Ecosystem function and benefits provided by vegetation in stormwater management

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Vegetation in stormwater practices affects natural processes and can provide a variety of ecosystem services. This page provides a summary of the habitat benefits of vegetation used in stormwater management.

Content on the following co-benefits of vegetation will be added to this section of the manual in the future:

Carbon Sequestration
Oxygen & air quality benefits
Soils
Food
Timber
Climate Regulation
Aesthetics, health, and safety
Educational
Spiritual
Recreation

Habitat benefits of vegetation in stormwater

Pollinators and insects

There are an almost uncountable variety of pollinators that are highly beneficial to the functioning of an ecosystem. Pollinators and insects help promote vegetation establishment, growth, and long-term vegetation survivability. Considerations of vegetation selection and insect/pollinator interaction are highly encouraged when designing landscaping and building green infrastructure. Extensive research has been done into pollinators that established their place as a key ecosystem group of species that is instrumental in ecosystem cascading.

Bees are a vital and keystone species to the long-term stability and sustainability of our ecology. Bees provide multiple benefits such as pollination, medicine, food, and seed dispersal. It is estimated that there are about 400 different species of bees in Minnesota. These bees are among many of the pollinators and insects that are beneficial to vegetation.

It is highly encouraged to take into consideration design methods that will attract pollinators and insects and help them thrive and grow. Additionally, soil compaction during construction should be taken into consideration as well because an estimated 70% of bee species are ground nesting. Tightly packed soils will not allow proper establishment of vegetation and prevent colony establishment for insects and pollinators that make their habitats in soil. Additionally, vegetation considerations should be focused on the feeding, above ground nesting, or sheltering for these species that access ground space through vegetation stems.

Birds

The presence of birds can signify a healthy and robust ecosystem. Birds provide a vital ecosystem service that can help determine the success or failure of a site when it comes to vegetation and wildlife.

Birds are important to vegetation design for a variety of reasons. The presence of birds can promote cross pollination, fertilize plants, increase soil fertility, act as insect control, rodent control, among other wildlife control. They add beauty to nature with their colorful songs and plumage while some provide for the removal of dead animals.

When designing vegetation for bird use, consider what types of birds you would like to attract, the type of vegetation needed to attract their food source, what their food source is, and if human use of the site will have an impact on their survivability. The use of chemicals to stabilize and/or grow plants can be detrimental to wildlife and inadvertently prevent bird propagation.

The presence of birds helps in a variety of ways, such as:

Cross Pollination
Movement of plant gametes
Fertilizing plants
Soil fertility increases
Insect Control
Some birds will eat rodents, snakes, and fish
Seed propagation
Enhance the beauty of nature
Removal of animal carcasses

For more readings:

Mammals

Reptiles

Reptiles can be considered a critical species when developing habitats for wildlife in stormwater management. Reptiles act as both a predator and prey species by feeding on smaller wildlife such as mice, insects, and spiders and then being preyed on by larger species such as birds of prey, coyotes, and foxes. These species being the centerpiece of a food chain acts as an indicator of environmental health.

Reptiles prefer areas that are open and provide direct sunlight for basking while also maintaining nearby rocks and vegetation for shelter and protection from the elements. Similar to building a terrarium, reptiles desire light, heat, and temperature.

Amphibians

Similar to reptiles, amphibians provide multiple benefits. They can operate as an ecosystem indicator, provide insect and pest control, and provide services to help clean water quality through plants they eat. With up to 40% of amphibians classified as endangered, creating minor adjustments to ecosystem designs can create opportunity for this wildlife to thrive. Other animals also rely upon amphibians as a prey and the addition or removal of plants that sustain amphibians can mitigate or promote this effect.

Amphibians are sensitive to their surrounding environments. Toxic chemicals associated with urban development can alter their ability to survive and thrive. Chemistry, pH, and temperature of urban runoff may negatively impact amphibians. Amphibians also experience increased mortality due to crossing impervious surfaces. Consideration and selection of vegetation can help protect the ecosystem’s ability to sustain amphibians.

Beneficial vegetation the improves water quality, removes nutrients, stabilize pH, prevents excessive siltation and provides desirable shade and protection for amphibians should be considered. Amphibians like damp, dark areas that have controllable access points with them. Consideration of using rock formations in conjunction with vegetation should be considered. Vegetation that also attracts food sources such as mosquitoes, worms, mice, and any other small creatures that can fit into an amphibians mouth is beneficial to amphibian populations.

Below is a list of additional reading, including stormwater design considerations.

Humans

Human use of green spaces is the primary focus of many designers jobs. When designing a landscape that will be occupied by humans it is advised that the space utilized takes into consideration the species of wildlife that can cohabitate/exist alongside humans to ensure that the environmental impact of the build is minimized.

Human impact on green spaces has a wide variety of impacts. Water quality and soil compaction are two of the most concerning activities when it comes to establishing vegetation. Unintended human use after seeding, planting, or grading can significantly alter the landscape and prevent successful vegetation establishment. Water quality from human use is also significant as the more pollutants introduced into the water is a significantly limiting factor for what types of plants will be successful in the vegetation plan.

The downstream impact from a development site is a common design consideration that is often overlooked. The impact of stormwater and vegetation isn’t just an isolated system that only impacts the area that it is developed on; the design also has downstream consequences if there are pollutants introduced to a water source if they are not filtered, treated, or distanced far enough away from a water source. Different landscapes can achieve desirable interactions with humans and provide the aesthetic pleasantries that humans enjoy such as rain gardens, water detention/retention systems, reuse irrigation systems, and wildlife habitats. Recreational purposes and drinking purposes are other uses that should be taken into consideration with how humans will interact with the area.

Consideration of the application of stormwater vegetation systems is highly encouraged. Design considerations involving cisterns, rain barrels, groundwater table, distance to water sources, erosion control blankets, impermeable liners, among other techniques should be thought of to see if the onsite vegetation can be self-sustaining and minimize the impact between vegetation and the way humans use the landscape.

Aquatic Species

The construction of urban structures can cause major changes in the temporal and spatial make up of water systems. This can lead to increased peak flows, decreased minimum flows, increased flow variability, higher flood rates, and warmer temperatures in the summer and decreased temperature in the winter.

Wildlife and aquatic species use conveyance systems to move around areas and they are all interconnected through a food web. These conveyance systems have a major impact on the surrounding region through the provisioning services, regulatory services, supporting services, and cultural services that they affect. This should be taken into consideration as ecosystem collapse, unintended alterations, or undesirable conditions may develop if these considerations aren’t planned for.

Final water output conditions desired at the end of construction should be established early in the planning phase and during this time frame it is important to determine what sort of pollutant load the vegetation and incoming stormwater will be exposed to. Phosphorus and nitrogen are two compounds that should be accounted for during selection of aquatic species as their tolerance to these nutrients may be required to properly establish a feasible vegetation or ecological restoration plan. Alterations can also impact the water quality through varying nutrient loads, local food webs, pesticides, contaminants, local aquatic habitats, species assemblages, and ecosystem processes.

When designing for aquatic species a survey of the surrounding area is strongly recommended to determine what sort of environmental stressors are applied to that zone. Some examples are wastewater treatment plants, industrial discharges, storm sewers, septic systems, lawns, gardens, roads, nearby vegetation and parking lots. Local wildlife will be attracted to this area as well and should be considered when selecting aquatic species as some animals may thrive under certain conditions or eat plants before full establishment.