The rapid development of urbanization has changed landscape patterns and biological habitats severely and, therefore, affected biodiversity. In this study, we selected 75 townships in Lishui, a mountainous area in eastern China, to conduct bird surveys for two years. We analyzed the birds’ composition characters in townships with different levels of development in order to identify the effects on bird diversity of the urban development level, land cover pattern, landscape pattern, and other factors. In total, 296 bird species from 18 orders and 67 families were recorded between December 2019 and January 2021. A total of 166 species of birds belonged to Passeriformes (56.08%). The seventy-five townships were divided into three grades by K-means cluster analysis. The average number of bird species, richness index, and diversity index were higher in G-H (highest urban development level) compared with the other grades. At the township level, landscape diversity and landscape fragmentation were the key factors that positively affected the bird species number, diversity index, and richness index. Landscape diversity had a greater effect than landscape fragmentation, particularly on the Shannon–Weiner diversity index. The diversity and heterogeneity of urban landscapes could be improved by constructing biological habitats in future urban development planning to maintain and increase biodiversity. The results obtained in this study provide a theoretical basis for urban planning in mountainous areas, and a reference for policymakers to formulate biodiversity conservation strategies, construct reasonable biodiversity patterns, and solve practical biodiversity conservation problems.

BackgroundThis study aimed to develop a combined model to quantify the net absorption of volatile fatty acids (VFA) in the large intestine (LI) of pigs.MethodsFifteen female growing pigs (Duroc × Large White × Landrace) were ranked by body weight (30 ± 2.1 kg) on day 0 and assigned to one of three treatments, namely the basal diet containing different crude fiber (CF) levels (LCF: 3.0% CF, MCF: 4.5% CF, and HCF: 6.0% CF). The pigs were implanted with the terminal ileum fistula and the cannulation of the ileal mesenteric vein (IMV), portal vein (PV), and left femoral artery (LFA) from days 6 to 7. [13C]‐Labeled VFA and P‐aminohippuric acid were constantly perfused into the terminal ileum fistula and the cannulation of the IMV (day 15), respectively. Blood samples were collected from the PV and the LFA during perfusion (5 h), and LI samples were collected.ResultsThe net flux of [12C]‐acetic acid in the PV was greater for LCF versus MCF (p = 0.045), but no difference was observed in the net flux of [12C]‐propionic acid (p = 0.505) and [12C]‐butyric acid (p = 0.35) in the PV among treatments. The deposition of [12C]‐acetic acid in the LI was greater for LCF versus MCF (p = 0.014), whereas the deposition of [12C]‐propionic acid (p = 0.007) and [12C]‐butyric acid (p = 0.037) in the LI was greater for LCF versus HCF.ConclusionsIn conclusion, this pig model was found conducive to study the net absorption of VFAs in the LI, and LCF had more net absorption of VFAs in the LI than MCF and HCF.

Landscape context can reflect the habitat structure and play an important role in bird species occurrences and abundance. For local biodiversity conservation and restoration, we examined the effects of landscape context on bird communities at different altitude gradients. Our study was conducted in four altitude gradients (<300 m, 300–599 m, 600–899 m, 900–1200 m) of subtropical evergreen broad-leaved forest in Wuyishan National Park, China. The bird survey was carried out in 115 transects in spring, summer, autumn and winter. We examined the effects of altitude, season and landscape context. The result showed that (1) species richness and abundance at <300 m altitude were highest among the four altitude gradients, and they showed more significant differences than those at other altitude gradients; (2) the species richness of birds was associated with altitude, season and landscape context, as the season is more significant than other explanatory variables; (3) at the landscape level, habitat configuration is more important. The average canopy height and contagion index positively correlated with the species richness and abundance of birds at all four altitude gradients. In particular, the average canopy height is significant at 300–599 m and 600–899 m altitude gradients. The study results can provide a theoretical basis and guidance for future national park conservation and management and ecological restoration in the subtropical evergreen broad-leaved forest regions.