Population dynamics and local specialization in a clonal perennial (Ranunculus repens). I. The dynamics of ramets in contrasting habitats

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.

[1]  T. Royama.  Population Persistence and Density Dependence , 1977 .

[2]  J. Harper,et al.  Studies on plant demography Ranunculus repens L., R. bulbosus L. and R. acris L. I. Population flux and survivorship , 1973 .

[3]  R. Sharitz,et al.  Population Dynamics of Two Competing Annual Plant Species , 1973 .

[4]  J. Sarukhán.  A study of the population dynamics of three Ranunculus species. , 1970 .

[5]  John L. Harper,et al.  INTERFERENCE IN DUNE ANNUALS: SPATIAL PATTERN AND NEIGHBOURHOOD EFFECTS , 1977 .

[6]  P. Grubb.  THE MAINTENANCE OF SPECIES‐RICHNESS IN PLANT COMMUNITIES: THE IMPORTANCE OF THE REGENERATION NICHE , 1977 .

[7]  J. Sarukhán.  On Selective Pressures and Energy Allocation in Populations of Ranunculus repens Lpc Rp bulbosus Lp and Rp acris L , 1976 .

[8]  W. Abrahamson.  PATTERNS OF RESOURCE ALLOCATION IN WILDFLOWER POPULATIONS OF FIELDS AND WOODS , 1979 .

[9]  J. Sarukhán.  Studies of plant demography : Ranunculus repens L., R. bulbosus L. and R. acris L. II. Reproductive strategies and seed population dynamics , 1974 .

[10]  John L. Harper,et al.  THE GROWTH, DISTRIBUTION AND NEIGHBOUR RELATIONSHIPS OF TRIFOLIUM REPENS IN A PERMANENT PASTURE , 1989 .

[11]  J. Harper.  Population Biology of Plants , 1979 .

[12]  J. Harper,et al.  The Demography of a Sand Dune Annual: Vulpia Fasciculata: I. The Natural Regulation of Populations , 1978 .

[13]  R. Jefferies,et al.  Demography of Hieracium Pilosella in a Breck Grassland , 1978 .

[14]  M. Gadgil,et al.  Studies on Plant Demography: Ranunculus Repens L., R. Bulbosus L. and R. Acris L.: III. A Mathematical Model Incorporating Multiple Modes of Reproduction , 1974 .

[15]  R. Lewin,et al.  Biological flora of the British Isles , 1948 .

[16]  J. Harper,et al.  The reproduc-tive strategy of higher plants. 1. The concept of strategy with special reference to Senecio vulgaris L. , 1970 .

[17]  John L. Harper,et al.  The Growth, Distribution and Neighbour Relationships of Trifolium Repens in a Permanent Pasture: I. Ordination, Pattern and Contact , 1979 .

[18]  A. Watkinson,et al.  CLONAL VARIATION IN POPULATIONS OF RANUNCULUS REPENS , 1979 .

[19]  J. Noble.  Population biology of plants with clonal growth : I. Morphology and structural demography of Carex arenaria , 1979 .