Forestry & Society Silviculture HORT/RGSC 302 J.G. Mexal Fall 2005.
Traditional Forestry where timber management is based mostly on the economics of commodity...
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• Traditional Forestry where timber management is based mostly on the economics of commodity extraction
Silviculture (Forestry)???
Plant Seedlings
Grow Trees, Apply
Fertilizers, Pesticides
Cut Trees
Burn Slash
REPEAT
Traditional Forestry
Collecting leaves for fodder (animal food), Himalayan India
-this is illegal
In Nepal, 40% of annual feed of buffalo is leaves, 25% for a cow.
In dry tropical forests, livestock not survive without forest grazingRef: Patel-Weynand & Vogt 1999
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???
Palm oil production big in Asia, right converted tropical rain forest, lower right palm oil fruit, left red colored palm oil (used in cooking)
CONVERSION FORESTS INTO AGRICULTURE: Former tropical forests now terraced palm oil plantations
ECOTOURISM LODGES
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
RESULT: OVERHARVESTING RESOURCE
Sri Lanka
Southwest Mexico – pine needles collected from forests to add to agricultural fields, nurseries as fertilizer
CONSERVATIONFOREST
PRACTICES
Sustainable Forestry
ECONOMICS/GLOBAL
MARKETS
Sustainable Forestry
We have struggled with minimizing our ecological footprint on the landscape and determining our capacity to survive on a smaller land base
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BIOSPHERE 2 Arizona
FOOD
Wildlands
PEOPLE
TOTALLY HUMAN CONSTRUCT AND MANAGED
BIO 2, Arizona
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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 13
Definitions:
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. 14
Definitions: (cont’d)
Photographer: Chris Schnepf, University of Idahohttp://www.forestryimages.org/browse/detail.cfm?imgnum=1174018
CLEARCUT
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Sustainable forestryVariable 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?
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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
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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
http://www.invasive.org/browse/detail.cfm?imgnum=4799015
Green tree retention
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Woody Debris
Brown cubical rot
Photographer: Chris Schnepf, University of Idahohttp://www.forestryimages.org/browse/detail.cfm?imgnum (1169021, 1171003, 1171065)
Snags
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Photographer: Chris Schnepf, University of Idahohttp://www.forestryimages.org/browse/detail.cfm?imgnum=1171066
Snags
http://www.forestryimages.org/browse/detail.cfm?imgnum=1171058
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Photographer: Chris Schnepf, University of Idahohttp://www.forestryimages.org/browse/detail.cfm?imgnum=1172046
Huckleberry
http://www.forestryimages.org/browse/detail.cfm?imgnum=1172048
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?
Complexity and interactions within an ecosystem
ForestsPast: 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 productsRecreational opportunitiesWildlife habitatSustainable flow of clean water
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What’s in a forest?• More than just large vertebrates; 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
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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
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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 26
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 27
CLAMS
Exp. #1 - Instant hot heat
Put in BOILING WATER
Exp. #2 - Slowly increase heat
Put in COOL WATER and heat slowly
Changes in our ecosystem may be slow and not apparent. For example, FOREST HEALTH – when will you detect the problem? 28
Mt. St. Helens, 1980 29
Mt. St. Helens, 1980 – surrounding landscape 30
Mt. St. Helens, 1980 – surrounding landscape 31
Mt. St. Helens, covered the surface of the ground, most soils in PNW formed from volcanic materials (tephra) 32
• 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
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Important lessons ecologists learned from the eruption of Mt. St. Helens:
• Educated us about how forests respond to catastrophes 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 to how we manage for natural forest processes (mimic?).
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Important lessons ecologists learned from the eruption of Mt. St. Helens: (cont’d)
http://outreach.forestry.oregonstate.edu/ecosystem/ppt/Puettmann.pdf35
http://outreach.forestry.oregonstate.edu/ecosystem/ppt/Puettmann.pdf36
15% aggregated retention with no visual impact mitigation
15% dispersed retention with no visual impact mitigation
15% dispersed retention with visual impact mitigation
15% aggregated retention with visual impact mitigation
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.
http://www.cfr.washington.edu/research.demo/research/social_perceptions/Social_perceptions_text.htm37
Host: Douglas-fir Pseudotsuga menziesii (Mirbel) Franco Photographer: Doug Maguire, Oregon State University Wilmer Location:Oregon, United States http://www.invasive.org/browse/detail.cfm?imgnum=2714011
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Wildlife scientists prefer aggregated spatial patterns; Hydrologists like a dispersed spatial pattern
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, wildlife habitat, or recreation. It involves consideration of three basic principles:
1. Incorporation of biological legacies (features of pre-
disturbance forests) into harvesting prescriptions
2. Incorporation of natural stand development processes into intermediate treatments
3. Allowing appropriate recovery periods between regeneration harvests
http://ncrs.fs.fed.us/fmg/nfmg/fm101/silv/p4_ecology.html
Principles of Ecological Forestry(or New Forestry or Ecosystem Management)
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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.
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• 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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Lessons learned