Land Use of the Three Gorges Reservoir Area and the Effect on Its Landscape Pattern in the Recent 50 Years

The paper makes detailed analysis on the changing processes of the main types of land use in Three Gorges Reservoir Area through the techniques of RS （Remote Sense） and GIS （Geography Information System）. Based on the theory of landscape ecology, many types of landscape pattern indexes are calculated and made correlation analysis. The results indicate that： in 1995 the ecological environment of Three Gorges Reservoir Area was the most vulnerable in the recent 50 years, but resumed in 2002; the landscape pattern diversity index, fractal dimension index and fragmentation index has close correlation with the area of land use/cover change （LUCC）. The research also releases that the increase of the cultivated land, grassland and construction land deteriorates the landscape ecological pattern, while the increase of forest land area will help restore the landscape ecological pattern to its original state. The rapid change of grassland is an important index of the change of landscape pattern, because it has the most effect on change of landscape pattern index.     

landscape Changes in Wenchuan—A Mountainous County in Sichuan, China

Based on the collection of land use maps of three repre sentative years (1972, 1986 and 1995) with a scale of 1 = 100 000, which were derived from interpreted aerial photographs and field surveys, landscape pattern were studied in Wenchuan County of Aba Prefecture, northwest of Sichuan Province, China, Six land use categories were classified according to the actuality of the study area and digitized by manual with the assistance of Geographic Information System (GIS). Landscape spatial and temporal changes were analyzed quanti ficationally by a series of structure, shape, pattern indices, which indicated that grassland dominates in number of patch while both grassland and shrub-land dominate in total area of patch over time. During the last 23 years, the fractal dimension of grassland and shrub-land were decreased while the other types were increased. Highest dominance and fragmentation and lowest diversity characterized the landscape of 1972. In 1986, the landscape pattern had the highest diversity and lowest dominance and fragmentation, which is contrary to the pattern in 1972, Slight change of diversity, dominance and fragmentation has been displayed from 1986 to 1995.     

Stability of patches of oasis landscape in arid areas:A case study of Sangong River Watershed,Xinjiang,China

The stability of oases is one of the key scientific issues in the process of evolution and management of oases in arid areas. The stability of oases and its representation are also different at different scales. This paper deals with the stability of oases at the landscape patch scale with a case study in the Sangong River Watershed of Tianshan Mountains. We employed the remote sensing, geographic information system and mathematical statistical methods to process the remote sensing images of three periods in 1978, 1987 and 1998, and put forward the approaches for representing the oasis stability at the landscape patch scale. The landscape control capacity of oasis patches is a kind of natural driving forces of the dynamic landscape change. The control capacity of a certain patch type on landscape change increases with its area and shape complexity and contrasts between it and other patches, and reduces with its spatial distances between it and other patches. The patch type with the strongest control capacity should be the matrix of landscape. The conversion of oasis landscape patches results from both natural and anthropogenic driving forces, particularly the anthropogenic driving forces. The higher the conversion proportion is, the lower the stability of patch types is and the stronger the anthropogenic disturbance is. The patch type with the strongest net control capacity in the Sangong River Watershed in 1987 was the desert grassland, which was the matrix of landscapes; but the matrix of landscapes had been changed into the irrigated lands in 1987 and 1998. The control capacities of landscape patches on the oasis landscape evolution have gradually reduced with time in the Sangong River Watershed, and the change extents also have reduced gradually. This reveals that the interaction among the landscape patch types generally tends to reduce, and the natural stability of the oasis landscape patches generally tends to increase. However, the conversion among the landscape patches occurs more frequently due to the increase of intensive human activities, which probably causes the lower stability of environmental resources patch and higher stability of introduced patches in the oasis landscape.     

