Data from: Early life conditions and precipitation influence the performance of widespread understory herbs in variable light environments

1. The understory of tropical forests is heterogeneous across time, and
plants that inhabit this layer may exhibit adaptations (e.g. trait
plasticity) that enable them to exploit this variability to their
advantage. We tested the hypothesis that two widespread understory herbs
would perform equally well in a variable as in a constant environment,
using a two-year shade-house experiment. 2. We measured demographic traits
(growth and survival), a physiological trait (maximum photosynthetic
capacity), and life history traits (leaf lifespan and biomass allocation)
of Heliconia tortuosa and Calathea crotalifera. We investigated how these
traits were affected by light availability at the seedling stage,
precipitation, and whether individuals experienced a constant or variable
light environment. 3. Whether or not a variable environment was favorable
for plants depended upon precipitation and the environment in which
individuals started life. At low precipitation, plants in a variable light
environment grew more than those in a constant environment, but only when
individuals had lived as seedlings in low light. At high precipitation,
plants in a constant environment grew more than those in a variable
environment, regardless of early conditions. Survival was lower in a
variable environment at low precipitation, and more so at high
precipitation. Photosynthetic capacity was lower for individuals in a
variable environment than in a constant environment when they had lived in
high light as seedlings. 4. Calathea grew faster and survived more poorly
than Heliconia, independently of the treatments. Calathea grew more at
high than low precipitation while Heliconia grew more at low than high
precipitation. Leaf lifespan and biomass allocation did not differ among
treatments, although Calathea had a significantly greater proportion of
its biomass aboveground versus that of Heliconia. 5. Synthesis
Environmental variability had a neutral or positive effect on biomass
allocation, photosynthetic capacity, and leaf lifespan for these species.
Survival was the only trait that was always lower in a variable
environment. The effect of environmental variability was dependent on
early life conditions as well as precipitation, suggesting that generalist
species may experience high fitness as forest environments become more
variable by maintaining high growth at the expense of survival.