Table 1.
Numbers of significant intra- and interspecific nonparametric correlations for the 84 most abundant species in the BCI forest
| Type of correlation | Significance | Expected no. of significant positive or negative intra- and interspecific correlations | Quadrat size (length and width in meters) | No. of species (or species pairs) showing significant r values at one or more quadrat sizes*
|
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 10 | 20 | 50 | 100 | |||||||||
| Observed no. significant intra- and interspecific correlations
| ||||||||||||
| Pos. | Neg. | Pos. | Neg. | Pos. | Neg. | Pos. | Neg. | Pos. | Neg. | |||
| a (Basal area of conspecifics in quadrat vs. adult survival) | 0.05 | 1.38 (1.06) | 0 (1) | 3 (2) | 1 (0) | 4 (0) | 0 (1) | 1 (1) | 1 (1) | 3 (2) | 4 | 16 |
| 0.01 | 0.27 (0.21) | 0 (0) | 1 (0) | 0 (0) | 1 (1) | 0 (0) | 0 (1) | 0 (0) | 0 (1) | P = 0.02* | ||
| 0.002 | 0.07 (0.05) | 1 (1) | 3 (0) | 0 (0) | 3 (1) | 1 (0) | 1 (0) | 1 (0) | 1 (0) | (3) | (5) | |
| 69 (53) ssp. | n.s. | |||||||||||
| b (Basal area of conspecifics in quadrat vs. juvenile survival) | 0.05 | 1.5 (1.36) | 2 (1) | 4 (1) | 2 (2) | 3 (2) | 1 (2) | 3 (2) | 3 (1) | 2 (0) | 8 | 18 |
| 0.01 | 0.3 (0.27) | 1 (0) | 1 (0) | 2 (0) | 1 (0) | 1 (0) | 1 (0) | 0 (0) | 0 (0) | n.s. | ||
| 0.002 | 0.08 (0.07) | 0 (0) | 3 (0) | 2 (0) | 2 (0) | 2 (0) | 3 (0) | 1 (0) | 2 (0) | (3) | (6) | |
| 75 (68) spp. | n.s. | |||||||||||
| c (Basal area of conspecifics vs. survival for both adults and juveniles) | 0.05 | 1.7 (1.7) | 3 (2) | 6 (1) | 2 (2) | 4 (1) | 0 (3) | 1 (2) | 5 (3) | 2 (3) | 13 | 20 |
| 0.01 | 0.34 (0.34) | 0 (1) | 0 (1) | 1 (0) | 4 (1) | 0 (0) | 1 (1) | 4 (0) | 0 (1) | n.s. | ||
| 0.002 | 0.09 (0.09) | 1 (0) | 4 (0) | 2 (0) | 2 (0) | 3 (0) | 4 (1) | 0 (1) | 3 (0) | (4) | (10) | |
| 84 (84) spp. | n.s. | |||||||||||
| d (Basal area of conspecifics in quadrat vs. no. of recruits per adult) | 0.05 | 1.7 (1.7) | 0 (3) | 13 (0) | 0 (1) | 11 (3) | 3 (1) | 5 (6) | 2 (1) | 1 (4) | 5 | 67 |
| 0.01 | 0.34 (0.34) | 0 (0) | 6 (0) | 0 (0) | 11 (0) | 0 (0) | 0 (1) | 0 (0) | 1 (1) | P < 0.001 | ||
| 0.002 | 0.09 (0.09) | 0 (0) | 35 (0) | 0 (0) | 23 (0) | 0 (0) | 5 (0) | 1 (1) | 5 (0) | (8) | (13) | |
| 84 (84) ssp. | n.s. | |||||||||||
| e (Basal area of conspecifics in quadrat vs. r) | 0.05 | 1.7 (1.7) | 2 (1) | 15 (2) | 1 (0) | 10 (2) | 3 (4) | 2 (3) | 3 (2) | 2 (1) | 7 | 54 |
| 0.01 | 0.34 (0.34) | 0 (1) | 3 (1) | 0 (1) | 1 (1) | 2 (0) | 2 (0) | 0 (2) | 1 (0) | P < 0.001 | ||
| 0.002 | 0.09 (0.09) | 0 (0) | 28 (0) | 0 (0) | 23 (0) | 1 (0) | 5 (0) | 0 (0) | 4 (0) | (9) | (8) | |
| 84 (84) ssp. | n.s. | |||||||||||
| f (r of species vs. basal area of all other trees in quadrat) | 0.05 | 1.7 | 1 | 1 | 8 | 2 | 4 | 0 | 5 | 5 | 22 | 7 |
| 0.01 | 0.34 | 3 | 1 | 2 | 0 | 5 | 0 | 0 | 0 | P < 0.02 | ||
| 0.002 | 0.09 | 1 | 0 | 3 | 1 | 2 | 0 | 0 | 0 | |||
| 84 spp. | ||||||||||||
Census data from 1982 and 1990 were employed. The data from within-species correlations are presented first, followed by data from between-species correlations in parentheses. The type of correlation is indicated in the first column, and the second shows the three significance levels that were distinguished, along with the number of species used in each correlation. In some cases the number is less than 84. This is because nine species are reproductive by the time they reach 1 cm diameter at breast height (DBH), so that all trees of these species that have been censused must be considered adults. This left 75 species in which juvenile survival could be distinguished, and which could be included in correlation b. In 15 species, fewer than 10 adult trees died, and these species were not included in correlation a. This reduction in numbers also affected the expected numbers of positive or negative correlations based on chance alone, which are shown in column 3. To obtain the recruitment measure, the trees that were recruited (achieved ≥ 1 cm DBH) in each quadrat between 1982 and 1990 were counted and divided by the number of adult trees of that species in the quadrat in 1982. Trees that were recruited in quadrats that contained no adult trees of that species in 1982 were excluded from the calculations.
Equality of the numbers of species in the last two columns of the table was examined with the sign test, on the assumption that equal numbers of species should be found in the two columns.