We have been working for over a month to remove invasive species from the ravine and surrounding area outside the fence near the south parking lot of Barton Springs Pool. We have more volunteer workdays coming up on Sat (9-noon) next Tue for several ACC classes and then on Sat, June 4th as part of National Trails Day (sign-up here) In all cases, meet at the south parking lot off of Robert E. Lee Drive, wear long pants and bring a water bottle.
Additionally, we had help from Bartlett Tree Experts on a particularly difficult hillside section and our great volunteers Jerry and Nadene. And the City Parks Forestry team has been great at picking up our cut, hauled and piled trees and turning them into mulch.
But we wanted to show you a few pictures as we remove the invasives (mostly ligustrum, chinaberry and nadina)
If we can pull them out roots and all, that is our first and best choice, we do so by using a great tool called a weed wrench. It comes in several sizes, works on trees or shurbs with one inch or less diameter trunks and its better when the soil has some moisture. Here’s a picture of some of the puled trees – they pile up quite quickly as you can see.
If they are bigger than a inch or two, we will cut them using hand saws. We usually cut them at knee height – we call this high stumping. This is so we bring in professionals who can cut them flush to the ground with chainsaws and apply herbicide that prevents them from re-sprouting. We cut them at knee height so as the native grasses and plants re-sprout, we can find them. Knee-height stumps are also harder to trip over, which it make it easier when working in and around already cut areas. A good example of most areas is the picture below which shows a mix of native trees standing with the stumps mixed in. Note the bare ground with little understory grasses and plants, a great example that the invasives were already shading out any complementary native plants from growing and helping hold the soil in place.
The picture above shows several piles awaiting pickup by the city forestry crews. We try to pull out all of the cut and wrenched trees out of the wooded areas and into the open.
Where the canopy of invasives – especially – ligustrum is really dense, there are few native trees and little ground cover. With their removal, light reaches the ground and we see native trees begin to flourish and native grasses re-sprout. This is true even in a drought. This critical in areas that are near creeks and streams as grasses and smaller plants hold the soil in place, reducing erosion. In areas where invasives are dominant, erosion is often worse. Here’s a good example where it was all invasives with bear soil and some leaves from the cut trees as the only things left. This area will recover.
This area will recover nicely and with some monitoring over a year or two, we’ll keep any invasive seeds at bay by picking the sprouts quickly. We’ll be posting more updates as we continue in our efforts.