Construction of ecological network based on MSPA-Conefor-MCR at the county scale: A case study in Yanqing District, Beijing, China.

The acceleration of urbanization and the frequent occurrence of natural disasters have led to increasingly fragmented habitats and decreased ecological connectivity, which in turn hinder rural sustainable development. Constructing ecological networks is a key direction in the spatial planning. By strengthening source protection, corridor construction, and ecological control, it can effectively alleviate the contradiction between regional ecological and economic development imbalance and promote biodiversity enhancement. With Yanqing District as an example, we constructed the ecological network by means of the morphological spatial pattern analysis, the connectivity analysis software, and the minimum cumulative resistance model. We analyzed various network elements from a county perspective, and provide suggestions for the development of towns. The results showed that the ecological network of Yanqing District as a whole presented the distribution characteristics of "the Mountain and the Plain". A total of 12 ecological sources were identified, covering an area of 1085.54 km2, accounting for 54.4% of the total area. 66 ecological corridors were screened with a total length of 1057.18 km, including 21 important corridors and 45 general corridors, with the length of which accounting for 32.6% and 67.4%, respectively. 27 first-class ecological nodes and 86 second-class ecological nodes were identified, which were concentrated in "the Mountain" such as Qianjiadian and Zhenzhuquan. The distribution of ecological networks in different towns was closely related to their geographical environment and development orientation. The towns such as Qianjiadian and Zhenzhuquan were located in "the Mountain", covering a wide range of ecological sources and corridors. Strengthening protection of ecological source was the focus of network construction, which can promote the coordinated development of ecology and tourism in towns. The towns such as Liubinbao and Zhangshanying were located at the junction of "the Mountain-Plain", hence strengthening corridor connectivity was the main direction of network construction, which could promote the construction of ecological landscape in towns. The towns such as Yanqing and Kangzhuang were located in the "the Plain", with serious landscape fragmentation due to the lack of ecological sources and corridors. Those towns need to build green livable towns through increasing ecological nodes and strengthening ecological restoration. This study enriched the construction of ecological networks at the county scale, explored the interface with spatial planning, strengthened ecological restoration and ecological control, which had reference value for promoting the sustainable development of towns and the construction of a multi-scale ecological network.

[Temporal and spatial variations of carbon storage and carbon sink improvement strategy at the district and county level based on PLUS-InVEST model: Taking Yanqing District as an example]. / 基于PLUS-InVESTæ¨¡åž‹çš„åŒºåŽ¿ç¢³å‚¨é‡æ—¶ç©ºæ ¼å±€å˜åŒ–ä¸Žç¢³æ±‡æå‡ç­–ç•¥­­ä»¥å»¶åº†åŒºä¸ºä¾‹.

Under the background of the carbon peaking and carbon neutrality goals, the evolution of the spatiotemporal pattern of carbon storage has recently emerged as a research hotspot. The change in land use and land cover (LULC) is the primary driver of carbon storage changes. Understanding the spatiotemporal variations of LULC and carbon storage at the small scale of district and county level and proposing strategies to improve carbon sink, will contribute to the ecological conservation, restoration and sustainable development of districts or counties. With Yanqing District in Beijing as an example, we calculated carbon storage from 1990 to 2020 based on the InVEST model and used the PLUS model to predict LULC type changes under three scenarios (natural growth, ecological conservation and economic development) from 2020 to 2050. We further predicted the carbon storage and proposed mea-sures to improve carbon sink. The results showed that the key LULC change in Yanqing between 1990 and 2020 were the conversion of 88.9% of grassland to forest, 50.1% of farmland to forest, and 39.5% of cropland to impervious surface. The total carbon storage showed an upward trend, with an increase of 3.34×106 Mg. The spatial distribution of carbon storage presented "high in the northeast, low in the southwest, and high in the mountainous areas, low in the riverine areas." The increase in forest and the decrease in grassland were the main reasons for the increase and decrease in carbon storage, respectively. Between 2020 and 2050, the ecological restoration efforts under the ecological protection scenario increased, and the probability of other LULCs transforming into forest increased, resulting in a 5.8% increase in carbon storage, which had the highest increase and carbon storage under the three scenarios. High-value carbon storage areas were concentrated in the northeast, northwest, and south of Yanqing District, basically corresponding to the mountainous regions of Yanqing with high forest coverage, and the low-value areas generally corresponded to the plains with high development intensity and low forest coverage. We could implement comprehensive ecological protection and restoration measures, including forest and grassland ecosystem protection, water environment ecological restoration, farmland ecological restoration, to promote sustainable development in Yanqing District and to achieve the "dual carbon" goal.

