The impact of urbanization on ecosystem services: Both time and space are important to identify driving forces.

Rapid urbanization is one of the key factors in threatening regional ecological security and undermining human well-being. Understanding of the impacts of urbanization on ecosystem services (ESs) could provide comprehensive information for policy making to support ecological governance. In this study, the spatial and temporal distributions of four ESs, namely water yield (WY), soil conservation (SC), nitrogen export (NE), and habitat quality (HQ), and four factors of urbanization, namely construction land percentage, economic density, population density, and nighttime lighting, were analyzed in the Xiangjiang River Basin (XJRB) from 1990 to 2020. The impacts of urbanization on ESs at the sub-watershed and county level were investigated using the space-for-time and change-over-time methods. The results showed that: (1) WY, SC, and NE fluctuated throughout the study period, while HQ significantly decreased and urbanization factors significantly increased. (2) Each urbanization factor had a significant influence on the spatial heterogeneity of ESs, with the contribution at the county level being 2.88%-56.11% higher than that at the sub-watershed level. Moreover, there were enhanced interactions between factors in general, although spatial heterogeneity effects on NE and HQ were weaker at the county level. (3) Urbanization and ESs had a significant nonlinear relationship, and there was a threshold of relationship change between them, with the impact of urbanization on ESs showing evident spatial heterogeneity in terms of both the driving direction and intensity of change over time. (4) The change-over-time method identified 1992-1995 and 2008-2013 as key periods of change in the relationship between urbanization and ESs in the XJRB, and the method had the advantage of revealing the spatial heterogeneity of the effects of driving factors. These findings provide a reference for decision making related to urban planning.

Assessment of soil erosion in the Dongting Lake Basin, China: Patterns, drivers, and implications.

Soil loss caused by erosion is a global problem. Therefore, the assessment of soil erosion and the its driving mechanism are of great significance to soil conservation. However, soil erosion is affected by both climate change and human activities, which have not been quantified, and few researchers studied the differences in the driving mechanisms of soil erosion depending on the land use type. Therefore, the spatiotemporal characteristics and changing trends of soil erosion in the Dongting Lake Basin were analyzed in this study. Geographic detectors were used to identify the dominant factors affecting soil erosion in different land use types. In this study, a sensitivity experiment was conducted to clarify the relative contributions of climate change and human activities to soil erosion changes. In addition, we studied the effects of different land use types and vegetation cover restoration on soil erosion. The results show that soil erosion in the Dongting Lake Basin decreased from 2000 to 2018. Human activities represented by land use types and vegetation coverage significantly contributed to the alleviation of soil erosion in the Dongting Lake Basin, whereas climate change represented by rainfall slightly aggravated soil erosion in the study area. The restoration of grassland vegetation and transfer of cultivated land to woodlands in the study area improved the soil erosion. The slope steepness is the key factor affecting the intensity of soil erosion in dry land, paddy fields, and unused land, whereas the vegetation coverage is the key factor affecting the intensity of soil erosion in woodland, garden land, and grassland. Detailed spatiotemporally mapping of soil erosion was used to determine the connections between soil erosion and potential drivers, which have important implications for vegetation restoration and the optimization of land use planning.

Cultivated Land Change, Driving Forces and Its Impact on Landscape Pattern Changes in the Dongting Lake Basin.

Comprehending the dynamic change characteristics of land use/cover and the driving factors causing the change are prerequisites for protecting land resources. This paper analyzes changes in cultivated land, the driving factors that cause them, and their tremendous impact on landscape pattern changes in the Dongting Lake Basin. For this purpose, we used mathematical statistics, buffer analysis, trend analysis, landscape pattern index, and logistic regression model to analyze the land use data of the study area from 1980 to 2018. The results show that the cultivated land showed a decreasing trend, with the total area decreased by 4.76% (or 716.13 km2) from 1980 to 2018, and the activity of mutual transformation with other land use types decreased. The spatial distribution pattern of cultivated land and landscape shows the change characteristics gradually from Dongting Lake to the surroundings. Among the driving factors of cultivated land changes, the influence of human activities was gradually increasing, while the natural factors were decreasing. The cultivated land landscape pattern index and the overall landscape pattern index have a significant positive correlation, showing relatively consistent change trend and spatial distribution characteristics. We believe that the decrease of cultivated land area has a certain relationship with the increase of landscape fragmentation in the Dongting Lake Basin. Our research is expected to provide a reference for strengthening regional cultivated land management and rational development and utilization of regional land resources.

