Case Studies - California Compliant

Cape-ivy removal at Stinson Beach:

"HydroMechanical Obliteration (H_M_O ℠) in the Golden Gate National Recreation Area"

Abstract

Source

We are reporting on the use of a new control technique, HydroMechanical Obliteration (H_M_O ℠), on six invasive plant species in Marin County, California at the Golden Gate National Recreation Area (GGNRA). Data collection consisted of a combination of before and after plots while others were recorded with photo-documentation. H_M_O ℠ involves the use of small amounts of water at 3500-7000 PSI to remove woody and herbaceous perennial plants. The result is a leave-in-place mulch with herbaceous plants or in the case of French Broom (Genista monspessulana) mature plants were removed and piled. For Cape-ivy (Delairea odorata) and English ivy (Hedera sp.) significant reductions in both species were achieved with a single treatment. For Harding grass (Phalaris aquatica) multiple treatments over time were required. We had great success with CapeĞivy and panic veldt grass (Ehrharta erecta) control as a followup to our initial mechanical removal of Cape-ivy conducted two years previously . On jubata grass (Cortaderia jubata) only small plants were removed with one treatment, larger plants have taken 3-4 treatments over 12 months and French broom (Genista monspessulana) growing among compacted rock along Bolinas Lagoon removal was also successful. We found H_M_O ℠ to be a beneficial and cost-effective addition to our IPM toolbox.

Maria Alvarez*¹, Cameron Colson², Maria Morales²,Liz Ponzini³, Aliza Segal¹, and Sarah Cusser^{1 1}Golden Gate National Recreation Area, CA, ²CAMCO, CA, ³Golden Gate National Parks Conservancy, CA. Maria_alvarez@nps.gov (415) 331-0732

Case Study: Cape-ivy removal at Stinson Beach

Objective

Determine the effectiveness of H_M_O ℠ to control Cape-ivy in sandy soil.

Methods

Sampling: Point-intercept sampling of vegetation cover was collected before treatment and six weeks after treatment: 30 points in a 9 x 10 meter square.

Treatment

The plot was entirely cleared of visible Cape-ivy using the H_M_O ℠ technique and 150 gallons of water. No limbing of willows occurred.

Result

H_M_O ℠ significantly Decreases Cape-ivy and English-ivy cover without removing canopy species.

Methods and Materials

HydroMechanical Obliteration℠ uses low volume water at very high pressure to micro-minimize vegetative matter in-situ.

H_M_O Rx is a highly targetable growth control process. It works well on reducing light, weedy vegetation and frustrating plant growth.

Scenarios

Woody materials are subjected to three possible scenarios:

1. Controlled defoliation of green vegetation and dead biomass on and around the living plant to reduce fuel.
2. Removing plant by root via liquefaction.
3. Or girdling the plant by killing by removing outer bark around the tree/plant.

Since all materials are left in place the nutrients are recycled back to the soil in which they came.

The H_M_O ℠ application works in any interface, urban weed control, wildland, and water.

IVY

Before	Immediately After	Six Weeks After

Results of Additional Applications

H_M_O ℠ has been used as an invasive plant removal technique in the GGNRA on:

• French Broom (Genista monspessulana)
• Harding Grass (Phalaris aquatica)
• Panic Velt Grass (Erharta erecta)
• Jubata grass (Cortaderia jubata)
• Fennel (Foeniculum vulgare)

French Broom

H_M_O ℠ was able to rapidly cut plants at the soil level to be collected.

During Treatment	After Treatment

Harding Grass

Four treatments of H_M_O ℠ applied over 18 months resulted in 100% reduction in seed head production.

Before Treatment	After Treatment

Jubata

50% of the smaller plants were removed after one treatment; larger plants needed three to four treatments over 12 months.

Before Treatment	After Treatment

Fennel

One treatment was able to successfully remove all but two fennel plants. Only small portions of those two plants remained and there was no need to retreat the sites:

Before Treatment	After Treatment

Panic Velt Grass

H_M_O ℠ was used successfully as a follow-up to a prior mechanical removal for Cape-ivy and panic veldt grass.

Advantages of H_M_O ℠

Fast

• Time spent hauling herbaceous biomass from site is eliminated.
• "Bare Ground" initial treatments for species like cape-ivy are completed in significantly less time than traditional manual methods.
• One applicator can obliterate one quarter to one acre of vegetation in one day (depending on species type).

Clean

• Eliminates the exposure to Herbicides and other Chemicals
• Avoids use of engine driven cutters which pollute and can cause fires.
• Can be used with reclaimed water

Minimally Disruptive

• Does not cause erosion
• Recycles nutrients from the obliterated vegetation back to the soil.
• Allows the applicator to be incredibly specific in obliterating the target species
• Leaves canopy layer undisturbed.

Other Benefits

• Systems can be mobilized for certain applications where access and target species are deep in impassable vegetation.
• Systems are built to suit a wide range of tasks.

Limitations

Revisitation

• Hydro-Mechanical Obliteration often requires multiple treatments, especially when removing plants with large underground root masses like Harding and Jubata grass.
• It can unintentionally girdle trees and shrubs when used sub-soil.

Proximity

• Systems are limited by hose. 400 feet max line.

Training

Future Studies

To better understand the capabilities and limitations of H_M_O ℠ more studies must be preformed investigating:

• Long term invasive control
• Seed mortality/obliteration
• Seasonality considerations and constrictions
• Effectiveness on other invasive species

Acknowledgements

Funding for this project was provided by the National Fish and Wildlife Foundation. Thank you to Craig Scott for helping us Print this poster. Funding for the production of this poster was provided by the Golden Gate National Parks Conservancy and the National Park Service.