Understanding the mechanisms controlling forest carbon accumulation is crucial for predicting and mitigating future climate change. Yet, it remains unclear whether the dominance of ectomycorrhizal (EcM) trees influences the carbon accumulation of entire forests. In this study, we analyzed forest inventory data from over 4000 forest plots across Northeast China. We find that EcM tree dominance consistently exerts a positive effect on tree, soil, and forest carbon stocks. Moreover, we observe that these positive effects are more pronounced during unfavorable climate conditions, at lower tree species richness, and during early successional stages. This underscores the potential of increasing the dominance of native EcM tree species not only to enhance carbon stocks but also to bolster resilience against climate change in high-latitude forests. Here we show that forest managers can make informed decisions to optimize carbon accumulation by considering various factors such as mycorrhizal types, climate, successional stages, and species richness.

Soil extracellular enzymes play a key role in mediating the degradation of soil organic matter, but little is understood as to how the pattern of soil extracellular enzymes could be altered by nitrogen (N) addition. In this study, the effects of N addition (started from 2006, four treatments: control, 0 g N·m^–2·yr^–1; low N addition, 2.5 g N·m^–2·yr^–1; high N addition, 5.0 g N·m^–2·yr^–1) on soil extracellular enzymes and microbial biomass in a natural secondary forest of Northeastern China. The results showed that the activity of urease, sucrase, peroxidase and N-acetyl-β-D-glucosidase decreased with N addition, and the activity of acid phosphatase and leucine aminopeptidase increased significantly with N addition. Soil total N, temperature at 5 cm soil depth, pH value, microbial biomass carbon and microbial biomass N were the key factors affecting soil enzyme activity. In summary, the enzyme activity related to soil organic matter degradation shows a decreasing trend under N addition. The results suggest that the increase in N deposition will slow down the degradation of soil organic matter in natural secondary forest, which is more conducive to the accumulation of organic matter in the soil.

Elevated atmospheric N deposition has the potential to alter litter decomposition patterns, influencing nutrient cycling and soil fertility in boreal forest ecosystems. In order to study the response mechanism of litter decomposition in Larix gmelinii forest to N deposition, we established four N addition treatments (0, 25, 50, 75 kg N ha⁻¹ yr⁻¹) in the Greater Khingan Mountains region. The results showed that (1) both needle and mixed leaf litter (Betula platyphylla and Larix gmelinii) exhibited distinct decomposition stages, with N addition accelerating decomposition for both litter types. The decomposition of high-quality (low C/N ratio) mixed leaf litter was faster than that of low-quality needle litter. (2) Mixed leaf litter increased the decomposition coefficients of litter with lower nutrients. (3) All N addition treatments promoted the decomposition of needle litter, while the decomposition rate of mixed leaf litter decreased under high-N treatment. (4) N addition inhibited the release of N and P in needle litter and promoted the release of N in mixed leaf litter, while high-N treatment had no positive effect on the release of C and P in mixed leaf litter. Our research findings suggest that limited nutrients in litter may be a key driving factor in regulating litter decomposition and emphasize the promoting effect of litter mixing and nitrogen addition on litter decomposition.

The purpose of this study was to determine which shrub species will enhance soil anti-scouring resistance on an ecological slope. Root traits and soil anti-scouring resistance of three shrubs (Amorpha fruticosa Linn (AFL), Swida alba Opiz (SAO) and Lespedeza bicolor Turcz (LBT)) were measured. Results showed that root biomass and root morphological traits of three shrubs were significantly correlated with the soil anti-scouring resistance index. According to the composition characteristic values, root morphological traits among the three shrubs had a high contribution rate. Under two slopes and two rainfall conditions, when root biomass and root morphological traits (e.g., root length, root volume and root surface area) were identical, AFL had the highest soil anti-scouring resistance index. These results suggested that root biomass and morphological traits of AFL had more significant effects on soil anti-scouring resistance comparing with SAO and LBT. Therefore, in engineering practice, AFL with stronger soil anti-scouring resistance can be selected as slope plants.

The short legacy effects of growing season nitrogen (N) addition and reduced precipitation on nongrowing season soil respiration (Rs), autotrophic respiration (Ra), and heterotrophic respiration (Rh) are still unclear. Therefore, a field manipulative experiment to determine the responses of nongrowing season Rs and its components to growing season N addition and reduced precipitation was conducted in a temperate forest. The results show that growing season N addition and reduced precipitation significantly increased nongrowing season Rs by regulating the response of Ra and Rh. The combination of N addition and reduced precipitation also showed a much stronger effect on Rs and its components, but the magnitude and direction largely depended on the snowpack thickness. The effects of growing season N addition and reduced precipitation on nongrowing season Rs and its components were mediated by different sampling periods. N addition significantly decreased Rs by decreasing Rh in early winter and significantly increased Rs by increasing Ra in deep winter and late winter. All treatments decreased temperature sensitivity (Q₁₀) of Rs and Rh. Our findings contribute to a better understanding of how nongrowing season Rs and its components will change under growing season N addition and reduced precipitation and could improve predictions of the future states of the soil C cycle in response to climate change.