Stochastic processes shape the functional and phylogenetic structure of bird assemblages at the mine area in southwest China.

Understanding the mechanisms of community assembly is a key question in ecology. Metal pollution may result in significant changes in bird community structure and diversity, with implications for ecosystem processes and function. However, the relative importance of these processes in shaping the bird community at the polluted area is still not clear. Here, we explored bird species richness, functional, and phylogenetic diversity, and the assembly processes of community at the mine region of southwest China. Our results showed that the 3 dimensions of diversity at the mine area were lower than that at the reference sites. In the community assembly, the result was 0 < NRI/ NFRI < 1.96, which indicated deterministic processes (environmental filtering) might drive community clustering. The results of the neutral community model, and normalized stochasticity ratio, showed the dominant role of stochastic processes in shaping the bird community assembly. We further quantified the community-level habitat niche breadth (Bcom), and we found that there was no difference in Bcom-value between the mine area and reference sites. This indicates that the bird communities at the mine area and 3 reference sites were not subjected to extreme environmental selection (same or different resource allocation) to form a highly specialized niche. These findings provide insights into the distribution patterns and dominant ecological processes of bird communities under metal exposure, and extend the knowledge in community assembly mechanisms of bird communities living in the mine area.

Interaction of Nitrogen-Rich Cations with Azotriazolone Anions through Ion Exchange Results in the Formation of Energetically Stable and Insensitive Compounds.

In our pursuit of promoting the green development of energetic materials and harnessing their functional benefits, we strive to address the inherent contradiction between energy and low sensitivity. In this regard, we have successfully constructed an azotriazole framework via environmentally friendly electrochemistry with a satisfactory yield of 62.3%. Through a simple ion-exchange process, we then synthesized nitrogen-rich salt derivatives of azotriazolone. These nitrogen-rich salts exhibit a wide range of nitrogen contents, ranging from 32.16 to 68.80%. Remarkably, crystallographic analysis of these green energy-containing salts reveals substantial advantages in terms of thermodynamic stability and low sensitivity. Experimental investigations have demonstrated a positive relationship between the nitrogen content and the pyrothermal performance of the azotriazolone derivatives. Of particular significance is compound 5, a triaminoguanidine salt, which exhibits an exceptionally high nitrogen content of 68.80%. It displays a detonation pressure of 28.2 GPa and a detonation velocity of 7939.4 m s-1. Moreover, the derivatives of azotriazolone salts demonstrate the formation of nitrogen-rich compounds, characterized by insensitive properties, attributed to the hydrogen-bonded network structures resulting from anion-cation interactions. With the exception of compound 5, which exhibits a friction sensitivity of 252 N, the remaining derivatives show a similar value of approximately 360 N. This suggests that azotriazolone serves as a promising material possessing both stabilizing properties and better detonation performance, thereby providing a favorable platform for the synthesis of novel compounds with advantageous properties.

Comparison of gut microbiota between immigrant and native populations of the Silver-eared Mesia (Leiothrix argentauris) living in mining area.

The complex gut bacterial communities have a major impact on organismal health. However, knowledge of the effects of habitat change on the gut microbiota of wild birds is limited. In this study, we characterized the gut microbiota of two different subspecies of the Silver-eared Mesia (Leiothrix argentauris), the native subspecies (L. a. rubrogularis) and immigrant subspecies (L. a. vernayi), using 16S rRNA gene high-throughput sequencing. These two subspecies live in a trace metal-contaminated area, and L. a. vernayi was trafficked. They are an excellent system for studying how the gut microbiome of wild animal changes when they move to new habitats. We hypothesized that the immigrant subspecies would develop the same adaptations as the native subspecies in response to habitat changes. The results showed that there were no significant differences in the composition, diversity, or functional metabolism of gut microbiota between native and immigrant subspecies under the combined action of similar influencing factors (the p values of all analyses of variance >0.05). In addition, the composition and functional metabolism of gut microbiota in two subspecies showed adaptation against trace metal damage. Linear discriminant analysis effect size (LEfSe) analysis revealed that Massilia in the intestinal microbiota of immigrant subspecies was significantly higher than that of native subspecies, suggesting that immigrant subspecies suffered habitat change. Finally, we found that these two subspecies living in the mining area had an extremely high proportion of pathogenic bacteria in their gut microbiota (about 90%), much higher than in other species (about 50%) living in wild environment. Our results revealed the adaptation of intestinal microbiota of immigrant Silver-eared Mesias under heavy metals stress, which would provide guidance for biodiversity conservation and pollution management in mining area.

Multiple trace elements exposure of Grey-cheeked Fulvettas Alcippe morrisonia, a nuclear member in bird mixed-species flocks, and implications for bioindicator.

Birds are vulnerable to metal pollution, which can serve as indicators of environmental safety monitoring. In this study, we evaluated three non-essential (Pb, Cd, and As) and two essential (Cu and Zn) trace elements of living (only feathers) and deceased (feathers and tissues) Grey-cheeked Fulvetta (Alcippe morrisonia) at a highly polluted mine tailings and a reference site. Five metal concentrations in the feathers of living Grey-cheeked Fulvettas were higher at the mine site. Among these, the levels of Cd and Pb in most feathers exceeded the threshold, resulting in an ecotoxicological concern. The correlation analysis suggested that feathers from Grey-cheeked Fulvettas might be useful bioindicators for local metal contamination assessment. The toxicological effects of trace metals on Grey-cheeked Fulvetta might affect its leadership ability. Therefore, understanding the effects of metal pollution on Grey-cheeked Fulvetta would show important practical implications for the conservation of bird communities.