Comparison of Risk/Hazard Rating Systems for Mountain Pine Beetle in Black Hills Ponderosa Pine Forests (Classic Reprint) PDF Download

Author: Judith E. Pasek
Publisher: Forgotten Books
ISBN: 9781396784101
Category : Business & Economics
Languages : en
Pages : 78

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Book Description
Excerpt from Comparison of Risk/Hazard Rating Systems for Mountain Pine Beetle in Black Hills Ponderosa Pine Forests Stevens et al. (1980) described a system for rating ponderosa pine stands in the Black Hills for susceptibility to mountain pine beetle (mpb), Dendroctonus ponderosae Hopkins, using parameters of stand structure (one or two-storied), average diameter at breast height (deh), and average basal area (ba). This mpb risk-rating system was incorporated into a model subroutine called ponbug, which is linked to the Rocky Mountain Resource Inventory System (rmris) database used by National Forests in the Rocky Mountain Region, so that mpb risk could be automatically calculated in the program called rmstand. Results can be displayed in the optional field bug_risk in the table r2ris_site. Values of 1, 3, and 5 indicate low, medium, and high mpb stand risk, respectively. The program was modified in 1993 for the Black Hills and Nebraska National Forests based upon results of Schmid and Mata They suggested that 120 sq. Ft. Per acre may be the critical BA for separating high risk stands of susceptible-sized trees in the Black Hills, rather than 150 sq. Ft. Per acre. This risk-rating program is often used by district personnel during project planning to help prioritize pine stands for thinning or harvesting. As Rapid City Service Center staff became involved in assisting district personnel with analyses of mpb risk, it became apparent that the ponbug model did not always produce the same results as hand calculations of the method published by Stevens et al. Closer examination of the computer program ponbug revealed that it used average diameter and BA of trees 2 1 inch qmd (quadratic mean diameter, an estimate of average stand diameter) rather than those for trees 2 5 inches in diameter, as specified by Stevens et ai. In addition, Stevens et al. (1980) did not define one-storied and two storied stand structure in their rating system. In order to use the stand structure parameter in the ponbug model, a stand was designated as two-storied if BA of trees 2 1 inch qmd was 30 sq. Ft. Per acre and number of live trees between 1 and 5 inches qmd was 250 per acre. Stands without these conditions were designated as one-storied. By this method, most stands in the Black Hills would be designated as one-storied. Whether or not this is an accurate portrayal of stand structures of ponderosa pine in the Black Hills is debatable. The ponbug designations for stand structure may not represent what Stevens et al. (1980) envisioned when they described their rating system. The omission of trees smaller than 5 inches deh from their model suggests that they considered such small trees to be unimportant for risk rating mountain pine beetle susceptibility and may also reflect a scarcity of such trees in stands of high risk. Their two-storied stands were likely to contain scattered mature trees with an understory of pole-sized trees, typical of stands found some years following shelterwood or seed tree harvesting. A quantitative means of describing such stands for use in risk/hazard rating systems for mountain pine beetle in ponderosa pine has not been developed to date. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.