Hao Chen

Increases in drought-induced forest mortality have raised worldwide concerns regarding forest drought recovery. Precipitation sensitivity (S_Pre), the magnitude of forest vegetation growth response to precipitation variation, is believed to strongly influence drought recovery. However, direct evidence is lacking, limiting its use in forecasting forest resilience under climate change. Using multiple remote-sensing datasets, we reveal that S_Pre is a pivotal factor shaping global forest recovery following extreme drought years, comparable to and even surpassing other well-known factors. In contrast to previous expectations, drought recovery is highest at intermediate S_Pre, and declines at lower and higher values. Over the past three decades, climate change increases S_Pre in 56% of global forests, and 30% experience S_Pre increases associated with a decline in drought recovery-particularly sub-tropical forests. Our results illuminate the widespread importance of S_Pre in global forests, and highlight incorporating S_Pre into ecological models to improve predictions of forest resilience.

Summary: Resource allocation theory posits that nutrient acquisition by soil microbes must optimize extracellular enzyme production and microbial growth, yet their specific strategies under changing resource conditions remain uncertain. Litter, the dominant nutrient source for soil microbes, is undergoing sustained shifts globally due to press and pulse disturbances. Understanding microbial responses to these changes, especially over longer timescales, is critical for predicting global nutrient cycling. We synthesize global litter manipulation experiments to assess how litter addition and removal influence microbial nutrient acquisition strategies, based on nitrogen (N)‐ and phosphorus (P)–related soil enzyme activities and their temporal dynamics. We identify two consistent types of microbial responses. First, litter addition stimulates N‐ and P‐acquiring enzyme activities, with stronger investment in the most limiting nutrient (N at N‐limited sites, P at P‐limited sites), but this effect weakens over time. Second, litter removal initially suppresses enzyme activities and favors P acquisition, but shifts toward N acquisition and microbial growth over time. Our findings illustrate the plasticity of microbial nutrient acquisition strategies, providing new insights into microbial resource allocation theory and a mechanistic understanding of how changing plant litter inputs alter soil nutrient availability via microbial nutrient acquisition processes.

Nitrogen (N)-fixing species are widely used in forestation and agriculture. The effects of planting N-fixing species on soil organic carbon (SOC) stock, however, remain uncertain, limiting policy development and their application towards a possible climate change mitigation strategy. Here we conduct a global meta-analysis of 385 datapoints from 136 studies comparing SOC stock with planting N-fixing versus non-N-fixing species. Planting N-fixing species increases SOC stock by 16% compared with non-N-fixing species. This SOC increase is closely accompanied by soil N increases, with an average accumulation of 7.8 g of SOC per gram of soil N increase. Climate mediates SOC responses, with greater SOC sequestration observed in drier and warmer regions, particularly in the tropics. We estimate that an additional increase of 0.29–0.75 PgC yr⁻¹ in global SOC stock could be achieved by adopting N-fixing species for forestation, agriculture and regeneration of marginal lands, highlighting their potential for climate change mitigation.

Soil phosphorus (P) availability is crucial for plant productivity, and salinization is generally expected to reduce plant productivity in global terrestrial ecosystems. However, the response of soil P availability to salinization remains unclear, making it difficult to assess its role in shaping plant responses to salinization. Here, we conducted a meta‐analysis of 823 observations from 87 published articles to investigate the effects of salinization on soil P availability and plant productivity across global terrestrial ecosystems. Across these studies, salinization decreased soil total P by an average of 4.6%, available P by 11.2%, and phosphatase activity by 25.4%. The effect of salinization on soil P availability was primarily modulated by salinization magnitude and exposure duration, vegetation types, ecosystem types, and climate conditions. Specifically, the negative effects of salinization on soil P availability were exacerbated with increasing salinization magnitude and duration, and were stronger in ecosystems dominated by herbaceous vegetation and in regions with lower precipitation. Across global ecosystems, the negative effects of salinization on soil P availability were associated with the declines in plant productivity. Our meta‐analysis provides a comprehensive understanding of how salinization impacts soil P availability across diverse vegetation and ecosystem types worldwide, and highlights that optimizing fertilization strategies and plant community composition are crucial for enhancing plant productivity and ecosystem functioning in salt‐affected areas.

It has long been assumed that nitrogen and phosphorus cycles are closely coupled. However, this assumption has not been rigorously examined under global change, limiting the predictive power of nitrogen and phosphorus cycling. We conducted a meta‐analysis of 1341 data points from 107 published articles on the response of leaf nitrogen and phosphorus resorption efficiency to major global change factors (i.e. warming, drought, increased rainfall, elevated CO ₂ , nitrogen fertilization and phosphorus fertilization) over the last two decades. We showed contrast responses of plant nitrogen and phosphorus resorption to these global change factors, indicating a decoupling of plant nitrogen and phosphorus cycles in the face of global change. These divergent responses were primarily driven by the shifts in nitrogen and phosphorus limitations induced by global change, suggesting that the decoupling of nitrogen and phosphorus cycles may be a plant adaptation strategy in response to nutrient limitation. Furthermore, multiple global change factors exerted additive effects on nitrogen and phosphorus resorption, with nitrogen fertilization being the most influential among them. Synthesis. Our results highlight that the decoupling of plant nitrogen and phosphorus cycles should be incorporated into ecological models to accurately predict ecosystem responses to global change.

Aims Phosphorus (P) availability commonly limits the growth of tropical plants, yet how this limitation changes with tree age remains uncertain.Methods Here we investigated the effect of tree age on P limitation in a tropical forest by examining three functional plant groups: fast-growing, slow-growing, and nitrogen (N)-fixing tree species. We measured leaf N and P resorption efficiency (NRE and PRE), and used the ratio of PRE to NRE (PRE:NRE) as an indicator of plant P limitation.Results Our results revealed a significant increase in both PRE and PRE:NRE with tree age across all functional plant groups, indicating a widespread intensification of P limitation as plants mature. Furthermore, such increase in P limitation was more pronounced in slow-growing and N-fixing species compared to fast-growing species.Conclusions These findings underscore the crucial role of tree age in influencing P limitation in tropical forests, a factor that should be incorporated into terrestrial biogeochemical models, which have traditionally overlooked this effect.

Cadmium (Cd) contamination in agricultural soils is a common issue, posing health risks as it enters the human body through the food chain. Commonly used phosphate fertilizers (PFs) not only provide essential phosphorus (P) nutrients to crops but also serve as P-containing materials for immobilizing heavy metals (HMs) like Cd in soils. Therefore, understanding the passivation effects of PFs on soil Cd and their potential influencing factors is crucial for mitigating soil Cd pollution. In this study, the impact of multi-crop applications (75 mg P kg⁻¹, 150 mg P kg⁻¹) of four kinds of PFs on reducing soil Cd toxicity and decreasing Cd accumulation in spinach was investigated. The results indicated that under the low application rate (75.0 mg P kg⁻¹), all PFs could passivate Cd, and CMP demonstrated the most effective passivation of Cd. However, under the high application rate (150 mg P kg⁻¹), the immobilization effect diminished or even activated Cd. Among the different types of PFs, CMP application alleviated soil acidification and significantly reduced soil-available Cd, showing the best performance in promoting spinach growth and Cd inhibition. These results suggest that PF application in Cd-contaminated soils affects spinach growth and Cd accumulation, with soil pH, available phosphorus (AP), and Cd dynamics being crucial; moreover, low-P, micronutrient-rich, alkaline PFs like CMP optimize spinach yields and minimize Cd uptake, and excessive application of soluble PFs decreases pH, increases Cd mobility, and poses health risks, suggesting a need for balanced fertilizer use.