Transcript Folie 1 - uni

Positive and negative dynamics of plantplant interactions and their functional role in
regulating ecosystem processes
Lea L.A. Märtin, SER summer school in Münster, 29.06.-03.07.2009
Ecological background
The Jena Experiment, Germany
Results from large-scale
grassland
biodiversity experiments suggest positive
relationship between biodiversity and
ecosystem functioning!
Cedar Creek, USA
Facilitation &
“Ecosystem Engineers”
(Jones 1997)
Insurance Hypothesis
(McNaughton 1977,
Tilman 1994)
log diversity
Stress Gradient
Hypothesis
(Bertness & Callaway 1994)
(Berendse 1979,
Loreau & Hector 2001)
total resource
use
log diversity
Niche Complementarity
Theory
altered belowground processes
log diversity
facilitation
(from legumes)
(Naeem & Thompson 1994,
Tilman 2000)
ecosystem
stability
Biodiversity-Productivity
Relationship
productivity
N2 fixed by legume
abiotic stress
Overview
Garchinger
Heide
(restoration
ecology)
Stress
Grad. ecosystem
Stress Grad.
BD-Prod,
BD-Prod,
We
aim
to
understand
processes
responsible
for
varying
Theoretical background
Hyp.,
Hyp.,
Stress Grad. Hyp.
N-transfer
Insurance Hyp.
N-transfer
services in grasslands along gradients
of
Biotic gradient
X
X
X
(X)
(species richness)
a) species and functional diversity
Abiotic gradient (nutritional
X
(X)
X
status in soil)
b) abiotic factors like soil N-status and (weather) disturbances
FCE
(facilitationcompetition)
AsDe
(assemblydecomposition)
EVENT
(biodiversity–
climate change)
Methods:
Fluorescence
measurements + LAI
d15N natural abundance
to apply the results to restoration projects.
X
X
d15N tracer study
Cover + Biomass
X
X
X
X
(Xplanned)
Restoration Project „Garchinger Heide“
• restoration of calcareous grassland
• treatments applied in 1993 (collaboration: Kathrin Kiehl)
• August 2007: collection of plant pairs (legume+neighbour)
• pairs of target (stress tolerant) and non-target (mesic) species were collected
• evaluation of d15N and N-content of plant leaves
no topsoil removal
topsoil removal
Restoration Project „Garchinger Heide“
H1: The presence of a legume species will facilitate N-content of neighbouring
species.
H2: Different legume species will affect the d15N signature and the N-content of neighbouring species differently.
H3: Positive interactions, reflected by d15N and N-values, will increase along a
gradient of abiotic stress.
Collected species:
Tri = Trifolium pratense L. (legume)
Lot = Lotus corniculatus L. (legume)
mesic species:
Gal = Galium mollugo agg. (herb)
Ant = Anthyllis vulneraria L. s. l. (legume)
Dor = Dorycnium germanicum (Gremli) Rikli (legume)
Hel = Helianthemum nummularium (L.) Mill. s. l. (herb)
stress-tolerant species:
Restoration
Projectbetween
„Garchinger
Heide“
Close correlation in
non-legume species
the foliar
δ15N and
• number of target species, the ratio NH4+:NO3- in soil
No close correlation between the foliar δ15N and
soil removal
soil removal
•
total number of species,
other
soil
N-parameters
(N
,
N
, δ15N)
min
total
hay transfer
no
hay
transfer
no soil removal
hay transfer
no soil removal
no hay transfer
Open questions:
• Why are the δ15N values so extremely low in +r+h treatment?
• What are is the reason for the successive increase in the δ15N values with
decreasing restoration effort?
• Why does the hay transfer affect the δ15N signal over such a long time
periode?
Restoration Project „Garchinger Heide“
H1: The presence of a legume
Neither
species
confirmed
will facilitate
nor rejected:
N-content of neighbouring
species.
• method does not work to investigate facilitation in soil-removal treat.
H2: Different legume species will affect the d15N signature and the N-content of neigh• soil N-dynamics seems to override facilitation signal
bouring species differently.
• now we try to separate N-dynamics signal from facilitation signal
H3: Positive interactions, reflected by d15N and N-values, will increase along a
gradient of abioticdstress.
15N-signal as indicator for restoration success?
-soil removal/-hay (mowed)
-soil removal/+hay
+soil removal/-hay
+soil removal/+hay
Thanks to all the people who helped and supported me during my work!
FZ Jülich:
FZ Jülich:
FZ Jülich:
Vicky Temperton,
Uwe Rascher,
Ulrich Schurr,
Beate Uhlig
Vicky Temperton,
Uwe Rascher,
Ulrich Schurr,
André Moersch
Vicky Temperton,
Uwe Rascher,
Ulrich Schurr,
Edelgard Schölgens
Manfred Michulitz and his
team (ZCH) for element
analysis
Universität Bayreuth:
Andreas Lücke (ICG-4) for
15N-analysis
Andreas Lücke (ICG-4) for
15N-analysis
Carl Beierkuhnlein,
Anke Jentsch,
Jürgen Kreyling,
Mirjam Pfeiffer,
Christin Merczynski,
Kerstin Grant,
Thomas Gollan
TU München:
Kathrin Kiehl (now in OS),
Daniela Röder
and:
Ingo Scholz
Thank you for your
attention!