[Effects of landscape complexity and local management on bee pollinator diversity in apple orchards in Changping District, Beijing, China.] / åŒ—äº¬æ˜Œå¹³åŒºæ™¯è§‚å¤æ‚åº¦å’Œå±€åœ°ç®¡ç†å¯¹è‹¹æžœå›­ä¼ ç²‰èœ‚å¤šæ ·æ€§çš„å½±å“.

Pollinators provide important ecosystem services for crop production and food security. With the development of agricultural economy and the increasing intensity of land-use, a large number of natural or semi-natural habitats have been converted to croplands. Landscape homogenization and intensive management lead to the decline of wild bee diversity and threaten the sustainable agricultural production. In this study, we investigated the effects of landscape complexity (proportion of semi-natural habitats), local management practices (local flowering plant diversity and soil total nitrogen), and their interactions on diversity of bee pollinators in apple orchard in Changping District, Beijing. A total of 8642 bee individuals were captured, including 5125 honey bees and 3517 wild bees from 5 families, 14 genera, and 49 species. The optimal landscape scale for the response of bee diversity to landscape complexity and local management intensity was 500 m. Within 500 m radius of the site, the abundance of overall bees and wild bees significantly increased with increasing proportion of semi-natural habitats. The landscape complexity interacting with local flowering plant diversity significantly affected the richness of overall bee and wild bee. When the proportion of semi-natural habitats surrounding the apple orchards was low (≤29.9%), we found a positive effect of flowering plant diversity on the richness of overall bee and wild bee, whereas a reversed trend was found when the proportion of semi-natural habitats surrounding the apple orchards was high (>29.9%). In addition, the abundance of honey bees significantly increased with the increase of local flowering plant diversity and soil total nitrogen. The soil total nitrogen interacting with local flowering plant diversity significantly affected the honey bee abundance. At low levels of soil total nitrogen (≤1.9 g·kg-1), there was a positive effect of flowering plant diversity on honey bee abundance; whereas this trend was reversed at high levels of soil total nitrogen (>1.9 g·kg-1). Increasing the proportion of semi-natural habitats in agricultural landscape was beneficial to the increase of wild bee abundance, and flowering plant diversity could promote bee diversity but depending on landscape scale (proportion of semi-natural habitats) and local scale (nitrogen application). Therefore, multi-scale factors should be considered to develop conservation strategies to maintain the diversity of wild bees in agricultural landscape. Maintaining a higher proportion of cultivated land as much as possible is still a long-term requirement for production, while maintaining intermediate landscape complexity, increasing the diversity of flowering plants on the ground, and reducing the application of nitrogen fertilizer would be effective ways to promote the diversity of pollinating bees in apple orchards.

Family graveyards form underappreciated local plant diversity hotspots in China's agricultural landscapes.

In the intensively farmed, homogenous agricultural landscape of the North China Plain, family graveyards form distinct cultural landscape features. In addition to their cultural value, these graveyards represent semi-natural habitat islands whose potential roles in biodiversity conservation and ecological functioning has remained poorly understood. In this study, we investigated plant species richness on 199 family graveyards of different ages and sizes. In accordance with biogeography theory, both overall and insect-pollinated plant species richness increased with area and age of graveyards. Even small graveyards show a strong potential for conserving local plant richness, and a mosaic of both large and small family graveyards could play an important role in the conservation of farmland biodiversity and related ecosystem functions. The launch of agri-environmental measures that conserve and create semi-natural habitats, in turn benefitting agricultural biodiversity and ecological functioning, has proven difficult in China due to the shortage of dispensable arable land. Given the great value of family graveyards as semi-natural habitats reflected in our study, we propose to focus preliminary efforts on conserving these landscape features as existing, widespread and culturally important semi-natural habitat islands. This would represent an effective, complementary policy to a subsequent re-establishment of other semi-natural habitats for the conservation of biodiversity and ecological functioning in agricultural landscapes.

[Spider diversity and community characteristics in cropland and two kinds of recovery habitats in Bashang area, China]. / åä¸Šåœ°åŒºå†œç”°åŠä¸¤ç§æ¢å¤ç”Ÿå¢ƒä¸­èœ˜è››å¤šæ ·æ€§ä¸Žç¾¤è½ç‰¹å¾.

