SILVICULTURE SILVICULTURE 10/8/2018. Ecological forestry (Ecosystem management)

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1 SILVICULTURE SILVICULTURE Dave Peterson University of Washington School of Environmental and Forest Sciences Thanks to Kristi McClelland, Boyd Evison, and Greg Ettl Silviculture The science and art of growing and tending forests for the production of wood and other benefits Conduct a risk assessment for growing trees, then implement risk management and a management plan throughout the life of a stand Regardless of definition: Operational objectives are needed to meet your vision and goals Ecological forestry (Ecosystem management) Forestry that mimics natural disturbance processes with a goal of providing enhanced ecosystem services and values: Biological diversity Diverse composition and structure Wildlife habitat Timber opportunities Ecological forestry (Ecosystem management) Focus on large landscapes Retain biological legacies (e.g., logs, snags) Promote stands with heterogeneous ages and spatial patterns Connect forest health and resilience with disturbance regimes Forest stewardship Management by caring for, promoting, protecting, renewing, or re-establishing forests and associated resources This benefits both the landowner and natural resources This promotes each landowner's objectives, best management practices, and legal requirements 1

2 What is a healthy forest? Has the ability to sustain desired tree species and biophysical processes Provides habitat for desired vegetation and animals Accommodates the present and future needs of people for a variety of values, products, and services Note: A healthy forest can have unhealthy and dead trees Silviculture starts with Forest understanding Ecological the fundamental Characteristics biophysical requirements of different tree species Water Temperature Sunlight / shade tolerance Nutrients Insects and disease Microbiota / fungi Then match these requirements with your goals and actions Native trees and plants Healthy forests Wildlife habitat Tree growth Healthy soils Water resources Income Aesthetic values Silvicultural practices will help you achieve your goals Many factors determine the future of your forest land Owner s goals and objectives Biological capabilities of location Current condition/health of stand Weather events Skills of landowner and operator Planning is critical! 2

3 Different tree species have different requirements and potentials The amount of light required to photosynthesize varies greatly among tree species Characteristics such as water requirement and shade tolerance are important criteria in determining silvicultural alternatives that have a high probability of success Very Tolerant Tolerant Interm. Tolerance Intolerant Very Intolerant Western hemlock Western redcedar Pacific silver fir Alaska yellowcedar Mountain hemlock Grand fir Subalpine fir Sitka spruce Bigleaf maple Cascara Shore pine Western white pine Inland Douglas-fir Pacific madrone Douglas maple Cottonwood Oregon white oak Coastal Douglas-fir Noble fir Ponderosa pine Red alder Lodgepole pine Western larch Hooker s willow How do you start? First, evaluate what you have Know your land Map your stands Different stands Tree & vegetation inventory Riparian resources Forest health issues Soil types Wildlife habitat Can you see into the future??? Silviculture affects multiple aspects of forest management Wildfire hazard abatement Tree density management Timber harvest Tree planting Creating wildlife habitat 3

4 Silvicultural treatments help you manage toward your goals Knowledge of Many Silvicultural Pathways NO ACTION The starting point for active management 1999 RETENTION DELAY THIN THIN, LATER RETENTION Site preparation Depends on your objectives and resources Consider soils, topography, vegetation, animals, fuel loads Availability of equipment Vegetation management Site preparation Move and/or modify slash to allow access for planting Reduce plant competition and modify animal habitat Reduce fire hazard where necessary Site preparation Too clean! Conifer stand initiation Easier said than done? 4

5 Conifer stand initiation challenges Matching species to site Unsuitable or poor quality planting stock Improper handling and storage Competition with other vegetation for water and light Animal damage Shade Wet soil Drought Frost Browse 1 = intolerant 5 = tolerant Douglas-fir seed transfer zones Red alder seed transfer zones Reforestation = tree planting Successful regeneration requires: Seedlings that are healthy and adapted to the climate and site Seedlings that have been handled, stored, and planted correctly Favorable microsites for planting Minimal competition from other vegetation during early development The right plant in the right place Microsite (amount of sun/shade, soil moisture, soil depth) Ease of establishment Potential for root growth Potential mature height Adequate spacing for vigorous growth 5

