In this paper, we developed a series of assessment indexes based on the evaluation of ecological effects, which consists of the ecosystem structure, qualities, services, and main impacting factors for these changes. Comprehensive monitoring and assessment methods that focused on the planning objectives of ecological conservation and restoration project were developed based on field observation, remote sensing monitoring and quantitative simulation of ecological processes. Then we assessed the ecological effects of the first-stage of ecological conservation and restoration project in Sanjiangyuan region by adopting the trend analysis of dynamics in ecosystem structure and services. The results showed that since the beginning of the project eight years ago, the macro-situation of ecosystem in this region has been getting better but not reached the best situation in the 1970s. The continued degradation trends of grassland have been initially contained, but it is difficult to achieve the expected objective of "the vegetation coverage of grassland increasing by an average of 20%-40%". The wetland and water-body ecosystems have been restored. The water conservation service of ecosystem and water supply capacity of watershed were increased, and the volume of?ecosystem water conservation reached the objective of increasing by 1.32 billion m3. The ecological restoration in the project regions tended to be better than that outside the project regions. In addition to climate change, implementation of the ecological conservation and restoration project had obvious and positive effects on vegetation restoration. However, the degradation situations of grassland were not fundamentally reversed, and the implementation of the project has not been curbing the increasing trend of soil erosion. Therefore, the local and preliminary characteristics of the first-stage of the project highlighted the long-term and arduous ecosystem conservation and protection in the Sanjiangyuan region.
In this paper, field sampling data, remote sensing data, and ground meteorological observation data were used to estimate the net primary productivity (NPP) in the grassland ecosystem in Inner Mongolia from 2001 to 2012 based on a light use efficiency model. The spatiotemporal distribution of the NEP in the Inner Mongolia grassland ecosystem was then analyzed by estimation of the NPP and soil respiration from 2001 to 2012. This paper also investigated the response of the NPP and NEP to main climatic variables on the spatial and temporal scales from 2001 to 2012. Results showed that most of the grassland area in Inner Mongolia has functioned as a carbon sink since 2001 and that the annual carbon sequestration rate amounts to 0.046 Pg C·yr-1. The total net carbon sink of the Inner Mongolia grassland ecosystem over the 12-year period reached 0.557 Pg C. The carbon sink area accounted for 60.28% of the total grassland area and sequestered 0.692 Pg C, whereas the C source area accounted for 39.72% of the total grassland area and released 0.135 Pg C. The NPP and NEP of the Inner Mongolia grassland ecosystem have more significant correlations with precipitation than with temperature, and the Inner Mongolia grassland ecosystem has great potential for carbon sequestration.
In this study, we selected Hunan province as the study area. The vegetation NPP and its changes from 2000 to 2013 were calculated using improved Carnegie-Ames-Stanford Approach (CASA) model with MODIS-NDVI data at a 250 m×250 m spatial resolution and meteorological data. Furthermore, we quantitatively analyzed the correlation between NPP and climate for various land-cover types so as to provide reliable information for local environment and sustainable development. The results indicate that: (1) The annual amount of NPP decreased from 41.62 Tg C/yr in 2000 to 125.40 Tg/yr in 2013, with an average being about 86.34 Tg C/yr. In general, the total amount of NPP has decreased obviously since 2000, with an annual rate of about 2.70 Tg C/yr. (2) The annual NPP from 2000 to 2013 had significant spatial differences throughout the study area, decreasing from the southwest to the northeast. There were obvious differences over various vegetation divisions. (3) According to the changes rate of NPP from 2000 to 2013, the study area could be divided into five regions, namely, extremely remarkable increase rate (slope > 0, p < 0.01), remarkable increase rate (slope > 0, 0.01 ≤ p < 0.05), unnoticeable rate (p ≥ 0.05), extremely remarkable decrease rate (slope < 0, p < 0.01) and remarkable decrease rate (slope < 0, 0.01 ≤ p < 0.05), which accounted for 5.40%, 2.02%, 61.64%, 16.79% and 14.15%, respectively. In general, NPP decreased from 2000 to 2013 over different land-cover types, among which, the most significant change took place in grassland and forestland, followed by other types of land, construction land and farmland. (4) The spatial distribution of NPP had higher correlation with precipitation than with temperature.