Spiders are important natural enemies in agricultural ecosystems. The biodiversity and community characteristics of spider directly determine the quality of ecosystem services such as pest control in cropland. Cropland and its surrounding recovery habitats are important for spiders. We used trap method to examine species composition, species diversity, and functional characteristics of spider communities at three altitudes (871, 1360 and 1635 m) and three habitats (cropland, natural recovery grassland, artificial restoration woodland) in Chongli District, Zhangjiakou, Hebei Province, China. The results showed that diversity index of different habitats was significantly diffe-rent. The abundance of spiders in artificial restoration woodland was 124.3, which was significantly higher than that in natural recovery grassland (70.1) and cropland (38.6). Species richness of artificial restoration woodland (16.3) and natural recovery grassland (21.4) were not significantly different, but both were significantly higher than those of cropland (8.9). The Shannon diversity index of artificial restoration woodland (2.04) and natural recovery grassland (2.05) was not significantly different, and both were significantly higher than that of cropland (1.55). There were significant differences in community composition among all three habitats. Spider body length was positively correlated with spider hunting types. Large spiders tended to get food by hunting. Natural recovery grassland and cropland spiders were dominated by safari, and artificial restoration woodland with more web-forming spiders. Spiders at higher altitude were generally small. Both natural recovery grassland and artificial restoration woodland could increase spider diversity and played important roles in regional biodiversity protection. Spider community composition differentiated in different habitats, with the overall functional characteristics of spider communities being changed and some habitats being retained. The index of spider diversity of the two recovery habitats was higher than that of cropland habitats, with differences in the species composition of the two recovery habitats, both of which had the function of protecting endemic species. Our results were useful for the protection and restoration of spider biodiversity on cropland and regional scales.

The influence of landscape alterations on changes in ground beetle (Carabidae) and spider (Araneae) functional groups between 1995 and 2013 in an urban fringe of China.

Urbanization is one of the main causes of land use change, especially from 1990 to now in China, but knowledge of its effect on different functional groups of carabids and spiders in the adjacent rural areas over time remains limited. We assessed whether landscape alterations (1993 versus 2013) drove changes in carabid and spider functional groups (1995 versus 2013) in an agricultural landscape located on the fringe of a rapidly growing city in China. Although built-up land increased from 6.3% to 32% across the whole landscape, the overall species richness of carabids and spiders did not decline. In contrast to the reduction in species richness of large carabids, the species richness of small carabids increased. Species richness of both large and small spiders increased. The species composition of carabids and spiders significantly changed between 1995 and 2013. Species compositions of large, predatory carabids and large or ground-hunting spiders were more sensitive to the changes in built-up land than those of small, omnivorous carabids and small or web-building spiders. The amount of grassland (abandoned land covered by wild grass) also increased as farmers began to work in the city. The increased grassland significantly contributed to the increased species richness of predatory and macropterous carabids. However, increased landscape diversity did not affect species richness of either carabids or spiders. High landscape diversity was related to reduction in field size, resulting in a decrease in the mean body size of carabids. This indicates that evaluating the effect of landscape change on carabid and spider diversity should be based on their functional traits. Different taxa, even different functional groups, have different responses to landscape change. The increase in built-up land did not immediately reduce species richness at the urban fringe. Increasing wild grasslands and combining smaller fields may benefit farmland biodiversity in this region.

Possibilities and requirements for introducing agri-environment measures in land consolidation projects in China, evidence from ecosystem services and farmers' attitudes.

The reductions of ecosystem services (ES) initiated by land consolidation towards intensive agriculture has been recognized in many parts of the world. Land consolidation in China is experiencing a transformation towards sustainability, which may be promoted by learning the experience of Europe to introduce agri-environment measures (AEM). This paper focused on the typical engineering works of land consolidation projects (LCP) to discuss the requirements and possibilities of introducing AEM in LCP in China. Evidence was sought through the ES changes and farmers' attitudes. Based on a database collected from the literature, the changes of ES under LCP across China were evaluated. Household interviews were conducted to identify farmers' perception of ES changes under LCP and their preference of AEM in LCP. In consisted with our expectation, our study demonstrated the negative impacts of LCP on the environment, that the present agricultural-focused LCP in China have typically generated increases in the arable land but decreases in non-crop habitats, and extensively caused growths in food supply ES but reductions in biodiversity maintenance ES. This tendency would threaten the provision of multiple ES and the ultimate sustainability of agriculture. It reflected the urgent requirements of environment integration in LCP in China, for which AEM are efficient instruments. Our results further illustrated the high possibilities of introducing AEM in LCP based on the evidence that the AEM welcomed by the majority of farmers involved all the engineering works, although the farmers selected AEM mainly due to their pursuit of aesthetic instead of biodiversity consideration. To promote land consolidation in China towards sustainability, it is essential to integrate ES into the goals of land use policy, set up the quantitative parameter controlling for non-crop habitats, and introduce AEM in LCP guidelines.

