168 Kaoru Kitajima and Lourens Poorter
995(^25)
2
3
3
6
6
4
4
8
8
1
1
7
7
X
X X
X
X
X
X
X XX
X
X XX
X
XX XX
X
X
X
X
X
X
X
X
X
X
X
X
X XX
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
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X
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X
0
Shade Gap
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
−0.08
−0.06
−0.04
−0.02
0
0.02
0.04
0.06
0.08
Light regime
−0.04
−0.02
0
0.02
0.04
0.06
0.08
−0.08 −0.04^0 0.04
RGR in 1% light (day−^1 )
RGR in 27% light (day
−^1
)
0.2
0.4
0.6
0.8
1.0
0 0.2 0.4 0.6 0.8
Survival in shade
Survival in gaps
(a) (b)
(c) (d)
1% light 27% light
Figure 10.3 Survival and growth responses of woody seedlings on Barro Colorado Island (BCI), Panama, to sun
and shade conditions, presented as phenotypic reaction norms (a,c; two points connected by a line represent a
species) and as correlation plots between the two light environments (b,d; each point is a species mean). These figures
are shown in a manner to correspond to the analysis shown in Box 10.1. (a,b) Proportion of seedlings of nine canopy
tree species surviving from germination to 2 months in the shaded understory and treefall gaps (Augspurger 1984a).
(c,d) Seedlin grelative growth rate (RGR) of 50 woody species on BCI determined under 1% and 27% of full sun in a
screened enclosure from time of the expansion of first true leaves until cotyledons were lost or 10 weeks later (data
from Kitajima 1992).
across 18 species grown under high and low light
in a nursery (Augspurger 1984b).
Do species ranks of growth rates reverse
between two light environments? Relative growth
rate of seedlin gbiomass (RGR, rate of size incre-
ment per unit biomass per unit time) is ideal
for such analysis as it standardizes for size
differences amon gspecies. Relative growth rate
of seedlings exhibits an overall rank concor-
dance between high and low light environments
amon g15 Bolivian tree species alon ga wide ran ge
of light (Figure 10.2b) and among 50 woody
species on BCI grown under 1% and 27% full
sun (Figure 10.3c,d). Non-parametric statistics