How Sustainable Forestry Protects Soil and Water

By Jennifer Hunt (Content Writer) and Shane Fuller (Certified Wildlife Biologist)

Although it’s one of the most well-known aspects of forestry, harvesting trees isn’t all we do. In fact, healthy forests function as natural systems that regulate water flow, prevent erosion, and filter pollutants. Not only do tree roots stabilize soil by binding soil particles together, but the forest canopy also reduces the impact of heavy rainfall as leaves and branches intercept rain. Organic matter on the forest floor, like leaf litter, decaying wood, and humus, absorbs water and traps pollutants, all of which maintain the balance of the hydrologic cycle. Our job as foresters and land managers is to ensure these processes happen as effectively as possible. Our team understands and respects the critical role we play in protecting soil stability and water quality, and we use numerous sustainable forestry practices and conservation techniques to do just that.

Forestry is regulated by Best Management Practices (BMPs), which are voluntary or mandatory guidelines (depending on the state) and techniques used to minimize environmental impacts during operations. These can take many shapes and forms, but one example for protecting water quality and preventing erosion and sedimentation is riparian zones. Riparian zones and Streamside Management Zones (SMZs) are vegetated areas along streams, rivers, and lakes that protect water systems by stabilizing stream banks. In essence, they slow runoff and filter sediment, nutrients, and pollutants before they can reach water bodies. Not only is this an important function of protecting sources of drinking water, but riparian zones also provide wildlife habitat and biodiversity corridors. There is no one-size-fits-all width, as they are designed based on local conditions, including the slope of the land, soil type, nearby water body, rainfall, climate, and land use intensity. The width is determined by the size of the body of water in need of protection, meaning that a big stream would have a bigger buffer zone. Riparian zones are just one way that forestry responsibly stewards natural resources, and other specific conservation techniques, like filter strips and water bars, also provide benefits for watershed protection.

Filter strips are strips of vegetation, such as grass, shrubs, or trees, that are left between disturbed land and water bodies. The key difference between filter strips and riparian zones is that riparian zones are natural or semi-natural buffer ecosystems along the water’s edge, whereas filter strips are planned strips of grasses or low vegetation to slow runoff. Filter strips can be part of a riparian zone, but riparian zones are much larger and more complex. These targeted management tools function similarly to riparian zones as they trap sediment and pollutants, slow water runoff, and promote water infiltration.

Water bars are temporary or permanent structures that are built across trails or steep slopes that divert water. Instead of letting rainwater run straight downhill, causing soil erosion, water bars force water to disperse into the surrounding vegetation. Temporary water bars are often made with soil during logging operations until vegetation regrows, and permanent water bars are built with durable materials, like timber or rocks, and are used on long-term roads or trails. They are built at an angle, typically between 30 and 45 degrees, across a slope, and the lower end allows water to flow off the road or skid trail. Oftentimes, water bars are paired with small ditches to guide water away from logging roads, skid trails (paths used to drag logs), hiking or access trails, and sloped or disturbed ground in forest operations. They are especially important in areas with heavy rainfall, steep slopes, and loose or easily eroded soil.

Protecting soil and water go hand in hand during forestry operations. Foresters and land managers follow BMPs and other regulatory frameworks (depending on the state or region) to bring high-quality wood to forest markets while safeguarding soil and water that sustain not only human life, but also other life forms throughout the forest ecosystem.