Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Phytosociological Studies in the Pinelands of Southeastern Louisiana

William T. Penfound and Allan G. Watkins
The American Midland Naturalist
Vol. 18, No. 4 (Jul., 1937), pp. 661-682
DOI: 10.2307/2420659
Stable URL: http://www.jstor.org/stable/2420659
Page Count: 22
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Phytosociological Studies in the Pinelands of Southeastern Louisiana
Preview not available

Abstract

1. The results of phytosociological studies in three communities of the pinelands of Southeastern Louisiana are here presented. 2. The virgin longleaf pine association was characterized by a pure, parklike stand of slender, longleaf pine averaging 21.4 inches d.b.h., 107,1 feet high and 210 years old. No shrub stratum was present but grasses, sedges, and forbs formed a well-developed cover with Andropogon virginicus, A. scoparius, Aristida virgata, Etephantopus nudatus, and Panicum rhizomatum as the principal species. 3. In the second-growth stand of longleaf pine the trees averaged 12 inches d.b.h., 95 feet high and 93 years of age. Not only was the shrub stratum absent but little herbaceous cover was present. Andropogon virginicus, A. scoparius, Aristida virgata and a species of Panicum were the only contributors of importance. 4. The cut-over pineland community (pine barrens, savanna) is characterized by the absence of trees and shrubs, except for occasional seedlings, and by a much heavier herbaceous cover than obtained in the longleaf pine forest. Andropogon virginicus, Aristida virgata, Axonopus compressus, Rynchospora gracilenta, R. Wrightiana, and Sphagnum spp. were the most important components. 5. The slash pine-pond cypress swamp is a hydric community with slash pine usually much more abundant than pond cypress. The slash pine trees averaged 13.8 inches d.b.h., 102.1 feet high, and 135 years of age. No shrub stratum was present but a dense, herbaceous stratum, separable into three layers, concealed the ground. The most important species were Arundinaria tecta, Erianthus giganteus, Erigeron vernus, Eriocaulon decangulare, Panicum longifolium, P. virgatum, Rynchospora gracilenta, and Sphagnum spp. 6. Grasses and sedges contributed 37% of the 166 species listed in the quadrats in the pineland communities and because of their high frequency, and heavy covergrade are to be considered as the controlling species among the herbaceous plants. The herbaceous species in the second-growth stand of longleaf pine, and in the cut-over longleaf pinelands were similar to those in the virgin longleaf pine forest. This list of species, however, differs significantly from the list obtained in the slash pine-pond cypress swamp. 7. In view of the fact that the species-area curves break most strongly before the 15th quadrat is reached, and since the species encountered after the 15th quadrat have a low frequency and very meager coverage, it is concluded that 15 quadrats are sufficient for a phytosociological analysis of herbaceous vegetation in a community, at least in the pineland communities of Southeastern Louisiana. 8. On the basis of 25 quadrats of one square meter each the average frequency percentages in the various classes obtained were; 75, 15, 6, 4, 2. Compared to the longtime averages of Raunkaier and Kenoyer there is too high a percentage of species in the first class and too low a percentage in the last one. On the basis of quadrats of 2 square meters this is somewhat overcorrected. It is probable, therefore, that a quadrat size of one and a half square meters would have given frequency data conforming to the long period averages. 9. The herbaceous plants in the pinelands blossom but little until May, reach the zenith of anthesis in September, and continue to bloom even into the month of December. Since the species list in the spring differs considerably from that obtained in the autumn it is desirable to sample a community two or three times annually, ideally in May, August, and November. 10. Of the physical factors the water content of the soil is apparently the most critical in the distribution of species and communities in the Coastal Plain flatlands of Southeastern Louisiana.

Page Thumbnails

  • Thumbnail: Page 
661
    661
  • Thumbnail: Page 
662
    662
  • Thumbnail: Page 
663
    663
  • Thumbnail: Page 
664
    664
  • Thumbnail: Page 
665
    665
  • Thumbnail: Page 
666
    666
  • Thumbnail: Page 
667
    667
  • Thumbnail: Page 
668
    668
  • Thumbnail: Page 
669
    669
  • Thumbnail: Page 
670
    670
  • Thumbnail: Page 
671
    671
  • Thumbnail: Page 
672
    672
  • Thumbnail: Page 
673
    673
  • Thumbnail: Page 
674
    674
  • Thumbnail: Page 
675
    675
  • Thumbnail: Page 
676
    676
  • Thumbnail: Page 
677
    677
  • Thumbnail: Page 
678
    678
  • Thumbnail: Page 
679
    679
  • Thumbnail: Page 
680
    680
  • Thumbnail: Page 
681
    681
  • Thumbnail: Page 
682
    682