Showing papers in "Chinese Geographical Science in 2014"

Effects of Grazing Exclusion on Plant Productivity and Soil Carbon, Nitrogen Storage in Alpine Meadows in Northern Tibet, China

Abstract: Grazing exclusion is widely adopted in restoring degraded alpine grasslands on the Qinghai-Tibetan Plateau. However, its effectiveness remains poorly understood. In this study, we investigated the effects of grazing exclusion on plant productivity, species diversity and soil organic carbon (SOC) and soil total nitrogen (STN) storage along a transect spanning from east to west of alpine meadows in northern Tibet, China. After six years of grazing exclusion, plant cover, aboveground biomass (AGB), belowground biomass (BGB), SOC and STN were increased, but species diversity indices declined. The enhancement of AGB and SOC caused by grazing exclusion was correlated positively with mean annual precipitation (MAP). Grazing exclusion led to remarkable biomass increase of sedge species, especially Kobresia pygmaea, whereas decrease of biomass in forbs and no obvious change in grass, leguminous and noxious species. Root biomass was concentrated in the near surface layer (10 cm) after grazing exclusion. The effects of grazing exclusion on SOC storage were confined to shallow soil layer in sites with lower MAP. It is indicated that grazing exclusion is an effective measure to increase forage production and enhance soil carbon sequestration in the studied region. The effect is more efficient in sites with higher precipitation. However, the results revealed a tradeoff between vegetation restoration and ecological biodiversity. Therefore, carbon pools recover more quickly than plant biodiversity in the alpine meadows. We suggest that grazing exclusion should be combined with other measures to reconcile grassland restoration and biodiversity conservation.

Multiple cropping intensity in China derived from agro-meteorological observations and MODIS data

Abstract: Double- and triple-cropping in a year have played a very important role in meeting the rising need for food in China. How- ever, the intensified agricultural practices have significantly altered biogeochemical cycles and soil quality. Understanding and mapping cropping intensity in Chinas agricultural systems are therefore necessary to better estimate carbon, nitrogen and water fluxes within agro-ecosystems on the national scale. In this study, we investigated the spatial pattern of crop calendar and multiple cropping rotations in China using phenological records from 394 agro-meteorological stations (AMSs) across China. The results from the analysis of in situ field observations were used to develop a new algorithm that identifies the spatial distribution of multiple cropping in China from mod- erate resolution imaging spectroradiometer (MODIS) time series data with a 500 m spatial resolution and an 8-day temporal resolution. According to the MODIS-derived multiple cropping distribution in 2002, the proportion of cropland cultivated with multiple crops reached 34% in China. Double-cropping accounted for approximately 94.6% and triple-cropping for 5.4%. The results demonstrat that MODIS EVI (Enhanced Vegetation Index) time series data have the capability and potential to delineate the dynamics of double- and triple-cropping practices. The resultant multiple cropping map could be used to evaluate the impacts of agricultural intensification on biogeochemical cycles.

Impact of meteorological drought on streamflow drought in Jinghe River Basin of China

Abstract: Under global climate change, drought has become one of the most serious natural hazards, affecting the ecological environment and human life. Drought can be categorized as meteorological, agricultural, hydrological or socio-economic drought. Among the different categories of drought, hydrological drought, especially streamflow drought, has been given more attention by local governments, researchers and the public in recent years. Identifying the occurrence of streamflow drought and issuing early warning can provide timely information for effective water resources management. In this study, streamflow drought is detected by using the Standardized Runoff Index, whereas meteorological drought is detected by the Standardized Precipitation Index. Comparative analyses of frequency, magnitude, onset and duration are conducted to identify the impact of meteorological drought on streamflow drought. This study focuses on the Jinghe River Basin in Northwest China, mainly providing the following findings. 1) Eleven meteorological droughts and six streamflow droughts were indicated during 1970 and 1990 after pooling using Inter-event time and volume Criterion method. 2) Streamflow drought in the Jinghe River Basin lagged meteorological drought for about 127 days. 3) The frequency of streamflow drought in Jinghe River Basin was less than meteorological drought. However, the average duration of streamflow drought is longer. 4) The magnitude of streamflow drought is greater than meteorological drought. These results not only play an important theoretical role in understanding relationships between different drought categories, but also have practical implications for streamflow drought mitigation and regional water resources management.

Creative industries agglomeration, regional innovation and productivity growth in China

Abstract: This paper falls into the broad area of economic geography and economics of creativity, and it presents an alternative approach to explain why total factor productivity (TFP) growth is different across China’s regions. It establishes an empirical model to estimate the spatial agglomeration effects of creative industries on regional TFP growth, using China’s provincial panel data during the period of 2003 to 2010. We found that the creative industries agglomeration (CIA) has significant and positive impact on regional TFP growth. The result also implies that the CIA can facilitate regional TFP growth through promoting regional innovation instead of improving regional efficiency. Therefore, we argue that policy makers should take some measures to retain and establish more creative zones.

