Premium
The density dependence of plant responses to elevated CO 2
Author(s) -
Wayne P. M.,
Carnelli A. L.,
Connolly J.,
Bazzaz F. A.
Publication year - 1999
Publication title -
journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.452
H-Index - 181
eISSN - 1365-2745
pISSN - 0022-0477
DOI - 10.1046/j.1365-2745.1999.00357.x
Subject(s) - biomass (ecology) , shoot , seedling , density dependence , range (aeronautics) , brassica , plant density , environmental science , yield (engineering) , biology , agronomy , horticulture , zoology , botany , sowing , physics , materials science , population , demography , sociology , composite material , thermodynamics
1 Stands of the annual Brassica kaber were grown at a range of six densities in both ambient and elevated CO 2 environments, and measurements of shoot growth were made from seedling emergence through to reproduction. 2 Early in stand development (21 days following emergence), CO 2 enhancement (β) for above‐ground biomass was highly density‐dependent, ranging from 1.41 at the lowest density (20 plants m−2) to 0.59 at the highest density (652 plants m−2). 3 As stands matured and total biomass exceeded a relatively low threshold level (<10.0 g m −2; c. 20% of final yield), the density‐dependence of β disappeared. Above this shoot biomass threshold, β‐values remained remarkably stable (β = 0.34) across a broad range of stand biomass, independent of a stand's initial density or age. 4 Average stand‐level reproductive β‐values at a final harvest were very similar to biomass values (β = 0.38) and, as with biomass values at later stages, showed no apparent density‐dependence. 5 These results highlight the importance of considering density and the time‐course of stand development simultaneously when assessing the potential for CO 2 ‐induced growth enhancements in plants.