Spatiotemporal Evolution and Spatial Network Analysis of the Urban Ecological Carrying Capacity in the Yellow River Basin

Based on the panel data of 82 cities in the Yellow River Basin (YRB) during 2008–2017, this paper calculated the urban ecological carrying capacity (UECC) index by means of the entropy method, drew a spatiotemporal evolution map using ArcGIS10.3 software, used a spatial cold–hot spot model to explore the spatial characteristics of the UECC index, and used the revised gravity model to construct the spatial network of the UECC. In addition, through social network analysis, we obtained the spatial network correlation characteristics of the UECC of 82 cities in the YRB. The study found the following: (1) The UECC index of the cities in the YRB increased steadily, and showed strong non-stationarity in space. The cold and hot spot patterns both changed greatly. Overall, the changes of the hot and cold spots were very significant. (2) The spatial correlation and linkage effects of the UECC in the YRB were not significant. The central cities with higher point centrality and closeness centrality showed the same spatial distribution, and most of them are located in the midstream and downstream of the YRB. The central cities in the midstream and downstream of the YRB had high betweenness centrality, and stood in the center of the association network. (3) The four plates in the spatial correlation network of the UECC in the YRB all showed their advantages and functions. The first plate was the net spillover plate, which was principally allocated in the upstream and midstream of the YRB. The second plate was the broker plate, which was principally located in the midstream and downstream of the YRB, and a few cities in the upper reaches. The third plate was the net inflow plate, which was distributed sporadically in the upstream and downstream of the YRB. The fourth plate was the broker plate, which was scattered in upstream, midstream, and downstream of the YRB. Therefore, it is necessary to shorten the gap of and promote the improvement of the UECC in the YRB.

Research on the Influencing Factors of Urban Ecological Carrying Capacity Based on a Multiscale Geographic Weighted Regression Model: Evidence from China

Based on the comprehensive evaluation method, a comprehensive urban ecological carrying capacity (UECC) evaluation system is established. It includes ecological support, ecological resilience, and ecological pressure. Multiscale geographically weighted regression (MGWR) was used to conduct a thorough examination of the spatial and temporal patterns, and the factors that influenced the UECC of 286 prefecture-level cities in China from 2010 to 2019. The results show that (1) China’s UECC index ranges from 0.0233 to 0.2811 in 2019, which is still at a low level. (2) The spatial distribution is relatively stable: high-value agglomerations of UECC are distributed primarily in the Yangtze River Delta and Pearl River Delta, while low-value agglomerations are primarily distributed in the regions in the Central Plains. (3) All influencing factors have a positive effect on the improvement of UECC and are heterogeneous in spatial distribution. Lastly, this paper gives corresponding suggestions, so that governments can formulate differentiated policies and effectively improve UECC.

Physical and Ecological Carrying Capacity for Cave Tourism Management

Cave tourism is a nature-based tourism which has recently gained its popularity in Thailand. Cave sare natural attractions which are extremely vulnerable, especially caves with limitations in both size and area. Thus, this study aims at studying and determining the maximum and suitable carrying capacity to support physical and ecological tourism in Ban Tham Sua tourism community area to avoid overtourism. The methodology used in this research was a survey on the tourist’s utilization, duration, number of tourists, and tourism impacts. Moreover, the impact assessment using 16 indicators presented by 5 geological experts for ecological carrying capacity of the cave areas were also conducted. This area-based study was conducted in 3 areas: Thep Nimit Cave, Nang Fa Cave, and Sua Noi Cave. The study found that the number of tourists in these three caves were below carrying capacitywhich had no or insignificant impact on natural resources. However, it was found that SuaNoi Cave was a huge destruction of the original resources. The study suggests that carrying capacity of cave tourism should be well planned and managed to prevent the environmental degradation.

Novel nitrite reductase domain structure suggests a chimeric denitrification repertoire in Phylum Chloroflexi

Denitrification plays a central role in the global nitrogen cycle, reducing and removing nitrogen from marine and terrestrial ecosystems. The flux of nitrogen species through this pathway has a widespread impact, affecting ecological carrying capacity, agriculture, and climate. Nitrite reductase (Nir) and nitric oxide reductase (NOR) are the two central enzymes in this pathway. Here we present a previously unreported Nir domain architecture in members of Phylum Chloroflexi. Phylogenetic analyses of protein domains within Nir indicate that an ancestral horizontal transfer and fusion event produced this chimeric domain architecture. We also identify an expanded genomic diversity of a rarely reported nitric oxide reductase subtype, eNOR. Together, these results suggest a greater diversity of denitrification enzyme arrangements exist than have been previously reported.