Theme 1-1: Rangeland/Grassland Ecology--Oral Sessions
Description
We investigated species diversity effects and multifunctionality in an intensively managed grassland. A diversity experiment was set up with monocultures and mixtures comprising Lolium perenne, Dactylis glomerata, Trifolium pratense, and Trifolium repens, and was maintained for three years at 150 kg∙N∙ha-1∙ year-1. Ten functions were measured that represented i) forage production (aboveground biomass yield (μ), standard deviation of yield (σ), temporal stability (μ/σ), weed biomass), ii) N cycling (symbiotic-N2-fixation, N efficiency, NO3 in soil solution), and forage quality (crude protein content (CP), organic matter digestibility (OMD), metabolizable energy (ME)). We applied multivariate linear mixed-effects regression to estimate simultaneously species identity and diversity effects on the ten functions, and used the mean log response ratio (MLRR) across all functions to evaluate the diversity-multifunctionality relationship.
Across the three years, all functions regarding production and N cycling revealed significant beneficial effects in the four-species equi-proportional mixture (used as a reference) compared to averaged monocultures. The reference mixture had 61% more biomass yield, 8% less variation, 68% higher stability, 81% less weed biomass, 96% and 46% higher symbiotic-N2-fixation and N-efficiency, respectively, and 87% less NO3 (each P ≤ 0.05, except variation). The reference mixture and averaged monocultures did not significantly differ in CP, OMD (g∙kg-1∙yield), and ME (MJ∙kg-1∙yield). This, however, resulted in significant beneficial effects between 52% and 72% in all three forage quality functions on a hectare basis (kg or MJ∙ha-1∙year-1). On average across functions, the four-species reference mixture had 1.8 times the performance of averaged monocultures, indicating enhanced multifunctionality in mixtures.
The multivariate framework in combination with the MLRR as a measure of overall multifunctionality proved to be an effective tool for the evaluation of the diversity-multifunctionality relationship. We conclude that sown grass-legume mixtures at moderate N fertilization promote high multifunctionality and are a ‘ready-to-use’ option for sustainable intensification of agriculture.
Included in
Multifunctionality of Sown Grassland Is Enhanced by Combining Four Complementary Species
We investigated species diversity effects and multifunctionality in an intensively managed grassland. A diversity experiment was set up with monocultures and mixtures comprising Lolium perenne, Dactylis glomerata, Trifolium pratense, and Trifolium repens, and was maintained for three years at 150 kg∙N∙ha-1∙ year-1. Ten functions were measured that represented i) forage production (aboveground biomass yield (μ), standard deviation of yield (σ), temporal stability (μ/σ), weed biomass), ii) N cycling (symbiotic-N2-fixation, N efficiency, NO3 in soil solution), and forage quality (crude protein content (CP), organic matter digestibility (OMD), metabolizable energy (ME)). We applied multivariate linear mixed-effects regression to estimate simultaneously species identity and diversity effects on the ten functions, and used the mean log response ratio (MLRR) across all functions to evaluate the diversity-multifunctionality relationship.
Across the three years, all functions regarding production and N cycling revealed significant beneficial effects in the four-species equi-proportional mixture (used as a reference) compared to averaged monocultures. The reference mixture had 61% more biomass yield, 8% less variation, 68% higher stability, 81% less weed biomass, 96% and 46% higher symbiotic-N2-fixation and N-efficiency, respectively, and 87% less NO3 (each P ≤ 0.05, except variation). The reference mixture and averaged monocultures did not significantly differ in CP, OMD (g∙kg-1∙yield), and ME (MJ∙kg-1∙yield). This, however, resulted in significant beneficial effects between 52% and 72% in all three forage quality functions on a hectare basis (kg or MJ∙ha-1∙year-1). On average across functions, the four-species reference mixture had 1.8 times the performance of averaged monocultures, indicating enhanced multifunctionality in mixtures.
The multivariate framework in combination with the MLRR as a measure of overall multifunctionality proved to be an effective tool for the evaluation of the diversity-multifunctionality relationship. We conclude that sown grass-legume mixtures at moderate N fertilization promote high multifunctionality and are a ‘ready-to-use’ option for sustainable intensification of agriculture.
