lecture 10 fore 3218 forest mensuration ii lectures 10 site productivity avery and burkhart, chapter...
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Lecture 10FORE 3218
Forest Mensuration IIForest Mensuration II
Lectures 10Lectures 10
Site ProductivitySite Productivity
Avery and Burkhart,Avery and Burkhart,
Chapter 15Chapter 15
Lecture 10FORE 3218
Definition of Site Quality Definition of Site Quality
Site Site --The area in which a tree --The area in which a tree or a stand growsor a stand grows
Site QualitySite Quality -- Sum of all -- Sum of all environmental factors affecting environmental factors affecting the biotic community of an the biotic community of an ecosystemecosystem
Soil nutrients, moisture, and aerationTemperature regimesAvailable lightAmbient CO2 concentration
Climate and Soil
Lecture 10FORE 3218
Measurement of Site Quality for Wood-Measurement of Site Quality for Wood-Producing PurposeProducing Purpose
Direct measureDirect measure -historical records of yield -historical records of yield – Historical data do not exist for most sites, and Historical data do not exist for most sites, and – The actual yield can be affected by genetic The actual yield can be affected by genetic
composition, stand density, competition, and pests.composition, stand density, competition, and pests.
The most common indirect methodThe most common indirect method involves involves measurement of tree heightsmeasurement of tree heights
Lecture 10FORE 3218
Tree Height as a Measure of Site QualityTree Height as a Measure of Site Quality
Tree heightTree height is is– Sensitive to site qualitySensitive to site quality– Little affected by stand density and compositionLittle affected by stand density and composition– Strongly correlated to volumeStrongly correlated to volume
Tree height in relation to tree age has been found Tree height in relation to tree age has been found the most practical, consistent, and useful indicatorthe most practical, consistent, and useful indicator
Site index –the measure of site quality Site index –the measure of site quality – The average total height of dominant and co-dominant The average total height of dominant and co-dominant
trees in well-stocked, even-aged stands at a specific trees in well-stocked, even-aged stands at a specific index age, such as 25, 50, or 100 yearsindex age, such as 25, 50, or 100 years
Lecture 10FORE 3218
Methods of Measuring Site IndexMethods of Measuring Site Index
When the subject tree species is presentWhen the subject tree species is present– Application of site index curvesApplication of site index curves– Growth interceptGrowth intercept
When the subject tree species is not presentWhen the subject tree species is not present– Interspecies site index relationshipsInterspecies site index relationships– Environmental factors, ecosystem classification, Environmental factors, ecosystem classification,
indicatorsindicators
Lecture 10FORE 3218
Field Measurement of Site IndexField Measurement of Site Index
Select site treesSelect site trees– which are dominant or co-dominant, even-aged, which are dominant or co-dominant, even-aged,
showing no evidence of crown damage, disease, showing no evidence of crown damage, disease, sweep, crook, forking, or prolonged suppressionsweep, crook, forking, or prolonged suppression
Measure total height with a hypsometer and Measure total height with a hypsometer and breast-height age by extracting an increment breast-height age by extracting an increment corecore
At least 3 site trees are measured, the At least 3 site trees are measured, the number depends on ???number depends on ???
Lecture 10FORE 3218
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Age at breast-height (years)
To
tal h
eig
ht
(m)
Chen et al. 1998. For. Ecol. Manage. 102:157-165
Trembling aspen site index curves
Site Index Estimation Site Index Estimation from Total Height and from Total Height and Breast-Height AgeBreast-Height Age
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Lecture 10FORE 3218
Construction of Site-Index CurvesConstruction of Site-Index Curves
Early site-index curves Early site-index curves were constructed by were constructed by graphical techniques and graphical techniques and anamorphicanamorphic
Anamorphic curves can be Anamorphic curves can be constructed by regression constructed by regression techniquestechniques
110ln AbbH d
XbbY 10
Lecture 10FORE 3218
Construction of Site-Index CurvesConstruction of Site-Index Curves
An equation for site index can be constructedAn equation for site index can be constructed
110ln iAbbSLet H=S
110 ln iAbSbi.e.,
)(ln
ln11
1
11
11
i
i
AAbS
AbAbS
Substitute b0 into original equation ( )110ln AbbH d
Rearrange )(lnln 111
id AAbHS
Lecture 10FORE 3218
Potential Problems with Anamorphic CurvesPotential Problems with Anamorphic Curves
Anamorphic curves constructed using paired Anamorphic curves constructed using paired temporary height vs. age data can be biased temporary height vs. age data can be biased because in many timber types young stands are because in many timber types young stands are associated with generally better sites associated with generally better sites – Why?Why?
Anamorphic curves assume that a common Anamorphic curves assume that a common shape for all site classes. shape for all site classes. – For many species, height growth exhibits pronounced For many species, height growth exhibits pronounced
sigmoid shapes on higher-quality sites, and “flatter” sigmoid shapes on higher-quality sites, and “flatter” shape on lower-quality sitesshape on lower-quality sites
Lecture 10FORE 3218
Polymorphic CurvesPolymorphic Curves
Polymorphic: family of site index curves display Polymorphic: family of site index curves display differing shapes for different site-index classes differing shapes for different site-index classes
Additional Reading: Additional Reading: – Chen, H.Y.H., and K. Klinka. 2000. Height growth Chen, H.Y.H., and K. Klinka. 2000. Height growth
models for high-elevation subalpine fir, Engelmann models for high-elevation subalpine fir, Engelmann spruce, and lodgepole pine in interior British spruce, and lodgepole pine in interior British Columbia. Columbia. Western Journal of Applied ForestryWestern Journal of Applied Forestry 15(2): 15(2): 62-69 62-69
Lecture 10FORE 3218
Periodic Height GrowthPeriodic Height Growth
• Growth-Intercept Method Growth-Intercept Method – – The use of height The use of height growth for some relative growth for some relative short period during the short period during the life of the stand to assess life of the stand to assess site quality site quality
Applications in intensively Applications in intensively managed standsmanaged stands
Lecture 10FORE 3218
Interspecies Site-Index RelationshipsInterspecies Site-Index Relationships
Interspecies site Interspecies site index relationshipindex relationship
Carmean. 2000. OMNR NEST WP03: 21-39.
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Site index of white birch (m)
Sit
e in
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trem
blin
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spen
(m
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Lecture 10FORE 3218
Interspecies Site-Index RelationshipsInterspecies Site-Index Relationships
Relationships to Relationships to environmental environmental factors, ecosystem factors, ecosystem classification, classification, indicatorsindicators
Soil nutrient regime
VP P M R
Site
ind
ex
(m)
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Moderately drySlightly dryFresh and moist
Chen et al. 1998. Can. J. For. Res. 28:1743-1755
Lecture 10FORE 3218
Limitations Using Site Index to Determine Limitations Using Site Index to Determine Site QualitySite Quality
Exact stand age is often difficult to determine in field Exact stand age is often difficult to determine in field situations, and small errors can cause large situations, and small errors can cause large changes in the site index estimatechanges in the site index estimate
Concept of site index is not suitable for uneven-aged Concept of site index is not suitable for uneven-aged standsstands
Site index alone may not provide a valid estimate of Site index alone may not provide a valid estimate of the growing capacity for a particular sitethe growing capacity for a particular site
Site index may change due to environmental and Site index may change due to environmental and climatic variations or management activitiesclimatic variations or management activities
Site index for one species can not be translated into Site index for one species can not be translated into a usable index for a difference species on the same a usable index for a difference species on the same site site