Coastal sand dune ecosystems generally have infertile soil with low water-holding capacity and high salinity. However, many plant species have adapted to the harsh sand environment along the southeastern coast of China. Studying the microbial biomass in such an ecosystem can improve our understanding of the roles that microbes play in soil fertility and nutrient cycling. We investigated the differences in soil microbial biomass carbon (MBC) and nitrogen (MBN) contents and their seasonal dynamics in five forest types (a secondary forest and plantations of Casuarinas, Pine, Acacia, and Eucalyptus). The results indicated that the seasonal variations of soil MBC and MBN contents in all five forest stands were higher in spring and winter, but lower in summer and autumn. The MBC content was lower in the Casuarinas plantation than in the other plantations in the same soil layer. However, no significant differences were observed in MBN contents among the different forest types. The MBC and MBN concentrations were positively correlated with soil moisture, but negatively correlated with soil temperature. The MBC and MBN contents also decreased with increasing soil depth. Across all soil layers, secondary forest had the highest MBC and MBN concentrations. Our study also showed that the MBC and MBN contents were positively affected by total soil carbon (TC), pH, and litter N content, but were negatively impacted by soil bulk density and litter C content. Moreover, the MBN content was positively correlated with root N content. In summary, environmental factors and the differences in litter and fine roots, soil nutrient contents, as well as the soil physical and chemical properties caused by different tree species collectively affected the concentrations of the soil MBC and MBN.

Due to insufficient molecular biology and genetic research on Rosa anemoniflora, this endangered plant has not yet received effective protection. Therefore, the complete chloroplast genome sequence of R. anemoniflora, along with comparative analysis of the chloroplast genomes of related species, is necessary and crucial for reconstructing phylogenetic relationships and developing genetic markers to conserve these species. A series of analyses, including genome structure, GC content, gene number, selection pressure, and nucleotide diversity, were performed by comparing the chloroplast genomes of R. anemoniflora and its relatives. The results indicate that the chloroplast genomes of R. anemoniflora and its close relatives are highly conserved in all genome characteristics, and all protein-coding genes in R. anemoniflora have not experienced significant positive or negative selection pressures. Comparative analysis revealed several variation hotspots, such as the atpH-atpI region, which can serve as a DNA barcode for distinguishing R. anemoniflora from its close relatives. Finally, the results confirmed that R. anemoniflora belongs to Rosa section Synstylae and that R. anemoniflora and its close relatives likely originated from the Fujian and Taiwan regions of China and diverged approximately 3.24 million years ago. This study provides crucial information for future biodiversity conservation and genetic resource management.

Interspecific relationships can reflect the relevance of species in particular spatial distribution, and the degree of community adaptation under successional stages. In the past, numerous studies on subtropical forest communities primarily focused on the relationship between a specific dominant tree species or a single succession stage, lacking an understanding of interspecific relationships across different succession stages. Given this gap, this study used the method of space instead of time to study the community structure composition and interspecific relationship of trees with DBH > 1 cm in the subtropical 30-70 a Fagaceae community. The results showed that there was no significant difference in the important values of each tree species during the 30 a and 40 a of community succession. As succession advanced, the importance values of neutral and shade-tolerant species progressively escalated. The stand density reached its nadir during the mid-successional stage (50 years), concurrently achieving peak volume. Throughout succession, the diameter at breast height (DBH) distribution of sun-tolerant species conformed to an inverted J-shape, while shade-tolerant species shifted from an inverted J-shaped to a bell-shaped distribution. Positive interspecific correlations gradually intensified after 50 years, at which point both the biodiversity index and stand density reached their lowest levels, subsequently increasing as succession progressed. At the 70-year mark, a overwhelming majority (93.3%) of species pairs demonstrated no significant correlation, indicative of a more relaxed interspecific relationship. These studies show that in the early stage of community development, the community structure has not yet been finalized. With the advancement of community succession, the competition among species changes from strong to weak. In the later stage of succession, the interspecific relationship is relatively loose, and the phenomenon of seedling renewal and filling occurs in the forest, and a certain dynamic balance is maintained among various species. These results deepen the understanding of species interactions and spatial-temporal changes of community structure in different succession stages of Fagaceae communities in subtropical regions, and provide a theoretical basis for forest managers and vegetation ecological restoration in subtropical regions.

To examine the configurational linkages between urban forest development and maintenance (UFDM) and urban quality enhancement, this study conducts a configurational study using panel fuzzy-set qualitative comparative analysis (fsQCA) on 30 provincial capitals and centrally administered municipalities in mainland China over the period 2011–2022. From the perspective of administrative resource allocation, UFDM conditions are decomposed into three policy tools - green space planning and provision, fiscal investment in greening and supporting infrastructure, and air pollution control - and a composite configurational model linking these conditions to urban quality enhancement is constructed and tested. The results show that high-level urban quality configurations rely primarily on combinations of greening and depollution conditions, represented by green space planning and provision as well as air pollution control. In high-level configurations, urban hard quality (UHQ) and urban soft quality (USQ) co-occur within the same period. Per capita park green space, green coverage ratio, and air cleanliness are the core conditions constituting high-level urban quality pathways and are particularly critical. The study identifies two types of potential substitution relationships and eight high-level configurational pathways: per capita park green space and the air quality compliance rate are potentially substitutable in high-level UHQ configurations, while landscaping investment and air cleanliness are potentially substitutable in high-level USQ configurations. High-level pathways began to emerge in 2013, corresponded to the core contradictions of the sample cities at different development stages, exhibited stage-wise transitions, and showed no significant variation across the three major economic zones. Among them, the ”investment-led model” represented by Beijing, the ”investment-supported model” represented by Nanjing, and the ”resource-led model” represented by Fuzhou and Guangzhou are the most typical. This study delineates the urban quality configurations associated with UFDM and their spatiotemporal effects, emphasizing that cities should formulate differentiated strategies according to local conditions - expanding total urban forest volume, optimizing forest types, and continuously deepening pollution reduction and control - and comprehensively balance the relationships among urban living, production, and ecological spaces. The findings provide new empirical evidence for understanding the configurational linkages between UFDM and urban quality enhancement and offer a reference for administrative actors seeking to optimize resource allocation.

Niche theory is a cornerstone of ecology for understanding species coexistence. However, its application to guide conservation remains challenging. This study focuses on Rosa anemoniflora , a threatened plant endemic to China, and adopts a novel perspective by shifting from traditional interspecific niche comparisons to the analysis of intraspecific variation in niche breadth. We quantified niche breadth across different habitats using a newly developed circular sliding window technique, and then applied correlation, regression, and structural equation modeling to identify key soil factors associated with greater expression of intraspecific niche breadth. Our results indicate that high niche overlap in the herb layer may constrain population regeneration. Notably, soil total potassium (TK) and available potassium (AK) showed contrasting associations with niche breadth: TK was positively correlated, while AK was negatively correlated. This pattern suggests that variation in soil potassium status is closely associated with differences in the realized niche breadth of R. anemoniflora . Our sliding window–based analytical approach provides a methodological pathway for applying niche theory to precision conservation by linking fine-scale environmental variation to intraspecific niche expression. The approach offers a potentially transferable strategy and practical guidance for conserving other threatened species.