Dynamic Evolution of the Ecological Carrying Capacity of Poverty-Stricken Karst Counties Based on Ecological Footprints: A Case Study in Northwestern Guangxi, China.

The karst area in northwestern Guangxi is poor, underdeveloped, and ecologically fragile. It is experiencing rocky desertification, which creates challenges that are more severe than those of other regional ecological environments. In this paper, the ecological footprint (EF) model is used to analyze the ecological carrying capacity (EC) in northwestern Guangxi from 1995 to 2015, and the differences in karst counties with different poverty levels are discussed. The results show that (1) since 1995, the EC of northwestern Guangxi has continued to decrease, the EF has continued to increase, the ecological deficit (ED) has been expanding, and the status of the region has been unsustainable for a long time. (2) The evolutionary patterns, EF and EC of karst counties with different poverty levels are different. The county with the lowest poverty rate has the fastest growth rate of the per capita EF. The county with the largest proportion of karst area has the lowest EC. (3) It is recommended that different types of counties take different measures, including strengthening ecological environment protection, carrying out rocky desertification control and ecological resettlement projects, and reducing energy consumption. This study can provide information for the sustainable development of the karst region and provide decision support for regional poverty alleviation.

One-pot synthesis of thermosensitive glycopolymers grafted gold nanoparticles and their lectin recognition.

Thermosensitive glucose-functionalized glycopolymers grafted gold nanoparticles (Glyco@GNPs) with good colloidal stability and thermosensitive in aqueous solution were fabricated by reversible addition-fragmentation chain transfer (RAFT) mediated one-pot synthesis. The formation of core-shell morphology with about a 60 nm gold core in diameter and a glycopolymer shell of about 80 nm in thickness was indicated by transmission electron microscopy (TEM). The recognition ability of the Glyco@GNPs toward lectin concannavalin A (Con A) was verified by ultraviolet-visible spectroscopy and dynamic light scattering (DLS). The good cytocompatibility of the glycopolymers and Glyco@GNPs was proven by MTT assay on L-929 cells. Glyco@GNPs could effectively inhibit hepatoma cells SMMC-7721 growth after recognizing Con A was also proved by MTT assay and flow cytometry assay.

Thermoresponsive diblock glycopolymer by RAFT polymerization for lectin recognition.

A thermoresponsive double-hydrophilic diblock glycopolymer, poly(diethyl- eneglycol methacrylate)-block-poly(6-O-vinyladipoyl-d-glucose) (PDEGMA-b-POVAG), was successfully prepared by a combination of enzymatic synthesis and reversible addition-fragment chain transfer (RAFT) polymerization protocols using poly(diethyl- eneglycol methacrylate) (PDEGMA) as macro-RAFT agent. The block glycopolymer was characterized by (1)H NMR and GPC. UV-vis, DLS and TEM studies revealed that the glycopolymer PDEGMA-b-POVAG was thermoresponsive with LCST at 31.0°C, and was able to self-assemble into spherical micelles of various sizes in aqueous solution. The glucose pendants in the glycopolymer could interact with the lectin Concanavalin A (Con A), the average hydrodynamic diameters of glycopolymer micelles increased to 170nm from 110nm after recognizing Con A. The diblock glycopolymer micelles have excellent biocompatibility with pig iliac endothelial cells, as measured using the MTT assay, but micelles loaded with Con A could be used to induce apoptosis in human hepatoma SMMC-7721 cells.