Intensive Silviculture

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Intensive Silviculture

• Unit 12

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Intensive SilvicultureChapter 12

• Basic Silviculture Considerations
• Intensive silviculture close to population
  centers can relieve pressure on forests
• Silviculture can be used to produce whatever
  marketable product is desirable
• Intensive silviculture monocultures can be
  integrated into whole landscapes

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Intensive SilvicultureChapter 11

• Basic Silviculture Considerations
• Intensive silviculture close to population
  centers can relieve pressure on forests
• Silviculture can be used to produce whatever
  marketable product is desirable
• Intensive silviculture monocultures can be
  integrated into whole landscapes

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Intensive SilvicultureChapter 11

• Drainage
• Draining a forest site can change it into a
  different type of ecosystem
• Drainage projects can have significant off-site
  effects

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• Silviculture Systems, Coexistence, Biological
  Diversity
• Silviculture
• Theory practice of controlling forest
  establishment, composition, structure, and growth
• Harvesting techniques (regeneration methods) are
  coupled with intermediate treatments (thinning
  weed control) to form silvicultural systems
• Program of management for the entire life of an
  even-aged stand or for an entire rotation of an
  uneven-aged stand
• Coexistence in competitive world depends on three
  factors
• Coexestence through site variation
• Micro-site differences
• Micro-relief provides habitat to plants of
  different niches
• Coexistence through resource partitioning
• Herbs take advantage of low statute by maturing
  early
• Coexistence through stress and disturbance
• Species best suited to site grow rapidly and
  crowd out other species

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• Managing Stress Disturbance
• Improving the Site by Reducing Stress
• Fertilization
• Fertilization of stands will generally accelerate
  succession
• Lead to more rapid plant growth and intensity
  competitive exclusion and accelerate succession
• Fertilization of stands with open canopies
  usually results in a in a vigorous response of
  the herbaceous and shrub strata
• Fertilizer and lime can alter conditions for
  forest invertebrates, bacteria, and fungi
• Applications of municipal waste, industrial
  waste, industrial residues, and ash from biomass
  boilers may increase the exposure of wildlife to
  heavy metals and toxins such as dioxin
• Applications of municipal wastewater to forested
  sites can increase understory biomass yet cause
  reduced plan species richness

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Intensive SilvicultureChapter 11

• Drainage
• Draining a forest site can change it into a
  different type of ecosystem
• Drainage projects can have significant off-site
  effects

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Intensive SilvicultureChapter 11

• Improving the site by protection from disturbance
• Wildfire protection biological diversity
• Wildfire exclusion can change the vertical
  structure of forest stands
• Leads to development of mid-store trees and
  shrubs
• Forest normally only have overstory of large
  trees with thick fire-resistant bark
• Understory of grasses and herbs
• Wildfire exclusion can reduce the availability of
  early successional habitat

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• Improving the site by protection from disturbance
• Insects Disease Control Biological Diversity
• Insecticides have toxic effects on nontarget
  vertebrates
• DDT
• Most insecticides kill a broad range of nontarget
  insects
• Bacillus thuringiensis (kill whole order of
  insects, not just target species)
• Insecticides reduce food supplies available for
  insectivores
• Insecticide applications can lead to reduced
  pollination and fruit set
• By limiting the abundance of suitable habitat for
  pest species, integrated pest management can
  affect wildlife habitat diversity
• Exotic insects and infectious diseases can stress
  native trees and compete with native biota
• Air pollution is threatening biological diversity
  over vast areas
• Cause stress to species with varying abilities to
  respond
• One manifestation is attacks by secondary
  pathogens
• Bark beetles, aphids, root rots
• Thinned canopy allows stronger herb and shrub
  structure

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Intensive SilvicultureChapter 11

• Stand establishment
• Site preparation
• Weaken competitors and expose mineral soil
  seedbed for natural generation
• Remove competing vegetation and logging residues
  for tree planting
• Remove residues and prepare mineral soil seedbed
  for artificial direct seeding

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• Factors controlling post-disturbance response
• Character and intensity of the disturbance
• Size of area disturbed
• Growth rates of colonizing and residual plants
• Regeneration mechanisms of invading species
• Coincedence of weather, seed crop, and
  disturbance
• Density and multiplication rates of seed
  predators and competing plants
• Spatial pattern of disturbance and surrounding
  stands
• Time since last disturbance
• Character of last disturbance
• Productivity of site
• Season of year in which disturbance occurs

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• Basic Types of Site Preparation
• Prescribed burning
• Mechanical
• Crushing
• Windrowing
• Plowing
• Chemical

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Intensive SilvicultureChapter 11

• Site preparation biological diversity
• Site preparation will generally accelerate
  succession
• Light site preparation can increase wild fruit
  and forage production
• Intensive site preparation reduce fruit
  production and over time reduces the availability
  of understory plants
• Site preparation that eliminates cull trees,
  snags, and logs, can reduce biological diversity
• Site preparation burns may increase plant species
  diversity on the disturbed site
• Mechanical site preparation may foster greater
  plant species richness than chemical techniques

