Terrestrial ecosystems sequester about a third of anthropogenic CO₂ emissions by natural processes and, thus, play a critical role in mitigating climate warming. As climate change become more aggravated, the need to remove CO₂ from the atmosphere to the terrestrial and aquatic ecosystems becomes more urgent over time. A score of new techniques of carbon dioxide removal (CDR) have been recently proposed based on a notion of actively managing land carbon cycle processes to increase carbon sequestration and/or reduce greenhouse gas (GHG) emissions. These actively managed climate solutions by human (i.e., human-based) should be complementary to the nature-based climate solutions to combat climate change together with concurrent and dramatic economy-wide decarbonization. However, what are ecological principles behind the terrestrial CDR techniques? How can the ecological principles identified from these removal techniques be used to guide the design of more effective, future CDR techniques? These questions remain unanswered.

This presentation will show ecological principles we identified from our analysis of these existing CDR techniques and propose more effective techniques for carbon dioxide removal. We analyzed a dozen of existing CDR techniques, such as afforestation and reforestation, biochar from crop residues or slashed woods, and peatland restoration. All these existing CDR techniques manage carbon residence time more than carbon input. As carbon storage is jointly determined by carbon input and residence time, elongation of residence time or increase in carbon input or both all result in increased carbon sequestration (i.e., increased carbon dioxide removal from the atmosphere).  It appears that there are more rooms to manage carbon residence time than carbon input as carbon residence time can change from a few months or years to thousands of years. Thus, we can evaluate and design CDR techniques using methods that can substantially elongate carbon residence time. 

How to cite: Luo, Y.: Terrestrial carbon dioxide removal from the atmosphere: Ecological Principles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2943, https://doi.org/10.5194/egusphere-egu24-2943, 2024.

To help achieve carbon neutrality and mitigate climate change, vegetation restoration and wildlife conservation have recently been promoted as two key natural climate solutions. Although ecological studies have widely reported the profound top-down impacts of wildlife on the structure and function of vegetation, vegetation restoration and wildlife conservation are often viewed and implemented as two independent natural climate solutions. Combining field experiments in degraded coastal wetlands and meta-analyses of experimental studies from vegetated ecosystems globally, we explore the impacts of wildlife on vegetation restoration and related carbon cycling processes. In the field experiments, we find that vegetation restoration through planting alone failed to lead to vegetation recovery due to grazing by herbivores and did not increase plant and soil carbon stocks. In contrast, co-restoring threatened predators or simulating their consumptive or nonconsumptive effects facilitated the establishment of planted seedlings, led to successful recovery of vegetation, and increased plant and soil carbon stocks. These effects of herbivores and predators on vegetation restoration were generally supported in our global syntheses of experimental studies from all vegetated ecosystems, although these effects were context-dependent and often varied with biotic and climatic factors such as herbivore density, temperature, and precipitation. Taken together, these results suggest that vegetation restoration, if synergized with wildlife conservation, can be more promising for enhancing carbon sequestration in many ecosystems. We conclude by outlining possible ways to achieve synergies of vegetation restoration and wildlife conservation and by highlighting their policy implications.

How to cite: He, Q.: Synergizing vegetation restoration and wildlife conservation to enhance natural climate solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8586, https://doi.org/10.5194/egusphere-egu24-8586, 2024.

Currently, 25% of global terrestrial ecosystems are degraded, expected to rise by 75% by 2050, threatening 3.2 billion people worldwide. The United Nations launched “UN Decade on Ecosystem Restoration” to promote restoration efforts from 2021-2030. Additionally, achieving carbon neutrality has become an international consensus to combat climate change and protect the human living environment. However, there is a lack of existing international scientific programs for ecological restoration and carbon neutrality, coupled with insufficient long-term observations and experimental data, particularly in developing countries facing ecosystem degradation and management challenges. Therefore, it is crucial to integrate global efforts and establish monitoring and assessment systems for global ecological restoration and carbon neutralization. In this talk, we will introduce the Global Ecosystem Restoration and Carbon Neutrality (Global-ERCaN) program, which aims to promote global ecosystem restoration and carbon neutrality through monitoring and assessing the restoration process, exploring changes in carbon sinks and related processes, and summarizing sustainable ecosystem management models. Global-ERCaN plans to establish international cooperation for 1) sharing carbon neutral research methods and technologies, 2) assessing the role of ecological restoration in carbon neutrality, 3) proposing management and policy options for sustainable development of degraded ecosystems, ultimately accelerating carbon neutrality goals.

