Austin Heritage Tree Foundation
Protecting trees

Recs to BSP Maint. plan

The Forestry Tree Maintenance (mulching) plan for inside the fence at Barton Springs Pool may be discussed at the next BSP Joint Committee.

Please, support the recommendations below from AHTF to the Forestry BSP Tree Maintenance Plan, by emailing Gary Gregson Gary.Gregson@austintexas.gov and bspmasterplan@austintexas.gov .
Summary of AHTF recommendations to the Forestry BSP Tree Maintenance Plan:

Work area 3, inside the fence, north hill (shown with red lines in map):

Apply compost to 2 more trees, the leaning tree and the very large heritage tree east of the bath house, inside the fence. Compost will stay in place held by the grass, and won’t be an issue after 3 months or less. We agree with Walter that mulch shouldn’t be applied to these 2 trees because of the steep slope.

As also was requested by Michael Embesi, city arborist, and agreed by Walter last Friday, provide soil treatment to the large heritage tree to the west of the bathhouse, near the upstream dam, by the current ADA ramp. We recommend that compost be applied to the portion of the dripline that is inside the fence, covered with grass; and that compost and mulch be applied to the portion of the dripline that is outside the fence.

Work area 2, inside the fence, south hill (shown with blue lines in map):

Apply compost only, not mulch, to the entire dripline of the 6 trees closer to the pool, in the steepest part of the south slope. Floods will wash out this mulch in a season due to the proximity to the pool. This mulch will float in the pool and will have to be cleaned out by the lifeguards. This mulch costs time and money to apply. I got the impression that Walter agreed to this recommendation last Friday.

This compost should be applied to these 6 trees by Forestry crews, not volunteers. This part of the south hill is too steep for volunteers. Volunteers will get exhausted and will erode the hill. Forestry crews can do this with a truck with a grabber and 2 gators that can dump the compost close to the driplines. A couple of Forestry crew members can then rake the compost, spreading it under the driplines.

Apply compost to the 2 cotton woods by the diving board and the large elm in the center top of the south hill, to the entire dripline. These are the trees that would benefit the most from this soil treatment, and improving the health of these trees with a little compost will go along way to help these trees not become safety issues in the future. In addition, soil will be conditioned for future plantings.

Apply compost only, not mulch, to the remaining trees on the south hill (at the top of the hill), to the entire dripline. The mulch will get washed out and spread all over the hill. Compost works itself into the soil in 3 months, enriching the soil. People can lay down almost immediately on compost spread under the grass blade (it’ll be manure free). Mulch, however, needs years to work itself into the soil. Forestry’s mulch is not as fine as the one provided by nurseries, and has medium wooden pieces that will make it difficult to lay down or even sit down on the mulch. An alternative if these trees have to be mulched, would be to purchase truly fine mulch from a nursery like Organics by Gosh.

Don’t use the “jointed areas” approach to mulch. Apply mulch to the entire dripline instead, or as much of that area as possible. The Forestry plan is to apply mulch to jointed areas. These jointed areas are shown in pink in the drawing below. With this method, mulch will cover grassy areas that are beyond the dripline of the trees, while, at the same time, some portions of the driplines will not be covered. It’s a wasteful approach. Mulch needs to be applied where the tree roots are significant, to the dripline.

Minimize damage to the south hill trees (soil compaction) and grass (erosion) when doing this work by:

Instead of 150 volunteers, have Forestry crews do the work inside the fence. The 150 volunteers can, instead, mulch some of the many BSP trees outside the fence, by the bathhouse, playground, theater, etc.

Instead of 150 volunteers, have a few stellar volunteers from APF and AHTF do this work with Forestry crews support.

Have the 150 volunteers, but divide them into smaller groups per tree, and have a volunteer leader per tree. But also have volunteers walk on a specific path, not everywhere up and down the hill. A large number of volunteers need to be supervised closely to not erode the hill.

Instead of 150 volunteers, have several smaller volunteer events to do this work, combined with staff support with gators.

Soil compaction:

Regarding mulching the south hill to reduce soil compaction and help the trees, Don Garden and AHTF verified in Winter last year that most of the trees on the south hill don't have excessive soil compaction. We were able to insert a hand trowel with no problem. Don did some soil probe tests. The soil was compacted only on the portion of the dripline area that is used as a path. The exemption is the soil where the 2 cottonwoods are by the diving board. That soil is very compacted, but the Forestry plan doesn't include mulching these trees. Forestry should be aware that recent soil tests will probably show false results for soil compaction due to the drought. The most evident test is to look up at the trees canopies and realize that most of the trees are doing well, in spite of the drought. Soil compaction shows on the tree’s canopy like it’s showing on the cottonwoods by the diving board: these trees have dieback and a small canopy.

Please, see click onthe links below to read more details:

1) Background on previous meetings to discuss plans

2) AHTF Recommendations

3) Details of recommendations

Work area 1, outside the fence, south side (shown with yellow lines in map) was done by volunteers and PARD Forestry crew on 10.29.11.

Instead of applying compost and mulch separately to the 7 pecan trees by the fence, Forestry purchased a very nice compost/mulch mix. This will help these trees significantly. It's important in a time of drought to enrich the soil by applying compost not just mulch, for the special trees.

Due to this drought, it is also very important to spread mulch on the thin side, not more than 3 inches deep because mulch absorbs water and prevents it from reaching the soil and tree roots. Trees need to get all the water they can, including that from short rain events. The thicker the mulch, the less water the tree will get. Mulch thickness can make a big difference for mulched trees unless it rains (or they get watered) for a long time.

The remaining trees in the south soccer fields area received coarse shredded mulch, which will also help them with the drought. The mulch was applied by many volunteers and the Forestry crew.