Indigenous forests are important reservoirs of terrestrial arthropod biodiversity, but naturally patchy forests are understudied compared to human-fragmented forests. We evaluated the relative influence of landscape composition, patch size, and local characteristics on ants (Formicidae) and beetles (Coleoptera) in Southern Mistbelt Forests in South Africa. These forests exist as small patches within a fire-prone grassland matrix, with the grasslands undergoing modification for forestry, agriculture and rural development. Both taxa responded strongly to predictors at different spatial scales, especially through changes in species composition. Responses to local variables diverged between taxa, with ant assemblages being structured mostly by variation in vegetation openness and beetle assemblages responding to a wider variety of variables relating to ground cover, vegetation structure and woody debris. Species richness and evenness of both taxa, but only beetle assemblage composition, was influenced by the surrounding landscape, whereas patch size influenced ant and beetle assemblages. Assemblage changes were driven mostly by gradual species replacement along all environmental gradients, rather than species attrition. Surprisingly, no differences were detected between forest edges and interiors in biodiversity metrics or responsiveness to predictors, likely due to microclimatic buffering of structurally closed, natural forest edges. Our findings demonstrate that natural variation in local characteristics, patch size, and landscape context among Afromontane forest patches correlate with regional arthropod diversity in these landscapes. Conserving networks of forest patches that encompass the widest possible range of natural forest heterogeneity is critical for arthropod conservation, underscoring the importance of complementarity approaches that prioritize unique forest patches alongside larger, core forests.
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a major commercial tree species in southern China, where successive planting is widely adopted as the dominant forest management practice. However, repeated planting can disrupt nutrient cycling processes, accelerate soil degradation, and ultimately threaten long-term forest productivity and ecosystem sustainability. Soil physicochemical properties, enzymatic activities, and microbial communities are widely recognized as key indicators of soil health; nevertheless, the effects of successive planting on these attributes in Chinese fir plantations have not been comprehensively synthesized. To address this knowledge gap, we conducted a meta-analysis based on 2224 paired observations extracted from 121 independent studies to quantitatively assess the impacts of successive planting relative to first-generation forests. The results demonstrated that successive planting significantly increased soil bulk density, decreased topsoil (0–20 cm) pH, and increased subsoil (>20 cm) pH. In both soil layers, successive planting led to marked reductions in soil organic carbon, total nitrogen, total phosphorus, total potassium, available potassium, and microbial biomass carbon. In addition, ammonium nitrogen declined in the topsoil but increased in the subsoil. Successive planting also substantially altered soil microbial community composition, including shifts in the relative abundance of major microbial phyla, a decline in bacterial diversity, and changes in microbial community indices. These effects were further influenced by multiple environmental and management factors, including planting rotation intensity, stand age, mean annual precipitation, mean annual temperature, altitude, and latitude. Overall, successive planting of Chinese fir exerts detrimental effects on soil pH regulation, carbon, nitrogen, and phosphorus pools, as well as bacterial community structure. Our findings highlight the urgent need for targeted management strategies, such as agroforestry rotations and the application of appropriate soil amendments, to alleviate soil degradation and promote the sustainable management of Chinese fir plantation ecosystems.
Protecting threatened tree species is essential, but long-term persistence also depends on the demographic processes that sustain population replacement. For long-lived species, sparse juveniles may signal recruitment failure or a life cycle spanning centuries. We investigated the demographic processes shaping population persistence in Araucaria angustifolia, a Critically Endangered conifer historically logged and now protected by cutting restrictions. We used adult (2008–2021) and regeneration (2011–2014) data in a Bayesian annual stage-structured model for one focal population, estimating survival, stage transitions, and recruitment. We compared adult density and basal area across eight Araucaria Forest remnants in southern Brazil. The focal population was close to stability (λ = 1.021 [1.001–1.055]; P(λ ≥ 1) = 0.98). Seedlings were abundant (1120–1480 ind ha⁻¹), but most remained in the same stage; estimated annual advancement was 3.3% and mortality 13.6%, locating the bottleneck after establishment. Population growth was most responsive to proportional changes in adult survival (elasticity 0.67), whereas equivalent changes in recruitment and stage advancement had smaller effects. The net reproductive rate exceeded one in most posterior draws but remained highly uncertain (R₀ = 7.3 [1.1–44.2]), and generation time was 95 years [61–184]. Adult araucaria basal area increased across all remnants, although density trajectories varied. The focal population retained long-lived adults and a persistent seedling bank, while regional adult populations showed no immediate evidence of structural decline. These findings reconcile slow juvenile advancement with population persistence: adult survival underpins current stability, whereas episodic juvenile advancement remains essential for long-term replacement.
Ponderosa pine (Pinus ponderosa) is a foundational species in dry-forest landscapes across western North America. Ongoing warming and aridification intensify climatic stress across its native range. Prior research on ponderosa pine health is regional in scope and focuses on single disturbances, leaving the combined influence of climate, stand structure, and biotic agents on dieback and mortality poorly understood. To address these knowledge gaps, we surveyed sites across California, Colorado, Idaho, Montana, and Wyoming during 2024 and 2025. At each site, we characterized stand conditions, assessed tree health, and collected tissue samples for pathogen identification. Long-term changes in climate were also recorded at each site to test associations between tree health and biotic and abiotic factors. Recent climate trends included reduced precipitation, elevated mean temperatures, and changes in vapor pressure deficit, indicating the potential for climatic stress on trees. Of the 324 trees surveyed, 25.8% had detections of pathogens and symptoms consistent with pathogen infection. Pathogens were composed of two functional groups: (1) needle and branch pathogens, including the widely distributed endophyte, Sydowia polyspora, primarily associated with trees of moderately poor health status, and (2) vascular stain fungi that were strongly linked to recent mortality. Only S. polyspora showed significant relationships with abiotic conditions in generalized linear models, while non-metric multidimensional scaling revealed clear geographic structuring of pathogen assemblages. In summary, our study suggests that climatic stress is associated with increases in host vulnerability to biotic agents, while fungal pathogens exhibit distinct associations with moderate decline and recent mortality.
