Unraveling the impact of wildfires on permafrost ecosystems: Vulnerability, implications, and management strategies

Permafrost regions play an important role in global carbon and nitrogen cycling, storing enormous amounts of organic carbon and preserving a delicate balance of nutrient dynamics. However, the increasing frequency and severity of wildfires in these regions pose significant challenges to the stability of these ecosystems. This review examines the effects of fire on chemical, biological, and physical properties of permafrost regions. The physical, chemical, and pedological properties of frozen soil are impacted by fires, leading to changes in soil structure, porosity, and hydrological functioning. The combustion of organic matter during fires releases carbon and nitrogen, contributing to greenhouse gas emissions and nutrient loss. Understanding the interactions between fire severity, ecosystem processes, and the implications for permafrost regions is crucial for predicting the impacts of wildfires and developing effective strategies for ecosystem protection and agricultural productivity in frozen soils. By synthesizing available knowledge and research findings, this review enhances our understanding of fire severity's implications for permafrost ecosystems and offers insights into effective fire management strategies.

Do adaptive policy adjustments deliver ecosystem-agriculture-economy co-benefits in land degradation neutrality efforts? Evidence from southeast coast of China

Ecosystem restoration projects (ERPs) facilitate land degradation neutrality (LDN). However, the response dynamics and interactions of sectors within ecosystem-agriculture-economy nexus (EAEN) have not been sufficiently explored, which constrains the coordinated efficacy of LDN efforts. To bridge the knowledge gaps, the present study selected a land restoration hotspot in southeastern China as a case to investigate the simultaneous responses of the EAEN sectors to ERPs from a novel social-ecological system (SES)-based LDN perspective. Various biophysical models and Manne-Kendall trend test as well as multi-source spatially explicit data and socioeconomic statistics were applied to quantify the co-evolution of natural and socioeconomic indicators. ERPs converting cropland to woodland and grassland promoted vegetation restoration, reduced soil erosion, and enhanced carbon sequestration. However, cropland loss initially resulted in a decline in grain productivity. Policy adjustments and improvements in ecosystem restoration efforts and agricultural production conditions improved food security and increased agricultural production capacity. Effective policymaking and favorable resident engagement accelerated the transformation from a grain-production-based agriculture to diversified industries and, by extension, economic output, income, and population. The success of socioeconomic development under the SES framework for LDN demonstrated that this strategy could achieve the desired environmental, agricultural, and economic targets. EAEN under the SES conceptual framework provides an inclusive, comprehensive LDN perspective and improves ERP efficacy. The findings of the present work might be applicable to other land restoration areas challenged by the complex interactions among multidimensional factors. Comparably successful implementation of these ERPs could be realized if individual environmental and socioeconomic conditions are thoroughly considered during the formulation of coordinated development policies.

Win-win-win pathway for ecological restoration by balancing hydrological, ecological, and agricultural dimensions: Contrasting lessons from highly eroded agroforestry

Ecological restoration projects (ERP) can effectively reverse ecosystem degradation. However, some ERPs have failed to restore ecosystems under environmental constraints, and they were unable to achieve the desired ecological and economic benefits. To achieve a win-win-win target that balances the hydrological, ecological, and agricultural dimensions, we introduced the contrasting lessons from hotspots of ecosystem restoration in the arid Loess Plateau (LP) and the humid Karst Plateau (KP) in China, and discussed a novel strategy for coordinating ecosystem restoration, water and food security, and residents' livelihoods. The biophysical models and related statistical records showed that aggressive ERPs and soil and water conservation projects (SWCPs) significantly promoted vegetation restoration and reduced soil erosion and sediment yield in both areas. However, excessive afforestation in the arid LP exhausted water resources and threatened ecosystem sustainability. The accelerated replacement of cropland since 1999 in the LP aggravated cropland shortage which led to carbon sequestration and grain productivity declines in the initial years. However, the construction of terrace and check-dam fields and improvements in the conditions of agricultural production reconciled the cropland shortage and stabilized food security. The positive involvement of stakeholders in ERPs effectively minimized land degradation through economic development and the improved livelihoods of local residents. Therefore, based on the evidence from the KP and LP, the proposed win-win-win strategy is potentially applicable in other global regions that suffer from land degradation. This strategy can achieve considerable success if the planners have a good understanding of local environmental conditions as well as the social and economic needs of residents affected by ERPs.

