Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests

Cold air drainage is common in mountains, and leads to large, fine-scale differences in diurnal temperature range (DTR). DTR is hypothesized to drive plant community assembly, because areas with high DTR can be exposed to both extreme high and extreme low temperatures in the same day. We established...

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Main Authors: Adam L Mahood, David M Barnard, Jacob A Macdonald, David W Pittenger, Sarah M Hall, Paula J Fornwalt
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:Environmental Research: Ecology
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Online Access:https://doi.org/10.1088/2752-664X/adfa9e
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author Adam L Mahood
David M Barnard
Jacob A Macdonald
David W Pittenger
Sarah M Hall
Paula J Fornwalt
author_facet Adam L Mahood
David M Barnard
Jacob A Macdonald
David W Pittenger
Sarah M Hall
Paula J Fornwalt
author_sort Adam L Mahood
collection DOAJ
description Cold air drainage is common in mountains, and leads to large, fine-scale differences in diurnal temperature range (DTR). DTR is hypothesized to drive plant community assembly, because areas with high DTR can be exposed to both extreme high and extreme low temperatures in the same day. We established networks of temperature and relative humidity sensors along DTR gradients in two montane forest basins, and conducted plant surveys around each sensor ( n = 45). We studied the seasonal stability of DTR and its effects on fine-scale variation in plant community composition, and used topographic metrics to create spatial models of DTR. We found that mean DTR was stable throughout the year, although it was more variable around the mean (i.e. the standard deviation was higher) in winter months. It achieved both time series stability and distinguishability in less than 100 d, and was most strongly associated with daily minimum vapor pressure deficit. DTR measured in situ was the only variable that explained more than 50% of the within-basin variation in species composition for both basins, but among basins coarser-scale variables (actual evapotranspiration, topographic wetness index (TWI), and climatic water deficit) performed better. DTR had a small, negative effect on species richness. Our simple model of DTR explained 64% of the variation, using only TWI and elevation as predictors. These findings illustrate how at broad scales, average temperature and moisture conditions drive the regional species pool, but fine scale distribution of plant species within a basin is driven by microclimate. Accounting for fine-scale topoclimatic processes will lead to better models that capture abiotic gradients, allowing for improved representation of complex ecological processes in earth systems models. Future studies should account for microclimate, especially DTR, when designing experiments, as uneven sampling across microclimates will introduce bias into community observations.
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spelling doaj-art-7d3eec5f2d1642128ffd41199a6da06b2025-08-21T10:42:05ZengIOP PublishingEnvironmental Research: Ecology2752-664X2025-01-014303500710.1088/2752-664X/adfa9eDiurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forestsAdam L Mahood0https://orcid.org/0000-0003-3791-9654David M Barnard1Jacob A Macdonald2David W Pittenger3https://orcid.org/0009-0006-9049-7744Sarah M Hall4https://orcid.org/0009-0001-4559-766XPaula J Fornwalt5https://orcid.org/0000-0002-5252-408XWater Resources Systems Management, USDA-ARS , Fort Collins, CO, United States of AmericaWater Resources Systems Management, USDA-ARS , Fort Collins, CO, United States of AmericaWater Resources Systems Management, USDA-ARS , Fort Collins, CO, United States of AmericaValles Caldera National Preserve, National Park Service , Jemez Springs, NM, United States of AmericaValles Caldera National Preserve, National Park Service , Jemez Springs, NM, United States of AmericaUS Department of Agriculture, Forest Service, Rocky Mountain Research Station , Fort Collins, CO, United States of AmericaCold air drainage is common in mountains, and leads to large, fine-scale differences in diurnal temperature range (DTR). DTR is hypothesized to drive plant community assembly, because areas with high DTR can be exposed to both extreme high and extreme low temperatures in the same day. We established networks of temperature and relative humidity sensors along DTR gradients in two montane forest basins, and conducted plant surveys around each sensor ( n = 45). We studied the seasonal stability of DTR and its effects on fine-scale variation in plant community composition, and used topographic metrics to create spatial models of DTR. We found that mean DTR was stable throughout the year, although it was more variable around the mean (i.e. the standard deviation was higher) in winter months. It achieved both time series stability and distinguishability in less than 100 d, and was most strongly associated with daily minimum vapor pressure deficit. DTR measured in situ was the only variable that explained more than 50% of the within-basin variation in species composition for both basins, but among basins coarser-scale variables (actual evapotranspiration, topographic wetness index (TWI), and climatic water deficit) performed better. DTR had a small, negative effect on species richness. Our simple model of DTR explained 64% of the variation, using only TWI and elevation as predictors. These findings illustrate how at broad scales, average temperature and moisture conditions drive the regional species pool, but fine scale distribution of plant species within a basin is driven by microclimate. Accounting for fine-scale topoclimatic processes will lead to better models that capture abiotic gradients, allowing for improved representation of complex ecological processes in earth systems models. Future studies should account for microclimate, especially DTR, when designing experiments, as uneven sampling across microclimates will introduce bias into community observations.https://doi.org/10.1088/2752-664X/adfa9ecold air drainagediurnal temperature rangemicroclimateplant ecologytopographyvapor pressure deficit
spellingShingle Adam L Mahood
David M Barnard
Jacob A Macdonald
David W Pittenger
Sarah M Hall
Paula J Fornwalt
Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests
Environmental Research: Ecology
cold air drainage
diurnal temperature range
microclimate
plant ecology
topography
vapor pressure deficit
title Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests
title_full Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests
title_fullStr Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests
title_full_unstemmed Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests
title_short Diurnal temperature range drives understory plant community composition in micro-climatically complex temperate montane forests
title_sort diurnal temperature range drives understory plant community composition in micro climatically complex temperate montane forests
topic cold air drainage
diurnal temperature range
microclimate
plant ecology
topography
vapor pressure deficit
url https://doi.org/10.1088/2752-664X/adfa9e
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