Evaluation of soil fertility of the shelter-forest land along the Tarim Desert Highway

To study the changes of soil fertility of the shelter-forest land along the Tarim Desert Highway, soils from the forest land were collected at the layers of 0―10 cm, 10―20 cm, 20―30 cm. Different soil fertility parameters were measured, and quantitative evaluation of soil fertility was performed by the soil integrated fertility index (IFI). The main results show that the construction of the shelter forest along the Tarim Desert Highway improved the soil physical structure, increased soil porosity and enhanced wa- ter-holding capacity. With the increase of plantation time of the shelter forest, soil microbial biomass C, N, P and the activities of six types of enzyme were enhanced, which promoted the accumulation and transformation of soil nutrients of the forest land. Consequently, the soil nutrients in 12-year-old forest land were much higher than in the newer ones and drifting sand. However, soil salt content of the older forest land was higher owing to the drip-irrigation with salt water. Through the comprehensive evalua- tion, we found that soil fertility index in the forest land was enhanced with the forest age, and it had close correlations with the growth indices of the forest trees. In summary, construction of the shelterforest along the Tarim Desert Highway accelerated the improvement of aeolian soil in the forest land, and the soil fertility improved year by year. We conclude that the forest trees grow normally under the stress of the present drip-irrigation with salt water.     

Gradient Analysis of Urbanization Pattern Based on Class-level Landscape Metrics for Shanghai Region

The spatial pattern of urbanization in the Shanghai metropolitan area is quantified with GIS-based land use data set and gradient analysis of landscape metrics. A number of landscape metrics were computed along a 64 km long and 6 km wide west-east transect and another 66 km long and 6 km wide south-north transect. The results of transect analysis with class-level metrics showed that the spatial pattern of urbanization could be reliably quantified using landscape metrics with a gradient analysis approach, and the location of the urbanization center could be identified precisely and consistently with multiple indices of the landscape metrics used in this study. Different land use types exhibited distinctive, but not necessarily unique, spatial signatures that were dependent on specific landscape metrics. These results seemed to characterize the urban core of the Shanghai metropolitan area rather accurately and precisely: Agriculture patches were abundant and less fragmented; the urban land use types were extensive, having many small patches and highly fragmented.     

Carbonate rock dissolution rates in different landuses and their carbon sink effect

Research on karst processes is important for the determination of their carbon sink potential,as is research into terrestrial ecosystems in karst areas.Solutional denudation rates of soils from three karst spring watersheds supporting different land uses were studied.Solution rates showed a distinct pattern based on land use,with a generally higher rate being recorded in forest use soil.The mean values for tablet dissolution from the cultivated land,shrublands,secondary forest,grassland and primary forest were 4.02,7.0,40.0,20.0,63.5 t km-2 a-1 respectively.Changes in vegetation patterns could improve the size of karst carbon sinks;for example,in this study the carbon sink was 3 times higher in primary forest than in secondary forest soil and 9 times higher than under shrubland,equating to an increase from 5.71-7.02 to 24.86-26.17 t km-2 a-1 from cultivated land or shrub to secondary forest and to primary forest,respectively.     

Extracting change information of land use and soil erosion based on RS & GIS technologystration

Rapid landuse change has taken place in many arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. Landuse change and soil erosion dynamics were investigated by the combined use of remote sensing and geographic information systems (GIS). The objectives were to determine landuse transition rates and soil erosion change in Yulin prefecture over 15 years from 1986 to 2000. Significant changes in landuse and soil erosion occurred in the area over the study period. The results show the significant decrease in barren land mainly due to conversion to grassland. Agricultural land increased associated with conversions from grassland and barren land. The area of water erosion and wind erosion declined. The study demonstrates that the integration of satellite remote sensing and GIS is an effective approach for analyzing the direction, rate, and spatial pattern of landuse and soil erosion change.     

