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The Chinese government has made a strategic decision to reach ‘carbon neutrality’ before 2060. China’s terrestrial ecosystem carbon sink is currently offsetting 7–15% of national anthropogenic emissions and has received widespread attention regarding its role in the ‘carbon neutrality’ strategy. We provide perspectives on this question by inferring from the fundamental principles of terrestrial ecosystem carbon cycles. We first elucidate the basic ecological theory that, over the long-term succession of ecosystem without regenerative disturbances, the carbon sink of a given ecosystem will inevitably approach zero as the ecosystem reaches its equilibrium state or climax. In this sense, we argue that the currently observed global terrestrial carbon sink largely emerges from the processes of carbon uptake and release of ecosystem responding to environmental changes and, as such, the carbon sink is never an intrinsic ecosystem function. We further elaborate on the long-term effects of atmospheric CO 2 changes and afforestation on China’s terrestrial carbon sink: the enhancement of the terrestrial carbon sink by the CO 2 fertilization effect will diminish as the growth of the atmospheric CO 2 slows down, or completely stops, depending on international efforts to combat climate change, and carbon sinks induced by ecological engineering, such as afforestation, will also decline as forest ecosystems become mature and reach their late-successional stage. We conclude that terrestrial ecosystems have nonetheless an important role to play to gain time for industrial emission reduction during the implementation of the ‘carbon neutrality’ strategy. In addition, science-based ecological engineering measures including afforestation and forest management could be used to elongate the time of ecosystem carbon sink service. We propose that the terrestrial carbon sink pathway should be optimized, by addressing the questions of ‘when’ and ‘where’ to plan afforestation projects, in order to effectively strengthen the terrestrial ecosystem carbon sink and maximize its contribution to the realization of the ‘carbon neutrality’ strategy.

Rocky desertification is a common phenomenon in karst areas. Soil carbon and nitrogen storage is of great significance to the formation and evolution of ecosystems. Soil leakage is one of the important indicators in evaluating ecosystem stability. There are few studies on the response of carbon and nitrogen leakage below the surface of karst critical zones to forest ecosystems. The karst springs in the study area of Shibing Heichong, Bijie Salaxi and Guanling-Zhenfeng Huajiang in Guizhou, China, were selected to determine the variation characteristics of carbon and nitrogen content and karst spring outputs and their response to soil leakage. The results showed the following: (1) The content and output of carbon and nitrogen in karst springs in the three study areas showed obvious spatial differences. The carbon and nitrogen output of karst spring water was mainly concentrated in the rainy season. The carbon and nitrogen contents and output of karst springs in the Shibing Heichong study area were higher than those in the Bijie Salaxi and Guanling-Zhenfeng Huajiang study areas. (2) The carbon and nitrogen outputs of karst springs were mainly affected by flow. Land cover and land use in forests affect the carbon and nitrogen contents of karst springs and thus affect the output. (3) The higher the soil leakage of the karst spring was, the higher the carbon and nitrogen output. The leakage of the overlying soil in the Shibing Heichong study area was high, but the soil decline was small, and the stability of the forest ecosystem was relatively good. In summary, a lower degree of rocky desertification results in higher leakage from karst springs and higher risks of soil leakage; however, the ecosystem was relatively stable. Evaluating forest soil carbon and nitrogen loss and ecosystem stability in karst areas through the nutrient output of karst springs is of great significance for the prevention and control of rocky desertification areas.

