Experimental Air Warming of a Stylosanthes capitata, Vogel Dominated Tropical Pasture Affects Soil Respiration and Nitrogen Dynamics

Author(s)

Gonzalez-Meler, Miquel A. ; Silva, Lais B. C. ; Dias-De-Oliveira, Eduardo ; Flower, Charles E. ; Martinez, Carlos A.

• Document type: Journal article
• Source: FRONTIERS IN PLANT SCIENCE; v. 8, FEB 1 2017.
• Web of Science Citations: 5

Abstract

Warming due to global climate change is predicted to reach 2 degrees C in tropical latitudes. There is an alarming paucity of information regarding the effects of air temperature on tropical agroecosystems, including foraging pastures. Here, we investigated the effects of a 2 degrees C increase in air temperature over ambient for 30 days on an established tropical pasture (Ribeirao Preto, SAo Paulo, Brazil) dominated by the legume Stylosanthes capitata Vogel, using a T-FACE (temperature free-air controlled enhancement) system. We tested the effects of air warming on soil properties {[}carbon (C), nitrogen (N), and their stable isotopic levels (delta C-13 and delta N-15), as well as soil respiration and soil enzymatic activity] and aboveground characteristics (foliar C, N, delta C-13, delta N-15, leaf area index, and aboveground biomass) under field conditions. Results show that experimental air warming moderately increased soil respiration rates compared to ambient temperature. Soil respiration was positively correlated with soil temperature and moisture during mid-day (when soil respiration was at its highest) but not at dusk. Foliar delta C-13 were not different between control and elevated temperature treatments, indicating that plants grown in warmed plots did not show the obvious signs of water stress often seen in warming experiments. The N-15 isotopic composition of leaves from plants grown at elevated temperature was lower than in ambient plants, suggesting perhaps a higher proportion of N-fixation contributing to tissue N in warmed plants when compared to ambient ones. Soil microbial enzymatic activity decreased in response to the air warming treatment, suggesting a slower decomposition of organic matter under elevated air temperature conditions. Decreased soil enzyme capacity and increases in soil respiration and plant biomass in plots exposed to high temperature suggest that increased root activity may have caused the increase seen in soil respiration in this tropical pasture. This response along with rapid changes in soil and plant 15N may differ from what has been shown in temperate grasslands. (AU)

• FAPESP's process: 08/58075-8 - Miniface climate-change impact experiment to analyze the effects of elevated CO2 and warming on photosynthesis, gene expression, biochemistry, growth, nutrient dynamics and yield of two contrasting tropical forage species
• Grantee: Carlos Alberto Martinez y Huaman
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 12/17755-1 - Effects of elevated CO2 concentration on the dynamics of stable isotopes of carbon and nitrogen in two tropical forage (Panicum maximum and Stylosanthes capitata) cultivated in consortium
• Grantee: Laís Batista Carmo Silva
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• FAPESP's process: 12/03439-0 - Effects of elevated CO2 concentration on the dynamics of stable isotopes of carbon and nitrogen in two tropical forage (Panicum maximum and Stylosanthes capitata) cultivated in consortium
• Grantee: Laís Batista Carmo Silva
• Support Opportunities: Scholarships in Brazil - Master