How to cite: Zhang, R., Niu, S., Kutsch, W. L., and Yu, G.: Global Ecosystem Restoration and Carbon Neutrality Programme, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2440, https://doi.org/10.5194/egusphere-egu24-2440, 2024.

The Andean tropical forests (ATF) are a well-known biodiversity hotspot, and they provide numerous ecosystem services such as carbon storage and water regulation. However, human activities including establishing pastures, cultivating crops, and fires, have significantly reduced the area covered by tropical forests and altered their structure, composition, and function. To counter forest degradation, various active restoration programs have been conducted. However, there is limited understanding regarding what factors influence the success of Andean forest recovery. Using a network of observational and experimental plots, that allow an understanding of recovery pathways across time and over environmental conditions, we address the question: what are the driving factors influencing establishment success in reforestation efforts? We established 118 observational plots along different environmental conditions (e.g. climate and soil types), and 96 experimental plots across an elevation gradient in Ecuador. The observational plots were established in 18 different young reforested sites (5 -10 years) to assess carbon productivity. On the other hand, the experimental plots were installed at three elevations (2200, 2800, and 3200 m a.s.l.) to evaluate the effects of pasture competition and artificial shading, in a factorial design, on survival and growth rate of five native tree species. Our findings from the observational plots revealed that grazing exclusion, precipitation, planted species richness, and soil properties significantly influence carbon productivity in reforested sites. Preliminary results from the experimental plots revealed that the effect of grass competition and shade on seedling performance varied tremendously according to species and elevation. In summary, our results suggest that land management practices, planted species richness and species type, and climate conditions are determining factors in regard to successful forest recovery.

How to cite: Marín, F., Bauters, M., Báez, S., Palomeque, X., Perring, M., León-Yánez, S., and Verbeeck, H.: Identifying success factors for the recovery of Andean tropical forests using observational and experimental plots, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12484, https://doi.org/10.5194/egusphere-egu24-12484, 2024.

Between 2000 and 2020, global wildfires emitted approximately 7.32 billion metric tons of CO2, constituting about 18.5% of fossil fuel-related emissions. Despite a decrease in the global burned area, wildfire carbon emissions showed no significant trend. This is because carbon emission of forest fires is increasing, and thus compensates for the reduction in carbon emission from savanna fires. Forest fires is about 5% of global burned area but contribute roughly 20% (1.5 billion metric tons) of these emissions. Increases in forest fire carbon emissions, particularly in the northern high latitudes, are attributed to climate change and human activities. In recent years, the rise in extreme wildfire emissions affects over 40% of global vegetated lands, often linked to extreme fire weather conditions. Addressing this requires the development of advanced forest fire risk identification and prevention technologies.

How to cite: Liu, Z.: Spatial patterns and drivers of wildfire carbon emission since 2000, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2408, https://doi.org/10.5194/egusphere-egu24-2408, 2024.

The carbon sequestration potential of forest ecosystems is influenced by various factors, including climate change and forest management. Climate change directly impacts the rate of forest growth and the accumulation of biomass. Effective forest management measures could enhance the structural integrity of forests, thereby improving the carbon sequestration capacity and adaptability to climate change of forest ecosystems. However, the impacts of these factors on future carbon sequestration and its potential of forests remain unclear. There is a pressing scientific need to focus on whether future climate change will increase carbon sequestration potential, and how forest management should be carried out in the future, as part of the current efforts to develop nature-based climate solutions. This study focuses on the forests of Northeast China, located in a mid-latitude zone sensitive to global climate changes, possessing abundant forest resources and serving as one of China's primary carbon reservoirs, where extensive forest management has been implemented over the past decades. We assessed the carbon sequestration potential of Northeast China's forests under future climate change and forest management strategies. Specifically, we utilized multi-source data (such as forest inventory and remote sensing data), coupled with ecosystem process-based model LINKAGES and forest landscape model LANDIS PRO, to predict the forest succession and carbon storage dynamics of Northeast China during the 21st century. The study conducted multi-scale validation of the simulation results through multi-source data, thereby enhancing the accuracy of the model simulations. Then, we estimated the future forest above-ground carbon sequestration potential and quantified the impacts of climate change and forest management. The results suggested: (1) The simulation of the current spatial distribution of above-ground carbon storage and age structure in Northeast China's forests aligns closely with remote sensing products and inventory data; (2) Considering only forest succession, the above-ground carbon sequestration is projected to peak in 2060, with the rate of carbon sequestration reaching its apex in 2025-2030 at 0.08Pg C·a^-1; (3) Climate change is likely to enhance the carbon sequestration potential and rate of Northeast China's forests, but to a limited extent, with an increase of 7.3% and 13.6% under the SSP245 and SSP585 scenarios, respectively; (4) It remains essential to continue forest management practices in the future to address the challenges posed by climate change.

