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Models for Predicting leaf traits across functional groups using reflectance spectroscopy
Borealis
Kothari, Shan; Beauchamp-Rioux, Rosalie; Blanchard, Florence; Crofts, Anna L.; Girard, Alizée; Guilbeault-Mayers, Xavier; Hacker, Paul; Pardo, Juliana; Schweiger, Anna K.; Demers-Thibeault, Sabrina; Bruneau, Anne; Coops, Nicholas C.; Kalacska, Margaret; Vellend, Mark; Laliberté, Etienne — 2022-11-14 (2022-11-12) This repository contains the partial least-squares regression (PLSR) model coefficients to accompany the paper "Predicting leaf traits across functional groups using reflectance spectroscopy" by Kothari et al. (2023) <em>New Phytologist</em> (DOI: 10.1111/nph.18713). The repository includes the models in various sets of .csv files along with a README that contains detailed instructions about what the models mean and how to use them. 2023-04-06 Update: We have added models to predict EWT for fresh leaves under field conditions rather than rehydrated leaves. These models are found in the folder EWTCorrectedModels. It is recommended to use these rather than the other EWT models for most purposes.
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Data from: The importance of biotic filtering on boreal conifer recruitment at alpine treeline
Dryad
Crofts, Anna L.; Brown, Carissa D. — 2021-09-10 <p style="text-indent:0in;margin-right:20px;margin-bottom:10px;">Treeline, the ecotone where forest transitions to alpine or tundra ecosystems, is considered the thermal limit to tree growth and survival. Despite temperature increases across mountainous areas and high latitudes globally, there has been no ubiquitous change in treeline position. The process of range expansion must initially depend on increased recruitment at, or beyond current range limits and recruitment limitations have been hypothesized as a mechanism for the variable response of treeline position to climate warming.<b> </b>We conducted a unique series of observational and experimental studies to quantify early-life stage constraints, from seed production to seedling establishment, on black spruce (<i>Picea mariana</i>) and tamarack (<i>Larix laricina</i>) recruitment at a model alpine treeline in Newfoundland, Canada.<b> </b>We found recruitment at treeline to be simultaneously seed and establishment limited. The treeline population produced fewer seeds than the forest population and black spruce seeds produced at treeline were less viable. Tamarack was more seed limited than black spruce where seed viability was low regardless of altitudinal position.<b> </b>Post-dispersal seed predation greatly constrained recruitment across the altitudinal gradient; however, black spruce seeds experienced the lowest levels of invertebrate seed predation on the lichen mat at treeline. If seeds were not consumed, individuals at treeline were establishment limited where germination and seedling establishment was both less abundant and delayed on lichen substrate. Our study highlights the need for multiple factors to align temporally for significant recruitment at treeline to occur.</p>

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(Author: Crofts, Anna L.)

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