How global climate change will affect plant-soil interactions remains uncertain, including the effect of increasing heat stress (e.g., summer heat waves). We investigated the effects of heat waves (5 days at ambient plus 5 or 10 °C) on the plant's transfer of carbon (C) to soil and plant's absorption of nitrogen (N) from soil, and on soil microbial communities, in both laboratory (Andropogon gerardii) and field ( A. gerardii and Solidago canadensis in a tall-grass prairie at the University of Toledo Stranahan Arboretum, Toledo, Ohio).
• The heat waves did not affect plant water status and net photosynthesis of recently-expanded leaves in the laboratory; in the field, heat caused stomatal conductance in Andropogon to increase and leaf water potential to decrease. Solidago maintained the same water potential as it decreased stomatal conductance in heated plots.
• Shoot mass was unaffected in the laboratory, but root mass and root:shoot ratio increased. In the field, shoot mass increased only for Solidago. A decrease in N concentration in roots and an increasing demand for structural carbohydrate for root growth caused a decrease in root respiration and exudation of soluble carbohydrate and protein per gram of root mass.
• 13C-labeling of shoots indicated that heat waves increased transfer of recently fixed C from plant (Andropogon) to soil through increased fine-root turnover during heat waves. 15 N-labeling of soil indicated that heat waves decreased the efficiency of N uptake by Andropogon roots. The uptake of N by Solidago was, however, not negatively impacted by heat waves. These differential impacts of heat waves on the two co-existing species may make the tall-grass prairie increasingly dominated by Solidago in the future.
• More absorption of N by plants and an expanding microbial community during heat waves may have depleted extractable N in the soil that ultimately decreased soil respiration, though microbial biomass C and microbial abundance increased.
• These results highlight the need to consider the impact of heat waves in combination with other aspects of global environmental change (e.g., atmospheric CO2, N, precipitation) that are known to affect plant-soil linkages.
|School:||The University of Toledo|
|School Location:||United States -- Ohio|
|Source:||MAI 57/05M(E), Masters Abstracts International|
|Keywords:||Grass, Heat, Links, Plant-soil, Prairie, Soil, Tall-grass, Waves|
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