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Experiments were conducted in the Tabonuco forest at Luquillo Experimental Forest to determine the germination success of a number of species in different light environments. Species tested included: Byrsonima spicata, Calophyllum brasiliense, Carapa sp., Choven venosa, Guarea guidonia, Manilkara bidentata, Ochroma pyramidale and an unidentified species known locally as Jobo. Seeds were collected as they fell and placed on moist towling in horticulture trays at four sites. Seeds were kept moist and germination was recorded daily for 81 days and three times weekly for an additional 75 days. Light environments included a site exposed to full sun (FS) and sites with 55%, 75% and 80% cover. Instantaneous light measurements were made with a Licor 1800 spectroradiometer to determine the Red (660 nm) to Far-red (730 nm) ratio (R/FR) (Lee, 1987). Analysis of light data indicated that the four sites chosen provided three significantly different R/FR ratio environments, and that germination of some species was affected by the light environment (Smith, H. & Whitelam, G.C. 1990). Three species failed to germinate in any of the four light environments.
Table 1. Red/Far-red ratio & Percent Germination of five species in four sites.
site 
%cover
R/FR
Calophyllum
Manilkara
Ochroma
Carapa
Jobo
1
55
0.53
21%
46%
10%
40%
3%
2
80
0.20
16%
48%
14%
16%
8%
3
FS
1.2
4%
16%
12%
0
0
4
75
0.20
3%
32%
16%
16%
3%