How to cite: Liang, Y.: The effects of climate change and forest management on forest carbon sequestration potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3276, https://doi.org/10.5194/egusphere-egu24-3276, 2024.

Increasing water stress on forests is emerging as a global phenomenon, resulting in the episodes of tree mortality, canopy die-offs and declines in ecosystem resilience, threatening the progress of global carbon neutrality. The role of tree functional strategies is pivotal in regulating forest ability to cope with water stress. To date, the species-level water stress strategies including closing leaf stomatal early, investing in stronger water transport structures, dropping leaves, storing water and developing deeper roots are well documented. However, how strategies found at the tree or species level scale up to characterise forest communities and their variation across regions is not yet well-documented. By combining eight water stress-related functional traits with forest inventory data from the USA and Europe (219,518 plots), we investigated the community-level trait coordination and the biogeographic patterns of water stress strategies for woody plants, and analysed the relationships between the strategies and climate factors. We found that the range of water stress strategies which dominated at community-level were consistent with those available at species-level. Traits associated with acquisitive-conservative strategies formed one dimension of variation, while leaf turgor loss point, associated with stomatal water strategy, loaded along a second. Surprisingly, spatial patterns of local water stress strategies were better explained by temperature than by aridity, suggesting a greater selective pressure on water demand over supply. These findings provide a basis on which to build predictions of forest response under water stress which are grounded in the dominant functional strategy, with particular potential to improve understanding of forest carbon sink potential in a changing climate.

How to cite: Liu, D.: Integrating functional strategies to optimize temporal forest carbon sink potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16305, https://doi.org/10.5194/egusphere-egu24-16305, 2024.

Wetlands are an important part of the terrestrial carbon pool in the global carbon cycle, and exploring the impact of wetland restoration on soil organic carbon (SOC) is of great significance for implementing effective wetland restoration measures to mitigate global warming. We conducted a global meta-analysis to analyze the response of SOC content to different wetland restoration approaches by comparing restored wetlands with degraded and natural wetlands, respectively. We also aimed to identify their temporal evolution, driving factors and potential mechanisms of wetland restoration. The results of this study showed that natural restoration methods, such as farmland abandonment and grazing prohibition, were effective in increasing wetland SOC. Specifically, the SOC contents of wetlands restored using these methods were significantly higher than those of degraded wetlands. Wetland restoration initially caused SOC to show a rapid growth trend, peaking in years 10-20, before levelling off over a longer period of time. After 40 years of restoration, wetland SOC levels were able to approach those of natural wetlands. Important factors driving wetland SOC restoration include total nitrogen, mean annual temperature, and mean annual precipitation. This study would provide insights for mitigating climate change through wetland SOC restoration.

How to cite: Wu, Y., Zhang, R., and Niu, S.: Responses of soil organic carbon to wetland restoration—A global meta-analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3350, https://doi.org/10.5194/egusphere-egu24-3350, 2024.

Separating soil organic carbon (SOC) into particulate (POC) and mineral-associated organic carbon (MAOC) fractions has provided fundamental knowledge on the structure and protection of SOC. However, the global distribution and key drivers of POC and MAOC remain elusive. Here, we compiled a global database of POC and MAOC with 2744 observations across six continents. Initial analysis showed that the mean POC was 2.73 kg m^-2 and MAOC was 3.85 kg m^-2 at 0-30 cm. At the global scale, POC and MAOC accounted for 39.98 % and 63.48 % of SOC, respectively. The global distribution of POC and MAOC was driven collectively by vegetation, climatic, and soil attributes. The lowest POC and MAOC stock were observed in cropland, suggesting the possibility of increasing C sequestration in soils by using management practices that increase POC and MAOC in croplands. Despite this great potential, we predicted the largest reduction in MAOC in cropland under future climate change, highlighting the high vulnerability of SOC stock in cropland. Understanding the role of environmental controls in the global distribution of POC and MAOC could help designing terrestrial carbon sequestration strategies.

How to cite: Chen, J., Cotrufo, M. F., and Sun, S.: Global soil carbon storage and stability informed by the particulate and mineral-associated organic carbon fractions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7373, https://doi.org/10.5194/egusphere-egu24-7373, 2024.