Drought is one of the major abiotic stresses that limits plant growth. Roots, the primary organs responsible for water uptake, are the first to perceive and respond to water deficit conditions. Therefore, maintaining activity and promoting primary root elongation under drought stress are considered critical adaptive strategies for drought survival. However, despite increasing evidence of primary root elongation under drought stress, the underlying mechanisms, particularly hormonal regulation and its integration with environmental cues, remain poorly understood across different species and developmental contexts. Previous studies have shown that a highly coordinated network of plant hormone crosstalk plays a significant role in this adaptive process. In this review, data from diverse plant species confirmed the promoting effect of drought on primary root growth. This study further elucidated the role of abscisic acid (ABA) in enhancing primary root growth under drought conditions and explored the potential coordination of ABA with other hormones, including ethylene, auxin, and cytokinin, to synergistically promote primary root elongation. Furthermore, several physiological processes, such as cell cycle regulation, osmotic adjustment, and lateral root growth dynamics, had been systematically investigated for their contributions to this adaptive response. By dissecting these mechanisms, this study aims to propose feasible strategies to increase plant drought tolerance through targeted root system architecture modification, addressing challenges posed by future climate scenarios.

Tree planting is widely recognized as an effective strategy for enhancing terrestrial carbon sequestration, playing a crucial role in mitigating global climate change. However, our understanding of how it may affect soil fauna communities remains scarce. Here, we performed a global meta-analysis with 14 281 paired observations to evaluate tree planting effects on soil fauna abundance, biomass, and diversity across multiple former ecosystem types. Results showed that (i) tree planting had limited overall effects on soil fauna communities, only increasing Acari abundance, Protozoa abundance and Arthropod biomass by 36.9%, 56.9% and 777.3%, respectively, and decreasing the taxonomic richness of Collembola, the Pielou index of earthworm, and the Simpson index of Protozoa by 17.9%, 38.7%, and 77.1%, respectively; (ii) afforestation in non-forest lands showed strong positive effects on soil fauna abundance and diversity, especially in deserts where the abundance and Shannon-Wiener index of total soil fauna were increased by 92.5% and 65.8%, respectively, while reforestation in former forest lands generally had negative impacts; and (iii) tree planting effects on soil fauna were mediated by stand characteristics (e.g. stand age, canopy density, tree diameter) and pre-planting soil properties (e.g. bulk density, pH, carbon, nitrogen), but not by tree species type (leaf type or mycorrhizal association). These results demonstrate the contrasting effects of tree planting on soil fauna communities among different former ecosystem types, highlighting the importance of considering the legacy of former ecosystems when designing tree planting policies to restore/enhance carbon sequestration and biodiversity conservation under global environmental change scenarios.

Extreme climatic events often co-occur with persistent environmental disturbances, such as nitrogen enrichment, which may influence the resistance and recovery of plant communities to extreme climatic conditions. However, most studies have focused on the resistance and recovery of community functions (e.g. biomass) to climatic events while neglecting the corresponding responses of diversity. Here, we performed a soil nitrogen addition experiment in an alpine meadow from 2011 to 2020, with 2015 characterized by extreme drought. We explored the effects of nitrogen addition on the resistance and recovery of plant community biomass and diversity in response to extreme drought using measures including community biomass, taxonomic diversity (TD), phylogenetic diversity (PD) and functional diversity (FD). We found that nitrogen addition decreased biomass resistance, mainly due to species asynchrony rather than the diversity resistance, even though PD and FD resistance also declined. Meanwhile, nitrogen addition enhanced the recovery of biomass to drought. This was mainly attributable to the direct, positive impact of nitrogen on biomass recovery, coupled with an indirect influence of species asynchrony, without any diversity (TD, PD, FD) recovery effects. Our results indicate that soil nitrogen enrichment mainly influences plant biomass responses to extreme drought, with a relatively small effect on plant diversity. Additionally, the mechanisms driving diversity and biomass responses may operate independently, as changes in diversity response did not scale up to changes in biomass. We anticipate that maintenance of plant community biomass during extreme drought would be more challenging in conditions of high nitrogen deposition.

Herbivorous insects shape plant growth and community assembly, while conversely, plant traits, especially leaf traits, profoundly affect herbivore behaviors. However, which leaf traits and how they dominantly drive insect herbivory in a natural forest habitat remain undefined. In this study, we evaluated the background insect herbivory of 45 individual trees from five broadleaved tree species in the northeast of China. Based on that, 17 leaf traits representing four groups—leaf structural traits, photosynthetic pigments, nutrient traits, and secondary metabolites—were measured. Finally, the correlation between 17 leaf traits and background insect herbivory was investigated. The results indicated that the damaged leaf area (DLA) exhibited positive correlations with leaf structural traits (leaf mass per area and leaf size) and nutrient traits (soluble sugar (SS), non-structural carbohydrates (NSC), SS/NSC), and a negative correlation with photosynthetic pigments, nitrogen/phosphorus ratio, and anthocyanins. Meanwhile, SS/NSC, SS, leaf size, total phenol, and phosphorus were identified as the five relatively important leaf traits contributing to DLA by the quantitative estimation based on SHAP (SHapley Additive exPlanations) values. Furthermore, nutrient traits accounted for 52.9% of DLA explanation, showing the most important group of leaf traits. In addition, structural traits and secondary metabolites were found to interactively influence herbivory. These findings provide valuable insights into the complex interactions between host plants and herbivorous insects in forest ecosystems.

