Oral presentation at INTECOL 2013, London.

1. From trend to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
Jan H. Wanink & Ronald Bijkerk
Koeman en Bijkerk bv
Ecological Research and Consultancy
P.O. Box 111, 9750 AC Haren, The Netherlands
j.h.wanink@koemanenbijkerk.nl

2. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
BACKGROUND
TRADITIONAL METHOD
PROBLEM DEFINITION
ALTERNATIVE METHOD
WHY USE THE ALTERNATIVE?
CASE
STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
CONCLUSIONS

3. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
BACKGROUND
Environment managers increasingly have to take intervention
measures to meet ecological standards requested by, for instance,
the European Water Framework Directive
Such intervention measures often come with the obligation to
monitor for their effects

4. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
PROBLEM DEFINITION
Determination of statistically significant trends in response
parameters is commonly inhibited by large seasonal fluctuations in
the tested parameters
Using trend analysis, one can detect significant intervention effects
after several years only, hence making monitoring expensive

5. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
TRADITIONAL METHOD
Common practice: monitoring for at least five years, after which
intervention effects are evaluated using trend analysis

6. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE METHOD
Some years after the intervention measure: one-time sampling of
many paired stations
Only one station of each pair is subjected to the measure under
study
ALTERNATIVE
METHOD
The results are tested with pairwise statistical tests
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS

7. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
WHY USE THE ALTERNATIVE METHOD?
1) No seasonal distortion of the data >> statistical significance of
intervention effects can be determined more easily

8. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
WHY USE THE ALTERNATIVE METHOD?
2) Lower number of samples to analyse >> cheaper
PROBLEM
DEFINITION
TRADITIONAL
METHOD
Traditional
Alternative
Number of stations
10
200
Sampling frequency per year
9
0.2
Number of sampling years
5
5
450
200
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
Number of analyses (x € or £)

9. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
CASE SUDIES FROM DITCHES AND CANALS

10. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
CASE SUDIES FROM DITCHES AND CANALS
1) agricultural buffer strips
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
2) natural banks
1) mammal ladders

11. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
1) agricultural buffer strips
Poster B2.38 ̶ Wednesday August 21, 18:15 – 19:30
Testing for effects of agricultural buffer strips on the ecological
quality of adjacent surface waters

12. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
1) agricultural buffer strips
Buffer strips between farmland and adjacent watercourses
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
Fertilization and spraying of the strips prohibited

13. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
1) agricultural buffer strips
51 paired sampling stations
Sampled after 2 – 3 years
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS

14. INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
Jan H. Wanink & Ronald Bijkerk
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
1) agricultural buffer strips
Lower concentrations of N-compounds at A-stations
PROBLEM
DEFINITION
TRADITIONAL
METHOD
Variable
H1
t
n
p
Total P
A<B
1.08
41
0.8573
Total N
A<B
- 2.42
50
0.0095
Ammonia
A<B
- 2.21
37
0.0169
Nitrate
A<B
- 2.18
40
0.0175
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS

15. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
2) natural banks
Construction of natural banks along canals
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
(intervention measure to meet ecological standards WFD)

16. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
2) natural banks
Testing effects on macroinvertebrates

17. INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
Jan H. Wanink & Ronald Bijkerk
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
2) natural banks
Significant effects found for cluster 1
BACKGROUND
PROBLEM
DEFINITION
Sample size of cluster 2 too small
Power analysis used to predict optimal sample sizes
TRADITIONAL
METHOD
Tested parameters (WFD metrics)
DN = Dominant Negative indicator species
P = Positive indicator species
EQR = Ecological Quality Ratio
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
Stations
n
Δ %DN
Δ %P
Δ EQR
Cluster 1
9
-7
11
0.2
Cluster 2
4
-8
6
0.1
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS

18. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
3) mammal ladders
Sloping escape routes for mammals trapped in a canal
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
Two ladders per location, at opposite sides of the canal
Expected additional function: fish habitat

19. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
3) mammal ladders
One year after construction: testing by electrofishing
BACKGROUND
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
At 10 locations: 20 m inside and 20 m outside the two ladders

20. INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
Jan H. Wanink & Ronald Bijkerk
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
3) mammal ladders
EQR higher inside at 8 out of 10 locations (L)
BACKGROUND
PROBLEM
DEFINITION
Mean difference: 0.13 (13% of metric width)
Inside scores one class higher (good) than outside (moderate)
TRADITIONAL
METHOD
WFD classifications, based on Ecological Quality Ratio (EQR)
ALTERNATIVE
METHOD
bad
poor
moderate
good
high
WHY USE THE
ALTERNATIVE?
EQR
L-avg
p
inside
0.68
<0.05
outside
0.55
L-1
L-2
L-3
L-4
L-5
L-6
L-7
L-8
L-9
L-10
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
0.65 0.63 0.71 0.55 0.77 0.77 0.80 0.56 0.73 0.69
mammal ladders
CONCLUSIONS
0.33 0.72 0.49 0.62 0.59 0.59 0.70 0.33 0.70 0.44

21. Jan H. Wanink & Ronald Bijkerk
INTECOL 2013
Conservation management and policy
London, UK
August 20, 2013
From time-series to one-time pairwise testing
statistical and economic optimization in the evaluation of intervention effects in seasonal environments
OVERVIEW
CONCLUSIONS
BACKGROUND
Pairwise sampling and testing to evaluate intervention effects is:
PROBLEM
DEFINITION
TRADITIONAL
METHOD
ALTERNATIVE
METHOD
● effective
● relatively cheap
Effects on fast responding parameters can be shown quickly
WHY USE THE
ALTERNATIVE?
CASE STUDIES FROM
DITCHES AND CANALS
agricultural buffer strips
natural banks
mammal ladders
CONCLUSIONS
Preferably, sampling design should precede the measures