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Deep Sea Res
Healey, N., Oberbauer, S., & Hollister, R. (2016). Examination of Surface Temperature Modification by Open-Top Chambers along Moisture and Latitudinal Gradients in Arctic Alaska Using Thermal Infrared Photography.
Passive warming manipulation methodologies, such as open-top chambers (OTCs), are a meaningful approach for interpretation of impacts of climate change on the Arctic tundra biome. The magnitude of OTC warming has been studied extensively, revealing an average plot-level warming of air temperature that ranges between 1 and 3 degrees C as measured by shielded resistive sensors or thermocouples. Studies have also shown that the amount of OTC warming depends in part on location climate, vegetation, and soil properties. While digital infrared thermometers have been employed in a few comparisons, most of the focus of the effectiveness of OTC warming has been on air or soil temperature rather than tissue or surface temperatures, which directly translate to metabolism. Here we used thermal infrared (TIR) photography to quantify tissue and surface temperatures and their spatial variability at a previously unavailable resolution (3-6 mm(2)). We analyzed plots at three locations that are part of the International Tundra Experiment (ITEX)-Arctic Observing Network (AON-ITEX) network along both moisture and latitudinal gradients spanning from the High Arctic (Barrow, AK, USA) to the Low Arctic (Toolik Lake, AK, USA). Our results show a range of OTC surface warming from 2.65 to 1.27 degrees C (31%-10%) at our three sites. The magnitude of surface warming detected by TIR imagery in this study was comparable to increases in air temperatures previously reported for these sites. However, the thermal images revealed wide ranges of surface temperatures within the OTCs, with some surfaces well above ambient unevenly distributed within the plots under sunny conditions. We note that analyzing radiometric temperature may be an alternative for future studies that examine data acquired at the same time of day from sites that are in close geographic proximity to avoid the requirement of emissivity or atmospheric correction for validation of results. We foresee future studies using TIR photography to describe species-level thermodynamics that could prove highly valuable toward a better understanding of species-specific responses to climate change in the Arctic.
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Weerakoon, W. M. W., Ingram, K. T., & Moss, D. N. (2005). Atmospheric CO2 concentration effects on N partitioning and fertilizer N recovery in field grown rice (Oryza sativa L.).
Agriculture Ecosystems & Environment
, , 342–349.
Lowland rice (Oryza sativa L.) responds positively to increased atmospheric CO2 concentration. However, the efficiency of the canopy depends on the N status of the plant, which could vary with the change in uptake and partitioning of N with increased atmospheric CO2. A field experiment was conducted at the International Rice Research Institute (IRRI) to determine changes in N requirement of the rice crop and to propose suitable management strategies to overcome tissue N dilution with increased CO2 concentration. Rice variety IR72 was grown inside open top chambers at ambient (about 350 mu mol mol(-1)) or elevated (700 mu mol mol(-1)) atmospheric CO2 in combination with three levels of applied N (0, 90, or 200 kg N ha(-1)). Rooting of rice was linearly related to tillering, and the relationship did not change with CO2 concentrations, but with age of the crop. When adequate N was not supplied, rice plants grown at high CO2 became inferior to plants grown at ambient M. N uptake and fertilizer N recovery was higher in plants grown in high CO2 until maximum tillering, but the partitioning of N towards leaves decreased by 9%. Acclimation to high CO2 by rice may, therefore, be dependent on the N uptake. Increased N uptake under high CO2 environment was related to its larger root system, which was due to increased unproductive tillering. This suggests that if tillering is limited, rice plants at high CO2 may suffer from N limitation due to changes in both uptake and partitioning. It is concluded that management of the rice crop grown at high atmospheric CO2 should be different to that under current conditions. (c) 2005 Elsevier B.V. All rights reserved.
rice carbon dioxide N uptakes N partitioning roots Oryza sativa L. CARBON-DIOXIDE CONCENTRATION OPEN-TOP CHAMBERS ELEVATED CO2 NITROGEN NUTRITION ENRICHMENT RESPONSES PLANTS YIELD PHOTOSYNTHESIS ACCLIMATION
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