|Title||Integrating space and time: A case for phenological context in grazing studies and management|
|Publication Type||Journal Article|
|Year of Publication||2018|
|Authors||Browning D.M., Spiegal S, Estell RE, Cibils AF, H. Peinetti R|
|Journal||Frontiers of Agricultural Science and Engineering|
|ARIS Log Number||344834|
|Keywords||GPS collars, Jornada Experimental Range, land-surface phnology, livestock movement, LTAR, MODIS NDVI, rangeland|
In water-limited landscapes, patterns in primary production are highly variable across space and time. Livestock grazing is a common agricultural practice worldwide and a concern is localized overuse of specific pasture resources that can exacerbate grass losses and soil erosion. On a research ranch in New Mexico (MAP = 217 mm), we demonstrate with a quantitative approach that annual seasons vary greatly and examine foraging patterns in Angus-Hereford (Bos taurus) cows. We define five seasonal stages based on MODIS NDVI: Pre-Greenup, Greenup, Peak Green, Drydown, and Dormant and examine livestock movements in 2008. Daily distance traveled by cows was greater and foraging area expanded during periods with higher precipitation. A regression model including minimum NDVI, rainfall, and NDVI*rainfall explained 81% of the seasonal variation in distance traveled by cows (P < 0.01). Cows explored a daily average 81.1 ha while foraging but tended to explore smaller areas as the pasture became greener (Greenup, Peak Green). Cows foraged an average 9.7 hours daily and spent more time foraging as pastures became greener. Our findings suggest that phenological context can expand the capacity to compare and integrate findings and facilitate meta-analyses of grazing studies conducted at different locations and times of year.