Preserving Riparian Zones

July 22nd, 2016
Devil's River

Devil’s River State Natural Area.
TPW Photo by Earl Nottingham

This is Passport to Texas

Recent statewide flooding events beat up native vegetation in riparian zones, leaving behind tangles of uprooted trees and shrubs. Landowners’ first instinct is to clean up the mess, but is that the best action to take?

One of the most important and critical components of a riparian area is fallen vegetation.

Ryan McGillicuddy is a Texas Parks and Wildlife conservation ecologist.

As fallen wood—woody debris—start to decompose, they add nutrients to the soil. They act as fish and wildlife habitat. They act as cages that protect new plants. The next generation of trees. The next generation of grasses. It provides a little refuge for those plants to get started before they’re browsed on by wildlife or they’re trampled by foot traffic.

Despite the unsightly nature of this vagrant vegetation, McGillicuddy says it is a critical component of a healthy functioning riparian area. Provided it’s not creating a safety risk, he says to consider leaving it where it is.

Another thing it does is as flood waters do rise up and spill out of their banks, that wood can help slow some of that water down, and help capture sediment. And, when the sediment falls out of the water, it’s actually building the structure of the banks. Adding sediment and new layers of soil, as opposed to it being washed away when there’s not a diversity of species for something like a mowed lawn. Or an area that’s been over-grazed.

Texas Parks and Wildlife has worked with landowners along the flood ravaged Blanco River to revegetate with native plants.

The Wildlife and Sport Fish Restoration program supports our series.

For Texas Parks and Wildlife, I’m Cecilia Nasti.

The Reality of Weak Riparian Zones

July 21st, 2016
A healthy river and riparian zone.

A healthy river and riparian zone.

This is Passport to Texas

We call the land that flanks rivers and streams a riparian zone. When these areas are intact with native vegetation, they slow the forces of floodwaters, help capture sediment, filter nutrients, and slow runoff from upland sources. Yet, land use practices over the past 150 years have altered their natural state.

Things like mowing, excessive foot or vehicle traffic, or excessive browsing from either livestock or unmanaged wildlife…

Ryan McGillicuddy is a Texas Parks and Wildlife conservation ecologist.

So, water sheds off quicker, it can contribute to higher peak flows for flooding. And really, those areas become less resilient; they recover less quickly from disturbance events like floods.

Floodwater, can demolish stream and river banks that lack healthy stands of native vegetation.

What happens when you reduce the vegetation diversity and number of species is you lose some of the root stock that these native trees and grasses provide. These native species have very, very deep root systems that act like rebar holding the soil together. So they’re less resistant to erosional forces. So, we end up seeing less stable stream systems.

Helping the land recover after a devastating flood event. That’s tomorrow.

The Wildlife and Sport Fish Restoration program supports our series.

For Texas Parks and Wildlife, I’m Cecilia Nasti.

Benefits of Healthy Riparian Zones

July 20th, 2016
Brazos River

Brazos River. Image credit: Larry Hodge

This is Passport to Texas

A riparian zone is a transitional area between a stream or river and an upland ecosystem. Conservation ecologist, Ryan McGillicuddy says these strips of land, which can be from 25 to over 200 feet wide, perform vital ecological functions.

They provide excellent habitat for fish and wildlife both in stream and on the land. The leaf litter provides nutrient contributions. The fallen logs provide structural habitat in the stream for fish and wildlife. A lot of the nutrient and diet for some of our sport fish species and the food web within the channel comes from a land source. Structurally, riparian zones provide a number of functions. The plant roots act like rebar and hold the banks of the channel together to resist the force of erosion.

When rain events cause streams and rivers to overflow their banks, riparian zones are the first line of defense.

If you have an intact, healthy riparian zone, it will slow the forces of floodwaters. It will help capture sediment, filter nutrients, slow runoff from upland sources…

These healthy riparian zones also soak up water like a sponge, adding to stream flow during drier times.

Unfortunately, a lot of the land use practices over the last 150 years from really intense settlement have altered the natural state of some of these riparian zones.

Tomorrow: When riparian zones are weakened.

The Wildlife and Sport Fish Restoration program supports our series.

For Texas Parks and Wildlife, I’m Cecilia Nasti.

Riparian Zones: Life Along the Edges

July 19th, 2016
South Llano River

South Llano River

This is Passport to Texas

The technical name for the land along river and stream banks is riparian zone.

A riparian zone is that special transition zone between the stream channel and the uplands.

Ryan McGillicuddy, a conservation ecologist with Texas Parks and Wildlife, says riparian zones are diverse.

It’s comprised of different composition of plant species, and it’s critical to the health of both the channel and the uplands. So, it’s a narrow band, but it’s really important in the health and function of a stream and for fish and wildlife habitat.

Depending on the size of the river or stream, a riparian zone can be from 25 to over 200 feet wide. Identifying where the riparian zone ends and the uplands begins isn’t as hard as you might imagine.

It’s basically that area on the slope, coming up away from the channel, until you see things that are more typical of upland vegetation. In the Hill Country, that would be when you start seeing things like cedar and ash juniper.

These strips of land are more than places to bring a picnic or fishing pole.

Riparian zones perform a number of ecological functions, as well as structural functions in protecting streams and keeping them—I guess—resisting forces like erosion.

And we’ll learn more about that tomorrow.

The Wildlife and Sport Fish Restoration Program supports our series.

For Texas Parks and Wildlife, I’m Cecilia Nasti.

The Benefits of Flooding

July 18th, 2016
Pedernales Falls Flooding

Pedernales Falls State Park Flood May 24 2015
© Texas Parks and Wildlife Department

This is Passport to Texas

Torrential rains in 2015 and again in 2016 ended five years of exceptional drought across Texas, but also caused rivers to flood.

It’s important to recognize that floods are a part of a functioning river system.

Ryan McGillicuddy is a Texas Parks and Wildlife conservation ecologist. We tend to focus on the negative impacts of flooding, but ecologically, floods have beneficial functions, too.

Once the water spills out of its normal channel, it infiltrates into that riparian zone, and becomes absorbed by that soil and then acts as a time-release capsule that feeds the river channel; the water makes its way back to the channel in the drier times of the year. There are also a number of fish and animal species that are dependent on floodwaters. There are a number of tree species that thrive on floodwaters. So, ecologically, there are a number of things a functioning floodplains provide.

A riparian zone is the land that parallels rivers and streams. A broad and wide undeveloped floodplain contains plenty of vegetation that forces floodwaters to slow down, giving soil time to absorb them, thus protecting more developed areas downstream.

It gives water a place to go.

Getting to know riparian zones…that’s tomorrow.

The Wildlife and Sport Fish Restoration program supports our series.

For Texas Parks and Wildlife, I’m Cecilia Nasti.