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Research article - Peer-reviewed, 2019

Distinct seasonal dynamics of responses to elevated CO2 in two understorey grass species differing in shade-tolerance

Holub, Petr; Klem, Karel; Linder, Sune; Urban, Otmar;

Abstract

Understorey plant communities are crucial to maintain species diversity and ecosystem processes including nutrient cycling and regeneration of overstorey trees. Most studies exploring effects of elevated CO2 concentration ([CO2]) in forests have, however, been done on overstorey trees, while understorey communities received only limited attention. The hypothesis that understorey grass species differ in shade-tolerance and development dynamics, and temporally exploit different niches under elevated [CO2], was tested during the fourth year of [CO2] treatment. We assumed stimulated carbon gain by elevated [CO2] even at low light conditions in strongly shade-tolerant Luzula sylvatica, while its stimulation under elevated [CO2] in less shade-tolerant Calamagrostis arundinacea was expected only in early spring when the tree canopy is not fully developed. We found evidence supporting this hypothesis. While elevated [CO2] stimulated photosynthesis in L. sylvatica mainly in the peak of the growing season (by 55%-57% in July and August), even at low light intensities (50 mu mol m(-2) s(-1)), stimulatory effect of [CO2] in C. arundinacea was found mainly under high light intensities (200 mu mol m(-2) s(-1)) at the beginning of the growing season (increase by 171% in May) and gradually declined during the season. Elevated [CO2] also substantially stimulated leaf mass area and root-to-shoot ratio in L. sylvatica, while only insignificant increases were observed in C. arundinacea. Our physiological and morphological analyses indicate that understorey species, differing in shade-tolerance, under elevated [CO2] exploit distinct niches in light environment given by the dynamics of the tree canopy.

Keywords

Calamagrostis arundinacea; ecological niche; glass domes; light environment; Luzula sylvatica; manipulation experiment; seasonal dynamics

Published in

Ecology and Evolution

2019, volume: 9, number: 24, pages: 13663-13677
Publisher: WILEY

Authors' information

Holub, Petr
Czech Academy of Sciences
Klem, Karel
Czech Academy of Sciences
Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre
Urban, Otmar
Czech Academy of Sciences

UKÄ Subject classification

Ecology

Publication Identifiers

DOI: https://doi.org/10.1002/ece3.5738

URI (permanent link to this page)

https://res.slu.se/id/publ/103082