effect of mowing, fertilization and dominant removal on ecosystem characteristics and species trait...
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Effect of mowing, fertilization and dominant removal on ecosystem characteristics and species trait
composition.Jan Leps, Jiri Dolezal, and
David Zeleny
Department of Botany,
University of South Bohemia,
Ceske Budejovice, Czech Republic
VISTA Project
Mowing, Fertilization, Dominant removal
in factorial experiment (eight possible combinations), each in three replications
2m x 2m plots - central 1m2 (or smaller) sampled
Mowing and fertilization: feasible combinations of land (un)use types
Molinia removal: effect of dominant under different regimes
Experiment started in 1994 (baseline data)
Data from 2004 are used here
Where: Ohrazeni meadow, South Bohemia, southern part of the Czech republic
Molinion (Molinia caerulea) dominated meadow
Originally mown once a year
Traditional meadow: mown, unfertilized, without removal; up to 40 species per m2
Unmown, unfertilized, no removal: Molinia dominant, litter abundantabandoned meadow
Unmown, unfertilized, Molinia removed
Fertilized, mown, no removal (productive meadow)
Fertilized, unmown, no removal: abandoned eutrofized meadow
biomass June
biomass April
ANPP
SANPP
Number of species in 0.2x0.4m
H'
Evennes
Number of species in 0.5x0.5mlitter Aprillitter June
E0
MOWINGFERTIL
REMOV
RDA - “ecosystem properties”
Univariate Tests of Significance for spec50 (aggregaverSummary)Sigma-restricted parameterizationEffective hypothesis decomposition
EffectSS Degr. of
FreedomMS F p
InterceptMOWING
FERTIL
REMOV
MOWING*FERTIL
MOWING*REMOV
FERTIL*REMOV
MOWING*FERTIL*REMOV
Error
11881.50111881.50993.57490.00000088.17 1 88.177.37280.015285770.67 1 770.6764.44600.00000166.67 1 66.675.57490.03124016.67 1 16.671.39370.25503010.67 1 10.670.89200.3589848.17 1 8.170.68290.4207344.17 1 4.170.34840.563247
191.33 16 11.96
Number of species - Fertilisation has the fairly strongest effect (negative) - mowing and removal positive effect
unmown mown
unfertilized fertilized10
15
20
25
30
35
40
Nu
mb
er
of s
pe
cie
s in
0.5
x 0
.5 m
Molinia suppresses species richness only in unmown plots
Unfertilised plots
Univariate Tests of Significance for H' (aggregaverSummary)Sigma-restricted parameterizationEffective hypothesis decomposition
EffectSS Degr. of
FreedomMS F p
InterceptMOWING
FERTIL
REMOV
MOWING*FERTIL
MOWING*REMOV
FERTIL*REMOV
MOWING*FERTIL*REMOV
Error
88.28452188.28452605.04570.0000001.407691 1.407699.64740.0067940.598311 0.598314.10040.0598930.402281 0.402282.75700.1162980.499441 0.499443.42280.0828570.209611 0.209611.43660.2481490.040751 0.040750.27920.6044490.019311 0.019310.13240.7207682.33462160.14591
H’ (and similarly evenness) is affected mainly by mowing (positively)
Evenness: no effect is significant, but relatively largest effect of mowing
unmown mown
unfertilized fertilized1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
H'
Mowing - effect on litter; large amount of litter suppresses vegetation development in spring
Molinia - the largest producer of litter, particularly in unmown plots
Response of species traits to treatments - three matrices
Species1 Species2 Species3 Species4 Mowing Fertil RemovalPlot 1 xx.x xx.x xx.x xx.x 1 0 0Plot 2 xx.x xx.x xx.x xx.x 0 0 0Plot 3 xx.x xx.x xx.x xx.x 1 1 0Plot 4 xx.x xx.x xx.x xx.x 0 1 0Plot 5 xx.x xx.x xx.x xx.x 1 0 1Plot 6 xx.x xx.x xx.x xx.x 0 0 1Plot 7 xx.x xx.x xx.x xx.x 1 1 1
Height xx.x xx.x xx.x xx.xSLA xx.x xx.x xx.x xx.xGeoph 0 0 0 1Hemicrypt 0 1 1 0Chamaeph 1 0 0 0
Use of weighted averages - each site is characterized by average value of traits of constituent species, weighted by species abundance (e.g. proportion in biomass)
Height SLA Geoph Hemicrypt Chamaeph Mowing Fertil RemovalPlot 1 xx.x xx.x xx.x xx.x xx.x 1 0 0Plot 2 xx.x xx.x xx.x xx.x xx.x 0 0 0Plot 3 xx.x xx.x xx.x xx.x xx.x 1 1 0Plot 4 xx.x xx.x xx.x xx.x xx.x 0 1 0Plot 5 xx.x xx.x xx.x xx.x xx.x 1 0 1Plot 6 xx.x xx.x xx.x xx.x xx.x 0 0 1Plot 7 xx.x xx.x xx.x xx.x xx.x 1 1 1
For the categorial variables, we get proportion of each category.
