Red Brome Flowering and Senescence Forecasts, Contiguous United States, Current Year and Prior Year

The USA-NPN red brome forecast predicts flowering and senescence in real-time. The red brome forecast is based on Prevéy et al (in prep.), which predicts phenology of the species based on temperature (growing degree days, GDD) and daylength. Daily GDD accumulations are calculated using the simple averaging method, and adjusted based on daylength, where longer days are assumed to promote plant development. The photoperiod adjustment is calculated as [daylength hours]/[24]. Each day's growing degree day accumulation is multiplied by the photoperiod adjustment.

The flowering model uses a Dec 1 start date and a 23F base temperature. "Flowering soon" is predicted at 1283 GDDs (F), after which another week of average temperatures at 70F with 11 hours of daylight would be needed to trigger flowering. "Onset of flowering" is predicted at 1441 GDDs (F). The senescence model uses a Jan 1 start date and a 32F base temperature. "Starting to dry out and senesce" is predicted at 886 GDDs (F), after which another week of average temperatures of 80F and 14 hours of daylight would be needed to trigger senescence. "Senescence" is predicted at 1081 GDDs (F).

The forecasts can support ranchers in timing grazing after grasses have grown enough to provide good forage, but prior to unpalatable flowering and seeding stages. This practice reduces the development of new seeds and subsequent spread of the species. The forecasts also support the interpretation of satellite imagery of invaded grassland green up and dry down.

Forecasts are available for the current and prior year in the USA-NPN Visualization Tool (https://www.usanpn.org/data/visualizations) and the USA-NPN Geoserver (user access facilitated by the Geoserver Request Builder).

For all inquiries regarding this dataset, please contact the USA-NPN. This data is subject to the USA-NPN's Data Use Policy.