The identifying of land multifunctionality is a basic tool for organization, coordination and configuration of urban land, and is a key criterion for urban land functions forms, composite pattern and dynamic tradeoffs. This topic is of important theoretical and practical significance. An available identification system of urban land multifunctionality, however, had not been built for a long time. This paper develops a function classification system for urban ecological-production-living spaces from an integrated perspective of land function, ecosystem services and landscape function. We integrated a value function group of space function based on ecosystem services valuation. A comparison method of vertical and cross direction is proposed to identify dominant function type of urban land. The empirical results show that in the study area, function classification system of urban ecological-production-living spaces can reflect differentiated function types of different land use classes. The identified result of dominant function for urban space is matched with the functions of different land types. Meanwhile, we also found that there are some problems on urban land use, such as the low adjacency degree with different spaces, and poor complementarity with different space functions. The result indicates that the spatial distribution of urban ecological-production-living spaces is congregated in the study area.
Since 1973, the observed runoff of the uncontrolled areas of the section between Hekouzhen and Wubao of the Yellow River has remarkably decreased, or even, it had been dried up for a quarter of the years; based on the rainfall-runoff relationship between 1956 to 1972, the observed runoff decreased by 84% under the rainfall condition from 1973 to 2014. In this paper, the analysis results showed that the relationship between recharge, runoff and drainage of groundwater and in the Tianqiao spring region of the Yellow River has changed because of reservoir operation along the main stream of this section. This not only significantly reduced the spring recharge into the Yellow River on the left bank, but also increased the amount of leakage to the karst aquifer on the right bank. It is the main reason for the remarkable observed runoff reduction of the uncontrolled areas of section between Hekouzhen and Wubao of the Yellow River. In comparison of rainfall-runoff relationships in different periods, and analysis of water reducing effect of other underlying factors, such as vegetation, terraces and surface water evaporation of dams, the calculation results showed that changes of the recharge relationship between spring water and runoff resulted in runoff reduction of about 600-800 million m3 per year on average in the Yellow River.
Based on the river system data in the 1960s, 1980s and 2010s, the indicator system of quantitative description of river systems change characteristics was established, then the spatial-temporal changes of river systems and its relationship with urbanization in Jiaxing over the past 50 years was analyzed. Results indicated that: (1) Over the past half century, river systems of Jiaxing showed a decline trend. Specifically, the river development coefficient, river density and water surface ratio decreased by 58.91%, 28.94% and 14.09%, respectively. However, the degradation of the river systems varies in different urbanization stages. (2) In the whole urbanization process, the spatial differences of the changes of the river development coefficient and main river area length ratio were extremely large, and the spatial differences of the changes of the river density and water surface ratio were larger, but the spatial differences of the changes of the box dimension and river sinuosity were relatively small. (3) The decline trend of the river development coefficient, box dimension and river density was more significant in the urban area than that in the suburbs and outer suburbs, the decline trend of the water surface ratio was more significant in the outer suburbs than that in the suburbs and urban area, and the decline trend of the river sinuosity was more significant in the suburbs than that in the urban area and outer suburbs, but the spatial change trend of the main river area length ratio was insignificant. (4) The impacts of urbanization on river systems changes were extremely significant, and the changes of river systems were more drastic in higher urbanization level regions, but the impacts of urbanization on main river area length ratio and river sinuosity were larger than that on river development coefficient and river density.