Global environmental changes have posed threats to ecosystems worldwide. Safeguarding terrestrial ecosystem health in particular is fundamental to achieving global sustainability targets, yet land degradation, carbon depletion and climate extremes continue to undermine resilience due to climate change and human activities. Therefore, Understanding human‐environment interactions is increasingly important for enhancing the resilience of terrestrial ecosystems under global change. The collection for this special issue addresses urgent challenges of land degradation, soil carbon loss, and ecosystem vulnerability by assembling eight regionally grounded studies from diverse landscapes of Asia. Collectively, these contributions reveal how land‐use transitions, restoration strategies and climate variability shape ecosystem health and carbon dynamics, while advancing methodological and governance frameworks that link science with policy. The collection offers critical insights and practical lessons for scholars and policy planners to sustainably manage land resources within the GeoHealth paradigm. Human activities and climate change are putting stress on forests, grasslands and farmlands. These pressures lead to land degradation, soil carbon loss and reduced ability of ecosystems to provide food, water, and clean air. This special issue brings together eight studies from Asia that examine how land use, restoration, and climate change affect soil carbon and ecosystem health. The findings show that solutions must be tailored to local conditions, for example, grazing strategies differ across grasslands, and restoration success depends on soil type. Urban expansion creates trade‐offs between food and water security, while forests in arid regions are especially at risk. The studies highlight that sustainable management needs both science‐based approaches and strong governance. Changes in land use patterns and restoration practices are central drivers of terrestrial ecosystem health and soil carbon dynamics Ecosystem responses are context‐dependent, requiring site‐specific and scale‐appropriate approaches and interventions Integrating biophysical, socio‐economic and institutional factors creates cross‐sector pathways for sustainable management

The leaf economics spectrum[1,2] and the global spectrum of plant forms and functions[3] revealed fundamental axes of variation in plant traits, which represent different ecological strategies that are shaped by the evolutionary development of plant species[2]. Ecosystem functions depend on environmental conditions and the traits of species that comprise the ecological communities[4]. However, the axes of variation of ecosystem functions are largely unknown, which limits our understanding of how ecosystems respond as a whole to anthropogenic drivers, climate and environmental variability[4,5]. Here we derive a set of ecosystem functions[6] from a dataset of surface gas exchange measurements across major terrestrial biomes. We find that most of the variability within ecosystem functions (71.8%) is captured by three key axes. The first axis reflects maximum ecosystem productivity and is mostly explained by vegetation structure. The second axis reflects ecosystem water-use strategies and is jointly explained by variation in vegetation height and climate. The third axis, which represents ecosystem carbon-use efficiency, features a gradient related to aridity, and is explained primarily by variation in vegetation structure. We show that two state-of-the-art land surface models reproduce the first and most important axis of ecosystem functions. However, the models tend to simulate more strongly correlated functions than those observed, which limits their ability to accurately predict the full range of responses to environmental changes in carbon, water and energy cycling in terrestrial ecosystems[7,8]. © 2021. The Author(s).

Nitrogen (N) deposition-induced soil acidification has become a global problem. However, the response patterns of soil acidification to N addition and the underlying mechanisms remain far from clear. Here, we conducted a meta-analysis of 106 studies to reveal global patterns of soil acidification in responses to N addition. We found that N addition significantly reduced soil pH by 0.26 on average globally. However, the responses of soil pH varied with ecosystem types, N addition rate, N fertilization forms, and experimental durations. Soil pH decreased most in grassland, whereas boreal forest was not observed a decrease to N addition in soil acidification. Soil pH decreased linearly with N addition rates. Addition of urea and NH4NO3 contributed more to soil acidification than NH4-form fertilizer. When experimental duration was longer than 20 years, N addition effects on soil acidification diminished. Environmental factors such as initial soil pH, soil carbon and nitrogen content, precipitation, and temperature all influenced the responses of soil pH. Base cations of Ca2+, Mg2+ and K+ were critical important in buffering against N-induced soil acidification at the early stage. However, N addition has shifted global soils into the Al3+ buffering phase. Overall, this study indicates that acidification in global soils is very sensitive to N deposition, which is greatly modified by biotic and abiotic factors. Global soils are now at a buffering transition from base cations (Ca2+, Mg2+ and K+) to non-base cations (Mn2+ and Al3+). This calls our attention to care about the limitation of base cations and the toxic impact of non-base cations for terrestrial ecosystems with N deposition.

