Transcript Ecologie et croissance de Abies alba Mill. en peuplements purs et

49th Annual Conference
of the IAVS
Large scale mapping of soil
pH by plant presence/absence
bioindication
17/01/2006
J.C. Gégout, C. Piedallu, I. Seynave, J.C. Hervé
AgroParisTech - INRA - IFN
1
The need of nutritional direct variables for
plant distribution modelling
 Plant distribution models are built with climatic variables and
sometimes with proxies of soil resources (soil types, geology)
 Nutritional variables are of major importance to plant growth and
distribution
 Measures of soil variables are expensive. Thus, it is difficult to gather
enough measurements to make accurate maps
 Is plant species bioindication useful to map nutritional soil resources ?
2
Data
EcoPlant
3 835 floristic relevés
with pH measures
French National Forest Inventory (IFN)
Systematic sampling in forests
88 004 floristic relevés without pH measures
3
EcoPlant Indicator values
Indicator value
Response curve
Pres/abs
1
1
Response curve
0
0
Ecological variable
IV
Ecological variable
IV for 568 frequent plant species
4
Bioindication with IV
8.3
0.3
0.2
6.5
0.1
5.7
3.0
6.2
0
4.0
4.9
5.9
6.9
7.9
pH
Predicted pH : 6.0
Dryopteris filix-mas
Melica uniflora
Sambucus nigra
Predicted value : mean of species IV
Ellenberg (1974), ter Braak & Barendregt (1986)
5
pH prediction on IFN plots
88 004 IFN plots
with floristic
inventory
Mean of IV on each
plot
88 004 IFN plots +
pH_IV
6
pH mapping
IDW Interpolation
pH classes
3.0 - 3.5
3.5 - 4.0
4.0 - 4.5
4.5 - 5.0
5.0 - 5.5
5.5 - 6.0
6.0 - 6.5
6.5 - 7.0
7.0 - 7.5
7.5 - 8.0
8.0 - 8.5
lack of data
7
0
500 kms
Map validation
Measure of prediction errors
R2
^
REQM =  (1/N * (X - X2)
8
Measured pH
261 validation plots on a grid of 16 x 16 kms
Representative of French Forest
7
6
5
4
3
3
4
5
6
7
8
Mapped pH
R2 = 0.56, REQM = 0.82
8
Variables mapping by bioindication
Principle
A few expensive relevés with measures of variables to establish plant IV
A lot of cheap relevés without measures to map variables
Step
Plots variables
Sampling
Plots nb
Indicator value
Plant species & measured
variables
Stratified
according to x
few
Mapping
Plant species
Systematic
large
Map quality
Plant species & measured
variables
Systematic
few
9
A generalisable method
The databases « IV », « mapping » and
« quality » are constructed
Acidity (pH)
It is now easy to build up new maps of
resources with other EcoPlant IV
Nitrogen avail.
(C/N)
Towards new distribution models integrating
both climate and soil direct variables
IFN establish 7 000 - 10 000 new plots/year
-> Increase of map resolution
-> Possibility of monitoring by comparing maps of different periods
10
Thank you !
17/01/2006
11
Comparison of pH and C/N Maps
12
Map of the potential
distribution of Acer campestre
Validation data (88 004 plots)
Nutritional and climatic model
Présence
Absence
Climatic model
13
Climatic model, success: 54 %
Nutritional and climatic model, success: 73 %
Map of the Beech potential
productivity
14