Using multitemporal Landsat TM images at a 10-year interval, in this study, we (1) extracted information of spatial location, length, and tortuosity of coastline and landscape configuration, diversity and fragmentation in the bay areas of Xiangshangang Bay, China and Tampa Bay, USA as well from the four 10-year periods from 1985 to 2015; (2) constructed indices of artificial coastline and bay area landscape human disturbance; and (3) explored and discussed the impact of human activities on changes in bay area coastline and landscape types. Our analysis results demonstrate the following five points. (1) In the past 30 years, the length of natural coastline in Xiangshangang Bay and Tampa Bay was shrunk, while the length of their artificial coastline was first elongated and then showed a stable trend. Since there was a difference influence of human activities on coastline and landscape types between the two bay areas, Xiangshangang Bay experienced dramatic changes in parts of coastline geomorphologies and continuous decrease of coastline sinuosity while in Tampa Bay, there was a little change in coastline geomorphologies and its coastline sinuosity was almost unchanged. (2) The intensity of human activities in Xiangshangang Bay was continuously enhanced from 1985 to 1995, and then the degree of enhancement had slowed down after 1995. However, in the time period, the impacted extent of human activities gradually increased and finally covered almost entire coastline in the area. In Tampa Bay area, although the intensity of human activities was enhanced, the degree of enhancement was slow from 1985 to 2015 and the impacted area of human activates was concentrated in several coastal city areas. (3) The average area of landscape patches strongly disturbed by human activities in both Xiangshangang Bay and Tampa Bay generally showed a trend of decreasing from 1985 to 2005. However, during the period of 2005-2015, the mean patch area of landscape disturbed by different degree of human activities in Xiangshangang Bay changed differently, while in Tampa Bay it basically unchanged. (4) From 1985 to 2005, the indices of landscape diversity in various areas of human disturbance in Xiangshangang Bay gradually increased, while in Tampa Bay, changes in indices of the landscape diversity varied. From 2005 to 2015, the change in the intensity of human disturbance in both bay areas was from weak to strong while the indices of landscape diversity in Xiangshangang Bay and Tampa Bay increased first and then decreased. (5) Landscape fragmentation index in different human disturbance areas in both Xiangshangang Bay and Tampa Bay gradually increased from 1985 to 2005 while from 2005 to 2015, in both bay areas, the landscape fragmentation index presented a decreasing trend.
Data of coastal construction land around the South China Sea in 2010 and 1975 were extracted and the spatial-temporal characteristics of construction land expansion based on different geomorphologic backgrounds in this period was discussed. Results showed that: (1) In South China Mainland and Malay Peninsula, construction land in coastal zone was generally expanded rapidly; in Indochina, construction land in coastal zone was expanded moderately; in Sumatra, Kalimantan and Philippines, construction land in coastal zone was expanded slowly except Manila Bay. (2) There were significant differences in construction land expansion between different geomorphology types because of natural resources, development difficulty and hinterland area. As there were good conditions of water transport and wide hinterland, construction land in delta plain coast and estuary plain coast expanded rapidly; construction land expansion in mesa coast and barrier - lagoon coast was remarkable due to the suitability for building small or medium-sized ports; construction land expansion in gulf coast and mountain coast was relatively slow because there existed limited development potential; construction land expansion in flat dike coast was even slower because of the limited hinterland and underdeveloped water transport. (3) Development patterns varied according to coastal geomorphologic features. The spatial morphology of construction land was diverse in delta plain coast and estuary plain coast; in mountain coast, mesa coast and gulf plain coast, it presented agglomerating or zonal distribution; in barrier - lagoon coast, it presented agglomerating or star distribution; in flat dyke coast, it presented zonal, linear or point distribution.
Impacted by climate changes and human activities, the coastal zone of China has undergone various dramatic changes, among which, shape change of major gulfs (including bays and estuaries) is one of the most important aspects. In this paper, spatial dataset of gulf shoreline and gulf shape in seven phases since the early 1940s was delineated based on topographic maps and remote sensing imageries, and a group of indices including the ratio of natural shoreline, the shoreline utilization degree, shoreline swing direction, gulf area, gulf shape index and gulf centroid were used to analyze the spatial-temporal characteristics of gulfs in detail. It turned out that: in general, shape changes of major gulfs in the mainland of China were significant and complicated during the past 70 years, specifically, visible changes of shoreline structure, especially the decreases in both length and ratio of natural shoreline took place; the shoreline utilization degree increased remarkably because more and more natural shoreline had been artificalized; the fact that shoreline seaward shift caused by sea reclamation occurred in the majority of gulfs; spatial size (area) decreased in most of gulfs due to the fast and extensive sea reclamation; the geometric shape of most gulfs had become more complicated while the discrepancies among all the gulfs were narrowed; the centroid of most gulfs moved toward the sea; gulf-shape variations exhibited remarkable spatio-temporal differences. It is obvious that human activities, especially sea reclamation, have become the key driving force of gulf shape change since 1990. Based on the above-mentioned findings, classification management strategy based on dominant-function oriented gulf classification is strongly recommended, and gulf-based management should be strengthen in order to improve the abilities of Integrated Coastal Zone Management (ICZM) practices in China.
