Land use profoundly changes the terrestrial ecosystem and landscape patterns, and these changes reveal the extent and scope of the ecological influence of land use on the terrestrial ecosystem. The study area selected for this research was the middle reaches of the Heihe River. Based on land use data (1986, 2000, and 2014), we proposed an ecological risk index of land use by combining a landscape disturbance index with a landscape fragility index. An exponential model was selected to perform kriging interpolation, as well as spatial autocorrelations and semivariance analyses which could reveal the spatial aggregation patterns. The results indicated that the ecological risk of the middle reaches of the Heihe River was generally high, and higher in the northwest. The high values of the ecological risk index (ERI) tended to decrease, and the low ERI values tended to increase. Positive spatial autocorrelations and a prominent scale-dependence were observed among the ERI values. The main hot areas with High-High local autocorrelations were located in the north, and the cold areas with low-low local autocorrelations were primarily located in the middle corridor plain and Qilian Mountains. From 1986 to 2014, low and relatively low ecological risk areas decreased while relatively high risk areas expanded. A middle level of ecological risk was observed in Ganzhou and Minle counties. Shandan County presented a serious polarization, with high ecological risk areas observed in the north and low ecological risk areas observed in the southern Shandan horse farm. In order to lower the eco-risk and achieve the sustainability of land use, these results suggest policies to strictly control the oasis expansion and the occupation of farmland for urbanization. Some inefficient farmland should transform into grassland in appropriate cases.

https://www.mdpi.com/2071-1050/8/6/536/pdf

Dynamic Ecological Risk Assessment and Management of Land Use in the Middle Reaches of the Heihe River Based on Landscape Patterns and Spatial Statistics

Spatiotemporal patterns and modifiable areal unit problems of the landscape ecological risk in coastal areas: A case study of the Shandong Peninsula, China

Applied with remote sensing, GIS, and mathematical statistics, the spatial-temporal evolution characteristics of urbanization expansion of Yantai city from 1974 to 2009 was studied. Based on landscape pattern metrics and ecological risk index, the landscape ecological risk from the landscape pattern dynamics was evaluated. The results showed that the area of urban land increased by 189.77 km(2) with average expansion area of 5.42 km(2) y(-1) from 1974 to 2009. The urbanization intensity index during 2004-2009 was 3.92 times of that during 1974-1990. The land use types of urban land and farmland changed greatly. The changes of landscape pattern metrics for land use patterns indicated that the intensity of human activities had strengthened gradually in study period. The landscape ecological risk pattern of Yantai city shaped half-round rings along the coastline. The ecological risk index decreased with increase of the distance to the coastline. The ratio of high ecological risk to subhigh ecological risk zones in 2009 was 2.23 times of that in 1990. The significant linear relationship of urbanization intensity index and regional ecological risk indicated that the anthropological economic activities were decisive factors for sustainable development of costal ecological environment.

/pdf/effects-of-urbanization-expansion-on-landscape-pattern-and-2jfzyn2qd6.pdf

Effects of Urbanization Expansion on Landscape Pattern and Region Ecological Risk in Chinese Coastal City: A Case Study of Yantai City

Land use changes associated with urbanization may increase ecological risk and subsequent geohazard risk. Africa is particularly vulnerable at preset as, since 2005, the highest rates of rapid urbanization-associated forest degradation have occurred there. On August 14, 2017, a compound geohazard in Freetown, Sierra Leone, caused thousands of fatalities and destroyed hundreds of houses. Land use change is considered the main factor contributing to geohazard initiation. Here, we use Freetown as a case study to quantitatively assess the magnitude of the increase in ecological risk associated with land use changes. To achieve the aim, satellite images are used in the case study area from 2007 to 2017, the data are integrated into a geographic information system. A series of indices are then used based on the processed images to describe land use and ecological risk, including dynamic index, trend and state index, and ecological risk index. The results show that Freetown experienced a rapid urbanization process, together with an unbalanced increase in urban land and complex conversion of bare and grass land, from 2007 to 2017. Significantly degenerated forest was converted into urban land (2.77%), bare land (6.47%), and grassland (10.27%), while the ecological risk level increased from low to high. The ecological risk in the affected area of geohazard is found higher than that of the surrounding mountainous area. It indicates that vegetation may reduce the risk of disaster. This result is helpful for the trade-off between urban development and ecological protection and rational urban planning. For disaster resilience and sustainable development of Freetown, and also other rapidly urbanizing cities in mountainous areas, ecological protection must be incorporated into development planning.

Ecological risk resonance of urbanization and its effect on geohazard disaster: the case of Freetown, Sierra Leone

Integrating Ecosystem Health and Services for Assessing Ecological Risk and its Response to Typical Land-Use Patterns in the Eco-fragile Region, North China

By using RS and GIS technology, the ecological risk index (ERI) was constructed based on the analysis of land use change and structural characteristics in urbanization watershed of Songhua River in Harbin section. Afterwards, the spatial distribution and change characteristics maps of ERI obtained by using block Kriging were analyzed to reveal the spatial and temporal evolution characteristics, change rules and formation mechanisms of ecological risk based on land use under the background of urbanization, and to minimize land use risk during urbanization process. The results showed that during the past 18 years, moderate ecological risk level was major, while proportion of high ecological risk was the lowest, and the area of higher and lower ecological risk region changed most greatly; high and higher ecological risk were focused on urban region and the transition zone from urban to suburban region, while low and lower ecological risk mainly distributed in forestland with higher vegetation coverage, water bodies, grassland, shrub land and so on. Meanwhile, the transition zone from high to low ecological risk was very obvious. In addition, ecological risk became slightly worse in some region due to the transformation from cropland to residential and urban land, while it became slightly better in other regions because of the transformation from cropland to forestland; the center of gravity in lower ecological risk region shifted most greatly, while the shift was the smallest in high ecological risk region, namely 12.31 and 0.57 km respectively.

Yongfeng Dang

Papers

Study on Ecological Risk of Land Use in Urbanization Watershed Based on RS and GIS:A Case Study of Songhua River Watershed in Harbin Section