray dogs: An example of the city of petrozavodsk

The results of the census of stray dogs and data on their territorial distribution in the city of Petrozavodsk are reported. The population density of these animals has been found to vary within the urban area, depending mainly on the availability of secluded areas to live in and on population control by municipal services.     

Forest Cover Change,Physiography, Local Economy,and Institutions in a Mountain Watershed in Nepal

This study assessed changes in forest cover in a mountain watershed in central Nepal between 1976 and 2000 by comparing classified satellite images coupled by GIS analyses, and examined the association of forest change with major physiographic, economic, and local forest governance parameters. The results showed an increase in forested area (forest plus shrublands) by 7.6% during 1976–2000. Forest dynamism (changes including improvement, deterioration, gain, and loss) was highest in low-elevation, south-facing and less-steep slopes that were closer to roads. Proportionately the highest net improvement and gain to forested area also took place in those locations. Forest degradation occurred at twice the rate of improvement in high elevation areas (> 2300 m). Forests located in urban and semiurban areas (i.e., a market-oriented economy) experienced a proportionately higher amount of net improvement and gain than forests in rural areas (i.e., a subsistence economy). Among the three governance arrangements, proportionately the highest net improvement and gain took place in semigovernment forests (forested area legally under the forest department but with de facto control and claim of ownership by local communities and/or municipality) followed by formalized community forests (including leasehold). Government forests, which were mostly found in the southern high mountains and had virtually open access, remained relatively stable during the study period. Over 50% of the watershed forests have not come under community-based management despite favorable policy and more than two decades of government intervention with continuous donor support. The findings indicate that the present one size fits all approach of community forest handover policy in Nepal needs rethinking to accommodate biophysical and socioeconomic variations across the country.     

CHANNEL CHANGES DOWNSTREAM FROM A DAM1

ABSTRACT: A flood-control dam was completed during 1979 on Bear Creek, a small tributary stream to the South Platte River in the Denver, Colorado, area. Before and after dam closure, repetitive surveys between 1977 and 1992 at five cross sections downstream of the dam documented changes in channel morphology. During this 15-year period, channel width increased slightly, but channel depth increased by more than 40 percent. Within the study reach, stream gradient decreased and median bed material sizes coarsened from sand in the pools and fine gravel on the rime to a median coarse gravel throughout the reach. The most striking visual change was from a sparse growth of streamside grasses to a dense growth of riparian woody vegetation.     

应用SSIM模型反演与评估二氧化硫污染面源

针对在缺少有效二氧化硫低空面源排放清单的情况下,应用SSIM(SourceStrengthInversedModel)模式对SO2低空面源源强的反演功能,完成了天津市蓝天工程改燃措施实施后二氧化硫相对量化改善效果的模拟评估,同时模拟了SO2面源源强改善前后的空间分布,取得了较理想的效果。该模式所解决的污染面源源强核查难点问题,在城市大气环境容量核定中具有通用指导作用。     

洪水多站峰量同时模拟的随机模型

洪水过程是一复杂的随机动力系统，随机模拟技术至今仍是研究洪水过程时空统计特性的有力工具。该文以同时模拟上游站、下游站及其区间的最大洪峰流量、最大五日洪量和最大十二日洪量为例，建立了一种简便而适用的随机模型。实例结果表明，该随机模型是可行而有效的，在水资源系统工程的理论与实践中具有重要价值。     

INITIAL RESEARCH INTO CLIMATIC CHANGES AND GRASSLAND DEGENERATION IN INNER MONGOLIA

DuringtheimplementationoftheWestChinaDevelopmentStrategyinthetwenty firstcentury ,thenorthernsteppezoneplaysasignificantroleinsafeguardingtheecologicalsecurityandrealizingsustainabledevelopmentinChina .InnerMongoliaprairieliesinthemiddleofEurasiasteppezoneandisthetransitionzonefromthearidareasinthenorthwesttothehumidareasinthenortheastandthedryfarmingareasinNorthChina .Therigorousnaturalconditions ,thefluctuatingclimateandthecompli catedsocialandeconomicconditionsmakethisareaverysensitiveto…     

Analysis on Temporal and Spatial Changes and Driving Forces of Poverty-Stricken Areas in Hebei Province

1 INTRODUCTIONPoverty is a social phenomenon accompanying the processof human development (Shen Hong, 2000),it is also oneof the Three Ps problems (poverty, pollution andpopulation),alleviating and eliminating poverty has beenone of the major concerns in many countries. Since Chinesegovernment has implemented the anti-poverty programin a planned way in 1986, the number of impoverishedpopulation has decreased year by year, especially after theimplementation of National Seven-Year Anti-p…     

Monitoring morphological and vegetation changes and flow events in dryland river channels

Monitoring of impacts of floods in river valleys of dryland regions has become important with the onset and threats of desertification and is likely to become even more vital with predictions of increased effects of climate and land use change. It is also needed in order to conform to requirements of the EU Water Framework Directive. Monitoring in such regions sets particular challenges. This paper explains a system of low-cost monitoring of changes in morphology, vegetation and sediment cover in channels and valley floors of ephemerally flowing streams. It has been applied in SE Spain for 10 years and has proved very effective. In particular, the use of simple crest-stage recorders for measuring flow height and the use of real-time differential GPS for rapid and accurate survey and for relocating points have proved very valuable. Part of the monitoring is focused on the interaction of plants and channel processes. Small changes in and around vegetation associated with flow events have been detected by a combination of quadrat surveys and cross-profiling of the channel. A range of flow events has been measured over the period of monitoring, demonstrating their differing effects and the varying sensitivity and responsiveness of different sites. The sporadic occurrence of flood events in such an environment means that a strategy of monitoring several sites and of continuation over many years has great benefits.     

IMPACT OF SEWAGE TREATMENT MODIFICATIONS ON WATER QUALITY OF A RESERVOIR1

ABSTRACT. As a result of several investigations conducted in the Department of Civil Engineering through the Water Resources Research Center at The University of Tennessee, dating from 1966 to the present, a rather comprehensive surveillance of water quality conditions has been maintained in Forth Loudoun Reservoir on the Tennessee River near Knowville, Tennessee. During the period covered by these investigations, the Knoxville Third Creek Sewage Treatment Plant was upgraded from a primary plant to a secondary (activated sludge) treatment plant. Comparison of the collected data is being undertaken herein to elucidate the impact of these modifications upon water quality conditions in the reservoir. Consideration is given to the improvements of water quality as related to the expenditure for modification of the treatment facilities. In addition, comment is directed toward the public health significance of the water quality conditions determined.