Nature-Based Benefits in Focus: Protecting Grasslands Reduces Soil Erosion and Improves Water Quality

Avoided conversion of grassland projects are significant for protecting organic soil carbon, but also avert significant environmental degradation. Grasslands cover roughly 30% of the planet’s terrestrial landscape [1] contributing to a variety of essential ecosystem services. Avoided conversion carbon projects allow grassland, rangeland, and prairie ecosystems to function naturally, a benefit that continues in perpetuity thanks to the placement of no-till conservation easements.

Of particular concern is how recent pressure for cropland expansion in the US has converted areas with marginal biophysical characteristics. This means that constrained crop yields from newly converted lands are exacerbating GHG emissions due to severe soil carbon loss [2]. The effects of commercial agriculture are often a direct result of disturbing the soil surface and biotic community established there. When native grasslands are plowed, the surface layer that was stabilized by plants and roots is lost, profoundly altering the physical characteristics of a site. As a result, soil erosion and sediment transport tend to be magnified on tilled land where the surface has been cleared for row crops. Especially when outside the growing season, the exposed soil is more erodible due to the loss of natural vegetation cover and disturbance. Making matters worse, climate change scenarios predict more intense rainfall [3] which will lead to increased soil erosion from weather events. These factors indicate the need to limit anthropogenic actions known to cause soil erosion and should signal the urgency to preserve remaining grasslands. Another related co-benefit of protecting grasslands is linked to water quality. To compensate for reduced productivity on newly converted cropland, nitrogen and phosphorus fertilizers are commonly applied which can negatively impact local watersheds through excess nutrient run-off and downstream eutrophication [4]. Intact grasslands are integral to local watersheds, where natural vegetation and carbon rich soils act as a filter for removing contaminants. Pollution from agricultural runoff that enters waterways is not only bad for water quality, but has a number of negative impacts on aquatic life. The US National Water Quality Assessment found that runoff from agriculture is the leading cause of water quality impacts to rivers and streams [5] highlighting the imperative role that grasslands play in maintaining clean freshwater.

Limiting further soil erosion and protecting water quality are critical elements of grassland conservation. It’s important to recognize the benefits provided by existing environments and deploy strategies for protecting them since many of the ecosystem services provided by intact grasslands are difficult, if not impossible, to restore once lost. As previous Scorcher topics have emphasized, the unique co-benefits enabled by nature-based carbon offset projects add substantial intrinsic value to these efforts.

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