Biology subjects

Cernusak, L. A.

Publications and source records attributed to Cernusak, L. A..

4 recordsLinked to original sources

bioRxiv2025

Cytosolic water potential as a mechanistic driver of leaf airspace unsaturation and non-stomatal control of transpiration

1Mesophyll cells exhibit a previously underappreciated capacity to regulate water loss via low plasma membrane conductance (Lp), offering a non-stomatal mechanism for transpiration control. However, the structural basis and regulation of Lp remain poorly understood, limiting its integration into predictive models. In this study, we show that Lp responds dynamically to changes in cytosolic water potential ({psi}cy), decreasing as{psi} cy approaches the turgor loss point. This identifies{psi} cy as the primary physiological signal regulating Lp. We introduce a predictive, physiologically grounded model linking Lp to{psi} cy. Our model establishes a mechanistic connection between internal water status, leaf hydraulics, substomatal cavity unsaturation, and gas exchange. This framework opens new avenues for understanding and modelling plant water use under stress.

plant biology↗

bioRxiv2024

Unsaturation and Approximate Isotopic Homogeneity in Leaf Air Spaces

O_LIWe consider two assumptions of leaf isotope gas exchange measurements: that leaf air spaces are saturated with water vapour, and that this vapour is of a homogeneous isotopic composition. In particular, we consider whether these assumptions can concurrently hold and, if not, which assumption is preferable to retain. C_LIO_LIWe present two methods using independent measurements of both leaf surfaces to consider these assumptions. The first method determines the isotopic inhomogeneity between the abaxial and adaxial evaporative sites when saturation is assumed. The second method determines the unsaturation in the abaxial and adaxial substomatal cavities when isotopic homogeneity is assumed. The methods are applied on Gossypium hirsutum (cotton) under benign atmospheric demand conditions (1.0 kPa air saturation deficit). C_LIO_LIWe find evidence that assuming saturation contradicts isotopic homogeneity and vice-versa. We compare each assumption to pre-existing data and find that it is reasonable to assume isotopic homogeneity, but not leaf vapour saturation. Thus, we find that leaves experience unsaturation even under benign atmospheric demand conditions and have a spatial variation in their unsaturation, with lower humidities associated with the surface of least stomatal resistance. C_LIO_LIWe conclude that leaves cannot be considered to be both saturated and of a homogeneous vapour isotopic composition. They are best approximated as isotopically homogeneous. C_LI

plant biology↗

bioRxiv2021

Tropical tree growth sensitivity to climate is driven by species intrinsic growth rate and leaf traits

A better understanding of how climate affects growth in tree species is essential for improved predictions of forest dynamics under climate change. Long-term climate averages (mean climate) and short-term deviations from these averages (anomalies) both influence tree growth, but the rarity of long-term data integrating climatic gradients with tree censuses has so far limited our understanding of their respective role, especially in tropical systems. Here, we combined 49 years of growth data for 509 tree species across 23 tropical rainforest plots along a climatic gradient to examine how tree growth responds to both climate means and anomalies, and how species functional traits mediate these tree growth responses to climate. We showed that short-term, anomalous increases in atmospheric evaporative demand and solar radiation consistently reduced tree growth. Drier forests and fast-growing species were more sensitive to water stress anomalies. In addition, species traits related to water use and photosynthesis partly explained differences in growth sensitivity to both long-term and short-term climate variations. Our study demonstrates that both climate means and anomalies shape tree growth in tropical forests, and that species traits can be leveraged to understand these demographic responses to climate change, offering a promising way forward to forecast tropical forest dynamics under different climate trajectories.

ecology↗

bioRxiv2021

AusTraits: a curated plant trait database for the Australian flora

We introduce the AusTraits database - a compilation of measurements of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 375 traits across 29230 taxa from field campaigns, published literature, taxonomic monographs, and individual taxa descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological parameters (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual-, species- and genus-level observations coupled to, where available, contextual information on site properties. This data descriptor provides information on version 2.1.0 of AusTraits which contains data for 937243 trait-by-taxa combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data to increase our collective understanding of the Australian flora.

ecology↗