Extreme thermal heterogeneity in structurally complex tropical rain forests

Scheffers, Brett R.; Edwards, David P.; Macdonald, Stewart L.; Senior, Rebecca A.; Andriamahohatra, Lydou R.; Roslan, Nadiah; Rogers, Andrew M.; Haugaasen, Torbjørn; Wright, Patricia C.; Williams, Stephen E.

doi:10.1111/btp.12355

Cited by 50 publications

(68 citation statements)

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“…Leaf temperature is predominately determined by ambient temperature, but also regulated by leaf physical traits and transpiration (Defraeye, Verboven, Ho, & Nicolai, ; Lambers, Chapin, & Pons, ; Scheffers et al., ). When plants are exposed to hot conditions, they can reduce the amount of accepted radiation through reflection and movement and can dissipate excessive heat via radiation emission, heat convection, and transpiration.…”

Section: Introductionmentioning

confidence: 99%

Stronger cooling effects of transpiration and leaf physical traits of plants from a hot dry habitat than from a hot wet habitat

et al. 2017

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Leaf temperature exerts an important impact on the microenvironment and physiological processes of leaves. Plants from different habitats have different strategies to regulate leaf temperature. The relative importance of physical traits and transpiration for leaf temperature regulation in the hot habitat is still unclear. We investigated 22 leaf physical traits, transpiration, and thermal properties of 38 canopy species of seedlings in a greenhouse, including 18 dominant species from a hot wet habitat (HW) and 20 dominant species from a hot dry habitat (HD). To separate the impact of transpiration and leaf physical traits on leaf temperature, we measured the diurnal courses of leaf temperatures with and without transpiration. The temperature of a reference leaf beside each individual was measured simultaneously to render temperatures comparable. Generally, the species from HD showed lower leaf temperatures than the species from HW under the same conditions. Both transpiration capacity and cooling effect of leaf physical traits were stronger for the plants from HD. Active transpiration provides a suitable thermal environment for photosynthesis, while xeromorphic leaves can dampen heat stress when transpiration is suppressed. Higher vein density and stomatal pore area index (SPI) facilitated higher transpiration capacity of the plants from HD. Meanwhile, shorter leaves and thinner lower epidermis of the plants from HD were more efficient in heat transfer, although relationships were much weaker than the synergic effect of all the physical traits. Our results confirmed that transpiration and leaf physical traits provided double insurance for avoiding overheating, particularly for plant from HD. We emphasize that transpiration is a more effective way to cool leaves than physical traits when water is sufficient, which may be an important adaptation for plant from HD where rainfall is sporadic. Our results provide further insight into the relationship between physical traits and transpiration for the regulation of leaf temperature, and the co‐evolution of gas exchange and thermal regulation of leaves. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12923/suppinfo is available for this article.

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Section: Introductionmentioning

confidence: 99%

Stronger cooling effects of transpiration and leaf physical traits of plants from a hot dry habitat than from a hot wet habitat

et al. 2017

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“…Surface temperature measurements at high spatial resolution can easily be collected in the field using a handheld thermal camera. We used a FLIR model E40 camera, which costs ~US$4,000, weighs 825 g, and takes 19,200 measurements (160 × 120 pixels) in a single photo (FLIR, ; Scheffers et al, ). Various other models exist, including the smaller and more affordable FLIR ONE smartphone attachment at ~US$300, 34.5 g and a resolution of 80 × 60 pixels.…”

Section: Functionalitymentioning

confidence: 99%

“…As with any field study, the sampling design should aim to achieve sufficient coverage over the study area and over time, such that the images are representative samples of the treatments of interest. For example a single image of the ground from 1 m away encompasses an area of 0.9 × 1.1 m (1 pixel ≅ 0.5 cm 2 ) using a FLIR E40 camera (FLIR, ), and so it may be necessary to take multiple photos in different cardinal directions and at different times of day to effectively represent the temperature of a study plot (Scheffers et al, ; Senior, Hill, Benedick, & Edwards, ) (Figure ).…”

Section: Functionalitymentioning

confidence: 99%

“…While dataloggers remain instrumental in the field of thermal ecology (Bramer et al, ), technological advances in recent years have made thermal cameras an increasingly affordable and practical addition (Faye, Rebaudo, Yánez‐Cajo, Cauvy‐Fraunié, & Dangles, ; Scheffers et al, ). With one click a single thermal image provides thousands of spatially explicit surface temperature measurements at the mm‐cm scale.…”

