Figure 1.
Schematic of experimental design.
Seeds were planted individually or in competition with four conspecific neighbors and growth at low, intermediate, or high nitrogen levels. There were ten replicate pots per nitrogen x competition combination, five of which were grown in a shadehouse, and five of which were grown in full sunlight. The two light levels were analyzed as separate experiments (a). The photograph shows a sun-grown (left) and shade-grown plant (right) side by side (b).
Table 1.
MANOVA and profile analysis results for the response of Pentaclethra macroloba photosynthesis, biomass, and carbon-based metabolites (sugars, flavans, and saponins) to light, fertilizer, and competition.
Figure 2.
Means (SE) of photosynthesis, dark respiration, biomass, and carbon-based metabolites.
Values are from Pentaclethra macroloba seedlings grown in shade (a, c) or full sunlight (b, d) with and without competition.
Figure 3.
Interactions between experimental treatments and trade-offs in photosynthesis, growth, and defense production.
Path diagrams showing causal relationships (single headed arrows) and correlations (double headed arrows) between competition, fertilizer, photosynthesis (Amax), flavans, saponins, and biomass in Pentaclethra macroloba seedlings grown in the shade (A; χ2 = 0.8, df = 5, P = 0.98) or the sun (B; χ2 = 0.02, df = 1, P = 0.89). Bullets indicate negative relationships and arrows indicate positive relationships. Numbers are the standardized parameter estimates for relationships between variables. All relationships were significant with t-values >1.96 except where smaller t-values are indicated.