Oaks ‘n’ Folks – Volume 8, Issue 1 – March, 1993
One of the major obstacles preventing successful planting and establishment of oak seedlings on rangelands is browsing by herbivores such as rabbits, deer, and livestock. While screen cages have been used to protect seedlings from rabbits and deer, protecting seedlings from cattle has proved much more difficult. Cattle often nip off or trample unprotected oak seedlings. This damage is especially great in the late spring and early summer when other vegetation is drying up and young seedlings may be the only green plants around. Cattle also tend to pull up, stomp, or bend small protective cages or shelters.
Consequently, to date, it has generally been recommended that cattle either be excluded from oak seedling planting areas by building small cattle-proof exclosures, or kept entirely out of pastures where seedlings are planted.
Unfortunately, these approaches have significant costs associated with them. Small cattle exclosures are expensive to build and maintain. And eliminating livestock from large pastures for the five to ten years it can take for oaks to grow big enough to be resistant to browsing, takes land out of production, thus eliminating revenues.
This past year, an alternative approach – using Tubex treeshelters to protect individual seedlings in grazed pastures – was evaluated in a research project at the Concord Naval Weapons Station. Treeshelters are tall, slender, double-wall plastic tubes that protect seedlings from physical injury and create a greenhouse environment favorable to more rapid growth. Those used in this study were four feet tall and were held in place using six-foot tall metal T posts.
This project evaluated the field performance of valley oak seedlings protected with treeshelters (and two other protective covers) both inside and outside fenced exclosures. In addition to cattle, seedlings outside the exclosures were also subject to injury from a local elk herd which also grazed the area.
The results indicated that treeshelters can be effectively used to protect individual seedlings from cattle and elk. None of the 52 treeshelters in the were seriously damaged or rendered ineffective, except for a few that were rubbed on and tended to slip up on the metal posts, exposing part of the seedlings. This problem could be reduced or eliminated by securing the treeshelters to the posts with additional wire. In addition, seedlings inside treeshelters tended to grow rapidly. After one year from acorns, 58% of the seedlings inside treeshelters were alive, and average height was over 20 inches, with a sizable percent growing over three feet.
While protecting individual seedlings with treeshelters is not cheap – it costs approximately $5 for a four foot treeshelter and a metal fence post – it is certainly less expensive than building fences around planting spots. These devices also have the added advantages of protecting plants from insects and rodents, facilitating weed control, and promoting growth. They therefore appear promising as a method for successfully protecting plants in areas where livestock browsing is a concern.
prepared and edited by John M. Harper, Richard B. Standiford, and John W. LeBlanc