6 Site class assigns growth potential to general categories How to plant Douglas-fir, 50-year old trees Site I = 135 feet + BEST Site II = feet GOOD Site III = feet AVERAGE Site IV = - 95 feet BELOW AVERAGE Site V = < feet POOR Common mistakes Determining planting density (stocking level) SPECIES TREES PER ACRE SPACING BETWEEN SEEDLINGS (ft) Douglas-fir x14-12x12-8x8 Western hemlock x14-9x9-8x8 Lodgepole pine x14-10x10-9x9 Red alder x14-12x12-9x9 Controlling animal damage Mechanical barriers - Plastic mesh (but can damage seedlings) - Bud caps Repellants Western white pine x14-10x10 Western redcedar x14-12x12-8x8 Difficult to implement at a large scale Washington Forest Practices Act: 190 tpa westside, tpa eastside surviving after 3 years 6

7 Seedling support brush control Thinning to modify structure The decision to thin or not thin should happen at the time of planting Your desired product at harvest will dictate your thinning decision As trees grow over time, competition increases and they differentiate into crown classes Even-aged stands Dominant Co-dominant Intermediate Suppressed Mortality Multi-aged stands Even-age vs. Multi-age Even-age 1 or 2 age classes Narrow distribution of diameter classes Result of disturbance or harvesting method (shelterwood, clear cut) Rotation: beginning and end in terms of economic or biological maturity Multi-age 3 or more age classes Wide distribution of diameter classes Created by periodic removals throughout all diameter classes Perpetual cover with regeneration a goal of each cutting cycle 7

8 Thinning keeps trees and understory plants healthy and vigorous and sometimes less vulnerable to crown fires Thinning helps capture the capability of a site and allocate it to selected trees Hopefully when the trees are this size and continuing through their life time Failure to thin can reduce tree growth and vigor Thinning Pre-commercial Commercial Photo courtesy of Peter Kolb, Montana State University. Precommercial thinning Commercial thinning years old Cut trees are left on Sapling / pole the ground John Keller 2007 Andy Perleberg 8

9 Diameter breast height rule (handy guide for thinning) Avg. DBH in inches converted to feet = distance between trees Example: Avg. DBH = 10 inches; distance between trees = 10 feet See tables and other info in handout Height/diameter ratio (thinning risk guide) Tree height divided by diameter expressed in feet Example: 80-foot tree with 10-inch DBH = 96 Low risk for breakage H/d < 60 High risk for breakage H/d > 80 Stand density diagram Variable retention stands Variable density thinning Various spatial patterns of different tree densities Target: 20% open stands 20% dense stands 60% standard thin This can vary there are no rules. PA Skip Skip Gaps can be different sizes 0.6 acre 0.1 acre 9

10 Variable density thinning Example stand from Pack Forest, WA Pruning can achieve different objectives Harvested once in treatments: -- Thin to -- Thin to Thin to -- Clearcut (gaps) -- No harvest (skips) Planted 33 of Douglas-fir, w. hemlock, and w. redcedar where harvested PA Skip Skip Wood quality Wildlife habitat Forest health Lower fire hazard Aesthetics John Keller Pruning Removal of tree s lower branches: Generally 8-foot lifts Never more than 1/3 of live crown at a time Start pruning when small (4-6 inches DBH) In praise of hardwoods Hardwoods add diversity, especially in riparian areas Wildlife habitat Red alder and bigleaf maple have high value for wood products Firewood Resistance to conifer diseases Red alder fixes nitrogen Can underplant western redcedar Red alder thinning strategies Red alder stand density after thinning 10

11 Fertilizer application Potential for faster tree growth Applying nitrogen on low-nitrogen soils is most common Test your soil and foliage first Check with an expert about application rate Stay away from water In conclusion Manage your forest for tree species and other plants that are best adapted to local conditions. Promote a diversity of species, structures, and patterns to provide resilience in the long term. Decisions about forest management today will affect the condition of your forest in future decades. Most of your management actions will work, but some may not. This is normal. There are always options for adjusting your management plan help is available! Forest management starts here The best time to plant a tree was 20 years ago The second best time is today Management challenge #1 You bought your property 5 years after most of it was clearcut. Young red alder thickets now dominate the slopes, and salmonberry thickets dominate the level areas. Little natural regeneration has occurred. How would you manage this situation to promote conifer regeneration and growth? (Group 1) How would you manage this situation to promote hardwood regeneration and growth? (Group 2) Other ideas on how to manage? Management challenge #2 Red alder, about 70 years old, dominates 5 acres of your property. Many trees are 16 inches diameter and have good growth form; many trees have small crowns and are not vigorous; some have died. The understory contains mostly salmonberry and scattered small-diameter western redcedar and western hemlock. How would you manage this situation in the short term and long term to promote a productive, resilient forest? 11