Climate, topography, and tree structure have different effects on plant diversity that vary with spatial scale. In this study, we assessed the contribution of these drivers and how they affect the vascular plant richness of different functional groups in a temperate forest ecosystem in Northeast China. We investigated about 0.986 million plants from 3160 sites to quantify the impact of annual mean temperature, sunshine duration, annual precipitation, standard deviation of diameter at breast height, and forest type on richness of vascular plants (total species, tree, treelet, shrub, and herb, separately) using the gradient boosting model. The results show that annual mean temperature had the strongest impact on plant richness. The tree richness peaked at intermediate annual mean temperature and sunshine duration and increased with annual precipitation. The Shannon diversity index and Simpson dominance index increased with annual precipitation and standard deviation of diameter at breast height, decreased with sunshine duration, and peaked at intermediate annual mean temperature and forest type. The total richness and understory richness increased with annual mean temperature and standard deviation of diameter at breast height and peaked at intermediate sunshine duration and annual precipitation. A comprehensive mechanism was found to regulate the plant diversity in forest ecosystems. The relationship between tree richness and annual mean temperature with latitudinal effect could be affected by the differences in number and size of tree individuals, indicating that plant diversity varies with the utilization of energy. The force driving plant richness varied with the functional group due to the different environmental resource requirements and the life history strategies of plants layers.

Global climate change, characterized by nitrogen (N) deposition and precipitation reduction, can disrupt soil microbial stoichiometry and soil nutrient availability, subsequently affecting soil nutrient cycles. However, the effects of N deposition and precipitation reduction on microbial stoichiometry and the soil nutrient status in temperate forests remain poorly understood. This study addresses this gap through a 10-year field trial conducted in a Korean pine mixed forest in northeastern China where three treatments were applied: precipitation reduction (PREC), nitrogen addition (N50), and a combination of nitrogen addition with precipitation reduction (PREC-N50). The results showed that N50 and PREC significantly increased carbon-to-phosphorus (C/P) and nitrogen-to-phosphorus (N/P) imbalances, thereby exacerbating microbial P limitation, while PREC-N50 did not alter the nutrient imbalances. PREC decreased soil water availability, impairing microbial nutrient acquisition. Both N50 and PREC influenced soil enzyme stoichiometry, leading to increasing the ACP production. The results of redundancy analysis indicated that microbial nutrient status, enzymatic activity, and composition contributed to the variations in nutrient imbalances, suggesting the adaption of microorganisms to P limitation. These results highlight that N addition and precipitation reduction enhanced microbial P limitation, boosting the shifts of microbial elemental composition, enzyme production, and community composition, and subsequently impacting on forest nutrient cycles.

The purpose of this study was to develop a novel method for the external attachment of ultrasonic transmitters on hard fin‐spines fish (Sparidae). Acanthopagrus latus, one of the main stocking Sparidae fishes in the northern South China Sea, was employed to conduct the 40‐day tank experiment by using dummy ultrasonic transmitters. The experiment consisted of 3 treatment groups, i.e., drilling on dorsal fin‐spine (DD) group, drilling on anal fin‐spine (DA) group, and control (C) group, with each group having 3 replicates and 30 fish per replicate. The feasibilities of DD and DA for the external attachment of ultrasonic transmitters were tested and evaluated using parameters: the specific growth rate, survival rate, and tag retention rate of each group. And the tagging procedures for the external attachment of hard fin‐spines fish were also proposed. The results showed that there were no significant differences in the specific growth rate of fish between groups. Both the survival rates of DD group (96.67%) and DA group (94.44%) were less (but not significant) than C group (97.78%), while the tag retention rate of DA group (100%) was higher (but not significant) than DD group (98.89%). These results demonstrate that drilling on dorsal or anal fin‐spines is feasible as an external attachment method of ultrasonic transmitters on Sparidae fishes. In addition, considering the friction between the tagged transmitters and rocks at the bottom of natural waters, which possibly affect the fish behaviors such as swimming, feeding, etc., or lead to tag loss, so drilling on the dorsal fin‐spine is preferred for rocky‐bottom Sparidae fishes like A. latus as small as 14 cm body length.

Phosphorus (P) is essential for cellular processes, and P fractions within leaf tissues reflect distinct biochemical functions. However, the relationship among foliar P allocation, leaf functional traits, and soil properties in subtropical China remains poorly understood. Here, we investigated four tree species to examine the relationships among foliar P fractions (orthophosphate P, metabolic P, nucleic acid P, lipid P, and residual P), key leaf functional traits (LMA, A_mass, and leaf [N], and P concentrations), and soil properties. A negative correlation between the relative allocation of metabolic P (rPM) and nucleic acid P (rPN) suggested a trade-off between metabolic activity and growth. LMA was positively correlated with rPM and residual P (rPR) but negatively associated with rPN and lipid P (rPL). Similarly, leaf [N] correlated positively with rPN and negatively with rPR. Structural equation modeling (SEM) revealed that foliar P allocation was primarily driven by leaf functional traits independent of soil properties. These findings underscore the critical role of leaf functional traits in shaping P allocation patterns and highlight the adaptive strategies of tree species to cope with P-deficient environments in subtropical ecosystems.

Trees can build fine-root systems with high variation in root size (e.g., fine-root diameter) and root number (e.g., branching pattern) to optimize belowground resource acquisition in forest ecosystems. Compared with leaves, which are visible above ground, information about the distribution and inequality of fine-root size and about key associations between fine-root size and number is still limited. We collected 27,573 first-order fine-roots growing out of 3,848 second-order fine-roots, covering 51 tree species in three temperate forests (Changbai Mountain, CBS; Xianrendong, XRD; and Maoershan, MES) in Northeastern China. We investigated the distribution and inequality of fine-root length, diameter and area (fine-root size), and their trade-off with fine-root branching intensity and ratio (fine-root number). Our results showed a strong right-skewed distribution in first-order fine-root size across various tree species. Unimodal frequency distributions were observed in all three of the sampled forests for first-order fine-root length and area and in CBS and XRD for first-order fine-root diameter, whereas a marked bimodal frequency distribution of first-order fine-root diameter appeared in MES. Moreover, XRD had the highest and MES had the lowest inequality values (Gini coefficients) in first-order fine-root diameter. First-order fine-root size showed a consistently linear decline with increasing root number. Our findings suggest a common right-skewed distribution with unimodality or bimodality of fine-root size and a generalized trade-off between fine-root size and number across the temperate tree species. Our results will greatly improve our thorough understanding of the belowground resource acquisition strategies of temperate trees and forests.