Effects of Plant Diversity, Vegetation Composition, and Habitat Type on Different Functional Trait Groups of Wild Bees in Rural Beijing.

The loss of flower-rich habitats and agricultural intensification have resulted in significant losses of wild bee diversity from agricultural landscapes that is increasingly threatening the pollination of zoochorous agricultural crops and agricultural sustainability. However, the links of different wild bee functional trait groups with habitat types and plant resources in agricultural landscapes remain poorly understood, thus impeding the formulation of effective policies for bee conservation. We therefore analyzed how bees representing different functional groups responded to variations in habitat type, vegetation composition and plant diversity. Natural shrubland sustained the highest diversity in bees overall, in large-sized bees, solitary bees and belowground-nesting bees, while each habitat harbored unique species. In half of the functional bee groups, species were negatively linked to tree coverage and herb coverage, respectively, while plant diversity was positively related to all functional groups except large-sized bees and aboveground-nesting bees. Overall bee abundance was positively related to abundance of plants in the Sympetalae, and negatively related to abundance of plants in the Archichlamydeae. Different bee functional groups showed distinct preferences for different plant communities. In order to conserve the diversity of wild bees across functional groups to optimize associated pollination services, a diverse habitat mosaic, and particularly plant species in Sympetalae need to be promoted in agricultural landscapes. Future studies should aim to enhance our understanding of plant-pollinator associations and specific food requirement of different wild bee species for their effective conservation.

How agricultural multiple ecosystem services respond to socioeconomic factors in Mengyin County, China.

Provisioning services have always been the main focus of agriculture, and which have led to a decline in biodiversity and have damaged a number of other services. Agriculture should contribute to current and future food security while producing multiple ecosystem services (ES). Restoration outcomes of multiple ES were affected by different socioeconomic drivers, thus a better understanding of how multiple ES respond to socioeconomic drivers can help to restore multiple ES. This paper used rural people's perceptions of ES to quantify and map ecosystem service obtainment and demand in the Mengyin County, China. An integrative index of multiple ecosystem services (IMES) was used to effectively aggregate the values of multiple ES. The threat categorization framework is designed to communicate the degree to which the adequate and sustainable provision of multiple ES is threatened, in order to prioritize conservation actions. The results revealed that 6 townships in the Mengyin County exhibited an excessive obtainment situation (demand is less than obtainment) of multiple ES; an insufficient obtainment situation (demand is greater than obtainment) of multiple ES was mainly situated in the northern part of Mengyin County. Overall, the current state of multiple ES across Mengyin County is classified as "Endangered" classification according to application of threat categorization framework. It is necessary to restructure and manage socioeconomic factors for multiple ES. At national level, the macro decision-making (controlling population density) and the mechanisms (attracting high-quality human resources into the rural) will play an important role in promoting multiple ES management, and it is necessary to provide 3 or more years of tailored educational resources for rural residents to advance multiple ES in agricultural landscape. Development of agricultural PES programs in China that enable farmers to profit from production ES is a sustainable strategy for increasing multiple ecosystem services.

Disentangling effects of abiotic factors and biotic interactions on cross-taxon congruence in species turnover patterns of plants, moths and beetles.

