TY - JOUR
T1 - Detecting the role of individual species for overyielding in experimental grassland communities composed of potentially dominant species
AU - Roscher, Christiane
AU - Schumacher, Jens
AU - Weisser, Wolfgang W.
AU - Schmid, Bernhard
AU - Schulze, Ernst Detlef
N1 - Funding Information:
D. Weigel and several student helpers for their persevering assistance with the biomass harvest, sorting, counting and weighing of the plant material and their continuous support in carrying out the experiment. The Jena Experiment is funded by the German Science Foundation (FOR 456) with support from the Friedrich Schiller University of Jena and the Max Planck Society.
PY - 2007/12
Y1 - 2007/12
N2 - Several studies have shown that the contribution of individual species to the positive relationship between species richness and community biomass production cannot be easily predicted from species monocultures. Here, we used a biodiversity experiment with a pool of nine potentially dominant grassland species to relate the species richness-productivity relationship to responses in density, size and aboveground allocation patterns of individual species. Aboveground community biomass increased strongly with the transition from monocultures to two-species mixtures but only slightly with the transition from two- to nine-species mixtures. Tripartite partitioning showed that the strong increase shown by the former was due to trait-independent complementarity effects, while the slight increase shown by the latter was due to dominance effects. Trait-dependent complementarity effects depended on species composition. Relative yield total (RYT) was greater than 1 (RYT > 1) in mixtures but did not increase with species richness, which is consistent with the constant complementarity effect. The relative yield (RY) of only one species, Arrhenatherum elatius, continually increased with species richness, while those of the other species studied decreased with species richness or varied among different species compositions within richness levels. High observed/expected RYs (RYo/RYe > 1) of individual species were mainly due to increased module densities, whereas low observed/expected RYs (RYo/RYe < 1) were due to more pronounced decreases in module density (species with stoloniferous or creeping growth) or module size (species with clearly-defined plant individuals). The trade-off between module density and size, typical for plant populations under the law of constant final yield, was compensated among species. The positive trait-independent complementarity effect could be explained by an increase in community module density, which reached a maximum at low species richness. In contrast, the increasing dominance effect was attributable to the species-specific ability, in particular that of A. elatius, to increase module size, while intrinsic growth limitations led to a suppression of the remaining species in many mixtures.
AB - Several studies have shown that the contribution of individual species to the positive relationship between species richness and community biomass production cannot be easily predicted from species monocultures. Here, we used a biodiversity experiment with a pool of nine potentially dominant grassland species to relate the species richness-productivity relationship to responses in density, size and aboveground allocation patterns of individual species. Aboveground community biomass increased strongly with the transition from monocultures to two-species mixtures but only slightly with the transition from two- to nine-species mixtures. Tripartite partitioning showed that the strong increase shown by the former was due to trait-independent complementarity effects, while the slight increase shown by the latter was due to dominance effects. Trait-dependent complementarity effects depended on species composition. Relative yield total (RYT) was greater than 1 (RYT > 1) in mixtures but did not increase with species richness, which is consistent with the constant complementarity effect. The relative yield (RY) of only one species, Arrhenatherum elatius, continually increased with species richness, while those of the other species studied decreased with species richness or varied among different species compositions within richness levels. High observed/expected RYs (RYo/RYe > 1) of individual species were mainly due to increased module densities, whereas low observed/expected RYs (RYo/RYe < 1) were due to more pronounced decreases in module density (species with stoloniferous or creeping growth) or module size (species with clearly-defined plant individuals). The trade-off between module density and size, typical for plant populations under the law of constant final yield, was compensated among species. The positive trait-independent complementarity effect could be explained by an increase in community module density, which reached a maximum at low species richness. In contrast, the increasing dominance effect was attributable to the species-specific ability, in particular that of A. elatius, to increase module size, while intrinsic growth limitations led to a suppression of the remaining species in many mixtures.
KW - Complementarity effect
KW - Constant final yield
KW - Density
KW - Dominance effect
KW - Relative yield
UR - http://www.scopus.com/inward/record.url?scp=36448952730&partnerID=8YFLogxK
U2 - 10.1007/s00442-007-0846-4
DO - 10.1007/s00442-007-0846-4
M3 - Article
C2 - 17851699
AN - SCOPUS:36448952730
SN - 0029-8549
VL - 154
SP - 535
EP - 549
JO - Oecologia
JF - Oecologia
IS - 3
ER -