Pasture-tree systems – Modelling potential implications for animal performance and greenhouse gas emissions

The potential animal performance and greenhouse gas (GHG) abatement benefits from pastures and wide-spaced poplars on a typical lower-North Island sheep and beef farm operation were explored using farm-scale models. The analysis included reductions in understory pasture production, increased ewe reproductive performance (i.e. lambing and weaning percentage) with additional tree shelter and increased dry matter intake from poplar foliage. The pasture-tree (PT) systems demonstrated reductions in sheep stocking rates and total meat production but increases in ewe efficiency and emissions intensity, reflecting a shift in feed energy use from maintenance to production. Inclusion of ewe fecundity and supplementary feed benefits largely overcame reductions in stocking rate and meat production due to pasture shading. An integrated assessment of the multiple benefits of pasture-tree systems should be incorporated in future farming scenario testing, strengthening our knowledge on the impacts of these systems compared with pasture-only systems.