Section: Introductionmentioning

confidence: 99%

“…The extraction of data from FLIR thermal cameras specifically (one of the most commonly used brands) can be achieved using the freely available FLIR Tools software (https://www.flir.com/products/flir-tools; cf. Scheffers et al, ), but cannot be done in batch and the automatic conversion of raw values to temperature lacks transparency. The process was simplified by the development of the Thermimage package (Tattersall, ) in R (R Core Team, ).…”

Section: Introductionmentioning

confidence: 99%

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ThermStats: An R package for quantifying surface thermal heterogeneity in assessments of microclimates

2019

Self Cite

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Variation in temperature at a fine spatial scale creates critically important microclimates for many organisms. Quantifying thermal heterogeneity at this scale is challenging and, until recently, has been largely restricted to the use of dataloggers to record air temperature. Thermography is becoming an increasingly viable alternative. A single photo from a thermal imaging camera contains thousands of spatially explicit surface temperature measurements, making thermal cameras ideal for rapidly assessing temperature variation at fine scale. Here, we present an R package—ThermStats—for processing thermal images and other gridded temperature data. The package addresses current constraints on applying thermography in ecology, by speeding up and simplifying the extraction of data from thermal images, and by facilitating the calculation of different metrics of thermal heterogeneity. The metrics capture both the frequency distribution and spatial patterns of temperature, and the package functions are designed to accommodate different sampling strategies and data in either matrix or raster format. We demonstrate how ThermStats can be used to capture temperature variation at fine spatial scales in structurally complex habitat, such as tropical rainforest. Using thermal images collected in the field (~0.5 cm2 resolution), we found that thermal hetereogeneity varied little between primary and logged forest, but did vary with time of day. Comparing temperature extremes in a microclimate layer estimated from LIght Detection And Ranging data (LIDAR; 2,500 m2 resolution) , we found that both hot and cold extremes were hotter inside oil palm plantations than in the neighbouring forest. Our package simplifies the processing of thermal data, and our metrics capture key spatiotemporal temperature trends that underpin physiological, behavioural and demographic responses to environmental change. As such, ThermStats can advance a wide range of studies requiring fine‐scale surface temperature data for microclimate investigations.

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Behavioral thermoregulation in primates: A review of literature and future avenues

Thompson,

Hermann

2024

American J Primatol

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Primates face severe challenges from climate change, with warming expected to increase animals' thermoregulatory demands. Primates have limited long‐term options to cope with climate change, but possess a remarkable capacity for behavioral plasticity. This creates an urgency to better understand the behavioral mechanisms primates use to thermoregulate. While considerable information exists on primate behavioral thermoregulation, it is often scattered in the literature in a manner that is difficult to integrate. This review evaluates the status of the available literature on primate behavioral thermoregulation to facilitate future research. We surveyed peer‐reviewed publications on primate thermoregulation for N = 17 behaviors across four thermoregulatory categories: activity budgeting, microhabitat use, body positioning, and evaporative cooling. We recorded data on the primate taxa evaluated, support for a thermoregulatory function, thermal variable assessed, and naturalistic/manipulative study conditions. Behavioral thermoregulation was pervasive across primates, with N = 721 cases of thermoregulatory behaviors identified across N = 284 published studies. Most genera were known to utilize multiple behaviors ( = 4.5 ± 3.1 behaviors/genera). Activity budgeting behaviors were the most commonly encountered category in the literature (54.5% of cases), while evaporative cooling behaviors were the least represented (6.9% of cases). Behavioral thermoregulation studies were underrepresented for certain taxonomic groups, including lemurs, lorises, galagos, and Central/South American primates, and there were large within‐taxa disparities in representation of genera. Support for a thermoregulatory function was consistently high across all behaviors, spanning both hot‐ and cold‐avoidance strategies. This review reveals asymmetries in the current literature and avenues for future research. Increased knowledge of the impact thermoregulatory behaviors have on biologically relevant outcomes is needed to better assess primate responses to warming environments and develop early indicators of thermal stress.

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Extreme thermal heterogeneity in structurally complex tropical rain forests

Cited by 50 publications

References 56 publications

Stronger cooling effects of transpiration and leaf physical traits of plants from a hot dry habitat than from a hot wet habitat

Stronger cooling effects of transpiration and leaf physical traits of plants from a hot dry habitat than from a hot wet habitat

ThermStats: An R package for quantifying surface thermal heterogeneity in assessments of microclimates

Behavioral thermoregulation in primates: A review of literature and future avenues

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