Extraction and analysis of gully head of Loess Plateau in China based on digital elevation model

Abstract: In China’s Loess Plateau area, gully head is the most active zone of a drainage system in gully areas. The differentiation of loess gully head follows geospatial patterns and reflects the process of the loess landform development and evolution of its drainage system to some extent. In this study, the geomorphic meaning, basic characteristics, morphological structure and the basic types of loess gully heads were systematically analysed. Then, the loess gully head’s conceptual model was established, and an extraction method based on Digital Elevation Model (DEM) for loess gully head features and elements was proposed. Through analysing the achieved statistics of loess gully head features, loess gully heads have apparently similar and different characteristics depending on the different loess landforms where they are found. The loess head characteristics reflect their growth period and evolution tendency to a certain degree, and they indirectly represent evolutionary mechanisms. In addition, the loess gully developmental stages and the evolutionary processes can be deduced by using loess gully head characteristics. This study is of great significance for development and improvement of the theoretical system for describing loess gully landforms.

Road Impacts on Spatial Patterns of Land Use and Landscape Fragmentation in Three Parallel Rivers Region, Yunnan Province, China

Abstract: The structure and function of network is a central issue in landscape ecology. Road networks with hierarchical structure are crucial for understanding landscape dynamics. In this study, we compared the distribution of national road, provincial road, county road and rural road in the Three Parallel Rivers Region (TPRR) in Yunnan Province of China, and estimated the effect of roads (and other factors) on the spatial patterns of land use and land cover with logistic regression. In addition, we analyzed the land use and land cover change (LUCC) and landscape fragmentation in 1989–2005 along a buffer zone of the primary traffic corridor, national road G214. The results showed that, county and rural roads had much higher percentage of length extending into more natural habitats at higher elevation and steeper slope, compared with the higher level roads in this region. While the distributions of natural land cover types were dominated by environmental factors, human land use types i.e., building land and farmland types were significantly related with roads, linking more closely with lower level roads. The LUCC dynamics (1989–2005) of the G214 buffer zone showed a general trend of land transformation from conifer forests and valley arid shrubs to building land and farmland, and from ice and snow to alpine shrubs and forests. With the length of G214 unchanged during the time, the overall landscape pattern changed little in the buffer zone, but habitat fragmentation and area decrease had occurred for the natural vegetation types, in contrast to patch mergence and expansion of human land use types, and landscape fragmentation was intensified above 2500 m a.s.l. but declined below the elevation. The results indicated the dynamics of landscape composition and patch type level distribution in spite of the stability of the overall landscape pattern, and implied the potential role of roads, especially the low level roads on landscape changes.

Combining CLUE-S and SWAT models to forecast land use change and non-point source pollution impact at a watershed scale in Liaoning Province, China

Abstract: Non-point source (NPS) pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. In this study, NPS pollution load was simulated in urban planning, historic trends and ecological protection land use scenarios based on the Conversion of Land Use and its Effect at Small regional extent (CLUE-S) and Soil and Water Assessment Tool (SWAT) models applied to Hunhe-Taizi River Watershed, Liaoning Province, China. Total nitrogen (TN) and total phosphorus (TP) were chosen as NPS pollution indices. The results of models validation showed that CLUE-S and SWAT models were suitable in the study area. NPS pollution mainly came from dry farmland, paddy, rural and urban areas. The spatial distribution of TN and TP exhibited the same trend in 57 sub-catchments. The TN and TP had the highest NPS pollution load in the western and central plains, which concentrated the urban area and farm land. The NPS pollution load would increase in the urban planning and historic trends scenarios, and would be even higher in the urban planning scenario. However, the NPS pollution load decreased in the ecological protection scenario. The differences observed in the three scenarios indicated that land use had a degree of impact on NPS pollution, which showed that scientific and ecologically sound construction could effectively reduce the NPS pollution load in a watershed. This study provides a scientific method for conducting NPS pollution research at the watershed scale, a scientific basis for non-point source pollution control, and a reference for related policy making.

Evaluating conservation effectiveness of nature reserves established for surrogate species: Case of a giant panda nature reserve in Qinling Mountains, China

Abstract: Many nature reserves are established to protect the habitat needs of particular endangered species of interest but their effectiveness for protecting other species is questionable. In this study, this effectiveness was evaluated in a nature reserve network located in the Qinling Mountains, Shaanxi Province, China. The network of reserves was established mainly for the conservation of the giant panda, a species considered as a surrogate for the conservation of many other endangered species in the region. The habitat suitability of nine protected species, including the giant panda, was modeled by using Maximum Entropy (MAXENT) and their spatial congruence was analyzed. Habitat suitability of these species was also overlapped with nature reserve boundaries and their management zones (i.e., core, buffer and experimental zones). Results show that in general the habitat of the giant panda constitutes a reasonable surrogate of the habitat of other protected species, and giant panda reserves protect a relatively high proportion of the habitat of other protected species. Therefore, giant panda habitat conservation also allows the conservation of the habitat of other protected species in the region. However, a large area of suitable habitat was excluded from the nature reserve network. In addition, four species exhibited a low proportion of highly suitable habitat inside the core zones of nature reserves. It suggests that a high proportion of suitable habitat of protected species not targeted for conservation is located in the experimental and buffer zones, thus, is being affected by human activities. To increase their conservation effectiveness, nature reserves and their management zones need to be re-examined in order to include suitable habitat of more endangered species. The procedures described in this study can be easily implemented for the conservation of many endangered species not only in China but in many other parts of the world.

