species indicator values as an important tool in applied plant ecology session: databases and...
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Species indicator values as an important tool in applied plant ecology
Session: Databases and information systems
46th IAVS Symposium 8-14 June 2003Naples (Napoli), Italy
Martin Diekmann
Vegetation Ecology andNature Conservation Biology, IFOE
46th IAVS Symposium 8-14 June 2003, Naples
Contents
• Biological indication: Introduction
• Species responses and indicator values
• Applications of indicator values
• Indicator values and measurements
• Calibration of indicator values
• Conclusions
46th IAVS Symposium 8-14 June 2003, Naples
Examples
Indicator values for climatic and soil variables(Ellenberg et al. 1992) Indicators of habitat continuity (e.g. ancient forests)(Wulf 1997)
Indicators of management (e.g. mowing sensitivity)(Briemle & Ellenberg 1994)
Grime’s classification of species into habitat and strategy types(Grime et al. 1988)
Biological indication –making use of the specific reactions of organisms to their environment
46th IAVS Symposium 8-14 June 2003, Naples
Example: Reaction – soil or water pH (R)
1 Indicator of extreme acidity (Andromeda polifolia)2 Between 1 and 33 Acidity indicator (Pteridium aquilinum)4 Between 3 and 55 Indicator of moderately acid soils (Milium effusum) 6 Between 5 and 77 Indicator of weakly acid to weakly basic conditions (Hepatica nobilis) 8 Between 7 and 99 Indicator of calcareous or other high-pH soils (Primula farinosa)
Ellenberg values
46th IAVS Symposium 8-14 June 2003, Naples
Species responses and indicator values
Criticism: Species have no distinct ecological optima.
Gausscurve
Ecological gradient (e.g. pH)
Speciesresponse,
e.g. biomassproduction
46th IAVS Symposium 8-14 June 2003, Naples
A Gaussian response is preferable, but it is sufficient that the response is unimodal or linearly increasing/decreasing (skewed).
Most species response curves look that way, if
• The environmental variable in question is important.
• The total variation is large enough.
• The distribution of measured values along a gradient is more or less regular.
46th IAVS Symposium 8-14 June 2003, Naples
Response curves of forest vascular plants in Sweden(Diekmann, unpubl.)
Anemone nemorosa
Anemone ranunculoides
Melica nutans
Actaea spicata
46th IAVS Symposium 8-14 June 2003, Naples
Weighted site averages
Site score = (x1y1 + x2y2 + ... + xnyn) / (x1 + x2 + ... + xn)
x1, x2, ..., xn frequencies of species 1 to n;
y1, y2, ..., yn indicator values of species 1 to n.
Applications of indicator values
46th IAVS Symposium 8-14 June 2003, Naples
Weighted site averages serve to:
• Obtain information about the environment of relevés, habitat patches, grid squares, etc., and to make environmental comparisons between sites.
• Interpret ordination diagrams, by correlating the axis scores of sites with the corresponding values of measurements.
46th IAVS Symposium 8-14 June 2003, Naples
• ... calculate the size of the species pool of communities.
0 100 200 300 400
Coniferousforest
Halophytic
Tall herbvegetation
Freshwaterand bogs
Deciduousforest and
scrub
Talus andalpine
meadow
Anthropogenicheaths andmeadows
Ruderal
# species R > 6
0 20 40 60 80 100
Coniferousforest
Anthropogenicheaths andmeadows
Freshwaterand bogs
Deciduousforest and
scrub
Tall herbvegetation
Ruderal
Talus andalpine
meadow
Halophytic
% species R > 6
(Ewald, in press)
46th IAVS Symposium 8-14 June 2003, Naples
• ... predict the occurrence of species.
(Dupré &Diekmann
1998)[based on logistic regression]
46th IAVS Symposium 8-14 June 2003, Naples
• examine changes in environmental conditions and reconstruct historical site conditions on the basis of former species assemblages.
(Diekmann et al. 1999)
46th IAVS Symposium 8-14 June 2003, Naples
Weighted averages may be unreliable, if
• The plots studied are spatially highly heterogeneous.
• The environmental gradient is too short.
• The habitat is strongly affected by management (e.g. heavy grazing).
• There is a sudden environmental shift.
• The vegetation mainly responds to extremes and not to mean values.
46th IAVS Symposium 8-14 June 2003, Naples
Indicator spectra
(Diekmann 2003)
1 2 3 4 5 6 7 8 9
0
5
10
R indicator value
No.
of
spec
ies
Elm-ash forest
46th IAVS Symposium 8-14 June 2003, Naples
(Diekmann 2003)
1 2 3 4 5 6 7 8 9
0
1
2
3
4
5
6
7
8
9
R indicator value
No.
of
spec
ies
Basicolouspine forest
46th IAVS Symposium 8-14 June 2003, Naples
Indicator values and measurements
If weighted averages and measurements are
- highly correlated,We conclude that the indicator values for the variable in question work well.
