Nitrogen addition alters soil organic carbon (SOC) and total nitrogen (TN) accumulation in forest ecosystems, but the responses of SOC and TN sequestration rates and dynamics to nitrogen addition in forest ecosystems worldwide remain unclear. This study conducted a global analysis to evaluate the effects of the nitrogen application rate, nitrogen addition duration (time), and humidity on the SOC and TN accumulation rates from 257 data points (63 articles). Nitrogen addition increased SOC and TN by 4.48% and 10.18%, respectively. The SOC and TN accumulation rates were 0.65 and 0.11 g kg⁻¹ yr⁻¹, respectively. Moreover, the percentage changes of SOC and TN overall increased with the nitrogen application rate and duration of nitrogen addition; however, the accumulation rates of SOC and TN overall decreased with the nitrogen application rate and the duration of nitrogen addition. In addition, the percentage changes and change rates of SOC and TN increased overall with the humidity index. In conclusion, nitrogen addition promoted SOC and TN accumulation in forest soil, and the nitrogen application rate and nitrogen addition duration increased the percentage changes in SOC and TN; however, they decreased the accumulation rate, whereas humidity increased the accumulation rates of SOC and TN. These results enhance our understanding of soil carbon and nitrogen cycling in forest soils in the context of global nitrogen deposition.

Canopy gaps can result in abiotic heterogeneities and diverse niches from gap borders to centers, potentially affecting fine root decompositions mediated by soil fungal communities. Despite extensive discussions on the relationship between soil fungi and fine root decomposition, the mechanism by which gap locations regulate fine root decomposition through the soil fungal community remains elusive. Here, we conducted an in situ field decomposition experiment of Chinese Toon (Toona sinensis) fine roots in a low-efficiency weeping cypress (Cupressus funebris) plantation forest across three microhabitats: gap centers, gap borders, and closed canopy areas. Soil fungal communities were determined using internal transcribed spacer (ITS) sequencing after two years of field incubation. Results showed that soil properties and nutrient content in residual roots varied across the three microhabitats, with the gap borders exhibiting the highest decomposition rates. While fungal α-diversity remained relatively consistent, taxonomic compositions differed significantly. Decomposition rates did not show significant correlations with soil properties, observed fungal ASVs, or overall community composition. However, they positively correlated with the relative abundance of saprotrophic Sordariomycetes, which in turn positively correlated with soil total nitrogen (with a highest correlation), peaking at the gap borders. Overall community variations were primarily driven by soil temperature and magnesium content in residual roots. Further analysis revealed high fungal community similarities and low dispersal limitations between the gap borders and closed canopy areas, with more phylogenetically clustered communities at the borders. These results demonstrate that the gap borders possess a high decomposition rate, likely due to the centralization of functions driven by soil fungi such as saprotrophs existing in the “microbial seed bank” or migrating from closed canopy areas. These findings highlight the key role of soil fungi, especially saprotrophic fungi, in fine root decomposition at the gap borders, stressing the importance of soil fungi-driven mechanisms in nutrient cycling, and also informing sustainable forest management practices.

Subalpine forests provide crucial ecosystem services and are increasingly threatened by human alterations like bare-cut slopes from highway construction. External soil spray seeding (ESSS) is often employed to restore these slopes, but the cement it introduces can negatively affect soil fungi, which are vital for the ecological sustainability of restored slopes. Despite previous extensive discussions about ESSS-restored slopes, fungal dynamics and their underlying ecological mechanisms during ESSS-based restorations still remain elusive. Here, we conducted a 196-day simulation experiment using natural soils from a subalpine forest ecosystem. By using nuclear ribosomal internal transcribed spacer (ITS) sequencing, we revealed soil fungal dynamics and their ecological mechanisms during simulated ESSS-based restorations. Results showed a decline in fungal α-diversity and significant shifts in community structures from the initial day to day 46, followed by relative stabilities. These dynamics were mainly characterized by ectomycorrhizal, plant pathogenic, and saprotrophic fungi, with ectomycorrhizal fungi being depleted, while saprotrophic and pathogenic fungi showed enrichment over time. Shifts in nitrate nitrogen (${\mathrm{NO}}_3^{-}$−N) content primarily regulated these dynamics via mediating homogeneous selections. High ${\mathrm{NO}}_3^{-}$−N levels at later stages (days 46 to 196, especially day 46) might exclude those poorly adapted fungal species, resulting in great diversity loss and community shifts. Despite reduced homogeneous selections and ${\mathrm{NO}}_3^{-}$−N levels after day 46, fungal communities did not show a recovery but continued to undergo changes compared to their initial states, suggesting the less resilient of fungi during ESSS-based restorations. This study highlights the need to manage soil ${\mathrm{NO}}_3^{-}$−N levels for fungal communities during ESSS-based restorations. It provides novel insights for maintaining the ecological sustainability of ESSS-restored slopes and seeking new restoration strategies for cut slopes caused by infrastructure in subalpine forests.

Autotrophic carbon-fixing microbes can assimilate atmospheric carbon dioxide into biomass via the Calvin–Benson–Bassham (CBB) cycle (their primary carbon fixation pathway), thereby reinforcing soil carbon sequestration in the plantation ecosystem; however, the succession of RubisCO-harboring microbial communities across stand ages remains poorly understood. Here, we investigated the community succession of microbes carrying the gene encoding RubisCO, a key enzyme in the CBB cycle, across a stand-age chronosequence in a Picea asperata plantation ecosystem. Our results revealed a progressive decrease in microbial α-diversity and a significant restructuring of community composition with increasing stand age, characterized by an enrichment of Proteobacteria and a concomitant depletion of Actinobacteria. While the Shannon–Wiener index was most strongly correlated with soil total nitrogen content, redundancy analysis identified soil pH as the predominant environmental driver of community turnover, a relationship that was found to be threshold-dependent, with substantial community shifts occurring in response to pH variations of 0.5 to 1.0 units. These findings suggest that sustaining the diversity of RubisCO-harboring microbes in older stands—a process potentially enhanced by soil nitrogen management—provides a viable strategy for augmenting the carbon sequestration capacity of managed forests through targeted microbiome regulation.

Low-temperature stress is a key environmental factor limiting the introduction and cultivation of plants native to tropical and subtropical regions; however, the molecular mechanisms governing their cold tolerance are not fully understood. In this study, we identified a core circadian rhythm gene—PiLUX—in the ornamental and medicinal plant Plumbago indica L. (P. indica) and systematically analyzed its role in the plant’s response to low temperatures. Transcriptomic analysis and physiological measurements indicated that PiLUX is significantly upregulated following cold induction; furthermore, its transcriptional levels show positive correlations with cold-tolerance-related physiological indicators such as reactive oxygen species (ROS) scavenging capacity, osmoregulatory substance accumulation, and membrane lipid peroxidation. In transgenic Arabidopsis thaliana (A. thaliana), heterologous overexpression of PiLUX enhances cold tolerance but also delays flowering, suggesting that reproductive development is sacrificed to conserve nutrients for cold tolerance. VIGS experiments confirmed that PiLUX knockdown exacerbates oxidative damage in P. indica under cold stress and reduces its recovery ability. The experimental results and transcriptomic data suggest that PiLUX may participate in the low-temperature response downstream of, or in parallel with, the CBF pathway; however, direct regulatory evidence is still required. This study provides insights into the adaptation strategies of thermophilic plants under low-temperature stress and offers a theoretical basis and genetic resources for cold-tolerance breeding in P. indica.