Spatial patterns of trees in a Caribbean semievergreen forest.

Spatial patterns of trees >10 cm dbh were studied in a 4-ha forest plot on St. John, United States Virgin Islands, by measuring nearest-neighbor distances for 28 tree species and mapping 5 uncommon species. Tree species diversity was high, with an even distribution of dominance (28 species out of 132 individuals, and H' = 4.37). A clumped distribution pattern with short intertree distances was prevalent. All but five species had average nearest neighbor distances of <25 m and most were < 10 m. Indices of dispersion based on variance to mean rations for the 16 most abundant species suggested clumped distributions for 12 of the species, and only one regularly distributed species. Uncommon mapped species were located in distinct clumps of approximately 700-1300 mi2, also with small average nearest-neighbor distances. The combination of high species diversity with many clumped distribution patterns and low in- terindividual distances for both common and uncommon species, suggests that mechanisms other than species-specific predators are important in understanding tree diversity differences between temperate and tropical forests. The importance of microhabitats is suggested. Available published evidence indicates a prevalence of clumped and a paucity of regular distribution patterns for tree species in tropical forests.

[1]  R. Whittaker.  Evolution and measurement of species diversity , 1972 .

[2]  D. Jadan.  A guide to the natural history of St. John , 1971 .

[3]  P. Greig-Smith,et al.  QUANTITATIVE PLANT ECOLOGY , 1959 .

[4]  Claude E. Shannon,et al.  The Mathematical Theory of Communication , 1950 .

[5]  Stephen P. Hubbell,et al.  Tree Dispersion, Abundance, and Diversity in a Tropical Dry Forest , 1979, Science.

[6]  A. Hasler,et al.  Species Diversity in Lacustrine Phytoplankton. I. The Components of the Index of Diversity from Shannon's Formula , 1969, The American Naturalist.

[7]  C. Monk.  Tree Species Diversity in the Eastern Deciduous Forest with Particular Reference to North Central Florida , 1967, The American Naturalist.

[8]  P. Richards,et al.  The Vegetation of Moraballi Creek, British Guiana: An Ecological Study of a Limited Area of Tropical Rain Forest. Part II , 1933 .

[9]  D. Janzen.  Herbivores and the Number of Tree Species in Tropical Forests , 1970, The American Naturalist.

[10]  J. Hall,et al.  A catena in tropical moist semi-deciduous forest near Kade, Ghana. , 1970 .

[11]  V. M. Conway,et al.  Deciduous Forests of Eastern North America. , 1951 .

[12]  M. E. D. Poore,et al.  Studies in Malaysian Rain Forest: I. The Forest on Triassic Sediments in Jengka Forest Reserve , 1968 .

[13]  P. Greig-Smith,et al.  The Application of Quantitative Methods to Vegetation Survey: III. A Re- Examination of Rain Forest Data from Brunei , 1972 .

[14]  J. T. Curtis,et al.  The Use of Distance Measures in Phytosociological Sampling , 1956 .

[15]  G. A. Black,et al.  Some Attempts to Estimate Species Diversity and Population Density of Trees in Amazonian Forests , 1950, Botanical Gazette.

[16]  J. Pires,et al.  An Estimate of the Number of Species of Trees in an Amazonian Forest Community , 1953, Botanical Gazette.

[17]  G. B. Williamson,et al.  Treefalls and Patterns of Understory Species in a Wet Lowland Tropical Forest , 1975 .

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

[19]  P. Risser,et al.  An Evaluation of the Grassland Quarter Method , 1968 .

[20]  Donald A. Anderson,et al.  Sampling the Density of Tree Species with Quadrats in a Species-Rich Tropical Forest , 1971 .

[21]  F. Wadsworth,et al.  Common Trees of Puerto Rico and the Virgin Islands. , 1965 .

[22]  T. Whitmore,et al.  On the influence of soil properties on species distribution in a Malayan lowland Dipterocarp rain forest. , 1970 .

[23]  D. H. Knight,et al.  A Phytosociological Analysis of Species‐Rich Tropical Forest on Barro Colorado Island, Panama , 1975 .

[24]  J. Connell.  Diversity in tropical rain forests and coral reefs. , 1978, Science.

[25]  P. Richards.  Ecological Observations on the Rain Forest of Mount Dulit, Sarawak. Part II , 1936 .

[26]  T. Dobzhansky,et al.  Evolution in the tropics , 1950 .

[27]  D. Janzen,et al.  Predation on Scheelea Palm Seeds by Bruchid Beetles: Seed Density and Distance from the Parent Palm , 1972 .