Three-year changes of surface albedo of degraded grassland and cropland surfaces in a semiarid area

Diurnal, seasonal and interannual variations of surface albedo of degraded grassland and cropland surfaces at a semiarid area of Tognyu have been investigated based on the continuous three years observational data from 2003 to 2005. The changes of surface albedo with solar elevation angle and soil moisture have been discussed also. It has been found that surface albedo has almost the same diurnal and seasonal variations on degraded grassland and cropland surfaces in the semiarid area, while surface albedo is large in winter and small in summer. The diurnal variation of the surface albedo has relationship with the weather condition. The diurnal cycle of the surface albedo likes the ＂U＂ shape curve in sunny day, while it is low-high after the rain, and high-low after the snow. The surface albedo has large variation in cloudy day, while it has no any variation in overcast day. The large difference of the surface albedo can be 0.04 in winter between two land surfaces, because the snow has large effects on the surface albedo in winter. The rainfall is an important factor in summer on the surface albedo, while the difference of the surface albedo is 0.01 only between two land surfaces. The differences of the surface albedo can also be 0.04 in autumn due to vegetation growing. The seasonal-average surface albeo from 2003-2005 is 0.25, 0.22, 0.24, 0.32 respectively in spring, summer, autumn and winter on the degraded grassland surface, while it is 0.25, 0.21,0.22, 0.33 respectively in spring, summer, autumn and winter on the cropland surface. The surface albedo becomes smaller with the increase of solar elevation angle. When the solar elevation angle is greater than 40°, the surface albedo changes very little and tends to be a constant. The surface albedo has negative exponent functions with soil moisture in the growing season.     

Using 137Cs tracing technique to estimate wind erosion rates in the typical steppe region,northern Mongolian Plateau

Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using ^137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km^-2.a^-1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm. a^-1, and wind erosion rates up to 6723.06 t· km^-2. a^-1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not induce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.     

Using ~(137)Cs tracing technique to estimate wind erosion rates in the typical steppe region, northern Mongolian Plateau

Wind erosion is one of the major factors of land degradation in the typical steppe region, northern Mongolian Plateau. Using 137Cs tracing technique, we estimated the wind erosion rates of different pastures and abandoned farmland at Bayannur and Karakorum in Mongolia. The pastures and cutting grassland at Bayannur were slightly eroded by wind, with the rates of 64.58-169.07 t·km?2·a?1. The abandoned farmland in Karakorum, however, was strongly eroded by wind, with annual surface soil loss of 4.05 mm·a?1, and wind erosion rates up to 6723.06 t·km?2·a?1. The total loss of surface soil due to wind erosion has been 17.4 cm since the cultivation of the steppe land in the 1960s. The wind ero- sion rate at the abandoned farmland was much higher than that at the typical steppe sites, showing that the cultivation led to serious wind erosion in the typical steppe region, northern Mongolian Plateau. By contrast, traditional livestock grazing resulted in less disturbance to the surface soil, and did not in- duce to devastating wind erosion, which plays an important role in maintaining the stability of the steppe ecosystem in the northern Mongolian Plateau.     

Estimation of surface soil moisture from ASAR dual-polarized data in the middle stream of the Heihe River Basin

In this paper, a new approach was introduced to estimate surface soil moisture using alternating polarization (AP) data of advanced synthetic aperture radar (ASAR). First, synthetic aperture radar (SAR) backscattering characteristic of bare surface at C band was simulated using advanced integrated equation model (AIEM), and four bare surface backscattering models with different polarization were established. In addition, with simultaneous equations of the former four formulas, the surface roughness was eliminated, and models used to estimate soil moisture on bare surface were derived from simulated multipolarization and multiangle ASAR-AP data. Based on these, the best combination of polarization and incident angle was determined. Finally, soil moisture in the middle stream of the Heihe River Basin was estimated. The field measured data demonstrated that the proposed method was capable of retrieving surface soil moisture for both sparse grassland and homogeneous farmland area.     

