Question Species distribution modelling has most commonly been applied to presence‐only data and to woody species. Can similar methods be used to create detailed predicted abundance maps for forage species? These predictions would be of great value for agricultural management and land‐use planning. Location Northeastern USA. Methods We used field data from 31 grazed farms to model abundances for six forage species with three statistical methods: GLM, GAM and Random Forest models. A hierarchical ecological framework encompassing climatic, edaphic and topographic variables related to the plant species requirements for water, light and temperature was used to guide variable selection. Results Although many species distribution modelling studies have used only climatic variables, the inclusion of topography greatly improved explanatory power. Edaphic variables contributed little more beyond the information already provided by climate and topography. Random Forest models had higher overall predictive capability, and were used to produce the final potential abundance maps for the six forage species. Conclusions Climate‐only predictions may be suitable for state or regional planning, but topographic variables must be included in species distribution models used to support decision‐making at the farm and field scales.

The practice of fallowing pastures during the growing season is intended to increase plant diversity and allow natural reseeding of forage grasses. Fallowing delivers these benefits in New Zealand, but has been adopted on rotationally stocked farms in the northeastern United States with little or no quantitative assessment. Allowing the pasture to remain ungrazed may allow weedy species to produce seeds, and could reduce legume populations. We measured the seed bank composition (n = 23) and aboveground vegetation (n = 32) in paddocks that had been fallowed from 0–6 yr previously on an organic dairy in Maryland. Transect sampling was used to characterize the canopy cover of the dominant species three times per year for 3 yr. Germinable seed was identified from 5‐cm soil cores collected in the spring and autumn in 2 yr. Fallowing did not produce any changes that persisted for more than 2 yr in either the seed bank or the vegetation of this farm. Tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] and other pasture grasses set seed, increasing in the seed bank during the fallow year, but this did not produce long‐term changes in either the seed bank or the vegetation. The proportion of weedy forbs in the seed bank increased, and the legume cover decreased, but only temporarily. Natural reseeding of tall fescue promoted by fallowing did not cause changes in the vegetation, but could lead to increased endophyte infestation in the endophyte‐free tall fescue originally planted.

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Poor winter hardiness is one of the factors limiting the use of the palatable and productive cool‐season forage grass perennial ryegrass (Lolium perenne L) in the northeastern United States. We compared freeze tolerance among seedlings of 13 commercial cultivars of perennial ryegrass in a controlled environment chamber. After a 14‐d acclimation period, plants were chilled to −10, −15, or −20°C for 1 h, then gradually warmed. After 36 d, surviving plants were counted then harvested and weighed. Mortality rate varied significantly among cultivars (0–13% at −10°C, 47–100% at −20°C). The temperature at which 50% of plants would die (LT50) ranged from −12.9 to −20.8°C. Hardiness ratings provided by the breeder did not match well with LT50 except for the most hardy cultivars. Extreme minimum temperature predictions were extracted from regional climate forecasts for three 30‐yr periods: baseline (1960–1989), short‐term future (2015–2044), and long‐term future (2070–2099). During the baseline period, only 2 to 33% of the northeastern United States was warm enough for these cultivars to survive during at least 50% of winters. Potential tolerable area may increase to 57 to 88% by 2099. Although other factors such as snow cover and variability of winter temperatures affect winter survival in the field, breeding for freeze tolerance has increased the potential extent of perennial ryegrass. Further improvements and the changing climate may greatly increase the utility of perennial ryegrass as a forage in the northeastern United States.