High cross-taxon congruence in species diversity patterns is essential for the use of surrogate taxa in biodiversity conservation, but presence and strength of congruence in species turnover patterns, and the relative contributions of abiotic environmental factors and biotic interaction towards this congruence, remain poorly understood. In our study, we used variation partitioning in multiple regressions to quantify cross-taxon congruence in community dissimilarities of vascular plants, geometrid and arciinid moths and carabid beetles, subsequently investigating their respective underpinning by abiotic factors and biotic interactions. Significant cross-taxon congruence observed across all taxon pairs was linked to their similar responses towards elevation change. Changes in the vegetation composition were closely linked to carabid turnover, with vegetation structure and associated microclimatic conditions proposed causes of this link. In contrast, moth assemblages appeared to be dominated by generalist species whose turnover was weakly associated with vegetation changes. Overall, abiotic factors exerted a stronger influence on cross-taxon congruence across our study sites than biotic interactions. The weak congruence in turnover observed particularly between plants and moths highlights the importance of multi-taxon approaches based on groupings of taxa with similar turnovers, rather than the use of single surrogate taxa or environmental proxies, in biodiversity assessments.

[Landscape character assessment framework in rural area: A case study in Qiaokou, Chang-sha, China].

Based on the concept and methods of landscape character assessment (LCA) in England, this paper applied a complete process of landscape character assessment with a case study in Qiaokou Town, which is located in a typical southern paddy fields area in Changsha City. We drew the landscape character map of Qiaokou Town through desk classification and field survey, identified and compared the key characters of each character area, and proposed suggestions on the improvement and stewardship of landscape characters. The results showed that Qiaokou could be divided into 2 landscape character types and 7 landscape character areas with the main differences in cropland and vegetation pattern as well as aesthetic characters. The case study indicated that LCA could be a critical tool to identify the characteristics in rural area, and provide helpful guidance to protect, restore and maintain the unique culture and characters of rural landscape, which is useful for targeted rural landscape development. In the future, we suggested that the assessment on the effects of landscape construction measures on the ecosystem services should be incorporated in LCA research as well.

Diversity patterns of ground beetles and understory vegetation in mature, secondary, and plantation forest regions of temperate northern China.

Plantation and secondary forests form increasingly important components of the global forest cover, but our current knowledge about their potential contribution to biodiversity conservation is limited. We surveyed understory plant and carabid species assemblages at three distinct regions in temperate northeastern China, dominated by mature forest (Changbaishan Nature Reserve, sampled in 2011 and 2012), secondary forest (Dongling Mountain, sampled in 2011 and 2012), and forest plantation habitats (Bashang Plateau, sampled in 2006 and 2007), respectively. The α-diversity of both taxonomic groups was highest in plantation forests of the Bashang Plateau. Beetle α-diversity was lowest, but plant and beetle species turnover peaked in the secondary forests of Dongling Mountain, while habitats in the Changbaishan Nature Reserve showed the lowest turnover rates for both taxa. Changbaishan Nature Reserve harbored the highest proportion of forest specialists. Our results suggest that in temperate regions of northern China, the protected larch plantation forest established over extensive areas might play a considerable role in maintaining a high biodiversity in relation to understory herbaceous plant species and carabid assemblages, which can be seen as indicators of forest disturbance. The high proportion of phytophagous carabids and the rarity of forest specialists reflect the relatively homogenous, immature status of the forest ecosystems on the Bashang Plateau. China's last remaining large old-growth forests like the ones on Changbaishan represent stable, mature ecosystems which require particular conservation attention.

[Cooperative relations between non-cropped habitats and soil animals in suburban farmland Landscape: A case in Shenbei New District in Shenyang, China].

Non-cropped habitat in farm landscape plays a significant role in biodiversity, the functions of arable land and crop yields. This study focused on Shenbei New District in Shenyang City of Liaoning Province in Northeast China, which was a typical area with contradiction between biodiversity conservation and the high demand of agricultural production in the process of urbanization. Information entropy model, hand-picking and Baermann method were used for survey and identification of arthropods and nematodes in soils in urban suburban (US), urban fringe area (UFA) and rural area ( RA). The cooperative relations between the number of soil animals and types, structure as well as the total amount of non-cropped habitat were investigated in these three types of areas using linear regression. Our results showed that the area of single patch in non-cropped habitat was smaller than one hectare in Shenbei New District, and the types and the proportion of non-cropped habitat patches were increasing along with the increase of their distance to the urban center. But the proportion of non-cropped habitats areas appeared under an inverted U-type change. The proportion of non-cropped habitat patches was from 8.6% to 27.8%. The individual number of soil animals showed the U-type trend, while their species number changed irregularly. The individual number of soil animals increased with the increase of the proportion of non-cropped habitat patches in RA and US. There was no obvious correlation between the individual number of soil animal and the proportion of non-cropped habitat patches in UFA. The individual number of soil animals decreased with the increase of the proportion of non-cropped habitats areas. There was no cooperative relation in the proportion of non-cropped habitats and the number of soil animal species.

