Explore the problems and solutions associated with vegetation management in riparian areas by clicking through the slides using the slide-navigation buttons () below.
The black cottonwood forest that once covered the Jocko River Valley bottomlands has been reduced by riparian logging, agriculture and grazing, residential development, and transportation corridors. As the forest is lost, the stream responds physically and biologically. Removal of the mature trees alters the canopy overstory, exposing the stream to the sun, which increases water temperatures. It also reduces the potential for large woody debris to fall into the river. When streambank vegetation is removed and stream banks lose their ability to resist the erosive forces produced in the channel during high-runoff periods, the stream channel can widen.
The removal or diminishment of riparian forests for agricultural production has probably had the biggest impact on the overall ecology of Jocko River floodplains. But just stopping harmful agricultural activities will not always allow natural plant communities to reestablish. If other measures are not taken, the site can shift to one that supports non-natives, especially weeds.
Modify Harmful Practices
The first step should be to eliminate or modify the harmful land management practices (for example, the clearing of riparian brush, season-long or high intensity grazing, diversion of surface water for irrigation, draining of ground-water to dry out floodplain soils and logging). Then, if allowed, natural processes can promote the recovery of native riparian plants.
Promote Improved Ecological Conditions
Often, it takes more than just ending harmful practices. If native riparian vegetation is to return, managers will often have to promote a new set of ecological conditions, changing site factors such as water, light, nutrients, and soil conditions. Measures include implementing passive and some minimal active-restoration measures like controlling or eradicating noxious weed populations, enhancing soils with compost or wood mulch, reintroducing fire, adding woody debris, seeding, planting native plants, and managing pests.
If these passive and less-invasive active measures are not enough, more significant active measures may be called for. Those are explored in the next section.
Increased Forage
Healthy riparian areas are more productive since abundant water, shelter, and forage translate into more fish and wildlife and better production for livestock producers.
For example, the graph at left shows how a well-managed riparian area produced three times the forage of a degraded floodplain. Forage is important, but so is cover and water and all three increase dramatically under good management.
Less Damage
Meandering streams with healthy riparian areas can reduce flood damage. A well-vegetated floodplain slows flood waters and better enables it to absorb water. This reduces stream power and stream damage during floods. A straightened channel that has been overgrazed is a recipe for serious flood damage.
More Water When We Need It
We can't change how much rain and snow falls, but we can affect how much stays to water riparian vegetation, livestock, and wildlife, and how much flows in streams for fish.
Flooding is one way streams bank water. When a stream with healthy riparian vegetation overtops its banks, the water saturates the floodplain and raises the water table. Then in late summer, fall, and winter, when stream flows are naturally at their lowest, that groundwater flows back into the stream.
Poorly managed riparian areas can cause runoff to occur over a shorter time period and produce higher peak flows. That means less retention time for water to soak into the floodplain, which means less groundwater flowing back into the stream during late summer, fall, and winter when fish, wildlife, and people need it most.
Fish and Wildlife
One of the greatest benefits of healthy riparian areas is a diverse and vibrant wildlife community and healthy native fishery. Riparian areas are crucial to fish and wildlife. It is estimated, for example, that approximately 80% of our wildlife species—everything from birds to mammals—depend on riparian areas for all or part of their lifecycle. The more a riparian area is degraded, the fewer resources there are for wildlife (food, cover, nesting and denning places, travel corridors, etc.) and the greater the chance that some species will disappear from an area.
More Stable Channels with Natural Shapes and Sizes
Riparian vegetation reduces the horsepower of a stream by slowing water down through friction. A three-inch-deep rootmat resists erosion up to 20,000 times better than bare-soil streambanks. Deep-rooted grasses, forbs, brush, and trees stabilize stream banks and play a major role in defining channel shape and size (lower left).
Well-vegetated streams tend to be narrow and deeper than streams with degraded riparian zones. Without roots to hold things together, the cohesive nature of streambanks breaks down, and the stream becomes wide and shallow (lower right).
