Planting Isn’t Enough: How Restoring Drylands Stops Carbon Loss at Its Roots

Redacción HC
09/11/2024

In the fight against climate change, drylands—often overlooked due to their sparse vegetation—are emerging as key players in global carbon storage. While efforts to revegetate these arid regions have grown in recent decades, a new study reveals a less visible but equally crucial benefit: preventing wind erosion keeps carbon locked in the soil.

Published in Proceedings of the National Academy of Sciences (PNAS) in November 2024, the study brings together decades of data from China’s drylands to show that ecological restoration does far more than just grow plants. It protects the soil itself, reducing the loss of carbon through wind—a mechanism previously underestimated in land-based climate strategies.

Beyond Biomass: The Hidden Mechanism of Carbon Retention

When discussing carbon capture in ecosystems, most attention goes to photosynthesis and biomass accumulation. However, drylands present a different reality. Roughly 44% of the world's topsoil carbon is stored in these regions—but is highly vulnerable to wind-driven erosion, which physically removes nutrient-rich topsoil and releases carbon as CO₂ into the atmosphere.

The core question explored in this research: Is the improved carbon storage in restored drylands due more to increased plant growth or to the soil being shielded from erosion? The answer is surprising—over 80% of the gain is due to soil protection, not biomass increases.

Methodology: Pairing National Surveys with Long-Term Experiments

To uncover the mechanisms behind dryland carbon changes, the authors combined two powerful datasets:

1. A nationwide field survey of 4,279 paired plots across degraded and restored areas in China (2014–2016), covering over 3 million km² of grasslands, deserts, and farmlands.
2. A 13-year controlled field experiment in Duolun, Inner Mongolia, that tested various restoration strategies—including the exclusion of grazing and wind, simulating wind erosion, and measuring changes in soil nutrients and vegetation.

Researchers measured:

• Wind-driven loss of soil particles, carbon, nitrogen, and litter.
• Vegetation cover and net primary productivity (NPP).
• Soil carbon stock accumulation over time.

They applied machine learning (random forest) and structural equation models to isolate the contribution of different factors.

Key Findings: Soil Shielding Drives Carbon Gains

Massive Reductions in Wind Erosion

Restoration sites demonstrated:

• –96.9% in wind-driven litter loss
• –98.9% in total soil mass loss
• –96.9% in soil carbon loss
• –95.4% in nitrogen loss

These numbers highlight the protective effect of vegetation as a physical barrier against wind erosion.

Carbon Storage Mechanism: Mostly Mechanical, Not Biological

While previous assumptions credited carbon gains in restored ecosystems mainly to vegetation regrowth, this study finds:

• 80% of the increase in soil carbon was from reduced erosion.
• Only 20% was attributable to increased biomass.

This holds true both across the large-scale observational dataset and within the long-term experimental plots.

Restoration is not just about growing more plants—it’s about keeping what’s already there from blowing away, the authors explain.

Scaling Up: Implications for Climate Policy and Restoration Programs

A Major but Underestimated Climate Sink

At a national scale, China’s restored drylands are now retaining 7.87 teragrams of carbon per year thanks to reduced wind erosion:

• Equal to 38.8% of the gains from reforestation.
• Surpasses half of the benefit from protected forests.

These findings suggest that soil conservation could rival tree planting in climate impact—especially in arid and semi-arid zones.

Global Relevance, Especially for Latin America

Although based in China, the mechanisms are relevant to drylands across the globe—including:

• Northern Mexico
• Andean highlands in Peru
• Patagonia and the Monte Desert in Argentina

These are areas where land degradation, desertification, and climate vulnerability intersect. Restoring drylands in these regions may offer dual benefits for biodiversity and carbon capture.

Strategic Recommendations for Decision-Makers

1. Incorporate erosion reduction into carbon models and restoration metrics.
2. Broaden the definition of “success” in restoration to include soil protection, not just biomass gains.
3. Prioritize revegetation efforts in wind-exposed degraded lands, where marginal returns can be highest.
4. Expand international funding for dryland restoration as a climate mitigation strategy, especially in the Global South.

Conclusion: Drylands Are Not Empty Spaces—They’re Carbon Safes

This study reframes the narrative around ecological restoration in drylands. Rather than viewing these ecosystems as fragile or marginal, it positions them as critical carbon storage systems—as long as they are protected from erosion.

In the era of climate urgency, we cannot afford to ignore the soil under our feet. By investing in dryland restoration, countries can unlock powerful, cost-effective climate mitigation—where every blade of grass may act as a guardian of buried carbon.

Topics of interest

Climate