The dynamics of landscape-scale ecological connectivity based on least-cost model in Dongshan Island,China

As a hot topic in Landscape Ecology study,ecological connectivity is an important indicator for regional land sustainable use and biological protection. This paper conducted a systematic assessment of ecological connectivity using remote sensing images of Dongshan Island in 1994, 2003 and2011. Based on least-cost modelling, the method takes into consideration the type of barrier, the distance impact, and the adjacent land use types to obtain the Barrier Effect Index(BEI) and Ecological Connectivity Index(ECI). The application of this method to Dongshan Island showed the ecological connectivity index(ECI) was low in 1994, improved in 2003, and decreased significantly in 2011. The results of the dynamic analysis of landscape structure showed farmland and roads were the main landscape classes that caused the low observed ECI in 1994 and 2003;these tended to divide the landscape and cause fragmentation. Construction land and roads were the main landscape classes resulting in low ECI in 2011,while forest and grassland had a high ECI. Trajectory analysis showed ECI tended to decrease in the low mountain forest zone of the northwestern and southeastern parts of Dongshan Island as well as in the coastal protection forest area. The areas where ECI became high were located in the northeastern part of Dongshan Island where cities and towns are concentrated with high human populations.Therefore, rapid urbanization has been the most important factor driving changes in landscape structure and patterns during the last 17 years on Dongshan Island. The approach not only assists us in revealing the driving mechanism of landscape dynamics from another aspect, but also can assess the impacts of regional and urban plans on landscape structure and function.

Understanding coupled coordination relationships between social and ecological functions of urban green spaces

Urban Green Spaces(UGSs)can provide social and ecological benefits,and the coordination of these two functions will largely advance human-nature harmony in cities.As such,we proposed a comprehensive framework to evaluate UGSs multifunctionality,i.e.the coupling coordination relationship of ecological connectivity and spatial accessibility of UGSs.Wuhan City in Central China was taken as a case study,and multiple ecosystem service values of green space patches and the disordered use of UGSs multifunctionality were explored.The results demonstrated low-level coupling coordination of UGSs multifunctionality in Wuhan.More than 70%of UGSs were imbalanced,27.91%of which featured small sizes,low connectivity and accessibility.We suggest that planners should optimize UGSs arrangement to improve species reachability,especially for species with dispersal distance less than 4 km,and to create 15-minute community life circles for residents at the same time.Our findings are expected to support the promotion of UGSs multifunctionality and the balance of urban development and habitat conservation.

The effects of land consolidation on the ecological connectivity based on ecosystem service value： A case study of Da＇an land consolidation project in Jilin province

Land consolidation has a profound impact on landscape patterns and ecological functions at various scales through engineering and biological measures. In recent years, China invests more than 100 billion RMB yuan on land consolidation each year. To under- stand how land consolidation affects landscape patterns and ecosystems, we investigated the ecosystem service value and the ecological connectivity in a consolidated area of Da＇an city from 2008 to 2014 using a revised ecological connectivity index. The results indicated that land consolidation has certain negative influences on the ecosystem services in this area. The total ecosystem service value will decrease by nearly 30% in the late stage of consolida- tion. This decrease is caused by the loss of ecosystem service of the wetland and grassland, despite a sensible increase of cultivated land. In addition, land consolidation could change the ecological connectivity as well as the land use structure. Up to 85% of the entire area will be in low connectivity in the late stage of consolidation, representing a 6.23% increase in the total coverage compared to pre-consolidation. Finally, the different connectivity landscape and their key areas can be identified by the revised ecological connectivity index effectively. This study is helpful to trace out the relationships between landscape pattern and ecological process, and provides insights for ecological planning and designing of land consolidation in this area. We suggest that more attentions should be paid to improve the quality and eco- system service value per unit area of the landscape, to establish ecological compensation mechanism of wetland losses, and to create the ecological corridors along the least accu- mulated impendence surface in the key areas during land consolidation.

Exploring the spatio-temporal impacts of farmland reforestation on ecological connectivity using circuit theory:A case study in the agro-pastoral ecotone of North China

Farmland reforestation can contribute substantially to ecological restoration.Previous studies have extensively examined the ecological effects of farmland reforestation,but few of them have investigated the spatiotemporal responses of broad-scale landscape connectivity to reforestation.By using a typical agro-pastoral ecotone in northern China as a case study,we addressed this issue based on an innovative integration of circuit theory approach and counterfactual analysis.The forest connectivity through multiple dispersal pathways was measured using the circuit theory approach,and its spatiotemporal changes after reforestation were evaluated by counterfactual analysis.The results showed that from 2000–2015,the reforested farmland occupied 2095 km^2,and 12.5% was on steeply sloped land.Farmland reforestation caused a greater increase in ecological connectivity by adding new ecological corridors and stepping stones in scattered forest areas rather than in areas with dense forest distributions.The newly added corridors and stepping stones were fragmented,short and narrow and thus deserve powerful protection.Future reforestation to improve landscape connectivity should highlight pinch point protection and obstacle removal as well as the tradeoff between farmland loss and farmer survival.Our findings are expected to inform the optimization of the Grain for Green policy from the perspective of broad-scale biodiversity conservation.