In this study, summer long-cycle drought-flood abrupt alternation index (LDFAI) is calculated based on the monthly precipitation data from May to August obtained from 110 weather stations in South China from 1961 to 2014. LDFAI, which compares the precipitation amounts under different disaster conditions, can reflect the features of drought-flood abrupt alternation in South China in summer. The spatial-temporal change of summer LDFAI in South China have been studied by rotated empirical orthogonal function analysis, trend coefficient estimation, linear trend analysis, t-test, and Mann-Kendall test. Results show the following: (1) the overall change trend of the average LDFAI in South China was not remarkable, whereas the LDFAI intensity exhibited significant periodic changes, including two strong periods and a weak period. (2) The summer LDFAI can be divided into five main spatial regions. The analysis of the data from the representative stations in different spatial regions showed that the summer LDFAI values in Region 1 (North Guangdong and Northeast Guangxi) and Region 2 (West Guangdong and Southeast Guangxi) demonstrated downward trends. The decline in Region 1 was significant, and an abrupt decline occurred in 1988. The summer LDFAI values in Region 3 (East Guangdong) and Region 5 (Hainan Island) showed significant upward trends. An abrupt rise occurred in Region 3 in 1980. The LDFAI in Region 4 (West Guangxi) exhibited periodic change features. (3) As regards the interdecadal change features of the LDFAI for the study period, the LDFAI values in Region 1 and Region 2 declined, whereas the amount of precipitation in May and June increased over the years. In the 1990s and 2000s, The LDFAI values in Region 3 and Region 4 were high, and the precipitation amount in July and August were higher than that in other months. In Region 5, the LDFAI increased, and the precipitation in July and August increased over the years as well.
Based on the daily precipitation and temperature from a 0.5°×0.5° gridded dataset and meteorological stations during 1961-2013 released by the National Meteorological Information Center, the spatial and temporal changes of annual precipitation, rainfall, snowfall and snowfall/rainfall ratio (S/R) in the Tibetan Plateau in recent 53 years were analyzed by using Sen slope, Mann-Kendall mutation test, IDW (inverse distance-weighted) interpolation and Morlet wavelet. The results indicated that: (1) Generally, precipitation and rainfall show increasing trends by 0.6 mm·a-1 (p < 0.05) and 1.3 mm·a-1 (p < 0.001), respectively, while snowfall and S/R show decreasing trends by 0.6 mm·a-1 (p < 0.01) and 0.5%·a-1 (p < 0.001), respectively. (2) Precipitation and rainfall show increasing trends, but snowfall shows a decreasing trend in most parts of the Tibetan Plateau. On this basis, S/R shows a decreasing trend. (3) Abrupt and cycle analysis shows that the abrupt changes of the precipitation, rainfall, snowfall and S/R occurred in 2005, 2004, 1996 and 1998, respectively. The precipitation, rainfall, snowfall and S/R present cycles of approximately 5 years, 10 years, 16 years and 20 years, respectively. (4) As elevation increases, the trend magnitude for precipitation and rainfall shows a decrease-to-increase trend, and that for snowfall and S/R shows a decreasing trend.
This study analyzed the variation of extreme precipitation by introducing Generalized Additive Models in Location, Scale, and Shape (GAMLSS) Model in the non-stationary frequency analysis based on the precipitation extreme series in the first rainy season (April, May, June) in the period of 1960-2012 derived from 79 meteorological stations in the southeast coastal region of China which covers Shanghai, Zhejiang, Fujian, Guangdong and Hainan. The greenhouse gas emissions index represented by human activities and comprehensive climatic index were built by principal component analysis (PCA). Simultaneously, contribution analysis method and GAMLSS model are applied to identify the impact of climate change and human activities on precipitation extremes considering both factors. The results show that: (1) The areas with significant increase and strong enhanced variation of precipitation extremes are mainly located in the northeast of Zhejiang, central-northern and western coastal Guangdong, and eastern Fujian. (2) There is a significant correlation between human activity increase and precipitation extreme variability, especially in the developed areas. The contribution of human activity to precipitation extremes in the stage of rapid socio-economic development (1986-2012) is much greater than that in the stage of slow socio-economic development (1960-1985), especially in Zhejiang and Guangdong provinces. (3) The northeast of Zhejiang, much of Fujian and the central-northern and western coastal Guangdong are high risk areas in terms of extreme precipitation. Thus, we should strengthen the risk prevention for extreme precipitation and its secondary disasters.
