ON THE SPATIAL ORGANIZATION OF PLANT SPECIES IN A LIMESTONE GRASSLAND COMMUNITY

SUMMARY (1) Studies of the spatial organization of plant communities have been based on samples of the physical space occupied by communities. To determine the spatial organization of a community as the plant species themselves experience it (the 'plant's-eye-view'), it is necessary to use a sampling method in which the individual plant is the sample unit. The method of cluster sampling makes this possible in the absence of a census list from which to sample. (2) Cluster sampling is used to estimate the structure of a limestone grassland community as it 'appears' to seven common plant species ('target species') in the community. (3) The mean distances from the target species to the nearest neighbour of each target species indicate that, qualitatively, each experiences the other species in proportion to their abundance in the community, although there is evidence of within-species aggregation in several cases. (4) A similar picture emerges from the mean densities of species in the immediate neighbourhood of each target species. Although spatial patterns within certain species are highly non-random, the spatial patterns of different species are interlocked in such a way that there is little indication of interspecific associations. (5) The amount of neighbour-free space differs between target species. In most cases, this is not correlated with plant size. (6) Spatial organization of the community as exemplified by this study is most likely to be a result of the patterns of clonal growth, although the possibility of fine-scale niche differentiation is not excluded. Such organization could play an important role in shaping future interactions in the community, causing interspecific interactions to be weaker than intraspecific ones.

[1]  E. J. S.,et al.  Quantitative Plant Ecology , 1934, Nature.

[2]  A. Tansley.  The British Islands and their Vegetation , 1939 .

[3]  A. R. Clapham,et al.  Excursion flora of the British Isles , 1952 .

[4]  C. Pigott.  Soil Formation and Development on the Carboniferous Limestone of Derbyshire. I. Parent Materials , 1962 .

[5]  J. P. Grime,et al.  The Grassland Vegetation of the Sheffield Region: I. General Features , 1971 .

[6]  Vic Barnett,et al.  Elements of Sampling Theory , 1977 .

[7]  E. C. Pielou.  Population and Community Ecology: Principles and Methods , 1974 .

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

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

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

[11]  L. Aarssen,et al.  Neighbour relationships in grass–legume communities. I. Interspecific contacts in four grassland communities near London, Ontario , 1977 .

[12]  M. Wade,et al.  THE DETECTION OF SMALL-SCALE PATTERNS IN VEGETATION , 1979 .

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

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

[15]  P. Tomlinson,et al.  Adaptive architecture in rhizomatous plants , 1980 .

[16]  L. L. Doust.  INTRACLONAL VARIATION AND COMPETITION IN RANUNCULUS RE PENS , 1981 .

[17]  L. L. Doust,et al.  Population dynamics and local specialization in a clonal perennial (Ranunculus repens). I. The dynamics of ramets in contrasting habitats , 1981 .

[18]  J. Antonovics,et al.  Competition and Coexistence in a North Carolina Grassland: I. Patterns in Undisturbed Vegetation , 1981 .

[19]  Robert M. May,et al.  Theoretical Ecology: Principles and Applications , 1981 .

[20]  B. Shorrocks,et al.  Competition on a Divided and Ephemeral Resource: A Simulation Model , 1981 .

[21]  M. J. Liddle,et al.  Population dynamics and neighbourhood effects in establishing swards of Festuca rubra , 1982 .

[22]  P. D. Jong,et al.  The use of contact sampling in studies of association in vegetation , 1983 .

[23]  R. Rogers.  Small-Area Coexistence of Vernal Forest Herbs: Does Functional Similarity of Plants Matter? , 1983, The American Naturalist.

[24]  J. Noble,et al.  The population biology of plants with clonal growth. II: The nutrient strategy and modular physiology of Carex arenaria , 1983 .

[25]  F. Bazzaz,et al.  PHYSIOLOGICAL INTEGRATION AMONG INTRACLONAL RAMETS IN SOLIDAGO CANADENSIS , 1983 .

[26]  B. Shorrocks,et al.  Interspecific competition is not a major organizing force in many insect communities , 1984, Nature.

[27]  B. Casper,et al.  MORPHOGENETIC CONSTRAINTS ON PATTERNS OF CARBON DISTRIBUTION IN PLANTS , 1984 .

[28]  N. L. Fowler,et al.  The role of germination date, spatial arrangement, and neighbourhood effects in competitive interactions in Linum , 1984 .

[29]  R. Vance.  Interference Competition and the Coexistence of Two Competitors on a Single Limiting Resource , 1984 .

[30]  P. D. Jong,et al.  A reanalysis of interspecific association in an old pasture , 1985 .