Saturday, May 29, 2010

Southern California Vetiver Grass Tales: "Moondust & Shale"

Thomas Stickler, Wolfram Alderson (originally published on the Vetiver Network website)

Worst case scenario provided for Vetiver grass planting at California State Polytechnic University, Pomona.

Vetiver grass was given an opportunity to its demonstrate its tolerance of poor soil and environmental conditions in a "worst case scenario" provided at Land Lab, an 340 acre environmental study area at California State Polytechnic University, Pomona. Forty-four vetiver grass plants were planted along a cut face slope leading up to the Land Lab Information Center, during the summer of 1994.

Vetiver grass was included in a palette of plant materials that were in a revegetation project implemented by the Casa Colina Horticulture Therapy and Training Program, a program based in Pomona that provides employment and training for people with disabilities. It was provided by Land Lab and the Los Angeles County Sanitation District.

The primary goal of the revegatation project was to restore the ability of the native California Black Walnut trees located on the site to seed new generations of tree saplings. Prior to the project, there were mostly old growth trees and very few young trees surviving unfavorable conditions that had previously included over-grazing, construction activities, a canopy of invasive exotic weeds, and few surviving native or understory plants. Soil conditions were very poor and heavy erosion and landslides were prevalent.

The "moondust and shale" soil viewed here is what was left after a road was cut up to the Land Lab Information Center. Topsoil in addition to over ten feet of earth was removed leaving a shale-pocked substance that can be described as extremely dry and void of organic matter. Daily during the summer, this lifeless dust and rock experienced additional unishment by wind and sun and crumbled and cascaded down the slope face into the asphalt roadway. During the winter, the rains turned the material into a gray mud and frequently slipped downhill in mudslides or just simply washed down the drive in a milky flow. As a general reference, temperatures in the Los Angeles area range from 28 F to 110 F, with a mean of 64.4 F. Normal Los Angeles area annual rainfall is 14.68 inches (372.8 mm). Vetiver can survive with as low as 300mm of annual precipitation, but an average of 700mm (27.5inches) per year is considered preferable.

When the 4‰ container size Vetiver grass was planted, some irrigation occurred by portable rainbird sprinklers during the initial months after planting. Frequent water line breaks as well as other challenges left the plants starved for water and attention during the first year. No irrigation has occurred at all since the sporadic watering that occurred that first year. After a three-year revegetation period, the project funding was discontinued and the site maintenance was abandoned.

Remarkably, as of December, 1999, 90% of the Vetiver grass planted at Land Lab has survived the soil, the blazing sun, the afternoon winds, and even the large population of voracious rabbits (who get their water and food from the vegetation). The Vetiver grass specimens that remain would clearly look happier if they were to get a little more water. What is amazing is that the Vetiver grass has survived where other native plantings have not. When Vetiver grass plants are stressed, they "hunker down" growing lower to the ground, exhibiting more dried blades of grass. But, as you will see in additional Southern California Vetiver grass tales and images, Vetiver grass has survived here while other native sages and plants (considered to be more drought tolerant) have not. Quite an accomplishment for this simple little clump of "tropical grass"!


No comments: