Intraspecific aggregation and soil heterogeneity: competitive interactions of two clonal plants with contrasting spatial architecture
Background and aims
Intraspecific aggregation of plant individuals can promote species coexistence by delaying competitive exclusions. However, such impacts may differ among species with contrasting spatial architecture and rely on the spatial distribution of resources.
We grew a phalanx clonal plant Carex neurocarpa (with aggregated ramets) and a guerilla one Bolboschoenus planiculmis (with diffused ramets) in monocultures or in 1:1 mixtures with an even or a clustered distribution pattern of the two species in homogeneous or heterogeneous soils.
After 16 months, shoot biomass and ramet number were greater in mixtures than in monocultures in C. neurocarpa, but smaller in B. planiculmis. However, the growth of neither C. neurocarpa nor B. planiculmis differed between even and clustered mixtures. Soil nutrient heterogeneity did not significantly affect the growth of either species, but increased relative yield of B. planiculmis and decreased that of C. neurocarpa.
The relative importance of intra- vs. interspecific competition depends on the spatial architecture of plants, and soil nutrient heterogeneity slows down competitive exclusion by decreasing differences in competitive ability between plants. However, our results do not support the idea that intraspecific aggregation of individuals alters competitive interactions between species.
KeywordsAggregation Clonal growth form Clonal population Competition Environmental heterogeneity Guerilla and phalanx
We thank Rui Zhu, Bi-Cheng Dong, Pu Wang, Yong-Yang Wang, Jia-Yuan Li, Yong-Hong Gao and Xing-Xing Jiang for assistance with the experiment, and Jasper van Ruijven and two anonymous reviewers for valuable comments on the earlier version of the manuscript. This work was supported by NSFC (31570413 and 31761123001).
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