Document: MAR-3-29-20

Light response and drought tolerance in two South Florida Psychotria species.

ROBERTS, M.C.*

Florida International University, Miami, FL 33199 USA ¹

Abstract:
The light environment greatly influences the morphological and anatomical development and physiology of understory plants. However, recent research indicates that drought tolerance may be equally important in structuring understory communities in seasonally dry tropical forests. I investigated the growth responses of two South Florida native species of Psychotria in seasonally dry tropical hardwood hammocks. Psychotria nervosa and P. tenuifolia are closely related, co-occurring and ubiquitous components of the understory in these hardwood hammocks, and their distributions appear to be correlated with canopy cover. Growth experiments under various light regimes and drought tolerance experiments indicate differences in light response and drought tolerance. Psychotria tenuifolia responds to broad light conditions and is drought intolerant, while P. nervosa responds to narrower light conditions and is drought tolerant. These results help to explain observations that P. tenuifolia is more abundant in deep shade where moisture lingers during the dry season, and that P. nervosa is more abundant in open, drier areas.

Keywords: Light environment, drought tolerance, Psychotria

This abstract is being presented at: 10:30 AM in session:
Poster Session #1: Light Relations.