[Spatial distribution pattern of carabid assemblage in agricultural landscape of Miyun County, Beijing].

By the method of pitfall trap sampling, an investigation was conducted on the carabid assemblage in four typical habitats (maize field, peanut field, orchard, and semi-natural woodland) in the agricultural landscape in Xitiange Village of Miyun County, Beijing. Among the four habitats, orchard had the highest alpha-diversity of carabid assemblage, followed by woodland and maize field, and peanut field had the lowest one. The species composition of the assemblage in woodland, peanut field, and orchard had evident difference, but was similar to that in maize field to some extent. The number of the individuals of predatory and omnivorous carabid sub-assemblages was larger in orchard, and the predatory sub-assemblage presented more distinct difference in its species turnover rate than the omnivore sub-assemblage among the habitats. This study showed that low-intensively managed orchard habitat could sustain higher alpha-diversity of carabid assemblage than semi-natural woodland habitat, and the landscape with diversified habitats could benefit the beta-diversity of carabid assemblage and its predatory sub-assemblage. To attach importance to the conservation of diversified habitats and low-intensively managed farmland habitat would have significance for the conservation of carabid assemblage diversity and its pest control function in agricultural landscape.

[Diversity of geometrid moth (Lepidoptera: Geometridae) in cropland and reforested semi-natural habitats at different altitudes of Bashang Plateau, Hebei Province of China].

In order to understand the effects of landscape heterogeneity induced by habitat restoration and landform change on the biodiversity in degraded landscapes, an investigation by using light trap was conducted on the geometrid moth (Lepidoptera: Geometridae) diversity in the cropland and reforested semi-natural habitats in three villages at different altitudes of Bashang Plateau in 2006 and 2007. There existed significant differences in the species richness and individual number of geometrid moth between cropland and reforested semi-natural habitats and in the species richness of geometrid moth between the villages at different altitudes, but no significant differences in the individual number of geometrid moth between the villages at different altitudes and in the standardized sparseness index and Fisher' s alpha index between the villages and between the cropland and reforested semi-natural habitats within each village. The non-metric multi-dimensional scaling (NMDS) indicated that the community structure of geometrid moth in different habitats and at different altitudes differed significantly. This study indicated that the landscape heterogeneity induced by land-form change had significant effects on the community structure and diversity of geometrid moth on Bashang Plateau, and, both cropland and reforested semi-natural habitats were the important habits for geometrid moth. It was suggested that to protect the landscape mosaics containing cropland and reforested semi-natural habitats across the varied landform of Bashang Plateau would have significances in the conservation of high gamma-diversity of geometrid moth, but whether the reforestation and creation of semi-natural habitats could improve the biodiversity of geometrid moth should be monitored in long term.

[Spatial evaluation on ecological and aesthetic quality of Beijing agricultural landscape].

A total of ten single indices mainly reflecting the ecological and aesthetic quality of agricultural landscape, including ecosystem function, naturalness, openness and diversity, contamination probability, and orderliness were selected, their different weights were given based on field survey and expert system, and an integrated evaluation index system of agricultural landscape quality was constructed. In the meantime, the land use data provided by GIS and the remote sensing data of vegetation index were used to evaluate the Beijing agricultural landscape quality and its spatial variation. There was a great spatial variation in the agricultural landscape quality of Beijing, being worse at the edges of urban area and towns, but better in suburbs. The agricultural landscape quality was mainly related to topography and human activity. To construct a large-scale integrated index system based on remote sensing data and landscape indices would have significance in evaluating the spatial variation of agricultural landscape quality.

[Winter wheat yield gap between field blocks based on comparative performance analysis].

Based on a two-year household survey data, the yield gap of winter wheat in Quzhou County of Hebei Province, China in 2003-2004 was studied through comparative performance analysis (CPA). The results showed that there was a greater yield gap (from 4.2 to 7.9 t x hm(-2)) between field blocks, with a variation coefficient of 0.14. Through stepwise forward linear multiple regression, it was found that the yield model with 8 selected variables could explain 63% variability of winter wheat yield. Among the variables selected, soil salinity, soil fertility, and irrigation water quality were the most important limiting factors, accounting for 52% of the total yield gap. Crop variety was another important limiting factor, accounting for 14%; while planting date, fertilizer type, disease and pest, and water press accounted for 7%, 14%, 10%, and 3%, respectively. Therefore, besides soil and climate conditions, management practices occupied the majority of yield variability in Quzhou County, suggesting that the yield gap could be reduced significantly through optimum field management.

