G UIDELINES for ..................................................................................................... Commercial Thinning July 1999 Ministry of Forests Forest Practices Branch Canadian Cataloguing in Publication Data Main entry under title: Guidelines for commercial thinning ISBN 0-7726-3934-5 1. Forest thinning – British Columbia. 2. Forest management – British Columbia. I. British Columbia. Forest Practices Branch. SD396.5.G84 1999 634.9'53'09711 C99-960223-3 1999 Province of British Columbia To view a copy online, see: www.for.gov.bc.ca/hfp/pubs.htm Preface Commercial thinning is an intermediate harvest where the merchantable wood removed should cover part or all of the cost of harvesting. It is defined as a thinning “in which all or part of the felled trees are extracted for useful products…” (Smith, 1986). Commercial thinning, when carried out on the right stands at the right time under appropriate stand conditions, is a valuable strategic management tool that increases the flexibility in the timing and quantity of wood flow available at the forest estate level. The Guidelines for Commercial Thinning were developed with input from industry (COFI), Ministry of Environment, Lands and Parks, MOF regions and districts, Research Branch, Economics & Trades Branch, Resource Tenures & Engineering Branch, Compliance and Enforcement, and Forest Practices Branch staff. These guidelines provide information to forest practitioners considering commercial thinning and those that are currently planning and implementing commercial thinning programs in BC. This document provides important information on: 1. the effects of commercial thinning on the growth of trees and stands 2. the importance of planning at the regional, landscape and stand levels 3. the guidance for inclusion of silviculture prescription data elements for commercial thinning 4. project preparation and administration. To be successful, a commercial thinning program must be based on a clear statement of objectives, and have the appropriate age class structure and stand conditions to implement the program. This document provides background information for practitioners to assist in planning and implementing a commercial thinning program. Deviation from the guidelines outlined in this document should be based on dialogue between industry and government foresters. GUIDELINES FOR COMMERCIAL THINNING • iii Contents Preface ................................ ................................ ................................ ................................ iii Introduction ................................ ................................ ................................ ......................... 1 Commercial Thinning and the Forest Practices Code................................ ...................... 5 Forest Practices Code of British Columbia Act ................................ ............................... 5 Operational Planning Regulation ................................ ................................ .................... 5 Silviculture Practices Regulation ................................ ................................ .................... 6 Effect of Commercial Thinning on the Growth of Trees and Stands ............................... 8 Thinning intensity ................................ ................................ ................................ ........... 8 Thinning type................................ ................................ ................................ .................. 9 Timing of thinning ................................ ................................ ................................ ........... 10 Sub-regional Level Planning ................................ ................................ .............................. 12 Sub-regional level objectives................................ ................................ .......................... 12 Impacts of commercial thinning ................................ ................................ ............... 13 Landscape-level Planning ................................ ................................ ................................ .. 15 Visual landscapes ................................ ................................ ................................ .......... 15 Biodiversity................................ ................................ ................................ ..................... 15 Forest health ................................ ................................ ................................ .................. 15 Stand-level Planning ................................ ................................ ................................ ........... 17 Management objectives................................ ................................ ................................ .. 17 Stand selection................................ ................................ ................................ ............... 21 Reconnaissance and stand data collection................................ .............................. 22 Site and stand limiting factors................................ ................................ .................. 25 Forest health ................................ ................................ ................................ .................. 26 Tree decays ................................ ................................ ................................ ............ 26 Dwarf mistletoes (Arceuthobium spp.) ................................ ................................ ..... 28 Root diseases................................ ................................ ................................ .......... 28 Mountain pine beetl (Dendroctonus ponderosa) ................................ .................... 29 Defoliators ................................ ................................ ................................ ............... 29 iv • GUIDELINES FOR COMMERCIAL THINNIN The economics of commercial thinning................................ ................................ ........... 30 Guidelines for decision making................................ ................................ ................ 30 Economic considerations for thinning regimes................................ ......................... 31 Silviculture Prescriptions ................................ ................................ ................................ ... 35 Components of a silviculture prescription for commercial thinning ................................ .. 35 Scheduling a thinning to meet stand structural goals................................ ...................... 42 Consideration for multiple thinning regimes ................................ ................................ .... 42 Fertilization................................ ................................ ................................ ..................... 43 Damage assessment................................ ................................ ................................ ...... 43 Project Preparation ................................ ................................ ................................ ............. 47 Site assessment for silviculture prescription ................................ ................................ ... 47 Block layout and engineering................................ ................................ .......................... 47 Forest development plan ................................ ................................ ................................ 47 Silviculture prescription................................ ................................ ................................ ... 48 Marking ................................ ................................ ................................ .......................... 48 Cruising................................ ................................ ................................ .......................... 48 Cutting permit................................ ................................ ................................ ................. 48 Project Administration................................ ................................ ................................ ........ 50 Timber sale documentation and tendering for the Small Business Forest Enterprise Program ................................ ................................ ................................ ........ 50 Timber sale administration ................................ ................................ ............................. 51 Deactivation and post-harvest inspection ................................ ................................ ....... 51 Appendices 1. Economic decision making and benchmark regimes................................ .................. 52 2. Harvesting methods for commercial thinning ................................ ............................. 60 3. Commercial thinning inspection procedures................................ ............................... 63 4. References ................................ ................................ ................................ ................ 70 Figures 1. Commercial thinning is part of an even-aged silvicultural system............................... 1 2. Harvest forecast for a hypothetical timber supply area showing the impact of commercial thinning on harvest flow ................................ ................................ .......... 3 3. Planning for a commercial thinning program starts at the forest level and flows to the landscape and stand level................................ ...............................