Abstract Detail

Physiology & Ecophysiology

Perez, Timothy [1], Feeley, Kenneth [1].

Photosynthetic heat tolerances are correlated with maximum leaf temperatures.

The central role of photosynthesis in plants makes photosynthetic thermal tolerances a potentially important ecophysiological trait that can be used to match crops to suitable environments, understand species distributions and even their responses to climate change. A pervasive assumption among plant biologists is that species with higher photosynthetic heat tolerances (PHTs) are capable of tolerating hotter environments. Given rising temperatures due to climate change, there is increasing interest in role of PHTs for understanding which species will be most susceptible to climate change. To date, phenotypic plasticity and high within-community variation of PHTs has limited their utility for understanding how they relate to environmental conditions or may influence species responses to climate change. We hypothesize that if PHTs are useful for understanding environmental tolerances, they should represent adaptations to maximum leaf temperature. To address this hypothesis, we recorded leaf temperature between 45 and 104 times on 5-8 leaves for 19 different species of trees, shrubs, or lianas grown at Fairchild Tropical Botanic Garden (FTBG) in Coral Gables, FL USA. We calculated maximum leaf temperature per species and found it to be significantly correlated to PHTs (Pearson's r= 0.77, df = 17, p<0.01). To control for microenvironmental variation possibly biasing observed leaf temperatures, we collected air temperature and relative humidity data each time leaf temperature was measured to parameterize a leaf energy balance model (LEBM). The LEBM was also parameterized with species-specific physiological leaf traits that are known to influence leaf temperature. Maximum predicted leaf temperatures were significantly correlated with PHTs (Pearson's r= 0.6, df = 16, p< = 0.01). Lastly, we parameterized a LEBM using simulated microenvironmental conditions from across each species known distribution and with the thermoregulatory traits collected at FTBG. The resulting maximum predicted leaf temperatures were significantly correlated with observed PHTs (Pearson's r= 0.57, df = 11, p-value < 0.05). Our results suggest that PHTs are likely to reflect adaptations to maximum leaf temperature. Furthermore, our methods illustrate a simple "next-generation" vegetation model that incorporates plant physiology and species distribution modeling techniques to predict which populations, and species may be most vulnerable to climate change.

1 - University of Miami, Dept. of Bio. 215 Cox Science Center, 1301 Memorial Drive, Coral Gables, FL, 33146, United States

Keywords:
photosynthesis
Climate change
leaf energy balance
ecophysiology
Vegetation Mapping
stomatal conductance
leaf temperature.

Presentation Type: Oral Paper
Session: 39, Ecophysiology
Location: 114/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 8:45 AM
Number: 39004
Abstract ID:404
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation