Antecedent climate drives divergent, long-term restoration outcomes in the Western Great Plains, USA.

Abstract Converting croplands to grasslands can restore ecosystem functions and services. But there is uncertainty about why some restoration treatments succeed and others do not. Existing restoration strategies tailor species compositions of seed mixes according to mean conditions in hardiness zones. But individual years typically deviate from average climate norms such that restoration activities may be better informed by recent conditions than with climate averages in order to best direct management strategies. We monitored a field in eastern Colorado that was converted from wheat-fallow to native perennial grassland via seeding. The same seed mix was used to seed half the strips in 2013 (drier) and the other half in 2014 (wetter). The strips seeded in 2013 had only one native grass and shrub species from the seed mix establish, whereas in 2014 all native grasses established Higher soil moisture preceding seed application was positively associated with perennial grasses, while rhizomatous grasses, shrubs and introduced annuals were associated with other variables. We found evidence of facilitatory interactions between grasses and forbs, and antagonistic interactions between native perennial grasses and introduced annuals. These findings can assist land managers to improve upon current approaches by considering antecedent conditions during restoration planning.