Reis. 2013. Fluxes of CO2 above a sugarcane plantation in Brazil.Contact CEH NORA team at noraceh@ceh.ac.ukThe NERC and CEH trademarks and logos ('the Trademarks') are registered trademarks of NERC in the UK and other countries, and may not be used without the prior written consent of the Trademark owner. Fluxes of CO 2 were measured above a sugarcane plantation using the eddy-covariance 29 method covering two growth cycles, representing the second and third re-growth 30 (ratoons) harvested with stubble burning. The total net ecosystem exchange (NEE) in 31 the first cycle (second ratoon, 393 days long) was -1964±44 g C m -2 ; the gross 32 ecosystem productivity (GEP) was 3612±46 g C m -2 and the ecosystem respiration (R E ) 33was 1648±14 g C m -2 . The NEE and GEP totals in the second cycle (third ratoon, 374 34 days long) decreased 51% and 25%, respectively and R E increased 7%. Accounting for 35 the carbon emitted during biomass burning and the removal of stalks at harvest, net 36 ecosystem carbon balance (NECB) totals were 102±130 g C m -2 and 403±84 g C m -2 in 37 each cycle respectively. Thus the sugarcane agrosystem was approximately carbon 38 neutral in the second ratoon. Yield in stalks fresh weight (SFW) attained the regional 39 average (8.3 kg SFW m -2 ). Although it was a carbon source to the atmosphere, observed 40 productivity (6.2 kg SFW m -2 ) of the third ratoon was 19% lower than the regional 41 average due to the lower water availability observed during the initial 120 days of re-42 growth. However, the overall water use efficiency (WUE) achieved in the first cycle 43

The responses of Arabica coffee grown under long-term exposure to e[CO2] integrated structural and functional modifications, which balanced leaf area loss through improvements in leaf and whole-plant photosynthesis.

Leaves in different positions respond differently to dynamic fluctuations in light availability, temperature and to multiple environmental stresses. The current hypothesis states that elevated atmospheric CO2 (e[CO2]) can compensate for the negative effects of water scarcity regarding leaf gas exchanges and coffee bean quality traits over the canopy vertical profile, in interactions with light and temperature microclimate during the two final stages of berry development. Responses of Coffea arabica L. were observed in the 5th year of a free air CO2 enrichment experiment (FACE) under water-limited rainfed conditions. The light dependent leaf photosynthesis curves (A/PAR) were modelled for leaves sampled from vertical profile divided into four 50-cm thick layers. e[CO2] significantly increased gross photosynthesis (AmaxGross), the apparent quantum yield efficiency, light compensation point, light saturation point (LSP) and dark respiration rate (Rd). As a specific stage response, considering berry ripening, all parameters calculated from A/PAR were insensitive to leaf position over the vertical profile. Lack of a progressive increase in AmaxGross and LSP was observed over the whole canopy profile in both stages, especially in the two lowest layers, indicating leaf plasticity to light. Negative correlation of Rd to leaf temperature (TL) was observed under e[CO2] in both stages. Under e[CO2], stomatal conductance was also negatively correlated with TL, reducing leaf transpiration and Rd even with increasing TL. This indicated coffee leaf acclimation to elevated temperatures under e[CO2] and water restriction. The e[CO2] attenuation occurred under water restriction, especially in A and water use efficiency, in both stages, with the exception of the lowest two layers. Under e[CO2], coffee produced berries in moderate- and high light level layers, with homogeneous distribution among them, contrasted to the heterogeneous distribution under actual CO2. e[CO2] led to increased caffeine content in the highest layer, with reduction of chlorogenic acid and lipids under moderate light and to raised levels of sugar in the shaded low layer. The ability of coffee to respond to e[CO2] under limited soil water was expressed through the integrated individual leaf capacities to use the available light and water, resulting in final plant investments in new reproductive structures in moderate and high light level layers.

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Modelling studies on climate change predict continuous increases in atmospheric carbon dioxide concentration [CO 2 ] and increase in temperature. This may alter carbon-based phytochemicals such phenolics and modify plant interactions with herbivorous. We investigated the effects of enhanced [CO 2 ] and local climatic variation on young coffee plants, Coffea arabica L. cv Catuaí vermelho IAC-144 and Obatã vermelho IAC-1669-20, cultivated in the FACE (Free-Air Carbon Dioxide Enrichment) facility under two atmospheric [CO 2 ] conditions. Coffee leaves were evaluated for total soluble phenolics (TSP), chlorogenic (5-CQA) and caffeic (CAF) acids, diversity and population size of mites, along two dry and two rainy seasons. Elevated atmospheric CO 2 (e[CO 2 ]) signifi cantly decreased 5-CQA in cv. Catuaí but did not affect cv. Obatã. Species richness and population size of mites in coffee leaves were not affected by e[CO 2 ] but were strongly related to the seasonal variability of coffee leaf phenolics. In general, high levels of phenolics were negatively correlated with population size while the mite species richness were negatively correlated with 5-CQA and TSP levels. Our fi ndings show that [CO 2 ] enhancement affects phenolics in coffee plants differentially by cultivars, however seasonality is the key determinant of phenolics composition, mite species richness and population size.