Study on the Spreading of Environmental Impact of Human Being＇s Activities and Its Crucial Factors in Upper Minjiang River

This paper focuses on the historical transition of human being‘‘s activities and the eco-environment in the upper reaches of Minjiang River. The history is divided into 4 periods, each with its own feature.During the period of nomad immigration, the top-line of the subalpine forest was forced downward by the expanding subalpine meadow. During the period of farming nationality immigration, the bottom-line of middle mountain forest had moved upward forced by the needs for land or timber of the increasing population in the valley basin. During the period of the early exploiting, the focus resource was the timber. The total output was limited, comparing with the later period, because of the bad accessibility.But it was large enough to impact the forest ecosystem of the deforesting area. The recent 50 years is the crucial period of economic development and eco-environment degradation. This paper points out that the impact of human being‘‘s activities for environment lies on 3 factors: 1) physical features control the location and tendency eco-environmental change;2) population and productivity control the scale and speed of eco-environmental change; 3) regional accessibility controls the time and location of eco-environmental change.     

Vegetation Restoration Technique System and Its Ecological Functions of the Degraded Ecosystem in the Arid-Hot Valleys —— Taking the Example of Typical Mode in Small Watershed of Yuanmou

This paper concluded the vegetation restoration technique system in the arid-hot valleys and studied the anti-erosion function, environmental function and biological diversity effects of vegetation restoration on the ecosystem in the arid-hot valleys. The results showed that the soil erodibility decreased significantly after the vegetation restoration. The climate environment of the small watershed had a great improvement after the vegetation restoration, of which the temperature decreased, the humidity increased, the harsh environment of dry and hot in this region changed. The studies of the ecosystem biodiversity were mainly on the analysis of the relations between biodiversity and ecological function of the artificial ecological forest pattern and the natural enclosed treatment mode on the severely of degraded land. It could conclude that the natural enclosed treatment mode is helpful to the biodiversity of the ecosystem and the improvement and stability of the ecosystem, and Leucaena artificial forest restoration pattern reduced the species diversity but optimized the ecological function. Therefore, as to the severely and extremely severely degraded ecosystem in the arid-hot valleys, Leucaena pattern of gully control and natural enclosed treatment mode are the relatively optimal choices.     

Corridor effect of the spatial changes of landscape patterns in arid areas： A case study of the river corridor areas in the middle and lower reaches of Tarim River

The river corridor areas in the middle and lower reaches of the Tarim River are dominated by the traditional green corridors along the river section from the Qara Reservoir in Yuli County to the Taitema Lake in Ruoqiang County, which plays an important role in the social and economic development in the Tarim River Wate＇rshed with a extremely significant ecological functions. The buffer zones perpendicular to the watercourse were defined along both riversides at a 5-km interval beginning from the watercourse （10 km wider） using the method of the buffer zone analysis. The landscape pattern indexes of each buffer zone were calculated, and the indexes of the main landscape patterns were analyzed so as to reveal the radiative effect and the characteristics of the river corridors on landscape and patch levels. The results show that the radiative width is generally 30 km in the study area, and can be up to 50-70 km in subregion FG1 because the study area is located in two drainage basins, with an ecological interstitial zone between them. The landscapes of woodlands and wetlands are generally distributed within the 10 km buffer zone （it means that the buffer zone is 5 km away from the watercourse; the same hereafter） along both riversides. Moreover, the closer the buffer zone is to the watercourse, the higher the patch density and the largest patch index are. In the ecological and environmental regeneration for the study area, the extent of ecological effect of the river corridors must be fully considered, and the projects must be scientifically and rationally planned and designed.     

Corridor effect of the spatial changes of landscape patterns in arid areas:A case study of the river corridor areas in the middle and lower reaches of Tarim River

The river corridor areas in the middle and lower reaches of the Tarim River are dominated by the traditional green corridors along the river section from the Qara Reservoir in Yuli County to the Taitema Lake in Ruoqiang County, which plays an important role in the social and economic development in the Tarim River Watershed with a extremely significant ecological functions. The buffer zones perpendicular to the watercourse were defined along both riversides at a 5-km interval beginning from the watercourse (10 km wider) using the method of the buffer zone analysis. The landscape pattern indexes of each buffer zone were calculated, and the indexes of the main landscape patterns were analyzed so as to reveal the radiative effect and the characteristics of the river corridors on landscape and patch levels. The results show that the radiative width is generally 30 km in the study area, and can be up to 50-70 km in sub- region FG1 because the study area is located in two drainage basins, with an ecological interstitial zone between them. The landscapes of woodlands and wetlands are generally distributed within the 10 km buffer zone (it means that the buffer zone is 5 km away from the watercourse; the same hereafter) along both riversides. Moreover, the closer the buffer zone is to the watercourse, the higher the patch density and the largest patch index are. In the ecological and environmental regeneration for the study area, the extent of ecological effect of the river corridors must be fully considered, and the projects must be scientifically and rationally planned and designed.     