Land use effects on soil organic carbon, microbial biomass and microbial activity in Changbai Mountains of Northeast China

Abstract: Land use changes are known to alter soil organic carbon (SOC) and microbial properties, however, information about how conversion of natural forest to agricultural land use as well as plantations affects SOC and microbial properties in the Changbai Mountains of Northeast China is meager. Soil carbon content, microbial biomass carbon (MBC), basal respiration and soil carbon mineralization were studied in five selected types of land use: natural old-growth broad-leaved Korean pine mixed forest (NF); spruce plantation (SP) established following clear-cutting of NF; cropland (CL); ginseng farmland (GF) previously under NF; and a five-year Mongolian oak young forest (YF) reforested on an abandoned GF, in the Changbai Mountains of Northeast China in 2011. Results showed that SOC content was significantly lower in SP, CL, GF, and YF than in NF. MBC ranged from 304.4 mg/kg in CL to 1350.3 mg/kg in NF, which was significantly higher in the soil of NF than any soil of the other four land use types. The SOC and MBC contents were higher in SP soil than in CL, GF, and YF soils, yielding a significant difference between SP and CL. The value of basal respiration was also higher in NF than in SP, CL, GF, and YF. Simultaneously, higher values of the metabolic quotient were detected in CL, GF, and YF soils, indicating low substrate utilization of the soil microbial community compared with that in NF and SP soil. The values of cumulative mineralized carbon and potentially mineralized carbon (C0) in NF were significantly higher than those in CL and GF, while no significant difference was observed between NF and SP. In addition, YF had higher values of C0 and C mineralization rate compared with GF. The results indicate that conversion from NF into agricultural land (CL and GF) uses and plantation may lead to a reduction in soil nutrients (SOC and MBC) and substrate utilization efficiency of the microbial community. By contrast, soils below SP were more conducive to the preservation of soil organic matter, which was reflected in the comparison of microbial indicators among CL, GF, and YF land uses. This study can provide data for evaluating soils nutrients under different land use types, and serve as references for the rational land use of natural forest in the study area.

Carbon sequestration effects of shrublands in Three-North Shelterbelt Forest region, China

Abstract: Three-North Shelterbelt Forest (TSF) program, is one of six key forestry programs and has a 73-year construction period, from 1978 to 2050. Quantitative analysis of the carbon sequestration of shrubs in this region is important for understanding the overall function of carbon sequestration of the forest and other terrestrial ecosystems in China. This study investigated the distribution area of shrubland in the TSF region based on remote sensing images in 1978 and 2008, and calculated the carbon density of shrubland in combination with the field investigation and previous data from published papers. The carbon sequestration quantity and rate from 1978 to 2008 was analyzed for four sub-regions and different types of shrubs in the TSF region. The results revealed that: 1) The area of shrubland in the study area and its four sub-regions increased during the past thirty years. The area of shrubland for the whole region in 2008 was 1.2 × 107 ha, 72.8% larger than that in 1978. The Inner Mongolia-Xinjiang Sub-region was the largest shrubland distribution area, while the highest coverage rate was found in the North China Sub-region. 2) In decreasing order of their carbon sequestration, the four types of shrubs considered in this study were Hippophae rhamnoides, Caragana spp., Haloxylon ammodendron and Vitex negundo var. heterophylla. The carbon sequestration of H. rhamnoides, with a maximum mean carbon density of 16.5 Mg C/ha, was significantly higher than that of the other three species. 3) The total carbon sequestration of shrubland in the study region was 4.5 × 107 Mg C with a mean annual carbon sequestration of 1.5 × 106 Mg C. The carbon density in the four sub-regions decreased in the following order: the Loess Plateau Sub-region, the North China Sub-region, the Northeast China Sub-region and the Inner Mongolia-Xinjiang Sub-region. The paucity of studies and data availability on the large-scale carbon sequestration of shrub species suggests this study provides a baseline reference for future research in this area.

Land-use Change and Socio-economic Driving Forces of Rural Settlement in China from 1996 to 2005

Abstract: While urbanization has accelerated, the rural population in China has started decreasing in recent years. However, the expansion of rural settlement has not been sufficiently curbed. The questions of why this has happened and who has driven the land-use change (LUC) of rural settlement in China have aroused great interests among researchers. In this paper, it is suggested that population is not always a positive driving force for the LUC of rural settlement in China. Furthermore, socio-economic driving forces other than urbanization, population and industrialization are analyzed. On a national scale, the major driving forces are the per-capita rural housing area and the cultivated land area. On a regional scale, the main driving forces in the eastern China are the house-building capacity of rural households and the per-capita rural housing area; while in the central China, the main driving forces are rural housing investment, the proportion of primary industry employees in the rural working population, and the cultivated land area. For the western China, the main driving forces are rural register population and cultivated land area.

