Publication Date:
2017-12-29
Description:
Continuing enrichment of atmospheric CO 2 may change plant community composition, in part by altering the availability of other limiting resources including soil water, nutrients, or light. The combined effects of CO 2 enrichment and altered resource availability on species flowering remain poorly understood. We quantified flowering culm and ramet production and biomass allocation to flowering culms/ramets for ten years in C 4 dominated grassland communities on contrasting soils along a CO 2 concentration gradient spanning pre-industrial to expected mid-21 st century levels (250 – 500 μL L −1 ). CO 2 enrichment explained up to 77% of the variation in flowering culm count across soils for three of the five species, and was correlated with flowering culm count on at least one soil for four of five species. In contrast, allocation to flowering culms was only weakly correlated with CO 2 enrichment for two species. Flowering culm counts were strongly correlated with species aboveground biomass (AGB; R 2 0.34 to 0.74), a measure of species abundance. CO 2 enrichment also increased soil moisture and decreased light levels within the canopy but did not affect soil inorganic nitrogen availability. Structural equation models (SEMs) fit across the soils suggested species-specific controls on flowering in two general forms: 1) CO 2 effects on flowering culm count mediated by canopy light level and relative species AGB (species AGB/total AGB) or by soil moisture effects on flowering culm count; 2) effects of canopy light level or soil inorganic nitrogen on flowering and/or relative species AGB, but with no significant CO 2 effect. Understanding the heterogeneity in species responses to CO 2 enrichment in plant communities across soils in edaphically variable landscapes is critical to predicting CO 2 effects on flowering and other plant fitness components, and species potential to adapt to future environmental changes. This article is protected by copyright. All rights reserved.
Print ISSN:
1354-1013
Electronic ISSN:
1365-2486
Topics:
Biology
,
Energy, Environment Protection, Nuclear Power Engineering
,
Geography
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