The spatial distribution of forest carbon sinks and sources in China

Forest ecosystems play an important role in the global carbon cycle.The implementation of the United Nations Framework Convention on Climate Change(UNFCCC) and the Kyoto Protocol has made the study of forest ecosystem carbon cycling a hot topic of scientific research globally.This paper utilized Chinese national forest inventory data sets(for the periods 1984-1988 and 1999-2003),the vegetation map of China(1:1000000),and the spatially explicit net primary productivity(NPP) data sets derived with the remote sensing-based light use efficiency model(CASA model).We quantitatively estimated the spatial distribution of carbon sinks and sources of forest vegetation(with a resolution of 1 km) using the spatial downscaling technique.During the period 1984 to 2003 the forest vegetation in China represented a carbon sink.The total storage of carbon increased by 0.77 PgC,with a mean of 51.0TgCa 1.The total carbon sink was 0.88PgC and carbon source was 0.11 PgC during the study period.The carbon sink and carbon source of forest vegetation in China showed a clear spatial distribution pattern.Carbon sinks were mainly located in subtropical and temperate regions,with the highest values in Hainan Province,Hengduan mountain ranges,Changbai mountain ranges in Jilin,and south and northwest of the Da Hinggan Mountains;carbon sources were mainly distributed from the northeast to southwestern areas in China,with the highest values mainly concentrated in southern Yunnan Province,central Sichuan Basin,and northern Da Hinggan Mountains.Increase in NPP was strongly correlated with carbon sink strength.The regression model showed that more than 80% of the variation in the modeled carbon sinks in Northeast,Northern,Northwest and Southern China were explained by the variation in NPP increase.There was a strong relationship between carbon sink strength and forest stand age.     

Effect of land use on microbial biomass－C, －N and －P in red soils

Eleven red soils varying in land use and fertility status were used to examine the effect of land useon microbial biomass -C, -N and -P. Microbial biomass-C in the red soils ranged from about 68 rag C/kg to 225 mg C/kg, which is generally lower than that reported from other types of soil, probably because of low or-ganic matter and high acidity in the red soils. Land use had considerable effects on the amounts of soil Cmic.The Cmic was the lowest in eroded fallow land, followed by woodland, tea garden, citrus grove and fallow grassland, and the highest in vegetable and paddy fields. There was significant correlation between Cmic and organic matter content, suggesting that the influence of land use on Cmie is mainly related to the input and ac-cumulation of organic matter. Microbial biomass-N in the soils ranged from 12.1 Nmg/kg to 31.7 Nmg/kg andwas also affected by land use. The change of Nmic with land use was similar to that of Cmic. The microbial C/N ratio ranged from 5.2 to 9.9 and averaged 7.6. The Nmic was significantly correlated with soil total N and available N. Microbial biomass-P in the soils ranged from 4.5 mg P/kg to 52.3 rag P/kg. The microbial C/P ratio was in the range of 4-23. The Pmic was relatively less affected by land use due to differences in fertili-zation practices for various land use systems.     