Forest carbon storage and tree carbon pool dynamics under natural forest protection program in northeastern China

Abstract: The Natural Forest Protection (NFP) program is one of the Six Key Forestry Projects which were adopted by the Chinese Government since the 1980s to address important natural issues in China. It advanced to protecting and restoring the structures and functions of the natural forests through sustainable forest management. However, the role of forest carbon storage and tree carbon pool dynamics since the adoption of the NFP remains unknown. To address this knowledge gap, this study calculated forest carbon storage (tree, understory, forest floor and soil) in the forest region of northeastern (NE) China based on National Forest Inventory databases and field investigated databases. For tree biomass, this study utilized an improved method for biomass estimation that converts timber volume to total forest biomass; while for understory, forest floor and soil carbon storage, this study utilized forest type-specific mean carbon densities multiplied by their areas in the region. Results showed that the tree carbon pool under the NFP in NE China functioned as a carbon sink from 1998 to 2008, with an increase of 6.3 Tg C/yr, which was mainly sequestrated by natural forests (5.1 Tg C/yr). At the same time, plantations also acted as a carbon sink, reflecting an increase of 1.2 Tg C/yr. In 2008, total carbon storage in forests covered by the NFP in NE China was 4603.8 Tg C, of which 4393.3 Tg C was stored in natural forests and 210.5 Tg C in planted forests. Soil was the largest carbon storage component, contributing 69.5%–77.8% of total carbon storage; followed by tree and forest floor, accounting for 16.3%–23.0% and 5.0%–6.5% of total carbon storage, respectively. Understory carbon pool ranged from 1.9 to 42.7 Tg C, accounting for only 0.9% of total carbon storage.

Poverty reduction, environmental protection and ecosystem services: A prospective theory for sustainable development

Abstract: Poverty reduction and environmental protection are two global tasks for sustainable development. The study perspective has changed over time, from narrowly focusing on poverty reduction to comprehensively strengthening human-welfare. We reviewed key references targeting the theoretical content and practical approach relying on poverty, environment protection and ecosystem services. We discussed the contradicting views on the relationship of poverty and environmental degradation, and then illustrated the study progress of a cutting-age topic-ecosystem services which pave a way to address poverty reduction and environmental protection together. At last, we investigated essential factors that affect the development and environmental protection. Considering the evolution of the concept of poverty, we found that the environment has occupied an increasing proportion in the cognizance of poverty. The relationship between poverty and environmental degradation is regional uniqueness. In practical aspect, projects based on the management and valuation assessment of ecosystem services draw researchers’ attention all over the world. The appropriate scale, essential economic incentives, morality, law and social equality are key factors affecting individuals’ decisions which directly relate to the sustainable development.

Biomass carbon storage and its sequestration potential of afforestation under natural forest protection program in China

Abstract: Based on the data from China’s Seventh Forest Inventory for the period of 2004–2008, area and stand volume of different types and age-classes of plantation were used to establish the relationship between biomass density and age of planted forests in different regions of the country. Combined with the plantation area in the first-stage of the Natural Forest Protection (NFP) program (1998–2010), this study calculated the biomass carbon storage of the afforestation in the first-stage of the program. On this basis, the carbon sequestration potential of these forests was estimated for the second stage of the program (2011–2020). Biomass carbon storage of plantation established in the first stage of the program was 33.67 Tg C, which was majority accounted by protection forests (30.26 Tg C). There was a significant difference among carbon storage in different regions, which depended on the relationship of biomass carbon density, forest age and plantation area. Under the natural growth, the carbon storage was forecasted to increase annually from 2011 to 2020, reaching 96.03 Tg C at the end of the second-stage of the program in 2020. The annual growth of the carbon storage was forecasted to be 6.24 Tg C/yr, which suggested that NFP program has a significant potential for enhancing carbon sequestration in plantation forests under its domain.

Nitrogen deposition and its spatial pattern in main forest ecosystems along north-south transect of eastern China

Abstract: A continuous three-year observation (from May 2008 to April 2011) was conducted to characterize the spatial variation of dissolved inorganic nitrogen (DIN) deposition at eight main forest ecosystems along the north-south transect of eastern China (NSTEC). The results show that both throughfall DIN deposition and bulk DIN deposition increase from north to south along the NSTEC. Throughfall DIN deposition varies greatly from 2.7 kg N/(ha·yr) to 33.0 kg N/(ha·yr), with an average of 10.6 kg N/(ha·yr), and bulk DIN deposition ranges from 4.1 kg N/(ha·yr) to 25.4 kg N/(ha·yr), with an average of 9.8 kg N/(ha·yr). NH4 -N is the dominant form of DIN deposition at most sampling sites. Additionally, the spatial variation of DIN deposition is controlled mainly by precipitation. Moreover, in the northern part of the NSTEC, bulk DIN deposition is 17% higher than throughfall DIN deposition, whereas the trend is opposite in the southern part of the NSTEC. The results demonstrate that DIN deposition would likely threaten the forest ecosystems along the NSTEC, compared with the critical loads (CL) of N deposition, and DIN deposition in this region is mostly controlled by ag- ricultural activities rather than industrial activities or transportation.

