Agenda - 08-10-1994 - Laserfiche WebLink

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Productivity Rating: The productivity rating is based on the productivity of the designated indicator tree species for each soil. An indicator species is defined in the SCS National Forestry Manual as"that species which is common in the area and is generally the most productive on the soil in question." The indicator species for each soil is determined from the woodland interpretation tables contained on the Orange County Soil Survey. The indicator species is the first species listed under the column heading"Productivity Potential."The indicator species for Orange County soils are shown in Appendix D. Productivity ratings for each soil are derived from site index values. Site index values are also determined from the woodland interpretation tables in the Soil Survey and refer to the average height an indicator tree species will reach by the age of 50 years. Productivity ratings are determined from the SCS National Forestry Manual according to the indicator tree species and site index value for each soil type. Site index values and productivity ratings for each Orange County soil are shown in Appendix D. Individual productivity ratings are then arranged in as many as 10 groups. The range of productivity ratings shown in Table 2.2.7 was derived from the SCS National Forestry Manual and recommended for use in North Carolina. The highest productivity class in the range is rated 1.00. The ratings assigned to the other classes are relative values derived by dividing the average productivity of each class by the highest average productivity. For example, the average for the second class (121-166) is 144, and it is assigned a rating of 144/166 or 0.87. The average for the third class (79-120) is 100, and it is assigned a rating of 100/166 or 0.60. TABLE 2.2.7 - PRODUCTIVITY RATINGS Productivity Range (Cubic Feet/Acre/Year) Rating 166+ 1.00 121-165 0.87 79-120 0.60 51-78 0.39 21-50 0.22 <20 0.00 Sources: 1/ Soil Survey of Orange County, NC, USDA, Soil Conservation Service 2/National Forestry Manual, USDA, Soil Conservation Service Indicator Species Rating: This rating is based on the value of the indicator species that occur in the county. Table 2.2.8 below lists the various indicator species in order of decreasing value for the major wood product in the area, building timber and firewood. The most valuable indicator is always assigned a rating of 1.00. The ratings for other species are relative values determined by dividing mill value of the next indicator species by the mill value of the most important species. For example, the indicator species oak has a mill value of$135, and it is assigned a rating of 135/150 or 0.90. The indicator species mixed hardwood has a mill value of$85, and it is assigned a rating of 85/150 or 0.57. 2.2.15