Effects of Land Use Change on the Ecosystem Services Value in the Dry-Hot Valley

The objective of the study reported here was to determine whether LANDSAT TM images could be used to quantify changes in land-use and ecosystem services in Yuanmou County. The sizes of six land use/land cover （LUCC） categories were estimated in Yuanmou County according to the LANDSAT TM images in the summer of 1986 and 2005. Coefficients published by Xie Gaodi and co-workers in 2003 were used to value changes in ecosystem services delivered by each land use/land cover category, and the ecosystem services sensitivity analysis was conducted to determine the effect of manipulating these coefficients on the estimated values. The important results are summarized as followings. （1） The estimated size of cultivated land, pasture land, water area and unused land decreased by 6.39%, 1.35%, 2.25% and 10.67% respectively between 1986 and 2005. By contrast, the estimated size of forest land and construction land increased by about 2.23% and 71.15% respectively between 1986 and 2005. （2） The total ecosystem services value （EVS） of the study area increased from 2 142 132 609.46 yuan to 2 146 416 621.00 yuan, with the net increase of 4 284 011.54 yuan during the 20-year time period. （3） The coefficient sensitivity （CS） of the study are less than unity in all cases （CS 〈 1）. This indicates that the total ecosystem values estimated for the study area are relatively inelastic with respect to the ecosystem service coefficients. While this implies that our estimates are robust and the coefficient is reasonable, highly under or over valued coefficients can substantially affect the veracity of estimated changes in ecosystem service values overtime even when the CS are less than unity（CS 〈 1）.     

Scenario simulation and forecast of land use/cover in northern China

Modeling land use/cover scenario changes and its potential impacts on structure and functions of ecosystem in typical regions are helpful to understanding the interactive mechanism between land use/cover system and ecosystem. Based on the analysis of the existing land use/cover simulation and forecast models, a land use/cover scenario dynamics model by the integration of System Dynamics （SD） model, Back Propagation Neural Network （BPNN） and Cellular Automata （CA） model is developed with land use/cover scenario changes in northern China in the next 30 years and simulated in this paper. The model is to simulate the land use/cover scenario demands by using a SD model at first, and then allocating the land use scenario patterns at the local scale with the considerations of land use/cover suitability, inheritance ability and neighborhood effect by using BPNN-CA model to satisfy the balance between land use/cover scenario demands and supplies. It integrates the advantages of SD, BPNN and CA. Macro-driving factors and the micro-spatial pattern are also fully taken into account. The BPNN simplifies the identification of the factors＇ weights used in CA model and improves the reliability of the simulation results. The simulation accuracy of the model developed in this paper was found to be about 74%. It suggests that the model has the ability to reflect the complexity of land use/cover system at different scales to some extent and it is a useful tool for assessing the potential impacts of land use system on ecosystem. The simulated results also indicate that the urban land, water area and forest will increase significantly, and farmland and unable land will decrease gradually. Obvious land use/cover changes will take place in the farming-pastoral zone and the southeast area of northern China.     

Response of soil nutrients to different cropping systems in the oasis of arid land

In the process of transformation of tropic rain forest and semi-arid grassland to farmland, the soil degradation usually occurs. But the transformation of arid desert to oasis is likely to differ from that of tropic rain forest and semi-arid grassland. Taking an alluvial plain oasis as a study case, the oasis soil properties during the process of the transformation of different cropping systems have been investigated and evaluated. Selected cropping systems consist of saline tolerance crop （STC）, food crop （FC）, melon and vegetables （MV）, Economic plants-cotton （EP-C） economic plants-grape （EP-G）, Economic plants-Hop （EP-H）. Surface soil （0-20 cm） samples were collected in 1982, 1999 and 2003. Soil, organic matter （OM）, and available N （AN）, available P （AP） and available K （AK） were determined for each soil sample. SPSS statistical software was used to analyze the soil property data. The transformation of cropping systems in the Sangong River watershed was affected directly by the policy, law and market. The soil OM contents experienced a decline during 1982- 1999, then a rise during 1999-2003. AN, AP and AK contents increased significantly with cultivated time. Soil OM tends to decrease during the conversion from STC and FC to cotton but increase during the conversion from the cotton to the grape. The soil OM was increased gradually with the cultivation time, so the oasis soil presented carbon sink, which indicates that human activities was reasonable and favorable for improvement of the oasis-ecosystem.