- weakly correlated, there are two possible conclusions:1) The indicator values for that variable are unreliable.2) We have measured the wrong variable!
Criticism: Indicator values are not systematically derived from measurements,but mainly inferred from field experience. They may prevent us from conducting measurements!
46th IAVS Symposium 8-14 June 2003, Naples
Parameter Correlation Soil reactionpH (H2O), pH (KCl) + (Persson 1980, Degorski 1982,
or pH (CaCl2) Lawesson & Mark 2000, Wamelink
et al. 2002)+ (Rodenkirchen 1982)+ (Ellenberg 1992, Herzberger & Karrer 1992,
Seidling & Rohner 1993, Diekmann 1995, Hill & Carey 1997, Ertsen et al. 1998, Schaffers & Sýkora 2000, Diekmann, unpubl.)
Base saturation ++ (Degorski 1982, Seidling & Rohner 1993, Schaffers & Sýkora 2000)
Al/Ca ratio ++ (Seidling & Rohner 1993)Ca2+ saturation ++ (Schaffers & Sýkora 2000)Ca2+ amount ++ (Degorski 1982, Schaffers & Sýkora 2000)Total calcium ++ (Schaffers & Sýkora 2000)
46th IAVS Symposium 8-14 June 2003, Naples
Correlation measured values – weighted site scores
(Diekmann 2003)
Swedish forests
46th IAVS Symposium 8-14 June 2003, Naples
Parameter Correlation
NitrogenN PARAMETERSTotal N + (Vevle & Aase 1980, Schaffers & Sýkora 2000)
- (Hill & Carey 1997, Ertsen et al. 1998)Total C/Organic matter - (Hill & Carey 1997)
+ (Diekmann, unpubl.)C/N ratio + (Ellenberg 1992, Schaffers & Sýkora 2000)
- (Diekmann, unpubl.)Mineral N (NO3
- + NH4+) + (Schaffers & Sýkora 2000)
- (Lawesson, unpubl.)Mineral NO3
- + (Schaffers & Sýkora 2000)
% NO3- + (Schaffers & Sýkora 2000)
Total mineralisation + (Rodenkirchen 1982, Ellenberg 1992)- (Schaffers & Sýkora 2000,
Ammonification rate + (Diekmann, unpubl.)Nitrification rate + (Diekmann, unpubl.)Nitrification ratio ++ (Diekmann, unpubl.)
46th IAVS Symposium 8-14 June 2003, Naples
Correlation measured values – weighted site scores
(Diekmann 2003)
Swedish forests
46th IAVS Symposium 8-14 June 2003, Naples
Parameter Correlation
NitrogenOTHER NUTRIENTSTotal P + (Hill & Carey 1997, Ertsen et al. 1998)Available PO4
3- + (Ertsen et al. 1998, Schaffers & Sýkora 2000)
- (Lawesson, unpubl.)Total K + (Ertsen et al. 1998)Available K+ + (Hill & Carey 1997, Schaffers & Sýkora 2000)
- (Lawesson, unpubl.)Exchangeable Mg - (Lawesson, unpubl.)
VEGETATION-DERIVED PARAMETERSBiomass/”standing crop” + (Boller-Elmer 1977, Briemle 1986)
++ (Melman et al. 1988, Hill & Carey 1997, Ertsen et al. 1998, Schaffers & Sýkora 2000)
N accumulation of plants ++ (Ertsen et al. 1998, Schaffers & Sýkora 2000)Foliar N concentration ++ (Thompson et al. 1993)Tissue N concentration + (Schaffers & Sýkora 2000)
46th IAVS Symposium 8-14 June 2003, Naples
Calibration of indicator values
46th IAVS Symposium 8-14 June 2003, Naples
Three calibration approaches:
1) Observation of single species.
2) Indirect calibration on the basis of large phytosociological data sets.
3) Measurements of environmental parameters.
Criticism: Species may shift in their responses, especially across geographical gradients.
46th IAVS Symposium 8-14 June 2003, Naples
(Hill et al. 2000)
46th IAVS Symposium 8-14 June 2003, Naples
-3 -2 -1 0 1 2 3 4 5
-3
-2
-1
0
1
2
3
4
5
Calibrated R indicatorvalues in The Netherlands
Cal
ibra
ted
R in
dica
tor
valu
es in
Gre
at B
rita
in
R-squ adj. = 0.850
Galiumpumilum
(Diekmann 2003; data from Hill et al. 1999 and Schaffers & Sýkora 2000)
46th IAVS Symposium 8-14 June 2003, Naples
• Indicator values are subjective, but if they coincide with the ecological optima of species, they are very useful for many applications.
• Indicator values need to be verified by measurements and calibrated.
• Whenever possible, the use of indicator values should be accompanied by measurements.
Conclusions