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Title: Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA

Abstract

In order to plan for global changing climate experiments are being conducted in many countries, but few have monitored the effects of the climate change treatments (warming, elevated CO₂) on the experimental plot microclimate. During three years of an eight year study with year-round feedback-controlled infra-red heater warming (1.5/3.0°C day/night) and growing season free-air CO₂ enrichment (600 ppm) in the mixed-grass prairie of Wyoming, USA, we monitored soil, leaf, canopy-air, above-canopy-air temperatures and relative humidity of control and treated experimental plots and evaluated ecologically important temperature differentials. Leaves were warmed somewhat less than the target settings (1.1 & 1.5°C day/night) but soil was warmed more creating an average that matched the target settings extremely well both during the day and night plus the summer and winter. The site typically has about 50% bare or litter covered soil, therefore soil heat transfer is more critical than in dense canopy ecosystems. The Wyoming site commonly has strong winds (5 ms⁻¹ average) and significant daily and seasonal temperature fluctuations (as much as 30°C daily) but the warming system was nearly always able to maintain the set temperatures regardless of abiotic variation. The within canopy-air was only slightly warmed and above canopy-air was notmore » warmed by the system, therefore convective warming was minor. Elevated CO₂ had no direct effect nor interaction with the warming treatment on microclimate. Relative humidity within the plant canopy was only slightly reduced by warming. Soil water content was reduced by warming but increased by elevated CO₂. This study demonstrates the importance of monitoring the microclimate in manipulative field global change experiments so that critical physiological and ecological conclusions can be determined. Highly variable energy demand fluctuations showed that passive IR heater warming systems will not maintain desired warming for much of the time.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [4];  [5]
  1. United States Department of Agriculture, Fort Collins, CO (United States)
  2. United States Arid-Land Agricultural Research Center, Maricopa, AZ (United States)
  3. Univ. of Western Sydney, Sydney (Australia)
  4. Instituto di Biometeorologia, Firenze (Italy)
  5. Chinese Academy of Sciences (CAS), Beijing (China)
Publication Date:
Research Org.:
United States Department of Agriculture, Fort Collins, CO (United States); Univ. of Wyoming, Laramie, WY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1193634
Alternate Identifier(s):
OSTI ID: 1454916
Grant/Contract Number:  
SC0006973
Resource Type:
Accepted Manuscript
Journal Name:
PLoS ONE
Additional Journal Information:
Journal Volume: 10; Journal Issue: 2; Journal ID: ISSN 1932-6203
Publisher:
Public Library of Science
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

LeCain, Daniel, Smith, David, Morgan, Jack, Kimball, Bruce A., Pendall, Elise, Miglietta, Franco, and Liang, Wenju. Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA. United States: N. p., 2015. Web. doi:10.1371/journal.pone.0116834.
LeCain, Daniel, Smith, David, Morgan, Jack, Kimball, Bruce A., Pendall, Elise, Miglietta, Franco, & Liang, Wenju. Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA. United States. doi:10.1371/journal.pone.0116834.
LeCain, Daniel, Smith, David, Morgan, Jack, Kimball, Bruce A., Pendall, Elise, Miglietta, Franco, and Liang, Wenju. Fri . "Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA". United States. doi:10.1371/journal.pone.0116834. https://www.osti.gov/servlets/purl/1193634.
@article{osti_1193634,
title = {Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA},
author = {LeCain, Daniel and Smith, David and Morgan, Jack and Kimball, Bruce A. and Pendall, Elise and Miglietta, Franco and Liang, Wenju},
abstractNote = {In order to plan for global changing climate experiments are being conducted in many countries, but few have monitored the effects of the climate change treatments (warming, elevated CO₂) on the experimental plot microclimate. During three years of an eight year study with year-round feedback-controlled infra-red heater warming (1.5/3.0°C day/night) and growing season free-air CO₂ enrichment (600 ppm) in the mixed-grass prairie of Wyoming, USA, we monitored soil, leaf, canopy-air, above-canopy-air temperatures and relative humidity of control and treated experimental plots and evaluated ecologically important temperature differentials. Leaves were warmed somewhat less than the target settings (1.1 & 1.5°C day/night) but soil was warmed more creating an average that matched the target settings extremely well both during the day and night plus the summer and winter. The site typically has about 50% bare or litter covered soil, therefore soil heat transfer is more critical than in dense canopy ecosystems. The Wyoming site commonly has strong winds (5 ms⁻¹ average) and significant daily and seasonal temperature fluctuations (as much as 30°C daily) but the warming system was nearly always able to maintain the set temperatures regardless of abiotic variation. The within canopy-air was only slightly warmed and above canopy-air was not warmed by the system, therefore convective warming was minor. Elevated CO₂ had no direct effect nor interaction with the warming treatment on microclimate. Relative humidity within the plant canopy was only slightly reduced by warming. Soil water content was reduced by warming but increased by elevated CO₂. This study demonstrates the importance of monitoring the microclimate in manipulative field global change experiments so that critical physiological and ecological conclusions can be determined. Highly variable energy demand fluctuations showed that passive IR heater warming systems will not maintain desired warming for much of the time.},
doi = {10.1371/journal.pone.0116834},
journal = {PLoS ONE},
number = 2,
volume = 10,
place = {United States},
year = {2015},
month = {2}
}

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