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Intraspecific aggregation and soil heterogeneity: competitive interactions of two clonal plants with contrasting spatial architecture

Xue, Wei, Huang, Lin, Yu, Fei-Hai, Bezemer, T. Martijn
Plant and soil 2018 v.425 no.1-2 pp. 231-240
Bolboschoenus, Carex, biomass, clones, competitive exclusion, soil heterogeneity, soil nutrients
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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.