Adam Pelligrini


Environmental stress can cause populations to undergo differential evolutionary change. This evolutionary change can be a function of the intensity of the stress, other associated abiotic/biotic interactions, and species specific ontogenic factors. This study investigated the effects that temperature stress (5°C increase) combined with varying nutrient allocation has on two epiphytic bromeliad species, Vriesea cathyi and Tilandsia bulbosa on biomass production and growth rates over 40 days. I hypothesized that plants under high temperature would have a lower growth rate and lower biomass than control plants and that different nutrient levels will cause significant differences in biomass production and growth rate. Plants in the cooler temperature produced more relative biomass, specifically in the Phosphorus treatment in Tilandsia bulbosa, and had higher relative growth rate in both species. There was a significant effect of nutrient treatment (Nitrogen-Phosphorus treatment had the lowest growth) in the 27°C Tilandsia bulbosas and in the 27°C and 32°C Vriesea cathyi. There was not a significant effect of temperature on growth rate in the Tilandsia bulbosa but there was a significant effect of temperature on growth rate in Vriesea cathyi. Differential nutrient availability did not affect either an epiphyte’s response to temperature. Within the significant effects of both treatment and nutrients, I found different effects across species. For example, while the relative biomass data patterns were consistent across species, the relative growth rate were not, with new leaves in the V. cathyi growing significantly faster than new leaves in T. bulbosa. This study showed that temperature change affects epiphytes, a particularly vulnerable plant group, more so than nutrient levels changing.