Velvet ash (Fraxinus velutina Torr.) is a dioecious tree species, which is widely used as a part of urban greeneries in saline land of North China. Female and male trees have different nutrient allocation trade-offs in dioecious species. As the fruit production consumes a lot of nutrients, female F. velutina plants grow slowly and are vulnerable to insects and diseases. Ecological stoichiometry can be used to study the physiological mechanism of the growth difference between female and male plants. The purpose of this study was to compare the seasonal patterns of C, N and P stoichiometry and their trade-offs in different organs of female and male F. velutina plants planted in urban green spaces. The fruit C, N and P contents of female F. velutina plants were all lower than those of leaves in the early growing season, but higher than those of leaves in the middle and late growing season. During most months, the leaf C and P contents of females were higher than those of males, while the leaf N content was lower than that of males, which was consistent with the sex-specific resource requirements for reproduction (i.e., high carbon requirements for ovules and high nitrogen demands for pollen). Compared to the females, there were more significant correlations between the stoichiometric indices (element contents and their ratios) of branches and leaves in male plants, and this difference may be related to the fact that the male plants were not involved in nutritional allocation for fruits. The leaf N/P of F. velutina was lower than 14 in the whole growing season, which indicated N limitation. The female and male plants of F. velutina had different sex-specific resource requirements for sex organ formation.

Chinese fir (Cunninghamia lanceolata) is a cornerstone timber species in southern China. However, yet its plantation productivity frequently declines under successive rotations, threatening long-term sustainability. While belowground processes are suspected drivers, the mechanisms—particularly plant–soil–microbe interactions—remain poorly resolved. To address this, we examined a chronosequence of C. lanceolata plantations (5, 15, 20, and 30 years) in Jingdezhen, Jiangxi Province, integrating soil physicochemical assays, high-throughput sequencing, and extracellular enzyme activity profiling. We found that near-mature stands (20 years) exhibited a 60.7% decline in mean annual volume increment relative to mid-aged stands (15 years), despite continued increases in individual tree volume—suggesting a strategic shift from resource-acquisitive to nutrient-conservative growth. Peak values of soil organic carbon (32.87 g·kg⁻¹), total nitrogen (2.51 g·kg⁻¹), microbial biomass carbon (487.33 mg·kg⁻¹), and phosphorus (25.65 mg·kg⁻¹) coincided with this stage, reflecting accelerated nutrient turnover and intensified plant–microbe competition. Microbial communities shifted markedly over time: Basidiomycota and Acidobacteria became dominant in mature stands, replacing earlier Ascomycota and Proteobacteria. Random Forest and Partial Least Squares Path Modeling (PLS-SEM) identified total nitrogen, ammonium nitrogen, and total phosphorus as key predictors of productivity. PLS-SEM further revealed that stand age directly enhanced productivity (β = 0.869) via improved soil properties, but also indirectly suppressed it by stimulating microbial biomass (β = 0.845)—a “dual-effect” that intensified nutrient competition. Fungal and bacterial functional profiles were complementary: under phosphorus limitation, fungi upregulated acid phosphatase to enhance P acquisition, while bacteria predominately mediated nitrogen mineralization. Our results demonstrate a coordinated “soil–microbe–enzyme” feedback mechanism regulating productivity dynamics in C. lanceolata plantations. These insights advance a mechanistic understanding of rotation-associated decline and underscore the potential for targeted nutrient and microbial management to sustain long-term plantation yields.

Carbon, nitrogen and phosphorus transport within the fruit tree are complex processes involving source-sink interactions. Understanding the difference of leaf stoichiometry between fruiting branches and vegetative branches of winter jujube (Ziziphus jujuba Mill. cv. Dongzao) can provide sight into the source-sink relationship. The study investigated the seasonal dynamics and the difference of the leaf stoichiometry between vegetative branches and fruiting branches of winter jujube. The study investigated the seasonal dynamics and the difference of the leaf stoichiometry between vegetative branches and fruiting branches of winter jujube. The results showed that the leaf C content was significantly higher (p<0.05) in the fruiting branch than in the vegetative branch in most growth stages except for the Full flowering stage. The leaf N and P contents were both higher in vegetative branch than in fruiting branch in most growth stages, but only in a few growth stages, these differences reached a significant level. There was a significant correlation between the leaf stoichiometric indices examined such as N and C/N, P and C/P, P and N/P, C/P and N/P. The result showed that N and P were the key factors to determine the element ratio. The winter jujube trees incurred N and P co-limitation (14<N/P16) in other growth stages. Our study provides baseline information for describing the changes in nutritional elements with jujube growth, which will facilitate plantation management.