Folie 1

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Positive and negative dynamics of plant-plant
interactions and their functional role in
regulating ecosystem processes Lea L.A. Märtin,
SER summer school in Münster, 29.06.-03.07.2009
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Ecological background
Results from large-scale grassland biodiversity
experiments suggest positive relationship between
biodiversity and ecosystem functioning!
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Overview

• We aim to understand processes responsible for
  varying ecosystem services in grasslands along
  gradients of
• species and functional diversity
• abiotic factors like soil N-status and (weather)
  disturbances
• to apply the results to restoration projects.

FCE (facilitation-competition) AsDe (assembly-decomposition) EVENT (biodiversityclimate change) Garchinger Heide (restoration ecology)
Theoretical background BD-Prod, Stress Grad. Hyp. BD-Prod, N-transfer Stress Grad. Hyp., Insurance Hyp. Stress Grad. Hyp., N-transfer
Biotic gradient (species richness) X X X (X)
Abiotic gradient (nutritional status in soil) X (X) X
Methods Methods Methods Methods Methods
Fluorescence measurements LAI X
d15N natural abundance X X
d15N tracer study X (Xplanned)
Cover Biomass X X
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Restoration Project Garchinger Heide

• restoration of calcareous grassland
• treatments applied in 1993 (collaboration
  Kathrin Kiehl)
• August 2007 collection of plant pairs
  (legumeneighbour)
• pairs of target (stress tolerant) and non-target
  (mesic) species were collected
• evaluation of d15N and N-content of plant leaves

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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 neigh-bouring
species differently. H3 Positive interactions,
reflected by d15N and N-values, will increase
along a gradient of abiotic stress.
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Restoration Project Garchinger Heide

• Close correlation in non-legume species between
  the foliar d15N and
• number of target species, the ratio NH4NO3- in
  soil
• No close correlation between the foliar d15N and
• total number of species, other soil
  N-parameters (Nmin, Ntotal, d15N)

• Open questions
• Why are the d15N values so extremely low in rh
  treatment?
• What are is the reason for the successive
  increase in the d15N values with decreasing
  restoration effort?
• Why does the hay transfer affect the d15N signal
  over such a long time periode?

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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 neigh-bouring
species differently. H3 Positive interactions,
reflected by d15N and N-values, will increase
along a gradient of abiotic stress.

• Neither confirmed nor rejected
• method does not work to investigate facilitation
  in soil-removal treat.
• soil N-dynamics seems to override facilitation
  signal
• now we try to separate N-dynamics signal from
  facilitation signal

d15N-signal as indicator for restoration success?
-soil removal/-hay (mowed)
-soil removal/hay
soil removal/-hay
soil removal/hay
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Thanks to all the people who helped and supported
me during my work!
FZ Jülich Vicky Temperton, Uwe Rascher, Ulrich
Schurr, Beate Uhlig Manfred Michulitz and his
team (ZCH) for element analysis Andreas Lücke
(ICG-4) for 15N-analysis
FZ Jülich Vicky Temperton, Uwe Rascher, Ulrich
Schurr, André Moersch Universität Bayreuth Carl
Beierkuhnlein, Anke Jentsch, Jürgen Kreyling,
Mirjam Pfeiffer, Christin Merczynski, Kerstin
Grant, Thomas Gollan
FZ Jülich Vicky Temperton, Uwe Rascher, Ulrich
Schurr, Edelgard Schölgens Andreas Lücke (ICG-4)
for 15N-analysis TU München Kathrin Kiehl (now
in OS), Daniela Röder and Ingo Scholz
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Thank you for your attention!