[Landscape planning approaches for biodiversity conservation in agriculture].

Biodiversity conservation in agriculture not only relates to the sustainable development of agriculture, but also is an essential part of species conservation. In recent years, the landscape planning approach for biodiversity was highlighted instead of species-focused approach. In this paper, the landscape factors affecting the biodiversity in agriculture were reviewed, and the possible landscape approaches at three different scales for more efficient conservation of biodiversity in agro-landscape were suggested, including: (1) the increase of the proportion of natural or semi-natural habitats in agriculture, diversification of land use or crop pattern, and protection or construction of corridor at landscape level; (2) the establishment of non-cropping elements such as field margin at between-field level; and (3) the application of reasonable crop density, crop distribution pattern and rotation, and intercrop etc. at within-field level. It was suggested that the relevant policies for natural conservation, land use planning, and ecological compensation should be made to apply the landscape approaches for biodiversity conservation at larger scale.

Changes of soil organic carbon in an intensively cultivated agricultural region: a denitrification-decomposition (DNDC) modelling approach.

Regional modelling of soil organic carbon (SOC) dynamics is important for predicting large-scale patterns in carbon cycling and for assessing potential responses of soil carbon pools to land-use change. However, data uncertainties related to both spatial heterogeneity and small-scale differences in farming practice related to cropping systems affect the accuracy of regional models. A case study is presented from Quzhou County in the North China Plain, an area characterized by highly intensive farming. For this county, the DNDC model was validated using sampling data from 68 sites around the county under generalized farm practices. Unique modelling units based on soil type, soil texture and crop type were created and then used to model the spatial change of SOC under different farming practices. Considering the main factors affecting SOC sequestration, the results indicate that the DNDC model delivers acceptable modelling results at county level. The results show that there is a great potential for SOC sequestration in Quzhou County in its central, southern and eastern parts. Changes in farming practices show a strong effect on carbon sequestration. A very efficient and environmental friendly sequestration of SOC pools could be achieved even by decreasing nitrogen fertilizer inputs, when the amount of straw returned to the field is greatly increased.

[Spatial-temporal dynamic change of land resource degradation in China].

Large scale spatial and temporal land use survey data were used to study the dynamics of land use change in China recently. With the aid of GIS, the spatial-temporal dynamic change of land resource degradation at the national level was investigated using authoritative datasets from detailed land use surveys (early 1990s approximately 2003). As a result, seven major types of land degradation processes were identified, including sandy desertification, rocky desertification, secondary salinification, non-agricultural land occupation, deforestation, natural grassland degradation and wetlands shrinking. This paper comprehensively explored the characteristics of these land degradation processes and revealed the status and trend of the holistic land resource degradation in China. Results shows that: (1) Although land degradation has been controlled in local area, but it is still continuing to spread in the whole country. The total degradation index of the holistic land resource presented fluctuating trend. Indexes of non-agricultural construction occupation and wetland shrinking process are far more than that of other process, which are two primary causes contribution to heading straight towards full-scale land resource deterioration in China. (2) Land resource degradation process of China focused on natural grass land, and non-agricultural construction land, which attained 66.27%; Land resource degradation rehabilitation mainly focused on desertification and forest restoration, which accounts for 57.5%. (3) Sandy desertification and rocky desertification process have been reversing greatly. The total net change of their quantities was decreased by 15,578km2. But most of the rehabilitation of land desertification was concentrated on the originally ecological vulnerable northwestern zone, whereas newly added desertified land has been expanding and aggravating in eastern zone, especially around river watersheds. (4) Over two-thirds of non-agriculture land expansion came from cultivated land. In addition, almost 60 percent of the loss cultivated land occupied by non-agricultural land was appeared in the Northeast, the Eastern coast and Central China where have many high productive agricultural lands of China. This kind of land degradation has threatened food security of China seriously. (5) However, large scale reclamation of ecological land transferred into cultivated land was the most dominant factor of degradation. For example, the conversion of wetland resource to croplands by reclamation accounts for over 50 percent of wetland shrinking.