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Silviculture (Forestry)??? - PowerPoint PPT Presentation

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Silviculture (Forestry)???. Traditional Forestry where timber management is based mostly on the economics of commodity extraction. Plant Seedlings. Grow Trees, Apply Fertilizers, Pesticides. REPEAT. Burn Slash. Cut Trees. Traditional Forestry.

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Silviculture (Forestry)???

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  • Traditional Forestrywhere timber management is based mostly on theeconomics of commodity extraction

Plant Seedlings

Grow Trees, Apply Fertilizers, Pesticides


Burn Slash

Cut Trees

Traditional Forestry

In Nepal, 40% of annual feed of buffalo is leaves, 25% for a cow.

In dry tropical forests, livestock not survive without forest grazing

Ref: Patel-Weynand & Vogt 1999

Collecting leaves for fodder (animal food), Himalayan India

-this is illegal

Significant dependence on wood for heating, cooking (~80%)

India Himalayas – cutting trees for fire wood, obviously not enough supply since this is supposed to be a forest

Sustainable use of forests???

CONVERSION FORESTS INTO AGRICULTURE: Former tropical forests now terraced palm oil plantations

Palm oil production big in Asia, right converted tropical rain forest, lower right palm oil fruit, left red colored palm oil (used in cooking)


Palms collected for roofing especially on tourist lodgings

RESULT: Belize being over harvested and illegal collection in conservation areas

International community pushing as economic viable for indigenous communities to obtain income – non-timber forest products

Has not been shown to be viable


Sri Lanka

Southwest Mexico – pine needles collected from forests to add to agricultural fields, nurseries as fertilizer




Sustainable Forestry


Sustainable Forestry

We have struggled with minimizing our ecological footprint on the landscape and determining our capacity to survive on a smaller land base





BIO 2, Arizona






  • clear-cutting – cutting all trees in an area, no trees left for regeneration or for habitat, biodiversity (number of different species)

  • variable retention harvesting –

    • don’t remove all trees (can be scattered evenly or clumped distribution or both),

    • maintain all species at some degree,

    • leave biological legacies

  • legacies – remnants in ecosystem that can be live or dead that are important in determining how ecosystems function and their resilience


Definitions: (cont’d)

lifeboating of species – structures or functions, such as coarse wood, that allow species to survive or persist after a major change in the system, or a landscape matrix that will allow species to survive in other locations that will then function as sources of species

fragmentation – changing landscape matrix of tree distribution to small patches that increases edges and disconnects forest areas from one another

structural enrichment – manage forests so structures required by species remain as legacies in younger systems and can provide habitat such as owls roost and nest in younger forests when a few old trees are left, focusing on obtaining the maximum growth of trees for harvesting without considering all the other services that could come from the forest does not allow for or provide for structural enrichment.




Photographer: Chris Schnepf, University of Idaho

  • Sustainable forestry

  • Variable retention harvesting

  • Alternative to clear cutting

  • Manage for ecological values

  • Some biological legacies left behind (e.g., big, old, large-diameter trees)

  • Questions to ask when doing variable retention harvesting

  • What should we leave?

  • How much should we leave?

  • What spatial pattern do we want to attain?


  • Sustainable forestry (cont’d)

  • Reasons to do it

  • Lifeboat species and processes

  • Structural enrichment

  • Provide variety of habitats

  • Modeled on natural processes

  • Spotted owls can nest and roost in a non-old-growth forest IF the forest has the structural characteristics of an old-growth forest – legacies – owls respond to habitat needs


Green tree retention

Host: Douglas-fir Pseudotsuga menziesii(Mirbel) Franco Photographer:Scott Roberts, Mississippi State University

Description:H.J. Andrews Experimental Forest

Location: Oregon, US

Mature forest in back

Regenerating forest in the middle



Woody Debris

Brown cubical rot


Photographer: Chris Schnepf, University of Idaho (1169021, 1171003, 1171065)


Photographer: Chris Schnepf, University of Idaho



Photographer: Chris Schnepf, University of Idaho


Complexity and interactions within an ecosystem


  • Forests

    • Past: foresters’ idea of sustainable forestry was to plant trees, grow them, cut them, burn the slash, and repeat

    • Today: foresters manage with ecological values in mind - water, recreation, aesthetics, wildlife

  • What do we want from forests today?

    • Sustainable flow of wood products

    • Recreational opportunities

    • Wildlife habitat

    • Sustainable flow of clean water


  • What’s in a forest?

