2018-土壤生物多样性与土壤有机碳（英文版）-2mb

Summary of "Soil Biodiversity and Soil Organic Carbon: keeping drylands alive"

Core Content

This document, Soil Biodiversity and Soil Organic Carbon: keeping drylands alive, explores the critical role of soil biodiversity and soil organic carbon (SOC) in maintaining the health and functionality of dryland ecosystems. It highlights how these elements are essential for food production, water storage, and climate change mitigation, and underscores the importance of sustainable land management (SLM) in preserving them.

Main Views and Key Information

Importance of Soil Biodiversity and SOC

• Soil biodiversity is a key indicator of soil quality and contributes to the stability and resilience of ecosystems.
• Soil organic carbon (SOC) is a major component of soil organic matter (SOM), making up approximately 50-60% of SOM.
• Drylands account for 42% of the world's land surface, providing 44% of all cultivated land and 50% of the world's livestock.
• Soil biodiversity and SOC are vital for ecosystem services such as food production, water regulation, and climate resilience.

Benefits of SOC

• Increasing SOC improves soil fertility, structure, water retention, and productivity, which in turn supports ecosystem services.
• The global value of soil biodiversity is estimated at USD 1.5 to 13 trillion annually, emphasizing its economic significance.
• SOC plays a crucial role in carbon storage and climate regulation, with potential to contribute to emissions reductions needed to meet global climate targets.

Drylands and SOC

• Drylands are particularly important for carbon storage due to the permanence of SOC in these areas.
• Dryland soils are often near the tipping point for degradation, making restoration efforts urgent.
• The proportion of degraded land in drylands is similar to the global proportion, but management solutions must be adapted to the unique conditions of these regions.

Land Degradation and Climate Change

• Land degradation threatens food and water security, potentially reducing agricultural yields by 25%.
• Soil degradation leads to the release of greenhouse gases and disruption of water cycles.
• The 2030 Agenda for Sustainable Development highlights the need to protect soils for food, water, and energy security, as well as biodiversity and climate change mitigation.

Sustainable Land Management (SLM)

• SLM practices such as agroforestry, conservation agriculture, and pastoralism are effective in increasing SOC and biodiversity.
• However, these practices are underutilized in the world's poorest drylands, where the need for agricultural productivity and water security is greatest.
• SLM requires investment in labor, energy, skills, and knowledge, and incentives are needed to encourage its adoption.

Policy and Governance

• To achieve Land Degradation Neutrality (LDN), governments must protect and promote the multi-functionality of land.
• Key policy measures include:
  • Evaluating land management against the delivery of multiple goods and services.
  • Scaling-up SLM and landscape restoration through policies and legislation.
  • Strengthening local governance and extension services.
  • Enhancing land information systems.
  • Creating enabling conditions for private investment in SLM.

Key Figures and Data

• Global SOC stocks in the first meter of soil are estimated at 1500 GtC, exceeding the combined atmospheric and vegetation carbon.
• Drylands contribute one third to global SOC and soil biodiversity stocks.
• Soil erosion redistributes SOC, with significant losses when the soil is degraded.
• Soil biodiversity is estimated to contribute USD 1.5 to 13 trillion annually to ecosystem services.
• SOC levels in drylands are often low and close to the tipping point of irreversible degradation.

Case Studies and Examples

• Australia: Investing in SOC can provide climate resilience with estimated economic benefits of USD 5.6-6.9 per ton of carbon per hectare per year.
• China: Large-scale landscape restoration efforts are being implemented to improve soil health and biodiversity.
• West Asia: SOC and rangeland management are being used to enhance livestock and water security.
• Africa: Agroforestry and SOC management are helping to increase food production.
• Portugal and Jordan: Sustainable rangeland investments are being made to combat desertification and protect soil biodiversity.

Conclusion

This document emphasizes that soil biodiversity and SOC are foundational to the health and productivity of drylands, which are critical for global food and water security. It calls for greater awareness, investment, and policy support to ensure the sustainable management of dryland soils and their biodiversity, aligning with the Sustainable Development Goals (SDGs) and Land Degradation Neutrality (LDN) targets.