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.

Ecological Studies on the Rain Forest of Southern Nigeria: I. The Structure and Floristic Composition of the Primary Forest

P. W. Richards
Journal of Ecology
Vol. 27, No. 1 (Feb., 1939), pp. 1-61
DOI: 10.2307/2256298
Stable URL: http://www.jstor.org/stable/2256298
Page Count: 67
  • Read Online (Free)
  • Download ($18.00)
  • 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.
Ecological Studies on the Rain Forest of Southern Nigeria: I. The Structure and Floristic Composition of the Primary Forest
Preview not available

Abstract

1. The Rain Forest of south-western Nigeria was examined with the chief object of comparing it with Rain Forest in British Guiana and Sarawak previously studied by the author. 2. Originally if formed a belt parallel to the coast lying between a belt of lagoons and swamps of the seaward side and a belt of Mixed Deciduous Forest on the inland side. 3. Owing to the development of agriculture, the continuous belt of forest has been converted into isolated blocks, most of which are now set apart as forest reserves. Most of the forest within these reserves is secondary or heavily depleted and timber exploitation is still being carried on in them. Small relict areas still exist, however, in which some trees may have been felled in the past, but which probably represent fairly accurately the original primary forest of the region. An intensive study was made of some of these relict areas in the Shasha and Okomu Forest Reserves. 4. The Rain Forest of the whole of south-western Nigeria is situated near its climatic limits. The annual rainfall varies from over 2600 mm. to just over 1600 mm., but the dry season is strongly marked, 2-5 consecutive months have less than 50 mm. Where the annual rainfall falls below 1600 mm., the Rain Forest gives place to Mixed Deciduous Forest, but the annual rainfall is not believed to be the factor directly responsible for the boundary between the two. 5. Only two types of primary Rain Forest were met with, the Mixed Rain Forest and the Fresh-water Swamp Forest. The former is considered to be the climatic climax of the region and the latter an edaphic climax conditioned by a high-water table. 6. A number of soil profiles in primary Mixed Rain Forest are described: these soils belong to the Tropical Red Earth or Yellow Earth types. 7. The stratification of the Mixed Forest is described with the help of profile diagrams. There are three fairly well-defined stories of trees at 120-150 ft. (37-46 m.), 50-120 ft. (15-37 m.) and up to 50 ft. respectively. Beneath the tree stories there are ill-defined shrub and herb strata. The herb stratum is composed of synusiae of shade-loving and shade-tolerating species: the latter are analogous to the "wood marginal" species of temperate woodlands. 8. The synusiae of climbers and epiphytes are described. The epiphytic vegetation of the region is remarkably poor in species. 9. The floristic composition of the Mixed Forest was studied by enumerating according to their vernacular names all trees of 4 in. (10 cm.) diameter and over on sample plots each 160,000 sq. ft. (1.49 ha.) in area. Two plots were situated in the Shasha Reserve and one in the Okomu Reserve. By careful collecting the botanical equivalents of a large proportion of the vernacular names were obtained. On all three plots there is a mixture of species without marked dominance of any one species, though on one plot a single species formed as much as 35% of all trees 16 in. (41 cm.) diameter and over. The number of tree species per plot is relatively small, viz. 34-70. The composition differs considerably on the three plots, each representing what are probably different facies of the same association. 10. An account is given of the soil and structure of an area of Fresh-water Swamp Forest in the valley of a small stream. In structure this type of forest differs from the Mixed Forest chiefly in its greater irregularity. 11. On a sample plot of Fresh-water Swamp Forest the number of species present was small, though actually greater than on the poorest of the Mixed Forest plots. 36% of trees of 16 in. (41 cm.) diameter and over belonged to a species of Mitragyna: the majority of the subsidiary species also occurred in the Mixed Forest, but the remainder were confined to Swamp Forest. 12. Some remarks are made on the distribution and chief characteristics of the Mixed Deciduous Forest and the question of its status is touched on. 13. The chief differences between the Rain Forest of south-western Nigeria and that of British Guiana and Sarawak are reviewed and briefly discussed.

Page Thumbnails

  • Thumbnail: Page 
[1]
    [1]
  • Thumbnail: Page 
2
    2
  • Thumbnail: Page 
3
    3
  • Thumbnail: Page 
4
    4
  • Thumbnail: Page 
5
    5
  • Thumbnail: Page 
6
    6
  • Thumbnail: Page 
7
    7
  • Thumbnail: Page 
8
    8
  • Thumbnail: Page 
9
    9
  • Thumbnail: Page 
10
    10
  • Thumbnail: Page 
11
    11
  • Thumbnail: Page 
12
    12
  • Thumbnail: Page 
13
    13
  • Thumbnail: Page 
14
    14
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
15
    15
  • Thumbnail: Page 
16
    16
  • Thumbnail: Page 
17
    17
  • Thumbnail: Page 
18
    18
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
19
    19
  • Thumbnail: Page 
20
    20
  • Thumbnail: Page 
21
    21
  • Thumbnail: Page 
22
    22
  • Thumbnail: Page 
23
    23
  • Thumbnail: Page 
24
    24
  • Thumbnail: Page 
25
    25
  • Thumbnail: Page 
26
    26
  • Thumbnail: Page 
27
    27
  • Thumbnail: Page 
28
    28
  • Thumbnail: Page 
29
    29
  • Thumbnail: Page 
30
    30
  • Thumbnail: Page 
31
    31
  • Thumbnail: Page 
32
    32
  • Thumbnail: Page 
33
    33
  • Thumbnail: Page 
34
    34
  • Thumbnail: Page 
35
    35
  • Thumbnail: Page 
36
    36
  • Thumbnail: Page 
37
    37
  • Thumbnail: Page 
38
    38
  • Thumbnail: Page 
39
    39
  • Thumbnail: Page 
40
    40
  • Thumbnail: Page 
41
    41
  • Thumbnail: Page 
42
    42
  • Thumbnail: Page 
43
    43
  • Thumbnail: Page 
44
    44
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
45
    45
  • Thumbnail: Page 
46
    46
  • Thumbnail: Page 
47
    47
  • Thumbnail: Page 
48
    48
  • Thumbnail: Page 
49
    49
  • Thumbnail: Page 
50
    50
  • Thumbnail: Page 
51
    51
  • Thumbnail: Page 
52
    52
  • Thumbnail: Page 
53
    53
  • Thumbnail: Page 
[54]
    [54]
  • Thumbnail: Page 
[55]
    [55]
  • Thumbnail: Page 
[56]
    [56]
  • Thumbnail: Page 
[57]
    [57]
  • Thumbnail: Page 
[58]
    [58]
  • Thumbnail: Page 
[59]
    [59]
  • Thumbnail: Page 
[60]
    [60]
  • Thumbnail: Page 
[61]
    [61]