Special Lecture Stand Structural Diversity
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Transcript of Special Lecture Stand Structural Diversity
Special lectureFORE 3128
Special LectureStand Structural Diversity
Forest Mensuration II
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Biological Diversity
• Genetic diversity • Stand level diversity () • Local landscape diversity () • Regional diversity ()
Species richness
Evenness
Structure
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Objectives
• Concepts• Classification of stand structure• Measures of stand structural
diversity
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Stand structure attributes
• Living trees• Snags, CWD• Age• Composition
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Stand structure
• Arrangement of trees in space
– Vertical– horizontal
Stand structural diversity-Variability among trees vertically and horizontally within a stand
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Why stand structural diversity?
• Ecological– A measure of biodiversity– Wildlife habitat– Ecosystem process (e.g., productivity)
• Social– Visual quality
• Management - structure based
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Vertical structure
Single-storied/normal
Multi-storied/irregular
Multi-storied/inverse J
Two-storied/bimodal
Smith et al. 1997
Frequency (stems/ha)
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Measures of vertical structural diversity
• Shannon-Weiner index (H´) • Variance of tree size (S2)
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Shannon-Weiner index (H´)
i
n
ii pp
1
ln
0.330.69
H’Stand A
Stand B
P1 P2
0.9 0.10.5 0.5
Example
1.10Stand C 0.33 0.33 0.34
P3
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Shannon-Weiner index (H´)
i
n
ii pp
1
ln
DBH
Proportion (Freq.)
DBH
Proportion (BA)
Frequency(stems/ha)
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Variance of tree size
1
)(1
2
2
n
xxn
ii
S
x
DBH
Frequency
Frequency(stems/ha)
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Horizontal structure
Random Clumped (aggregate)
Uniform
Stand 1 Stand 2 Stand 3
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Random
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Clumped
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Clumped
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Uniform
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Measure of horizontal structure
Clark and Evans’ test (C)
se
obs
DDD
C exp
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Observed mean distance
n
dD
n
ii
obs
1
= (1.5+1.8+1.5+,,,)/15= 1.493 m
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Expected mean distance
Random (Poisson) distribution
AnD
/21
exp
Standard error
nADse
07.0
291.1100/152
1 m
176.015
10007.0
m
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Clark and Evans’ test
se
obs
DDD
C exp 147.1
176.0291.1493.1
Clumped Random Regular
0-1.96 1.96
C
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Three-dimensional structure
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x
y
z
x
y
z
Structural complexity index (SCI)
n
ii
n
ii
A
ATSCI
1
1
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Problem with SCI
Stand 1 Stand 2 Stand 3
Tree heights = 5 m Tree heights = 10 m Tree heights = 20 m
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Summary• Concepts• Classification of stand structure
– Vertical– Horizontal
• Measures of stand structural diversity– Vertical
• Shannon-Weiner index • Variance of tree size
– Horizontal: Clark and Evans test– Three-dimensional: SCI
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Possible research topics
• Does increasing structural diversity affect
Stand productivity?
Silvicultural feasibility?
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How do we measure landscape structural diversity?
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Criteria for Sustainable Forest Management
• Conserving Biological Diversity• Maintenance and enhancement of Forest Ecosystem
Condition and Productivity• Conservation of Soil and Water Resources• Forest Ecosystem Contributions to Globe Ecological
Cycles• Multiple Benefits to Society• Accepting Society’s Responsibility for Sustainable
Development