>Date: Tue, 07 Apr 1998 18:56:17 -0700 >To: owner-forest@listserv.funet.fi >From: John Foster <borealis@mail.wellsgray.net> >Subject: Re: Summary of Responses to Hardwood Midstory Removal (LONG) There are several excellent reviews and studies on girlding. One is by A.R.A. Noel. (1970) entitled The_Girdled_Tree, Botanical Review, 36 (2):162-195. The definition of girdling provided by Noel is technically known as the removal of the cambium, phloem and bark down to the secondary phloem. A report by the Comptroller General of the United States entitled Better_Data_Needed_To_Determine_The_Extent_to_Which_Herbicides_Should_Be_Use d_On_Forest_LLands revealed taht the success of herbicide spraying had been variable. It was estimated that 20 to 30 per cent of the treated land in the Klamath National Forest would need to be retreated again (GOA 1981). Manual treatments were generally successful, but some areas would need to be treated again because of resprouting. The efficacy of manual treatments was highly dependent on timing. In the Shasta and Trinity National Forests, spraying carried out in the first 3 years after planting required retreatment 50 per cent of the time. If spraying was carried out after 3 years, there would be a 90 per cent chance that retreatment was needed. For manual treatments, the optimum time of release was 3-5 years after planting, with early pulling the most efficacious at reducing densities. In the Willamete Forest, one district reported that 91 per cent of the area sprayed required retreatment. The other districts reported only minor control of vegetation. Minor damage to conifers and areas receiving treatment but not reguiring spraying was a also reported. An assistant forest surpervisor reported that "no one could determine the effectiveness of particular methods or when and how often a particular unti (whether herbicide or manually treated) would need retreatment." In Francis Marion and Sumter National Forest, aerial spraying was stopped longa ago. It was reported that mechanical site preparation reduced the need for any release treatment and that herbicide and manual site preparation increased the need for release. There were no formal evaluations for herbicide programs and pretreatment field inspection occurred one year after planting. Aerial spraying was stopped in 1971 because: a) there was a change from aerial seeding to planting, b) the amount of release needed was small, damage of spray to hardwoods left along streams and other areas, and d) an increase in public opposition to spraying had occurred. Hand spraying was stopped because the herbicide drifted onto pines and stunted their growth. On medford and Eugene Bureau of Land Management lands, herbicide was 80 per cent effective, while manual was effective but resprouting was a problem. On state forest lands manual treatments provided "undoubtedly satisfactory performance, and cost about the same as herbicide spraying. On the coastal areas, spraying was required 1.3 to 1.6 times. Washington state officials freely "acknowledged that mechanical and manual alternatives to herbicides had not been thoroughly evaluated." The GOA report concluded that limited data existed on alternatives to herbicide use, that research money had gone into the use of herbicide, but how much, how often and when was not known. In most districts, there was a dearth in cost and effectiveness data for the mechanical alternatives and only a few limited studies to evaluate the use of manual release methods (GAO 1981).
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