The soil microbiome comprises one of the most important and complex components of all terrestrial ecosystems as it harbors millions of microbes including bacteria, fungi, archaea, viruses, and protozoa. Together, these microbes and environmental factors contribute to shaping the soil microbiome, both spatially and temporally. Recent advances in genomic and metagenomic analyses have enabled a more comprehensive elucidation of the soil microbiome. However, most studies have described major modulators such as fungi and bacteria while overlooking other soil microbes. This review encompasses all known microbes that may exist in a particular soil microbiome by describing their occurrence, abundance, diversity, distribution, communication, and functions. Finally, we examined the role of several abiotic factors involved in the shaping of the soil microbiome.

The energy consumption structure is gradually evolving into a \"diversified energy structure\" against the backdrop of the global implementation of energy-saving and low-carbon policies. Coal, as the main energy source in China, is difficult to change in the short term, given the characteristics of China’s energy and resource endowments, as well as the actual social and economic development at the present stage. Nevertheless, coal mining inevitably leads to a range of ecological issues. Identifying the impact of coal mining on terrestrial ecosystems and adopting resilient recovery measures are crucial prerequisites for advancing green coal mining efforts and attaining carbon peaking and carbon neutrality goals. Using China’s open-pit coal mining as a case study: (1) the research examines the fundamental attributes and evolving patterns of spatial distribution among these mines within the country. Furthermore, it delineates the life cycle stages and distinctive features of the five principal open-pit coal mines. The life cycle of a coal mining area is divided into four distinct development phases: the initial phase, the accelerated phase, the stable phase, and the declining phase. The spatial relationship between the life cycle stages of coal mining and ecosystem succession is elucidated by examining the evolutionary types of ecosystems within coal mine area. In the accelerated and stable development phase, the adverse effects of coal mining on the ecosystem are in a long-term increasing trend, causing the key elements of the ecosystem to gradually surpass their threshold values. The ecosystem is out of balance, severely damaged, and gradually undergoing degradation or extreme degradation. The types of ecological succession in coal mining areas can be categorized as follows: terrestrial succession leading to a new terrestrial ecosystem, terrestrial to aquatic ecosystem transitions, or the development of an amphibious symbiotic ecosystem. (2) The research quantitatively assessed the impact of surface coal mining on terrestrial ecosystems by utilizing remote sensing data in conjunction with coal production information. In 2022, the affected areas of the five major open-pit coal mines due to coal mining activities amounted to approximately 0.02% of China’s total land area. Meanwhile, the nationwide affected areas of all open-pit coal mines combined reached to approximately 0.13% of China’s land area. Open-pit coal mining activities have a significant impact on the surface. (3) By incorporating the ecological resilience theory, we establish a model for the ecosystem’s elastic modulus in coal mining areas, taking into account landscape diversity, vegetation coverage, land type, and climate factors, which are based on the concepts of elastic strength and elastic limit. A conceptual model for recognizing ecological thresholds in coal mining areas is developed by incorporating the comprehensive integrity index of the ecosystem. The comprehensive integrity of the ecosystem within a coal mining area undergoes significant alterations as it crosses three distinct ecological thresholds: the elastic point, the yield point, and the mutational point. There should be a corresponding constant (or constant interval) at the three ecological thresholds of ecosystem resilience, the elastic point, the yield point, and the mutational point, which is closely related to the scale of mining operations, mining technology, and the service life in coal mining areas. The established models for identifying ecological thresholds and the resilience modulus degree serve as both theoretical references and practical bases for managing the progress and trends of ecosystem changes during coal resource extraction, making ecological restoration in coal mine areas more target-oriented and specific.

Heavy metals and metalloids are ubiquitous and persistent in the environment. Anthropogenic activities, including land use change, industrial emissions, mining, chrome plating, and smelting, escalate their distribution and accumulation in terrestrial ecosystems. Priority metals, including lead, chromium, arsenic, nickel, copper, cadmium, and mercury, pose enormous risks to public health, ecological safety, and biodiversity. The adverse effects of heavy metals on plant-animal interactions, pollen viability, species fitness, richness, and abundance are poorly understood. Hence, this review summarises the critical insights from primary investigations on the key sources of heavy metal pollution, distribution pathways, and their adverse effects on plants and pollinators. This study provides insights into how heavy metals compromise nectar quality, pollen viability, plant-pollinator growth, and reproduction. Biotic pollinators are responsible for approximately 90% of the reproduction of flowering plants. Heavy metals adversely affect pollinators that rely on angiosperms for nectar and pollen. Heavy metals interrupt pollinators’ and plants’ growth, reproduction, and survival. Evidence showed that bees near gold mines had their olfactory learning performances and head sizes reduced by 36% and 4% due to heavy metals exposure. Cadmium (Cd) interrupts the redox balance, causes oxidative stress, alters gut microbiota, and reduces the survival rate of Apis cerana cerana . Excess Cd exposure reduced the flight capacity, loss of mitochondria, and damaged muscle fibre of Bombus terrestris, while Zn stress reduced egg production and hatchability of Harmonia axyridis. Furthermore, heavy metals alter flower visitation, foraging behaviour, and pollination efficiency. Graphical Abstract

Terrestrial ecosystems are experiencing notable changes due to global change, making it crucial to determine their future responses under different climate scenarios. In previous theories, it has been proposed that resilience, which reflects the ability of ecosystems to withstand disturbances such as drought and wildfires, can serve as an indicator of the ecosystem structure and function. In this study, we applied ecosystem resilience as a metric to assess the state of terrestrial ecosystems. Our analysis revealed a positive trend in vegetation growth across different climate scenarios. Additionally, SSP5-8.5 having the least masked areas exhibits the smallest uncertainties among the considered scenarios. We further examined the theoretical recovery rates based on variance and lag-1 auto-correlation (AC1) to quantify resilience, considering three future periods (near-term, mid-term, and long-term). The theoretical recovery rates decrease from the near-term to the long-term, while larger uncertainties are observed in the long-term compared to the near-term. Notably, equatorial regions experience a significant degradation in resilience, despite the anticipated increase in vegetation growth. Our study highlights the complex dynamics between vegetation growth and ecosystem resilience, disentangling the resilience change of terrestrial ecosystems in the face of global change.

The continually increasing nitrogen (N) deposition is expected to increase ecosystem aboveground net primary production (ANPP) until it exceeds plant N demand, causing a nonlinear response and N saturation for ANPP. However, the nonlinear response of ANPP to N addition gradient and the N saturation threshold have not been comprehensively quantified yet for terrestrial ecosystems. In this study, we compiled a global dataset of 44 experimental studies with at least three levels of N treatment. Nitrogen response efficiency (NRE, ANPP response per unit N addition) and the difference in NRE between N levels (ΔNRE) were quantified to test the nonlinearity in ANPP response. We found a universal response pattern of N saturation for ANPP with N addition gradient across all the studies and in different ecosystems. An averaged N saturation threshold for ANPP nonlinearity was found at the N addition rates of 5-6 g m−2 yr−1. The extent to which ANPP approaches N saturation varied with ecosystem type, N addition rate and environmental factors. ANPP in grasslands had lower NRE than those in forests and wetlands. Plant NRE decreased with reduced soil C:N ratio, and was the highest at intermediate levels of rainfall and temperature. These findings suggest that ANPP in grassland or the ecosystems with low soil C:N ratio (or low and high rainfall or temperature) is easier to be saturated with N enrichment. Overall, these results indicate that the beneficial effect of N deposition on plant productivity likely diminishes with continuous N enrichment when N loading surpasses the N saturation threshold for ANPP nonlinearity.