Uni-Bayreuth grafik-uni-bayreuth



Role of legume presence in modifying plants response to extreme weather events in temperate grassland

Mohammed Abu Sayed Arfin Khan1, Kerstin Grant1, Carl Beierkuhnlein2, Juergen Kreyling2, Anke Jentsch1
1 Disturbance Ecology, University of Bayreuth, Germany
2 Biogeography, University of Bayreuth, Germany

O 3.7 in Ökosysteme: Funktion und Leistungen

11.10.2012, 16:00-16:15, H8

Nitrogen-fixing legumes have considerable effects on grassland ecosystems. However, little is known about whether legumes facilitate primary productivity of grasslands even in the face of extreme weather events. Here, we examine how the presence of a legume species modifies above-ground net primary productivity (ANPP) of non-legume grassland species under experimentally simulated, annually recurrent drought and, respectively, under heavy rainfall events. We do so by comparing responses of three non-legume grassland species with versus without legume presence during the years 2007-2010. Experimental grassland communities were annually exposed to local 100 or 1000-year weather extremes according to extreme value statistics. Legume presence had significant effects on ANPP of legume neighbors, i.e. target species growing under legume presence, compared to non-legume neighbors, i.e. target species growing under legume absence. Legume neighbors had significantly lower δ15N, higher plant N content and N concentration compared to non-legume neighbors. Extreme weather events also had significant effect on ANPP of both legume and non-legume neighbors. Although we observed evidence of a significant positive legume effect on ANPP of legume neighbors under heavy rainfall, ANPP of legume neighbors did not significantly vary under recurrent drought conditions. The main reason behind this non-significant legume effect in the face of drought (versus the significant effect under control) was probably the reduced N uptake ability of grassland species under conditions of soil water deficit. We conclude that the presence of a legume species could not effectively contribute to the buffering against negative effects of extreme drought events on ANPP of neighboring species in temperate grassland.

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Letzte Änderung 21.09.2012