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• Artificial Regeneration Biological Diversity
• Closed-canopy plantations often lack vertical
  structure and therefore have relatively low
  species diversity
• Arrangement of plantation trees can be
  manipulated to enhance vertical structure and
  thereby support more species
• Young plantations may support more plant species
  and produce more food for herbivores than closed
  canopy natural stands, but the reverse may be
  true of older, unthinned plantations
• Planting old fields to trees can reduce available
  openland habitat
• Establishing a mixture of species can improve
  both the species richness and vertical structure
  of plantations

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• Intermediate Treatments
• Release Treatments
• Thinning
• Pruning
• Prescribed Fire

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• Release Treatments
• Freeing seedlings from noncrop competitors
• Kill competing plants, or reduce density of crop
  trees, without destroying or stressing the crop
• Quite selective

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• Release treatments biological diversity
• Release treatments accelerate succession by
  helping the crop trees dominate the site sooner
• Herbicides have longer residual effect on target
  vegetation and plant species richness than
  cutting or burning
• Herbicide applications can be modified to
  maintain or build diversity
• Where crop species is overstocked, early spacing
  treatments can help maintain diversity
• Liberation treatments can foster habitat for
  cavity-nesting wildlife
• Early release treatments can have lasting effects
  on primary cavity nesters that rely on
  shade-intolerant tree species that form soft
  snags
• Concentrating release work around individual crop
  trees makes the work more efficient and helps
  build and maintain stand diversity

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• Thinnning
• Encourage natural tendency for few large trees to
  ultimately occupy space that once supported many
  small trees
• Competition induced mortality
• Most prevalent practice of intensive silviculture
• Thinnings favor growth of selected crop trees
  wheose greater value will compensate for reduced
  overall biomass produced
• Thinnings made in even-aged stands can result in
  financial return early in rotation from sale of
  pulpwood or fuelwood
• Thinnings can salvage the biomass of trees that
  die, or about to die, from competition
• Thinnings can foster grasses, forbs, shrubs
  beneath the forest canopy for wild and domestic
  animals

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Intensive SilvicultureChapter 11

• Thinning biological diversity
• Thinnings can change vertical diversity and thus
  alter species richness
• Many birds occupy specific microhabits among
  strata of forest
• Shallow canopy will only have simple avian
  community
• Open canopy enhances herb and shrub strata
• Crown thinnings can influence the quantity and
  quality of understory forage available for
  herbivorous animals
• Shade can reduce digestability of forage
• Higher cellulose content
• Thinning can contribute to reduced forage
  production over time
• Lead to development of mid-story shade-tolerant
  species
• May intercept more light than original canopy
• Reduction in forage production

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• Thinning biological diversity
• Heavy crown thinnings can significantly alter
  microclimate within a forest stand
• Makes it colder
• Encourages food for deer
• Low thinnings and dominant thinnings can reduce
  vertical structure and species richness
• Can remove significant habitat compenents for
  species living in lower canopy or those perching
  in those strata
• Low quality trees can be removed from competition
  in ways that augment habitat diversity
• Foster greater understory response than removing
  individual trees
• Girdle
• Herbicide
• Provide forage and nesting sites for cavity using
  wildlife

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Intensive SilvicultureChapter 11

• Pruning
• Removing lower limbs from tree
• Purpose
• Promote growth of knot-free lumber
• Improve air movement through a stand
• Lessening potential of fungal diseases
• Improve access
• Reduce chance of a surface wildfire climbing
  intothe tree crowns
• Improve appearance of a stand

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• Prescribe Fire in Forests
• Used to eliminate heavy accumulations of litter
• Which can fuel destructive wildfires
• Control competition of forest understory
• Recycle nutrients
• Control certain insects and diseases
• Maintain grasslands and grassy understorys
• Decrease water used by plants on watersheds
• Control invasive species

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• Prescribed fire in forest stands and biological
  diversity
• Prescribe fire can be used to control the degree
  of vertical diversity produced by thinning
• Thinning can stimulate growth of understory
  plants
• Special habitat elements such as den trees and
  fruit trees can be destroyed during prescribed
  fires
• Fires burn whatever is burnable
• Burning at different times of the year promotes
  habitat diversity
• Moisture content of soils and forest litter
  varies with the season
• Effects on each plant type vary depending on
  timing of burn
• Prescribed burning can influence the quality and
  quantity of forage for herbivorous animals
• Fires make new growth more nutritious, more
  digestable, and more accessible
• Frequency and intensity of prescribed burns can
  influence the fruit production of forest
  understory

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Intensive SilvicultureChapter 11

• Summary
• Intensive silviculture increasingly important to
  growing population
• Curb demand
• Yet supply efficiently
• Silviculture focuses on individual stands
• Landscape remains the scale