Building Resilience to Climate Change

by | Dec 7, 2022 | News | 0 comments

Restoring Riparian Refuges:
Part 1 – Building Resilience to Climate Change
By David Fields

Climate change is a present and growing threat to our ecosystems and coldwater streams across Canada. The impacts of climate change can include reduced snowpack, which will result in reduced volume and altered timing of peak stream flows; more frequent and more severe flood and drought events; higher water temperatures that will threaten coldwater species like trout; and changes to soil moisture and groundwater recharge that influence stream flow rates. These and other expected impacts of climate change can place additional stress on streams and riparian habitats that have already been degraded by development, logging, and agricultural practices.

 

Building Resilience to Climate Change

 

Intact riparian zones are highly productive ecosystems, which provide essential services and resources for both aquatic and terrestrial ecosystems. These services include food and habitat, sediment and nutrient capture, water temperature regulation, and so much more. The trees and plants found within riparian zones are adapted to natural disturbance, such as spring floods and summer low-flow periods, which makes these ecosystems potentially more resilient to the expected disruptions from climate change. The built-in resilience of riparian ecosystems makes them ideal candidates for protection and restoration to serve as refuge for vulnerable wildlife and plant species, while also helping human communities adapt to climate change.

 

Building Resilience to Climate Change

 

How Riparian Zones Can Be Climate Change Refuges

Corridors – Riparian areas connect land and water ecosystems, and they also connect upland ecosystems with those downstream. Wildlife and plants have evolved within habitats that have particular resources, such as food, microclimates, and relationships with other organisms. As habitats are disrupted, species may be pressured to migrate to other areas that can meet their needs, but there may be natural or human-made barriers to their movement. The connectivity that riparian zones offer may provide migration pathways for animal and plant species as they move to more suitable habitats.

Thermal Refugia (Heat Buffers) – On a hot day, you may find yourself drawn to shady spaces and waterbodies. Likewise, riparian areas act as heat buffers for plant and animal species, providing refuge from higher temperatures. The higher water content found in riparian areas absorbs heat while trees and other vegetation shade streams and rivers from sunlight, which, along with ground water inputs keeps the water cool for temperature-sensitive species like trout.

 

Building Resilience to Climate Change

 

Builds Biodiversity – In connecting land and water ecosystems, riparian areas make each more productive and support many different plant, animal, and insect species. For example, terrestrial plants trap sediment during floods by slowing water flow and allowing the sediment to settle in place, this in turn adds nutrients to the soil and improves conditions for tree and plant growth. The streamside trees and shrubs in turn provide woody debris for aquatic invertebrates and these emerging aquatic insects provide food for birds and bats. Intact and restored riparian areas have many of these mutually supportive land/water relationships that can increase the likelihood of species survival in the face of climate change disruptions.

Protects Biodiversity – Riparian zones are also structurally complex, that is the various plant communities form several different layers that can include ground cover (moss, ferns), low and high shrubs (Red-osier Dogwood, Bebb’s Willow), tree understory (Sassafras, Ironwood), and tree over story (Cottonwoods, Black Willow). The many layers present in a healthy riparian area provide habitat niches for a diversity of wildlife and insect species. For example, bird species like American Woodcock can be found on the ground hunting for worms among tree roots, while Wood Thrushes and Northern Cardinals seek out food in the shrubby understory, Northern Flickers and Red-headed woodpeckers seek out or create nesting cavities in the low tree canopy layer, and Blue Jays and Eastern Wood Peewee establish nests in the highest canopy layer. The more complex the structure, including age difference as well as vertical layers, the more diverse the wildlife a riparian area (or forest) can accommodate. A structurally complex riparian zone can also act as a barrier to invasive species by denying them a niche to infiltrate and shading out non-native pioneering species.

 

Building Resilience to Climate Change

 

As we have seen, healthy riparian zones hold great potential to provide refuge from the present and anticipated impacts of climate change by their inherent resilience to flood and drought, their connectivity between land and water and upland sites to downstream sites, their many and complex relationships between aquatic and terrestrial species, and their structural complexity providing habitat for a wide diversity of wildlife species and acting as a barrier to invasive species. In future installments we will look at other ways restored and intact riparian areas can mitigate and provide refuge to the impacts of climate change, and how they can help protect human communities from these threats.

 

Building Resilience to Climate Change

 

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