Impact of abiotic factors on the dynamic of carbon, nitrogen and oxygen stable isotopes of four forage species

Abstract

Anthropogenic activities increased atmospheric CO2 concentration from pre-industrial values of 270 µmol mol-1 to the current 400 µmol mol-1, leading to a continuous increase in the global surface temperature. Climate models indicate that earth surface temperature anomaly may reach values of up to 2ºC until 2100 if Paris Agreement goals were not achieved. These environmental alterations will produce more intense and frequent extreme climate events such as heat waves, droughts and floods. Several impacts of climate change have already concerned the production of many important plant species used for animal and human feed. However, there's little information about the effects of climate change in tropical and subtropical ecosystems, especially in forage species under field conditions. The dynamic of stable isotopes has been widely used as an important and a reliable technique to better understand plant water transport, water use efficiency, carbon dynamics at leaf-level, nutrient uptake and their responses to climate change variables. Therefore, the objective of this research proposal is evaluating the effects of warming, elevated [CO2], drought and soil nutrient availability in the dynamics of carbon (12C, 13C), oxygen (16O, 18O) and nitrogen (14N, 15N) stable isotopes in samples collected in Brazil along six growing seasons in different tissues of three forage species, Stylosanthes capitata (C3), Panicum maximum (C4, subtype PCK), and the hybrid Brachiaria Mavuno (C4, subtype PCK). During the international internship a new experiment with Panicum virgatum (C4, subtype NAD-ME) will be performed for comparative analysis. Our main hypothesis is that isotopes discrimination will differentially change as result of abiotic conditions, allowing a better understanding of long-term tropical pastures responses to climate change.