Population Dynamics and Local Specialization in a Clonal Perennial (Ranunculus Repens): I. The Dynamics of Ramets in Contrasting Habitats

Abstract

SUMMARY (1) Demographic investigations were made over a period of 18 months in two adjacent populations of the clonal perennial Ranunculus repens in park grassland and in mixed deciduous woodland in North Wales. Ramets were treated as units of population. (2) The carrying capacity of the woodland site for Ranunculus repens (inferred from the peak summer density of ramets) was twice as high as that of the grassland site (264 and 112 ramets m-2, respectively, in 1977). (3) Despite the presence of a large and viable seed bank in the grassland soil (>1000 seeds m-2), germination and establishment of new genets was rare in both sites. (4) The birth rate of ramets per rosette was apparently density-independent, but death rates per rosette were density-dependent, particularly in summer. (5) Clonal growth and the death of ramets were in phase throughout the study. The average production of new ramets by each rosette was similar at both sites (4.6 daughter ramets in woodlands, 4.0 daughter ramets in grassland). (6) Demographic treatment assumes that the units enumerated may validly be compared. This assumption was tested and daughter ramets were found to have the same biomass at both sites, but daughter ramets were differently constructed at the two sites; those in grassland had proportionately more dry matter in caudex and root tissue than those in the woodland, which had more biomass in stolons. (7) The terms 'phalanx' and 'guerilla' are introduced to describe patterns of clonal growth, and the two populations of Ranunculus repens are evaluated in these terms.