Peatlands store approximately one-third of global soil organic carbon (SOC) and clarifying SOC sources is essential to assess soil carbon (C) formation and stability in these C-rich ecosystems. However, large-scale patterns and drivers of plant- and microbial-derived C in peatlands remain poorly understood. This study applied lignin phenols and amino sugars as biomarkers for plant and microbial residues to investigate the regional distributions and controlling factors of plant- and microbial-derived C in surface peat (0–20 cm) across Zoige alpine peatlands. Our results showed that amino sugars contributed less while lignin phenols remained stable with SOC accrual, indicating the key role of plant-derived C in SOC accumulation. Soil nutrients and microbial properties explained the majority of the variation in lignin phenols, while soil nutrients and mineral protection played a more important role in amino sugars than microbial variables and climatic factors. Specifically, lignin phenols were negatively correlated with soil nutrients, fungal richness, and acid phosphatase activity, while showing a positive association with leucine aminopeptidase activity. In contrast, amino sugars were positively related to soil total phosphorus but negatively linked with Fe-associated C and Fe/Al-oxide. These findings provide the first empirical evidence of plant- and microbial-derived C and their divergent drivers in alpine peatlands over broad geographic scale, which advances our understanding of soil C formation and stability in these C-rich, climate-sensitive ecosystems.

Arbuscular mycorrhizal fungi (AMF) can enhance terrestrial plant growth by promoting nutrient uptake. However, the effects of interactions between AMF and nutrient inputs on plant functional traits and their trade-offs remain poorly understood. In this study, a pot experiment was conducted using Phragmites australis as the host species, with AMF inoculation and non-inoculation treatments under three levels of nitrogen addition and two levels of phosphorus addition. The results showed that AMF inoculation significantly increased AMF colonization in the roots of P. australis. Under unfertilized conditions, AMF significantly promoted plant morphological development and biomass accumulation. Nitrogen addition primarily enhanced aboveground growth, while phosphorus addition significantly stimulated root system development. Regarding photosynthetic traits, AMF inoculation significantly increased carotenoid content, whereas phosphorus addition significantly reduced net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) by 18.5%, 25.8%, and 28.2%, respectively. Furthermore, AMF inoculation increased leaf nitrogen and phosphorus contents but reduced stem nitrogen content and the N:P ratios in fine roots, rhizomes, and stems. Trait network analysis revealed that AMF inoculation shifted the central traits from leaf biomass to rhizome biomass, indicating a transition in hub traits from aboveground to belowground organs. These findings suggest that AMF inoculation significantly promotes the growth of P. australis although the magnitude of this benefit is modulated by soil nitrogen and phosphorus availability, with stronger effects observed under nutrient-poor conditions. This study advances our understanding of nutrient–AMF–plant interactions in wetland ecosystems and provides a theoretical foundation for ecological restoration and nutrient management in vulnerable aquatic habitats.

As global warming drives plant upward migration, the alpine tundra of Changbai Mountain is experiencing encroachment by Deyeuxia angustifolia (Komarov) Y. L. Chang, a low-elevation herb. However, its impact on native shrubs such as Rhododendron aureum Georgi remains unclear. Here, we analyzed the radial growth trends and climate sensitivity of R. aureum across elevations and encroachment gradients using linear and mixed-effects model methods, and explored the mediating roles of soil properties and plant traits. Our study revealed that R. aureum exhibited stronger positive long-term growth trend at higher elevations compared to lower elevations. Mild and moderate encroachment of D. angustifolia enhanced the positive growth trend of R. aureum, especially at the low elevations. Moreover, R. aureum showed weak climate sensitivity at mid-elevation but stronger responses to winter temperatures at low elevation and to spring–summer temperatures and precipitation at high elevation. D. angustifolia encroachment further intensified this sensitivity, characterized by stronger negative responses to spring, autumn, and winter temperatures but positive responses to summer temperatures and autumn precipitation. Overall, elevation primarily influenced R. aureum growth and its sensitivity to precipitation through soil conditions and plant size traits. Soil conditions and leaf economic traits influence temperature sensitivity. These findings advance understanding of alpine vegetation dynamics and contribute to ecosystem conservation under climate change.

Leguminous species have an advantage in acquiring phosphorus (P) compared with non-leguminous species. Nonetheless, it remains unclear whether this advantage would diminish under long-term nitrogen (N) deposition. In the seventh year of a simulated long-term N deposition experiment, we sampled surface soil to measure acid phosphatase activity (ACP) in stands dominated by leguminous and non-leguminous species, respectively. To assess the response of ACP to prolonged N addition, we also collected data on ACP in the second, eighth, twelfth, and thirteenth years of the experiment. We found that the difference in soil ACP between the two plantation types disappeared after long-term N input, and this process was accelerated under high N addition. This occurred due to an exacerbated P-limitation, which primarily prompts ACP production only in non-leguminous species. Additionally, there was a relatively decreased N contribution efficiency to ACP in the stand with leguminous species, indicating that soil N content no longer primarily governs ACP. This study demonstrates that prolonged high N deposition accelerates the loss of the “P-acquiring advantage” in leguminous plantations. To elucidate the differences in P usage strategies between leguminous and non-leguminous species under global change, more systematic research is warranted in the future.