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!