Swipe for Next Slide or Use Navigation Bubbles Above
The black cottonwood forest that once covered the Jocko River Valley bottomlands has been reduced by riparian logging, agriculture and grazing, residential development, and transportation corridors. As the forest is lost, the stream responds physically and biologically. Removal of the mature trees alters the canopy overstory, exposing the stream to the sun, which increases water temperatures. It also reduces the potential for large woody debris to fall into the river. When streambank vegetation is removed and stream banks lose their ability to resist the erosive forces produced in the channel during high-runoff periods, the stream channel can widen.
Swipe for Next Slide or Use Navigation Bubbles Above
The removal or diminishment of riparian forests for agricultural production has probably had the biggest impact on the overall ecology of Jocko River floodplains. But just stopping harmful agricultural activities will not always allow natural plant communities to reestablish. If other measures are not taken, the site can shift to one that supports non-natives, especially weeds.
Modify Harmful Practices
The first step should be to eliminate or modify the harmful land management practices (for example, the clearing of riparian brush, season-long or high intensity grazing, diversion of surface water for irrigation, draining of ground-water to dry out floodplain soils and logging). Then, if allowed, natural processes can promote the recovery of native riparian plants.
Promote Improved Ecological Conditions
Often, it takes more than just ending harmful practices. If native riparian vegetation is to return, managers will often have to promote a new set of ecological conditions, changing site factors such as water, light, nutrients, and soil conditions. Measures include implementing passive and some minimal active-restoration measures like controlling or eradicating noxious weed populations, enhancing soils with compost or wood mulch, reintroducing fire, adding woody debris, seeding, planting native plants, and managing pests.
If these passive and less-invasive active measures are not enough, more significant active measures may be called for. Those are explored in the next section.
Increased Forage
Healthy riparian areas are more productive since abundant water, shelter, and forage translate into more fish and wildlife and better production for livestock producers.
For example, the graph at left shows how a well-managed riparian area produced three times the forage of a degraded floodplain. Forage is important, but so is cover and water and all three increase dramatically under good management.
Less Damage
Meandering streams with healthy riparian areas can reduce flood damage. A well-vegetated floodplain slows flood waters and better enables it to absorb water. This reduces stream power and stream damage during floods. A straightened channel that has been overgrazed is a recipe for serious flood damage.
More Water When We Need It
We can't change how much rain and snow falls, but we can affect how much stays to water riparian vegetation, livestock, and wildlife, and how much flows in streams for fish.
Flooding is one way streams bank water. When a stream with healthy riparian vegetation overtops its banks, the water saturates the floodplain and raises the water table. Then in late summer, fall, and winter, when stream flows are naturally at their lowest, that groundwater flows back into the stream.
Poorly managed riparian areas can cause runoff to occur over a shorter time period and produce higher peak flows. That means less retention time for water to soak into the floodplain, which means less groundwater flowing back into the stream during late summer, fall, and winter when fish, wildlife, and people need it most.
Fish and Wildlife
One of the greatest benefits of healthy riparian areas is a diverse and vibrant wildlife community and healthy native fishery. Riparian areas are crucial to fish and wildlife. It is estimated, for example, that approximately 80% of our wildlife species—everything from birds to mammals—depend on riparian areas for all or part of their lifecycle. The more a riparian area is degraded, the fewer resources there are for wildlife (food, cover, nesting and denning places, travel corridors, etc.) and the greater the chance that some species will disappear from an area.
More Stable Channels with Natural Shapes and Sizes
Riparian vegetation reduces the horsepower of a stream by slowing water down through friction. A three-inch-deep rootmat resists erosion up to 20,000 times better than bare-soil streambanks. Deep-rooted grasses, forbs, brush, and trees stabilize stream banks and play a major role in defining channel shape and size (lower left).
Well-vegetated streams tend to be narrow and deeper than streams with degraded riparian zones. Without roots to hold things together, the cohesive nature of streambanks breaks down, and the stream becomes wide and shallow (lower right).