To be analyzed by Redundancy analysis (RDA - for all variables together), or by GLM (ANOVA) for individual variables separately
-0.5 0.3
-0.3
0.4
SLAheight
leaf P
leaf N
leaf C
leaf C/N
Leaf DMC
StemDMC
date of flowering
Hemicryptoph.
Geophytes
Chamaeph.
Grasses
graminoids
forbslegume
MOWING
FERTIL
REMOV
RDA - “species traits”
(treatment specific)
-0.4 0.4
-0.2
0.5
Grass
Graminoids
Forbs
Legumes
MOWING
FERTIL
REMOV
Proportion of four (functional?) groups in various treatments.
In mown plots, other grass species replaced the removed Molinia successfully, in unmown, the empty space was occupied by forbs and graminoids
In unmown plots, there is no functional replacement for removed dominant (Molinia)
Constant and plastic traits: e.g. life form is not affected by either mowing or fertilization, it is constant. Plant height (and similarly leaf nutrient content, specific leaf area - SLA, etc.) change with condition, sometimes considerably.
Change in aggregated characteristics can be caused either by change in species composition (for height: daisy is replaced by sunflower) or by trait variability (when fertilized, daisy grows taller). [Without further study, it is impossible to distinguish pure phenotypic plasticity from genetically caused variability.]
Suggested method: Repeated measurement (=split plot) ANOVA, treatments being the between plot effects, and the two trait values being the repeated measure: nonspecific (average over treatments) and specific for each treatment. The interaction between specificity and main effect signifies variability of the trait.
fertilized unfertilized
unmown
nonspecificspecific
20
25
30
35
40
45
50
55
60
65
70
75
plan
t hei
ght [
cm]
mown
nonspecificspecific
Plant heightFerilized plots support species that are genuinely taller. Comparison of nonspecific (constant for all the treatments) and specific values suggests that in mown plots, the same species are taller in fertilized conditions.
In mown plots, the effect is more pronounced and the direction of species composition change and trait variability is the same.
Reversed question: Could species traits predict species response to treatments? (Useful e.g. in conservation studies.)
First calculate the species response to a factor (by partial constrained RDA), and then try to predict the response with species trait(s) used as predictors.
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
Maximum height (from local Flora)
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
RD
A (
fert
)
Plants not able to grow tall disappear after fertilization
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
Maximum height (from local Flora)
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6R
DA
(fe
rt)
Cirsium palustre
The approach based on aggregated averages is dependent on dominants - it is useful for studying species traits together with ecosystem functioning. The trait plasticity can be distinguised from change in species composition. However, the subordinate species are not reflected in the analyses.
The approach based on individual species needs fixed species traits (because they are predictors). It is more useful in nature conservation and biodiversity projects (e.g. to estimate, which species might be endangered due to land use changes).
Thank you for your attention!