County is the basic unit of land space planning and management research. The identification and reconstruction of county ecological space network, an important way of space optimization, plays a positive role in the demarcation of ecological protection red line. However, the methodology of spatial network analysis is stagnant. Based on the construction and identification of the ecological space network in typical hilly areas and counties, this study expresses the characteristics of change brought about by specific disturbance with robustness analysis method, analyzes node importance degree, and evaluates network stability. The results show that nodes with high importance play a key role in maintaining the stability of ecological space network. The number of such nodes accounts for about 5% and most of them are located in the area of Luoxiao Mountain in Chaling county, and corresponding with woodland, water and grassland, garden and other ecological land landscape. The change value of the stability of the ecological space network is highly consistent with the number of nodes. When the failure rate of the network node is higher than 92%, it will be completely paralyzed; when the failure rate is lower than 20%, the stability can be restored. The change of connectivity robustness is more sensitive in the scenario of sabotage which is dominated by interference of human activities. Based on the distribution of important nodes and the judgment results of stability, combined with the red line demarcation scheme of ecological protection, this paper puts forward suggestions on the differentiated management of regional ecological protection and the reconstruction of ecological space network. The study not only provides effective support for county ecological space planning and ecological protection red line control, but also provides case reference for similar regional ecological space network research.

The ecological risks facing the landscape in the Ningjiang River Basin are influenced by multiple parameters. Landscape optimization is an effective way to assess the detrimental effects on the ecosystem. In this study, an integrated "natural-social-landscape" landscape ecological risk assessment system was produced, and the landscape ecological risk classification of the Ningjiang River Basin was based on spatial principal component analysis. Ecological resistance surfaces were constructed using the results of the landscape ecological risk analysis. The landscape resistance surfaces were produced based on the minimum cumulative resistance model (MCR). The results show that human activity and landscape patterns had a more significant influence on the final risk assessment than natural factors do, such as terrain and distance from water. The landscape ecological risk was generally high, and the high ecology risk region covered 523.99 km ², constituting the largest area and accounting for 36.06% of the research area. With the aim of decreasing the landscape ecological risk of the Ningjiang River Basin, areas of forestland greater than 50 km ² and areas of water greater than 0.2 km ² were selected as the eco-sources. Using interlinked points, lines and surfaces, a regional ecological network was constructed out of 15 ecological corridors. The length of the first level corridors was greater than 30000 m, the length of second level corridors was between 10000 m and 30000 m, and the length of the third level corridors was less than 10000 m. A total of 19 ecological nodes were produced. The landscape connectivity was significantly improved following landscape pattern optimization. The results of this study may help improve the ecological stability level in the study area and provide a scientific basis for both landscape ecological risk assessment and landscape pattern optimization research.

In view of the lack of research on the screening and comprehensive evaluation of vegetation ecological parameters based on remotely sensed date products, this paper firstly proposes a method to evaluate the vegetation eco-environmental quality in Tibet by PCA (principal component analysis). Based on five indicators, including fractional vegetation coverage (FVC), leaf area index (LAI), gross primary productivity (GPP), land surface temperature (LST) and modified wet (Wet) from MODIS satellite data, the law and mechanism of spatial-temporal changes of eco-environmental quality in Tibet in the last 10 years are explored. The experimental results show that: (1) The comprehensive quality of the eco-environmental quality in Tibet is relatively fragile, and the spatial difference in eco-environmental quality is significant. It is excellent in the southeast but poor in the northwest. (2) During the period from 2006 to 2016, the eco-environmental quality in Tibet shows a trend of improving overall. In terms of time series, the proportion of areas improved and degraded in the past 10 years was 31.88% and 4.13% respectively. In terms of spatial distribution, the improved areas are distributed in the northwestwen, central and eastern parts, but but the degraded areas are distributed in the southeastern parts. (3) Improvements in hydrothermal conditions (especially the increase in precipitation) and human protection policies have led to improvements in the eco-environmental quality in the western and central Tibet. The strengthening of social and economic activities is the main reason for the deterioration of the eco-environmental quality in the southeast of Tibet.

It is of fundamental significance to reveal the influencing mechanism of changes in human activities on ecological environment and landscape services, and to promote regional sustainable development that explores spatio-temporal variation and evolution of social-ecological resilience at the most operable landscape scale. Taking the loess hilly-gully region of Mizhi county as an example, this paper constructed an evaluation index system of social-ecological landscape resilience from the three dimensions of ecosystem, society system, and production system. The resilience of spatial-temporal evolution of the social-ecological landscape and subsystems were analyzed in this area along with their mutual relationships. The following results were obtained from this study: (1) During 2000-2015, the spatial distribution of the three subsystems resilience was prominently distinct and significantly strengthened. Among them, the resilience was significantly enhanced in the first stage of "Grain for Green Project" (2000-2009), and the resilience index of the three systems increased by 0.134, 0.048 and 0.028, respectively. (2) The spatial distribution of resilience on social-ecological landscape was also significantly distinct and the resilience index increased by 11.60%. The spatial distribution of resilience on social-ecological landscape presents a pattern of "high in center and low in eastern and western parts". (3) The positive relationships between the changes of the subsystems resilience and landscape system resilience were dominant, and the synergistic relationship between the resilience of the subsystems was obvious. The synergy rate of two or three systems is over 90%. In this study, OWA method was applied based on different weights of interference and adaptive ability indexes to set up situational preferences. Following this, simulation diagrams of social-ecological landscape resilience of the unsustainably oriented scenario, the current situation oriented scenario and sustainably oriented scenario were mapped, which provide a decision support for the adaptive management of regional landscape.