Examining forest net primary productivity dynamics and driving forces in northeastern China during 1982–2010

Abstract: Forest net primary productivity (NPP) is a key parameter for forest monitoring and management. In this study, monthly and annual forest NPP in the northeastern China from 1982 to 2010 were simulated by using Carnegie-Ames-Stanford Approach (CASA) model with normalized difference vegetation index (NDVI) sequences derived from Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modeling and Mapping Studies (GIMMS) and Terra Moderate Resolution Imaging Spectroradiometer (MODIS) products. To address the problem of data inconsistency between AVHRR and MODIS data, a per-pixel unary linear regression model based on least squares method was developed to derive the monthly NDVI sequences. Results suggest that estimated forest NPP has mean relative error of 18.97% compared to observed NPP from forest inventory. Forest NPP in the northeastern China increased significantly during the twenty-nine years. The results of seasonal dynamic show that more clear increasing trend of forest NPP occurred in spring and autumn. This study also examined the relationship between forest NPP and its driving forces including the climatic and anthropogenic factors. In spring and winter, temperature played the most pivotal role in forest NPP. In autumn, precipitation acted as the most important factor affecting forest NPP, while solar radiation played the most important role in the summer. Evaportranspiration had a close correlation with NPP for coniferous forest, mixed coniferous broadleaved forest, and broadleaved deciduous forest. Spatially, forest NPP in the Da Hinggan Mountains was more sensitive to climatic changes than in the other ecological functional regions. In addition to climatic change, the degradation and improvement of forests had important effects on forest NPP. Results in this study are helpful for understanding the regional carbon sequestration and can enrich the cases for the monitoring of vegetation during long time series.

Assessment of Human Impacts on Vegetation in Built-up Areas in China Based on AVHRR, MODIS and DMSP_OLS Nighttime Light Data, 1992-2010

Abstract: Since the reform and opening-up program started in 1978, the level of urbanization has increased rapidly in China. Rapid urban expansion and restructuring have had significant impacts on the ecological environment especially within built-up areas. In this study, ArcGIS 10, ENVI 4.5, and Visual FoxPro 6.0 were used to analyze the human impacts on vegetation in the built-up areas of 656 Chinese cities from 1992 to 2010. Firstly, an existing algorithm was refined to extract the boundaries of the built-up areas based on the Defense Meteorological Satellite Program Operational Linescan System (DMSP_OLS) nighttime light data. This improved algorithm has the advantages of high accuracy and speed. Secondly, a mathematical model (Human impacts (HI)) was constructed to measure the impacts of human factors on vegetation during rapid urbanization based on Advanced Very High Resolution Radiometer (AVHRR) Normalized Difference Vegetation Index (NDVI) and Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI. HI values greater than zero indicate relatively beneficial effects while values less than zero indicate proportionally adverse effects. The results were analyzed from four aspects: the size of cities (metropolises, large cities, medium-sized cities, and small cities), large regions (the eastern, central, western, and northeastern China), administrative divisions of China (provinces, autonomous regions, and municipalities) and vegetation zones (humid and semi-humid forest zone, semi-arid steppe zone, and arid desert zone). Finally, we discussed how human factors impacted on vegetation changes in the built-up areas. We found that urban planning policies and developmental stages impacted on vegetation changes in the built-up areas. The negative human impacts followed an inverted’ U’ shape, first rising and the falling with increase of urban scales. China’s national policies, social and economic development affected vegetation changes in the built-up areas. The findings can provide a scientific basis for municipal planning departments, a decision-making reference for government, and scientific guidance for sustainable development in China.

Valuation of lake and marsh wetlands ecosystem services in China

Abstract: Wetlands are highly productive natural ecosystems, providing valuable goods and services. There is growing interest in transferring ecosystem service value from the existing wetlands studied to other wetlands ecosystems at a large geographic scale. The benefit transfer method uses the known values from wetlands to predict the value of other wetland sites. This methodology requires only limited time and resources. The present study calculated the value of the ecological services provided by lake and marsh wetlands in China in terms of biodiversity indices, water quality indices and economic indices. Basic data on wetlands were obtained through remote sensing images. The results show that: 1) The total ecosystem service value of the lake and marsh wetlands in 2008 was calculated to be 8.1841 × 1010 United States Dollars (USD), with the marsh and lake wetlands contributing 5.6329 × 1010 and 2.5512 × 1010 USD, respectively. Values of marsh ecosystem service were concentrated in Heilongjiang Province (2.5516 × 1010 USD), Qinghai Province (1.2014 × 1010 USD), and Inner Mongolia Autonomous Region (1.1884 × 1010 USD). The value of the lakes were concentrated in Tibet Autonomous Region (6.223 × 109 USD), Heilongjiang (5.810 × 109 USD), and Qinghai (5.500 × 109 USD). 2) Waste treatment and climate regulation services contributed to 26.29% and 24.74% respectively, of the total ecosystem service value of the marsh wetlands. Hydrological regulation and waste treatment contributed to 41.39% and 32.75%, respectively, of the total ecosystem service value of the lake wetlands. 3) The total ecological service value of the lake and marsh wetlands was 54.64% of the total service value of natural grassland ecosystems and 30.34% of the total service value of forests ecosystems in China.

