A conceptual framework for the analysis of engineered biodiverse

18 Sown biodiverse permanent pastures rich in legumes (SBPPRL) were developed in 19 Portugal in the 1960`s and 1970’s as a strategy to increase grassland productivity by 20 Cite as: Teixeira, R.F.M., Proenca, V., Crespo, D., Valada, T., Domingos, T. (2015). A conceptual framework for the analysis of engineered biodiverse pastures. Ecological Engineering, 77: 85–97. 2 sowing mixtures of up to 20 species/cultivars of legumes and grasses. Compared to 1 semi-natural pastures, the resulting engineered system provides higher yields of better 2 quality pasture, significantly increasing sustainable stocking rates, with multiple 3 environmental co-benefits. Here, we propose a conceptual framework for the 4 sustainability assessment of SBPPRL and apply it with existing data. Our objective is to 5 inquire if this system is an example of sustainable intensification of livestock 6 production, i.e. an economic and ecological win-win solution that can answer many of 7 the causes for ecosystem degradation in semi-arid and sub-humid climate zones, such as 8 in the Mediterranean basin. We build on experimental results from previous studies, 9 which suggest that SBPPRL replenish soil organic matter pools and improve soil 10 structure. The high increase in stable soil organic matter acts as a carbon sink, turning 11 the system into an optimum tool for climate change mitigation and adaptation. Portugal 12 made use of this fact by supporting the expansion of SBPPRL areas and abating the 13 corresponding carbon from Kyoto Protocol emissions calculations. We resorted to the 14 literature to evaluate other environmental effects due to the absence of data specifically 15 for SBPPRL. Surface water runoff decreases and pirophyte shrub vegetation is 16 eliminated or much reduced. Nitrogen accumulates in stable forms in the soil after being 17 fixed by Rhizobium/legume symbiotic associations. Legumes depend on phosphorus 18 fertilization; as such the nitrogen cycle in SBPPRL relies on a potentially non19 renewable resource (required during the first years after installation of the pasture), 20 which may be a potential limiting factor in the future. The effects on wild biodiversity 21 are unclear. The methodology laid out in this article provides an innovative framework 22 to assess these effects as additional experimental data becomes available. 23 Cite as: Teixeira, R.F.M., Proenca, V., Crespo, D., Valada, T., Domingos, T. (2015). A conceptual framework for the analysis of engineered biodiverse pastures. Ecological Engineering, 77: 85–97.