    • More than just largevertebrates; also a vast number and array of small organisms (microflora)

    • Detritivores such as fungi, invertebrates, and insects extremely important to forest ecosystems because they break down organic matter – nutrients released

  • Biodiversity

    • Biodiversity can be higher in recently cut areas than in undisturbed forest, but this isn’t the entire issue

    • Must take into account the kinds of different species present and their functional roles – TYPE of biodiversity important

  • 24

    • Structure of the forest

      • Dead tree – snag – important for wildlife (habitat for cavity-dwellers such as bats)

      • Downed log – habitat, stream interaction, nutrient sources and nurse logs

      • Live tree – erosion control, habitat


    • Complexity of forest ecosystems

      • Example of important relationships:

      • spotted owls feed on flying squirrels which feed on below-ground fungi

      • Tree voles – live for many generations within a single tree – eat fir needles

      • Small organisms (detritivores) extremely important – make forest ecosystems run

      • Important things in a forest: green plants, detritivores

      • Past: natural forests of PNW called “biological deserts” because not many large organisms present

      • Today: we know that many small organisms such as fungi, insects, and other types of invertebrates are very important to forest ecosystems



    To be sustainable, it is difficult to know what to manage for since we don’t have a good ‘model’ of a system to aim for and we don’t know how the parts are put together


    Put in COOL WATER and heat slowly


    Exp. #2 - Slowly increase heat

    Exp. #1 - Instant hot heat

    Changes in our ecosystem may be slow and not apparent. For example, FOREST HEALTH – when will you detect the problem?


    Mt. St. Helens, 1980


    Mt. St. Helens, 1980 – surrounding landscape


    Mt. St. Helens, 1980 – surrounding landscape


    Mt. St. Helens, covered the surface of the ground, most soils in PNW formed from volcanic materials (tephra)


    Important lessons ecologists learned from the eruption of Mt. St. Helens:

    • Cumulative Effects - combined effects across a landscape –such as clearcutting with snow or rain effects that can result in huge erosion events

    • Legacies– their role in recovery, and how, defines our structure and function needed in management

    • Fragmentation– isolated blocks of forest with lots of edges do not provide good habitat

    • Landscape ecology–need to look at collective effect of our activities and fragmentation with isolated pockets of forests not being good habitat and not something to be managed for


    Important lessons ecologists learned from the eruption of Mt. St. Helens: (cont’d)

    • Educatedus about how forests respond tocatastrophes or disturbances.

      • Importance of survivors in the recovery process of the forests and this eventually is used to define what needs to be left in the forest for it to be sustainable – e.g., legacies (live or dead as logs or organic matter).

      • Made us rethink about fire’s role in systems and big storms that occur at decadal time scales and the legacies that they leave – this is important because it gets back tohow we manage for natural forest processes (mimic?).




    Key findings on aesthetics of cuts:

    If green-tree retention is dispersed, higher levels of retention produce higher perceived scenic beauty.

    Dispersed retention harvests require about 25% retention to avoid average perceptions of ugliness. 

    15% aggregated retention with visual impact mitigation

    15% aggregated retention with no visual impact mitigation

    15% dispersed retention with visual impact mitigation

    15% dispersed retention with no visual impact mitigation


    • Wildlife scientists prefer aggregated spatial patterns; Hydrologists like a dispersed spatial pattern

    Host: Douglas-firPseudotsuga menziesii (Mirbel) Franco Photographer: Doug Maguire, Oregon State University Wilmer Location:Oregon, United States


    Principles of Ecological Forestry

    (orNew ForestryorEcosystem Management)

    • Forest management, focused heavily on enhancing ecological complexity, is an evolving area of interest. It can be a major objective or be incorporated into management for objectives such as income, wildlifehabitat, or recreation. It involves consideration of three basic principles:

    • Incorporation of biological legacies (features of pre-disturbance forests) into harvesting prescriptions

    • Incorporation of natural stand development processes into intermediate treatments

    • Allowing appropriate recovery periods between regeneration harvests


    How do we incorporate what we’ve learned to maintain species and water quality that we value as well as to continue sustainable timber extraction?

    The key seems to be preserving ecosystem structure and processes.


    Lessons learned

    • Maintain habitat at both large and small scales; Especially by creating reserves with no resource extraction; Easier than restoring damaged habitat.

    • Maintain buffers and corridors along aquatic systems.

    • Pay special attention that roading doesn’t overly contribute to erosion and habitat fragmentation.

    • FINALLY, and only after the above factors are considered, plan for timber harvest incorporating principles learned from natural forest disturbances, such as green tree retention (“variable retention harvesting”).


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