Online resource 2

Journal: Plant and Soil

Linking effects of plant identity and species interactions on yield and trace gas exchanges in forage mixtures.

Ribas A.1,2,3, Llurba R.1,4, Gouriveau F.1, Altimir N. 1, Connolly J.5 and Sebastià M.T.1,4

1CTFC, Forest Sciences Centre of Catalonia, Crta. Sant Llorenç de Morunys, km 2, 25280 Solsona, Spain

2BABVE, Edifici C, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain 3CREAF, Cerdanyola del Valles 08193, Catalonia, Spain

4Depart. HBJ, ETSEA, University of Lleida, 25198 Lleida, Spain

5 UCD, School of Mathematical Sciences, Belfield, Dublin 4, Ireland

Corresponding author

Àngela Ribas

Forest Sciences Centre of Catalonia

Crta. Sant Llorenç de Morunys, km 2

25280 Solsona, Spain

e-mail: a.

OR2 Table 1. Average plant composition (± Standard Deviation (SD)) since establishment, calculated as the mean of the 2009-2011 species proportions in the spring harvests. In the mixtures average, which includes the three dominated and the centroid mixtures, the intended proportions are 1/3 of each sown species and the evenness average would be 0.63.

OR2 Table 2. Table OR2. Estimated coefficients (±SE) for the different variables included in the emission models of each studied gas (N2O, NH3, CO2 and CH4), including species identity effects (Fa: Festuca arundinacea, Ms: Medicago sativa, Ci: Cichorium intybus), sowing density (defined as a nominal variable with two levels with a 0 mean), fertilization (defined to give the effect per each 25 N kg ha-1 applied per regrowth) and evenness. Realized species proportions, calculated as the mean of the 2009-2011 species proportions in the spring harvests were used in this case. The values shown correspond to the July measurements, when 28 plots were sampled including monocultures, 1-species dominated communities and the centroid mixture at the two levels of density and at two N levels (nil and high). Note that the coefficients for the species effects give the exchange rates for the monocultures at mean density and at nil N application. Below, the emission differences between each pair of monocultures are given.