Differences in Leaf Temperature between Lianas and Trees in the Neotropical Canopy

Abstract

Leaf temperature (T leaf ) influences photosynthesis and respiration. Currently, there is a growing interest in including lianas in productivity models due to their increasing abundance and their detrimental effects in the carbon stock of tropical ecosystems. Therefore, understanding the differences of T leaf between lianas and trees is important for future predictions of productivity. Here, we determined the displayed leaf temperature (T d = T leaf − air temperature) of several species of lianas and their host trees during El Niño-Southern Oscillation (ENSO) and non-ENSO years to evaluate if the presence of lianas affects the T d of their host trees, and if leaves of lianas and their host trees exhibit differences in T d . Our results suggest that close to midday, the presence of lianas does not affect the T d of their host trees; however, lianas tend to have higher values of T d than their hosts across seasons, in both ENSO and non-ENSO years. Although lianas and trees tend to have similar physiological-temperature responses, differences in T d could lead to significant differences in rates of photosynthesis and respiration based on temperature response curves. Future models should thus consider differences in leaf temperature between these two life forms to achieve robust predictions of productivity.

Canopy Temperature Differences between Liana-Infested and Non-Liana Infested Areas in a Neotropical Dry Forest

“…Our study has documented that in general, liana-infested areas have a higher mean temperature than non-liana infested areas in the Santa Rosa National Park Environmental Monitoring Super Site. This temperature difference corroborates field-based observations by Sanchez-Azofeifa et al [24] and Guzmán et al [25], who also observed that, on average, liana leaves have a higher temperature than tree leaves in a Panamanian tropical dry forest.…”

“…The mean temperature difference between the liana-infested and the non-liana infested areas in our study is smaller than what was observed in previous studies by Sanchez-Azofeifa et al [24] and Guzmán et al [25]. Despite the observed small temperature differences, such differences can be important to enhance the current ability to detect the presence of lianas by remote sensing.…”

“…First, our study was conducted using a UAV remote sensing platform with a distance of approximately 110 m between the canopy and the sensor, unlike the previous studies by Sanchez-Azofeifa et al [24] and Guzmán et al [25] who acquired their data as contact measurements or from a distance of 1.8 m, respectively. Despite the high spatial resolution of 0.15 m of the thermal infrared data, it is possible that there is some spectral mixing between liana leaves and tree leaves [55], thus normalizing the differences that could be observed at the level of individual leaves or from a shorter distance.…”

“…One of the first studies to document the impact of lianas on the temperature of tropical canopies was conducted by Sanchez-Azofeifa et al who documented that liana leaves have a generally higher temperature than their host tree leaves [24]. Following this finding, Guzmán et al acquired thermal infrared data in Panama to study the temperature differences between lianas and their host trees [25]. Their studies suggest that liana leaves have higher average temperatures than tree leaves, but no clear effects (either negative or positive), induced by the presence of lianas, could be observed in the temperature of the host trees.…”

A Research Agenda for Microclimate Ecology in Human-Modified Tropical Forests

“…This would allow microclimate ecology to be integrated into classical landscape ecology and metacommunity dynamics (Hesselbarth et al, 2019;Senior et al, 2019), and also guide efforts to restore and increase connectivity in fragmented landscapes (e.g., through the rehabilitation of riparian buffer zones; Luke et al, 2019). It also provides an opportunity to assess the effectiveness of different forest and plantation management practices that aim to restore microclimate regimes by altering canopy structure and ecophysiology, such as natural regeneration, enrichment planting, and climber cutting (Rodríguez-Ronderos et al, 2016;Ichihashi et al, 2017;Guzmán et al, 2018). Moreover, this would also provide an opportunity to understand how different management interventions alter specific facets of microclimate (e.g., impact of liana cutting on transpiration) and whether these can be tailored to restore specific microclimatic conditions.…”