Age-related Changes of Carbon Accumulation and Allocation in Plants and Soil of Black Locust Forest on Loess Plateau in Ansai County, Shaanxi Province of China

Abstract: The effects of reforestation on carbon (C) sequestration in China’s Loess Plateau ecosystem have attracted much research attention in recent years. Black locust trees (Robinia pseudoacacia L.) are valued for their important use in reforestation and water and soil conservation efforts. This forest type is widespread across the Loess Plateau, and must be an essential component of any planning for C sequestration efforts in this fragile ecological region. The long-term effects of stand age on C accumulation and allocation after reforestation remains uncertain. We examined an age-sequence of black locust forest (5, 9, 20, 30, 38, and 56 yr since planting) on the Loess Plateau to evaluate C accumulation and allocation in plants (trees, shrubs, herbages, and leaf litter) and soil (0–100 cm). Allometric equations were developed for estimating the biomass of tree components (leaf, branch, stem without bark, bark and root) with a destructive sampling method. Our results demonstrated that black locust forest ecosystem accumulated C constantly, from 31.42 Mg C/ ha (1 Mg = 106 g) at 5 yr to 79.44 Mg C/ha at 38 yr. At the ‘old forest” stage (38 to 56 yr), the amount of C in plant biomass significantly decreased (from 45.32 to 34.52 Mg C/ha) due to the high mortality of trees. However, old forest was able to accumulate C continuously in soil (from 33.66 to 41.00 Mg C/ha). The C in shrub biomass increased with stand age, while the C stock in the herbage layer and leaf litter was age-independent. Reforestation resulted in C re-allocation in the forest soil. The topsoil (0–20 cm) C stock increased constantly with stand age. However, C storage in sub-top soil, in the 20–30, 30–50, 50–100, and 20–100 cm layers, was age-independent. These results suggest that succession, as a temporal factor, plays a key role in C accumulation and re-allocation in black locust forests and also in regional C dynamics in vegetation.

Vegetation Traits and Soil Properties in Response to Utilization Patterns of Grassland in Hulun Buir City, Inner Mongolia, China

Abstract: Numerous studies have focused on vegetation traits and soil properties in grassland, few of which concerned about effects of human utilization patterns on grassland yet. Thus, this study hypothesized that human disturbance (e.g., grazing, mowing and fencing) triggered significant variation of biomass partitioning and carbon reallocation. Besides, there existed some differences of species diversity and soil fertility. To address these hypotheses of grassland with diverse utilization patterns in Hulun Buir City, Inner Mongolia, China, we sampled in situ about aboveground biomass (AGB) and belowground biomass (BGB) to evaluate their biomass allocation. Species diversity and soil properties were also investigated. Subsequently, we discussed the relationship of species diversity with environmental conditions, using data collected from 23 sites during the ecological project period of Returning Grazing Lands to Grasslands (RGLG) program. The results were as follows: 1) both AGB and BGB were lower on grazing regime than those on fencing and mowing, but the ratio of root-to-shoot (R/S) was higher on grazing regime than the other two utilization patterns; 2) neither of evenness and Simpson Index was different significantly among all grassland utilization patterns in desert, typical, and meadow grassland at 0.05. In meadow grassland, species richness of fencing pattern was significantly higher than that of grazing pattern (p < 0.05); 3) both of soil organic carbon content and soil available phosphorous content were increased significantly on fencing pattern than grazing pattern (p < 0.05) in desert grassland, and mowing patterns increased the soil nutrients (soil organic carbon, soil total phosphorous, soil available phosphorous, and soil total nitrogen) significantly compared with grazing patterns (p < 0.05) in typical grassland. However, there were no significant differences among utilization patterns in meadow grassland. In conclusion, both of AGB and BGB were increased significantly by fencing. Moreover, species diversity and soil nutrients can be promoted via mowing and fencing. This study suggested that implementation of Ecological Project played a positive role in sustainable grassland utilization of Hulun Buir City and a strong positive influence on the entire temperate grassland.

Effects of nitrogen addition on plant functional traits in freshwater wetland of Sanjiang Plain, Northeast China

Abstract: To clarify the responses of plant functional traits to nitrogen (N) enrichment, we investigated the whole-plant traits (plant height and aboveground biomass), leaf morphological (specific leaf area (SLA) and leaf dry mass content (LDMC)) and chemical traits (leaf N concentration (LNC) and leaf phosphorus (P) concentration (LPC)) of Deyeuxia angustifolia and Glyceria spiculosa following seven consecutive years of N addition at four rates (0 g N/(m2·yr), 6 g N/(m2·yr), 12 g N/(m2·yr) and 24 g N/(m2·yr)) in a freshwater marsh in the Sanjiang Plain, Northeast China. The results showed that, for both D. angustifolia and G. spiculosa, N addition generally increased plant height, leaf, stem and total aboveground biomass, but did not cause changes in SLA and LDMC. Moreover, increased N availability caused an increase in LNC, and did not affect LPC. Thus, N addition decreased leaf C:N ratio, but caused an increase in leaf N:P ratio, and did not affect leaf C:P ratio. Our results suggest that, in the mid-term, elevated N loading does not alter leaf morphological traits, but causes substantial changes in whole-plant traits and leaf chemical traits in temperate freshwater wetlands. These may help to better understand the effects of N enrichment on plant functional traits and thus ecosystem structure and functioning in freshwater wetlands.

Urban sprawl and related problems: Bibliometric analysis and refined analysis from 1991 to 2011

Abstract: To shed light on the general patterns and trends in urban sprawl research, and to provide reference for future study, bibliometric analysis and refined analysis are conducted for publications in this area from 1991 to 2011. The general publication output, the global geographical distribution of the authors, the funding and institutions involved, the research areas, and the source titles are analyzed and discussed. Scholars in the United States and China have produced most of the documents in urban sprawl and these two countries are also the largest contributors in terms of funding and institutions. ‘Environmental Sciences & Ecology’, ‘Urban Studies’, and ‘Geography’ are the most common research areas, and the journal titled Urban Studies has contributed the most articles. Furthermore, the refined analyses on the 500 top-cited and most relevant publications have revealed that research on urban sprawl is closely associated with the categories of ‘Urban form and development’, ‘Land use/land development’ and ‘environment/ecology/biology’. Conclusions are made with respect to the basic paradigm of research on urban sprawl. The multi-disciplinary research into urban sprawl are expected to be more diversified and integrated.

Spatiotemporal patterns of road network and road development priority in three parallel rivers region in Yunnan, China: An evaluation based on modified kernel distance estimate

Abstract: Road network is a critical component of public infrastructure, and the supporting system of social and economic development. Based on a modified kernel density estimate (KDE) algorithm, this study evaluated the road service capacity provided by a road network composed of multi-level roads (i.e. national, provincial, county and rural roads), by taking account of the differences of effect extent and intensity for roads of different levels. Summarized at town scale, the population burden and the annual rural economic income of unit road service capacity were used as the surrogates of social and economic demands for road service. This method was applied to the road network of the Three Parallel River Region, the northwestern Yunnan Province, China to evaluate the development of road network in this region. In results, the total road length of this region in 2005 was 3.70 × 104 km, and the length ratio between national, provincial, county and rural roads was 1:2:8:47. From 1989 to 2005, the regional road service capacity increased by 13.1%, of which the contributions from the national, provincial, county and rural roads were 11.1%, 19.4%, 22.6%, and 67.8%, respectively, revealing the effect of ‘All Village Accessible’ policy of road development in the mountainous regions in the last decade. The spatial patterns of population burden and economic requirement of unit road service suggested that the areas farther away from the national and provincial roads have higher road development priority (RDP). Based on the modified KDE model and the framework of RDP evaluation, this study provided a useful approach for developing an optimal plan of road development at regional scale.

Effects of grazing exclusion on soil carbon and nitrogen storage in semi-arid grassland in Inner Mongolia, China

Abstract: The semi-arid grasslands in Inner Mongolia, China have been degraded by long-term grazing. A series of ecological restoration strategies have been implemented to improve grassland service. However, little is known about the effect of these ecological restoration practices on soil carbon and nitrogen storage. In this study, characteristics of vegetation and soil properties under continued grazing and exclusion of livestock for six years due to a nationwide conservation program—‘Returning Grazing Lands to Grasslands (RGLG)’ were examined in semi-arid Hulun Buir grassland in Inner Mongolia, China. The results show that removal of grazing for six years resulted in a significant recovery in vegetation with higher above and below-ground biomass, but a lower soil bulk density and pH value. After six years of grazing exclusion, soil organic C and total N storage increased by 13.9% and 17.1%, respectively, which could be partly explained by decreased loss and increased input of C and N to soil. The effects of grazing exclusion on soil C and N concentration and storage primarily occurred in the upper soil depths. The results indicate that removal of grazing pressure within the RGLG program was an effective restoration approach to control grassland degradation in this region. However, more comprehensive studies are needed to evaluate the effectiveness of the RGLG program and to improve the management strategies for grassland restoration in this area.

Changing concepts of city and urban planning practices in Guangzhou (1949–2010): An approach to sustainable urban development

Abstract: By focusing on Guangzhou, this paper examines how different concepts of city in terms of urban-rural relationships are shaped in transforming China since 1949, and explores how they influence the way in which urban planning are practiced. In the pre-reform era, the city was defined as a productive space under the system of urban-rural segregation established for securing rapid industrialization. Urban planning was thus only concerned with the development of urban areas. In the 1980s and 1990s after the reform, institutional change and economic transformation mobilized the urban-rural linkages. The development of suburban areas was then considered by urban planning, but this consideration was a passive response to urban problems such as population explosion and water resources protection. Since the new millennium, the agenda for sustainable development and problems of uneven urban-rural development have called for the development of urban-rural integration. In this context, the city is conceptualized as a complex of mountain, city, river, farmland and sea, reconstructing the ideology of urban-rural division in defining urban development. Urban planning has therefore sought in an active way to develop a sustainable city embracing rural and natural elements, and to balance economic growth and environmental protection. It is argued that developing the concept of city as a complex of urban and rural elements contributes to the urban planning for sustainable urban development, while this conceptualization relies on the recognition of the integrated urban-rural relationship.

