Forestland landscape change induced spatiotemporal dynamics of subtropical urban forest ecosystem services value in forested region of China: A case of Hangzhou city.

Understanding of urban forestland both type structure and change and their effects on forest ecosystem services (ES) is important for maintaining and enhancing the quality of life as well as ensuring sustainable urban planning in cities. In Hangzhou city of Zhejiang province in Southeast China, forestland covers more than 71% of its total land area, thereby providing a high variety of ES. Many studies have focused on the effects of land use change on ES value (ESV), but these have only applied to the first-level classification of land use. So there is an urgent need for studies to measure the effects of land use change on ESV applied to the second-level classification of land use. In this present study, from a rare insight into the forestland landscape change of Hangzhou city, the spatiotemporal dynamics of urban forest ESV (UFESV) during the period of 2000-2015 are analyzed based on the combination of remote sensing and a light-use-efficiency model (CASA). The results indicate that the total value of urban forest ES increases from 9.79 × 108 Yuan in 2000 to 12.31 × 108 Yuan in 2015, with a net increase of 2.52 × 108 Yuan in Hangzhou city, and forested land has the highest UFESV, contributing about 99.49% of the total services value, although the area of forestland decreases by 101.99 km2 over the past 15 years. Carbon fixation and oxygen release and organic matter production are the two dominant service functions, accounting for 87.56% of the total on average. The construction and planning of Hangzhou's forest city has a positive impact on the value of urban forest ES during 2000-2015.

Baseflow estimation for catchments in the Loess Plateau, China.

Baseflow is the portion of streamflow that originates from groundwater. It is pivotal to groundwater supply as well as the interactions between groundwater and surface water. In the Loess Plateau of China, the baseflow plays a fundamental role in sustaining the aquatic ecosystem. Rational estimation of baseflow is of critical importance for understanding the functioning of the groundwater system and informing management of regional water resources. In this study, a two-well parameterised digital filter was used to separate baseflow from observed daily total streamflow on the Weihe River Basin. Two parameters (maximum baseflow index (BFImax) and the recession constant) of this filter were estimated using UKIH and a recession analysis with physical meaning, respectively. The results show that the baseflow index increased from the upstream to downstream (0.27-0.32) of the Weihe River, and the baseflow of the river is summer dominant. In general, the baseflow has been increasing gradually owing to the implementation of soil conservation measures. This study provides an understanding of baseflow response to seasonal variability and water environmental management in basin scale.

Spatial and temporal changes of social vulnerability of cities to natural hazards in Zhejiang province, China.

Understanding how social dynamics interact with natural hazards is one of the main challenges at global and local scales in the world for studying social vulnerability to natural hazards. In this study, we explore the spatial and temporal changes of social vulnerability of cities in Zhejiang province to natural hazards in China for the last decade. Based on the Zhejiang province's census data and the demographics and socioeconomic data during the period from 2009 to 2018, we have characterized social vulnerability through the Social Vulnerability Index (SoVI) for 11 cities throughout the province during 2009-2018 and examined spatial changes in social vulnerability using equal interval method. The results indicated that although the comprehensive vulnerability of Zhejiang province shows a declining trend at a county level, the social vulnerability of different city at the provincial level has obvious differences.

Mapping and Assessment of Degraded Land in the Heihe River Basin, Arid Northwestern China.

Land degradation is a great threat in the Heihe River Basin, located in the aridinland of northwestern China and land desertification is one of the main aspects ofenvironmental changes in this basin. Previous studies have focused on water resourceutilization and soil erosion, but the status of degraded land in the Heihe River Basin, suchas its distribution, extent and precise characteristics is often inadequately known. Based onfield observations and TM images from the year 2003, this study provides classificationand evaluation information concerning the degraded land in the basin of the Heihe River.There are five types of degraded land types in the Heihe River Basin: water eroded in thesouthern mountains, sandified and vegetation degraded near the oases, aridized in the lowreaches, and salinized in the lowlands. The total degraded area covers 29,355.5 km²,22.58% of the land in the study area. Finally, degraded land in the Heihe River Basin wasevaluated according to changes in the physical structure and chemical components of soils,land productivity, secondary soil salt, and water conditions.

Oasis land-use change and its environmental impact in Jinta Oasis, arid northwestern China.

Land use change resulted in land degradation is a focus of research on global environmental changes and plays a significant role in the stability and economic development of oases in arid regions of China. Jinta Oasis, a typical oasis of temperate arid zone in northwestern China, was investigated to assess land-use change dynamics during 1988-2003 with the aid of satellite remote sensing and GIS, and to explore the interaction between these changes and oasis environment. Six land-use types were identified, namely: cropland, forestland, grassland, water, urban or built-up land, and barren land. The results indicate that cropland, urban/built-up land, and barren land increase greatly by 30.03, 13.35, and 15.52 km(2), respectively; but grassland and forestland areas decrease rapidly by 58.06, and 1.76 km(2), respectively. These results also show that obvious widespread changes in land-use occur within the whole oasis over the study period and result in severe problems of environmental degradation (i.e. land desertification, decline of groundwater, and vegetation degeneracy).

Water environmental degradation of the Heihe River Basin in arid northwestern China.

Water environmental degradation is a major issue in the Heihe River Basin belonging to the inland river basin of temperate arid zone in northwestern China. Mankind's activities, such as dense population and heavy dependence on irrigated agriculture, place immense pressure on available and limited water resources during the last century, especially the recent five decades. An investigation on the water environmental degradation in the Heihe River Basin and analysis of its causation were conducted. The results indicated that water environmental changes in the whole basin were tremendous mostly in the middle reaches, which reflected in surface water runoff change, decline of groundwater table and degeneration of surface water and groundwater quality. Some new forms of management based on traditional and scientific knowledge must be introduced to solve problems of water environmental degradation in the Heihe River Basin.