Legacy of episodic tropospheric ozone exposure on a weed community

MARTINEZ-GHERSA, M.A.; LANDESMANN, J.B.; MENENDEZ, A.I.; FOLCIA, A.M.; GUNDEL, P.E.; QUARLERI, N; VENTURA, L.; ROMERO A.M.; GHERSA, C.M.

Chicago, USA

Congreso; Annual Meeting of Weed Science Society of America.; 2008

Weed Science Society of America

It is well documented that domestic animal grazing and conversion of natural habitats to agriculture has led to marked changes in species diversity and composition at local and global scales, altering networks of feeding interactions (food webs). It is also clear that climate change and tropospheric pollution are profoundly affecting community structural and functional characteristics enhancing habitat change, which is the leading global cause of species extinctions and alterations in abundance of persisting species. Previous studies have demonstrated that land use history impacts on actual habitat quality and community structure; however the importance of troposphere contamination history on weed communities is less clear. Ozone is the most important troposphere pollutant producing changes in communities that might be crucially linked to their stability and function. Here, we analyze the legacy of 5 year exposure of an arable land herbaceous community to different levels of ozone episodes. The soil seed bank of the herbaceous community was stored in a dry environment during two and three years and then exposed to field conditions. The community structure considering plant and arthropod richness was evaluated. Also the characteristics of the dominant plant species regarding seed germination and ageing, and growth performance with and without herbivores were evaluated. Our results demonstrate that past stress imposed by air pollutants such as ozone, may have profound effects on community assemblies and energy flows along food web’s different pathways. Taking into account these effects may be particularly important for understanding succession and evolutionary trends driven by human activities in agroecosystems. Studies of human influences such as habitat change, fragmentation and climate change that focus solely on diversity and richness metrics might overlook important alterations if they do not consider the history of troposphere pollution.