Search

[Objective] Land use change and habitat quality in Nanyue key ecological function area of Hu'nan Province were studied to reveal the relationship between forest land reduction and habitat quality caused by human activities, in order to promote the coordinated development of ecological protection and economic construction in this area. [Methods] The land use transfer matrix was obtained based on the land use change data of 2009, 2012, 2015, 2018 and 2021, and the spatial-temporal distribution characteristics of land use structure and habitat quality in Nanyue key ecological function area were analyzed and predicted by InVEST model and CA-Markov model. Bivariate spatial autocorrelation was used to explore the correlation between forest land and habitat quality. [Results] ① From 2009 to 2021, forestland and cultivated land in the study area were mainly transferred to construction land. The area of construction land increased by 15.87%, among them, 45.37% and 36.25% were transferred from forestland and cultivated land respectively. ② From 2009 to 2021, the spatial distribution of habitat quality in this region was higher in the west and lower in the southeast. ③ The positive correlation between the spatial distribution of forest land and habitat quality in the study area gradually increased, and the high aggregation of forest land and excellent habitat quality was the main type. ④ The construction land in Nanyue District will increase by 4.36% in 2025 and reach 1 563.53 hm2 in 2030. The quality of habitat will slowly decline in the future. [Conclusion] The change of habitat quality is closely related to the decrease of forestland and expansion of construction land caused by human disturbance. Therefore, resource and environment control should be strengthened in Nanyue key ecological function zones.

Ecological carrying capacity focuses on the limits of human development, serving as a policy instrument for guiding regional sustainable development. Regional space exhibits openness and dynamics. Nonetheless, ecological carrying capacity assessments seldom account for the potential influence of dynamic elements. The endeavor to integrate ecosystem service flows into ecological carrying capacity assessment represents an innovative approach to address this issue. This paper reviews multiple methods of assessing ecological carrying capacity and highlights the deficiencies in representing dynamic elements. Subsequently, the research progress in ecosystem service flows is examined, encompassing connotations, features, and models. Based on common theories, intermediary linkages, and the impact of incorporating spatiotemporal dynamics, the relationship between them is analyzed. The advantages of ecosystem service flows are also elucidated, which provide explicit spatial information and integrate biophysical processes when representing dynamic elements. The framework for ecological carrying capacity assessment incorporating ecosystem service flows comprises five steps: key theory selection, objectives and scope establishment, identification of supply and demand matching and assessment of flow utility, ecosystem service flow analysis, and ecological carrying capacity assessment. In the future, the research will focus on conducting quantitative pilot projects in typical regions, removing barriers to ecosystem service flows, and developing a dynamic ecological carrying capacity assessment model that considers multiple factors. [ABSTRACT FROM AUTHOR]

Clearing and successfully characterizing ecosystem service flow paths has become a key bottleneck restricting in-depth research on the supply and demand relationships of ecosystem services. At present, although some explorations have been performed using water ecosystem services as a pioneer, the nature of its network and the fact that ecological base flow needs to be eliminated have been ignored. This study used InVEST and network models to consider ecological base flow, quantifying the supply, demand, and flow paths of freshwater ecosystem services in the Xiangjiang River Basin. The results showed that the overall distribution of the water supply in the Xiangjiang River Basin from 2000 to 2020 shows a pattern of higher supply in the south and lower supply in the north. The distribution of water demand shows higher levels in the north and lower levels in the south. The network density remains at its maximum level. The results of this study have provided a scientific basis for water resource management in river basins and improving ecological compensation mechanisms. [ABSTRACT FROM AUTHOR]

Vegetation restoration can dramatically affect soil carbon (C), nitrogen (N) pools and microbial communities. Yet, it is uncertain what effects of vegetation restoration have on autotrophic bacterial community and associated C-fixing potential. To investigate the responses of autotrophic bacterial community and microbial C-fixing rate to vegetation restoration of eroded agricultural land, three abandoned croplands (ES1, ES2 and ES3) and two secondary grasslands planted with Coronilla varia (GS1 and GS2) in the Qiaozi watershed of Chinese Loess Plateau were selected, and high-throughput sequencing and 13C stable isotope labeling were applied in this study. Results showed that vegetation restoration significantly (P < 0.05) improved soil C and N contents while reduced soil moisture level. Total autotrophic bacterial abundance and species diversity in nutrient-rich secondary grasslands were significantly (P < 0.05) lower than those in nutrient-poor croplands. However, positive responses of obligate autotrophic bacteria, such as Alkalililimnicola and Synechococcus, to vegetation restoration were observed. Correlation analysis showed that autotrophic bacterial abundance and diversity were positively (P < 0.05) correlated with soil moisture, while negatively (P < 0.05) correlated with soil C and N nutrients. Microbial C-fixing rate ranged from 0.621 to 1.414 Mg C km−2 y−1 and the maximum value was observed in the ES3 site, followed by the ES1 site (1.088 Mg C km−2 y−1). Microbial C-fixing rate in abandoned cropland was significantly (P < 0.05) higher than that in secondary grassland, and it was positively influenced by autotrophic bacterial abundance and diversity. Overall, vegetation restoration of eroded agricultural land has negative impacts on autotrophic bacterial community and microbial C-fixing potential. In arid and semi-arid regions, great transpiration loss induced by vegetation restoration may inhibit autotrophic bacteria growth, and which further reduces the potential of CO2 fixation by autotrophic bacteria. [ABSTRACT FROM AUTHOR]