Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Outline
- Definition and suitable Index
-The case study
-Estimator
-Are there enough sample plots?
-How to detect significant trends.
- Pro and Contra
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Magurran:
"a suitable measure of diversity should be chosen by means of evaluating whether it fulfillscertain functions or criteria"
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
If a system contains only one characteristic, the diversity equals zero
If by a given number of charcteristics n all charcteristicsare equally frequent, the maximum diversity in a system occurs
Nagel:
4 criterions for a diversity index
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
If there are multiple independent varying characteristics, the diversity of a pool of characteristics must equal the sum of the characteristics’ diversity
Given two systems with equal distribution of characteristics and number of characteristics n and n-1, the diversity of the system with n characteristics must be higher
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
1 21
'( , ,..., ) ln( )k
k i ii
H p p p p p
Shannon - Index
1,21 1
' ln( )n m
ij iji j
H p p
Pielou's hierarchical diversity
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
H'species = 0.69
H'heightclass = 0.69
H'species = 0.69
H'heightclass = 0.69
H'spec/height = 0.69 H'spec/height = 1.38
1 21
'( , ,..., ) ln( )n
n i ii
H p p p p p
1/ 21 1
' ln( )n m
ij iji j
H p p
1 2 1/2' ' 'T H H H
1 2
2' 'TK
H H
T = 0.69
K = 1
T = 0
K = 0
(Nagel, Weber)
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
The case studyData from the Swiss National Forest Inventory
3 inventory occasions(20 Years)
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
'1,2
1 1
ˆ ˆˆ ln( )ˆ ˆ
n mij ij
i j
N NH
N N
Char. 1: Tree speciesChar. 2: BHD classes
N = Basalarea
First Step: The Estimator
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Second Step: Are there enough sample plots?
"pooled quadratmethod"
or
"randomized sample accumulation curve"
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Third Step: Jackknife pseudovalues
ˆ( ') ( 1)( )i iVP nH n VJ
VJi = Jackknife Value when missing out the i-th sample plot
VPi= Jackknife pseudovalues
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Fourth Step: Analysis of Variance
K
NFI3 (2003-2006)
NFI1(1982-1986)
NFI2 (1993-1995)
H'species/DBH
H'DBHH'species
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
pro
-can beestimated withbasic NFI data
-olderinventory's canbe used
contra
-abstract index-values
-only trend canbe interpreted
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Outlook
Are observed trends relevant to Forest Politics and Ecologists?
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Thank you for your attention ...
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Fourth Step: Analysis of Variance and TukeyGroupings
1004521.82111AA
2104521.85405AA
3104521.87048AinvnrNMeanTukey Grouping
Means with the same letterare not significantly different.H'species
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Fourth Step: Analysis of Variance and TukeyGroupings
1004521.55254C
2104521.64056B
3104521.71579AinvnrNMeanTukey Grouping
Means with the same letterare not significantly different.H'DBH
Evaluating trends in structural diversity of forest ecosystems … a Swiss case study
Porto, Dezember 2006J�rgen B�hl
Fourth Step: Analysis of Variance and TukeyGroupings
1004523.32779BB
2104523.44163ABA
3104523.54007AinvnrNMeanTukey Grouping
Means with the same letterare not significantly different.
H'species/DBH