Thinning Methods Selection of leave trees will be made by the Contractor according to the following specifications, as well as those found in the Unit Description table (Exhibit D1) and in each property prescription. A. Live Trees: 1. Overall, most units burned at very high severity and have very high tree mortality across all species; as such, the majority of units and stands within units have very few living trees remaining. Retaining healthy, living trees throughout the units is of critical concern, specifically those within areas of high (>75%) mortality, and those individuals with mature tree-form, of greater age, with well-developed branch and crown structure, bark differentiation, and size. Retain trees with >30% crown ratios, regardless of species. Remove living conifers that are clearly in decline due to insect our drought stress, specifically Douglas fir and Ponderosa pine that show evidence of insect invasion. Where there remains competition between living trees (i.e., living trees are within dripline, being overtopped, pierced), follow the leave tree preference specified in each property prescription. 2. In areas where post-fire mortality is less than 50%, two contrasting thinning procedures are recognized. These are Simple Spacing Thinning and Diameter Limit Thinning. For each approach, where there is competition between live trees of similar characteristics, follow the leave tree preference specified in each property prescription. • Simple Spacing Thinning: When thinning on a spacing basis, Contractor will select and leave uncut the largest live trees (hardwood or conifer) of good form and vigor that will maintain the average spacing designated in the Unit Description Table. Overall, an average spacing of approximately 16-20 feet between individual leave trees will be targeted, where enough living trees remain. To maintain average spacing, Contractor may not need to cut as many trees immediately adjacent to gaps. However, clumps or patches should not be left unthinned to make up gaps in the stand. If the [JSWCD Forest Resource Conservationist or Forest Conservation Technician (local partner)] determines that narrower spacing is appropriate for portions of a Unit, 6' x 6' spacing will be used. Spacing is the average distance between trees that will result in the correct number of trees left per acre. The number of trees left per acre will be measured by SNW to determine compliance with the Per Acre Zone of Acceptance as described in Clause C02.