Effects of industrial relocation on Chinese regional economic growth disparities: Based on system dynamics modeling

Abstract: The economic growth of China has led to increasing growth disparities between regions. Such disparities are uncontrolled and are severely negative symptoms in the process of economic development. On the basis of system dynamics (SD) modeling and the relationship between industrial relocation and regional economic growth, we construct a model of the interrelationship between the two aforementioned phenomena. The model is an effective and creative exploration for examining effects of industrial relocation on Chinese regional economic growth disparities. The SD model is employed in this study to build an inter-regional labor migration SD model, an inter-regional capital migration SD model, an intra-industry SD model, an intra-regional population SD model, and an intra-regional SD model which are based on realities in labor and capital flow from the view of industrial relocation. VENSIM software is utilized to perform a system simulation based on the data of the eastern, middle, and western regions from 2000 to 2010. Results show that industrial relocation gradually narrows the relative disparity in GDP among the three regions. Moreover, the absolute one is enlarged continuously. The absolute and relative disparities in per capita GDP among eastern, middle, and western regions generally exhibit decreasing trends.

Spatial pattern evolution and casual analysis of county level economy in Changsha-Zhuzhou-Xiangtan urban agglomeration, China

Abstract: In order to evaluate whether or not the county units’ economy in the Changsha-Zhuzhou-Xiangtan (Chang-Zhu-Tan) Urban Agglomeration was growing as expected, this study analyzed the spatial economy pattern at county-level by using the Exploratory Spatial Data Analysis (ESDA) method. In this process, the global Moran’s I and local Getis-Ord G i * indexes were employed to analyze indicators including per capita GDP and three industrials (i.e. primary, secondary and tertiary industry) from 2000 to 2010. The results show that: 1) the county units’ economy in the Chang-Zhu-Tan Urban Agglomeration has exhibited a strong spatial autocorrelation and an accelerated integration trend since 2008 (Moran’ s I increased from 0.26 to 0.56); 2) there is a significant difference in economy development between the northern and southern county units in the Chang-Zhu-Tan Urban Agglomeration: the hotspot zone with high economic level was formed among the northern county units whereas the coldspot zone with low economic level was located in the southern areas. This difference was caused primarily by the increasingly prominent economic radiation effect of Changsha ‘upheaval’; 3) town density, secondary industry, and the integration policy are the major contributors driving the evolution of the spatial economy pattern in the Chang-Zhu-Tan Urban Agglomeration.

Corridors and networks in landscape: Structure, functions and ecological effects

Abstract: Chin. Geogra. Sci. 2014 Vol. 24 No. 1 pp. 1–4 Springer Science Press doi: 10.1007/s11769-014-0668-3 www.springerlink.com/content/1002-0063 © Science Press, Northeast Institute of Geography and Agroecology, CAS and Springer-Verlag Berlin Heidelberg 2014

Vulnerability of water resources and its spatial heterogeneity in Haihe River Basin, China

Abstract: To manage water resources effectively, a multiscale assessment of the vulnerability of water resources on the basis of political boundaries and watersheds is necessary. This study addressed issues on the vulnerability of water resources and provided a multiscale comparison of spatial heterogeneity under a climate change background. Using improved quantitative evaluation methods of vulnerability, the Theil index and the Shannon-Weaver index, we evaluated the vulnerability of water resources and its spatial heterogeneity in the Haihe River Basin in four scales, namely, second-class water resource regions (Class II WRRs), third-class water resource regions (Class III WRRs), Province-Class II WRRs, and Province-Class III WRRs. Results show that vulnerability enhances from the north to south in the different scales, and shows obvious spatial heterogeneity instead of moving toward convergence in multiscale assessment results. Among the Class II WRRs, the Tuhai-Majia River is the most vulnerable area, and the vulnerability of the Luanhe River is lower than that of the north of the Haihe River Basin, which in turn is lower than that of the south of the Haihe River Basin. In the scales of Class III WRRs and Province-Class III WRRs, the vulnerability shows obvious spatial heterogeneity and diversity measured by the Theil index and the Shannon-Weaver index. Multiscale vulnerability assessment results based on political boundaries and the watersheds of the Haihe River Basin innovatively provided in this paper are important and useful to characterize the real spatial pattern of the vulnerability of water resources and improve water resource management.

Spatial Heterogeneity of Soil Mineral Oxide Components in Depression Between Karst Hills, Southwest China

Abstract: In karst regions, the spatial heterogeneity of soil mineral oxides and environmental variables is still not clear. We investigated the spatial heterogeneity of SiO2, Al2O3, Fe2O3, CaO, MgO, P2O5, K2O, and MnO contents in the soils of slope land, plantation forest, secondary forest, and primary forest, as well as their relationships with environmental variables in a karst region of Southwest China. Geostatistics, principal component analysis (PCA), and canonical correlation analysis (CCA) were applied to analyze the field data. The results show that SiO2 was the predominant mineral in the soils (45.02%-67.33%), followed by Al2O3 and Fe2O3. Most soil mineral oxide components had a strong spatial dependence, except for CaO, MgO, and P2O5 in the plantation forest, MgO and P2O5 in the sec- ondary forest, and CaO in the slope land. Dimensionality reduction in PCA was not appropriate due to the strong spatial heterogeneity in the ecosystems. Soil mineral oxide components, the main factors in all ecosystems, had greater influences on vegetation than those of conventional soil properties. There were close relationships between soil mineral oxide components and vegetation, topography, and conventional soil properties. Mineral oxide components affected species diversity, organic matter and nitrogen levels.