Loess Plateau: from degradation to restoration

United Nations established 2021-2030 as the decade for ecosystem restoration and "prevent, halt and reverse the degradation of ecosystems worldwide". Ecosystem and land degradation are a global phenomenon. As a consequence of land degradation, in the late 1990s, the "Grain for Green Program" (GFGP) was established in Loess Plateau (China). It converted slope farmlands to forest or grassland over the, resulting in a visible "greening" trend. Other effects of GFGP on soil properties, land production, hydrological conditions, ecosystem services, and policy implications are the topics of this Special Issue. This Special Issue includes 17 contributions that cover recent research carried out in Loess Plateau in the mentioned topics at different spatial and temporal scales. The collection of papers presented in this Special Issue discusses critical issues in vegetation restoration and sustainable land management in the region. This Special Issue will contribute to United Nations strategy for ecosystems restoration.

Large-scale forest restoration stabilizes carbon under climate change in Southwest United States

Higher tree density, more fuels, and a warmer, drier climate have caused an increase in the frequency, size, and severity of wildfires in western U.S. forests. There is an urgent need to restore forests across the western United States. To address this need, the U.S. Forest Service began the Four Forest Restoration Initiative (4FRI) to restore four national forests in Arizona. The objective of this study was to evaluate how restoration of ~400,000 ha under the 4FRI program and projected climate change would influence carbon dynamics and wildfire severity from 2010 to 2099. Specifically, we estimated forest carbon fluxes, carbon pools and wildfire severity under a moderate and fast 4FRI implementation schedule and compared those to status quo and no-harvest scenarios using the LANDIS-II simulation model and climate change projections. We found that the fast-4FRI scenario showed early decreases in ecosystem carbon due to initial thinning/prescribed fire treatments, but total ecosystem carbon increased by 9-18% over no harvest by the end of the simulation. This increased carbon storage by 6.3-12.7 million metric tons, depending on the climate model, equating to removal of carbon emissions from 55,000 to 110,000 passenger vehicles per year until the end of the century. Nearly half of the additional carbon was stored in more stable soil pools. However, climate models with the largest predicted temperature increases showed declines by late century in ecosystem carbon despite restoration. Our study uses data from a real-world, large-scale restoration project and indicates that restoration is likely to stabilize carbon and the benefits are greater when the pace of restoration is faster.

Determining key monitoring areas for the 10 most important weed species under a changing climate

On a global level, weed species have a large potential to threaten ecosystems under a changing climate. The determination of key monitoring areas is an effective approach to prevent and control the spread of such species. The 10 most important weeds have been listed on a global scale. It is therefore crucial to delineate the areas with high monitoring ranks for the 10 most important weed species under climate change. We coupled conservation prioritization analysis with habitat suitability modelling to determine key monitoring areas for these species, based on different types and vulnerability levels of biomes under current and future (i.e., 2040-2069 and 2070-2099) scenarios. We determined some specific biomes (i.e., tropical and subtropical biomes, flooded grasslands and savannas, Mediterranean forests, woodlands and scrub, and mangroves) as key monitoring areas for the 10 most important weed species under a changing climate. These biomes are distributed in most regions of Latin America, the United States, Europe, central and south Africa, south and southeast Asia, southeast Australia, and New Zealand, including large vulnerable ecoregions. Tropical and subtropical grasslands, savannas, and shrublands were particularly vulnerable, because these biomes had the largest area with a high monitoring rank, and this rank was predicted to further increase in the near future. Our study highlights the importance of effective management strategies for the prevention and control of these species across different biomes on a global scale.