elucidating the mechanisms behind successful indicators of biodiversity joshua lawler national...
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Selecting Areas to Protect Biodiversity Maximize the representation of biodiversity Provide for viable populations and functioning ecosystemsTRANSCRIPT
Elucidating The Mechanisms Behind Successful Indicators
of Biodiversity
Joshua Lawler National Research Council / U.S. Environmental Protection Agency
Denis WhiteU.S. Environmental Protection Agency
Lawrence MasterNatureServe, Boston, Massachusetts USA
Overview
1. What surrogates are and why we use them
2. A comparison of surrogate group performance in two regions
3. An investigation of four potential explanations of surrogate group performance
Selecting Areas to Protect Biodiversity
• Maximize the representation of biodiversity
• Provide for viable populations and functioning ecosystems
Surrogates of Biodiversity
• Lack of data requires shortcuts
…successful shortcuts
Surrogates of Biodiversity
• Indicators
• Focal species
• Umbrellas
• Keystones
Testing Surrogates
• Correlations
• Hotspot Overlap
• Complementarity 020406080
100120140160
0 10 20 30 40
Amphibian species richness
Bird
spe
cies
rich
ness
Why do results differ?
• Types of tests are often different
• Different surrogate groups are tested
• Studies are conducted at different scales
• Location
How do surrogates work?
Study regions
Data: sampling grid
~650 km2
Species Occurrence Data
Compiled by The Nature Conservancy and Natural Heritage Programs.
Species Taxon East West
Fish 251 79
Birds 208 267
Butterflies 150 172
Mussels 93 6
Amphibians 78 34
Mammals 76 142
Reptiles 64 29
Site Selection
Stochastic optimization:
simulated annealing
A Comparison of Surrogate Performance
Is there consistency in the performance of surrogate groups across regions ?
East vs. West%
Non
-sur
roga
te g
roup
spe
cies
cov
ered
Surrogate group
EastWest
0102030405060708090
100
Conclusions
• Amphibians, reptiles, and mussels are better surrogates in the east.
• Mammals, birds, and butterflies are better surrogates in the west.
• Fish and rare species are the best surrogates in both regions
Why?
How do surrogates work?Or
What makes a good surrogate?
• They represent biodiversity hotspots
• They are taxonomically diverse
• They are rare
• They (as a group) inhabit diverse environments
Analysis of 100 groups of surrogates
• randomly selected 100 sets of 20 species from a pool of 920 species
• Selected sets of sites to include all species in each set at least one time
• compared performance of each group to group attributes including:
- hotspot overlap- taxonomic diversity- mean range size- environmental diversity
Performance of randomly selected surrogates
0
5
10
15
20
25
30
35
40
45 50 55 60 65 70 75 80
% Coverage
Freq
uenc
y
Hotspots
404550556065707580
3 4 5 6 7 8
% overlap with richness hotspots
% C
over
age
Taxonomic diversity
404550556065707580
4 5 6 7 8404550556065707580
2 7 12 17
% C
over
age
Classes Orders
Families
Genera
404550556065707580
8 13 18404550556065707580
14 16 18 20 22
%
Cove
rage
Range size
Maximum range diameter (km)
404550556065707580
300 400 500 600 700
% C
over
age
Environmental diversity
404550556065707580
0.3 0.4 0.5 0.6 0.7
Land-cover dissimilarity
% C
over
age
Comparison of random surrogates to the best surrogates
• randomly selected 100 sets of 20 species from the pool of 920 species
• optimally selected 100 of the “best” groups of surrogates
• Selected sets of sites to include all species in each set at least one time
• compared the two groups with respect to:- hotspot overlap- taxonomic diversity- mean range size- environmental diversity
Performance of randomly selected and optimally selected surrogates
0
10
20
30
40
50
60
% Coverage
Freq
uenc
y
45 50 55 60 65 70 75 80 85 90
RandomBest
Comparison of randomly selected and optimally selected surrogates
Attribute Random Best
Hotspot overlap (%) 6.0 (0.8) 4.7 (0.7)Taxonomic diversity: classes 6.4 (0.7) 6.3 (0.7) orders 11.0 (1.7) 11.6 (1.5) families 15.0 (1.8) 14.6 (1.9) genera 19.0 (1.1) 19.0 (1.1)Range diameter (km) 539 (68) 313 (59)Environmental dissimilarity 0.46 (0.05) 0.60 (0.03)
The simple answer
Number of sites (total area)
% C
over
age
40
50
60
70
80
90
100
0 2 4 6 8 10 12 14 16 18 20
The simple answer
Range size
Environmental diversity
Number of sites
Performance
Controlling for number of sites:Performance
0
10
20
30
40
50
60
% Coverage
Freq
uenc
y
45 50 55 60 65 70 75 80
RandomBest
Controlling for number of sites:Range Sizes
0
100
200
300
400
500
600
700
Ma x
imu m
rang
e di
a met
er
(km
)
Random
Best
Conclusions
• For relatively simple reasons good surrogate groups contain rare species that together occupy diverse environments.
• Neither taxonomic diversity nor hotspot representation appear to be key attributes of successful surrogates.
• Further research needs to be done to get to the root of surrogate performance
Acknowledgements
Pilar Hernandez, Roly Russell, Anne Guerry, John Van Sickle, National Research Council
(NRC), U.S. Environmental Protection Agency (EPA), Betsy Smith and EPA’s Regional
Vulnerability Assessment Program (ReVA)