Integrating space and time: a case for phenological context in grazing studies and management

Abstract

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 with average annual rainfall of 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 their interaction explained 81% of the seasonal variation in distance traveled by cows (P < 0.01). Cows explored about 81 ha$d-1 while foraging, but tended to explore smaller areas as the pasture became greener (greenup and peak green stages). Cows foraged an average of 9.7 h daily and spent more time foraging with more concentrated search patterns 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.

Factors Affecting Site Use Preference of Grazing Cattle Studied from 2000 to 2020 through GPS Tracking: A Review

“…Straighter movement paths are also associated with rainy weather and winds from the W–NW for predawn night-time hours, and stronger winds for daytime hours [ 22 ]. Moreover, as precipitation increases, cows spend less time grazing in each patch and return to grazed patches more often [ 45 ], whereas daily distance travelled is greater and foraging area is expanded during periods with higher precipitation in desert rangelands [ 46 ]. Additionally, a positive correlation between daily walking distance of cattle and atmospheric pressure was found in rangelands (continental climate) [ 35 ].…”

“…In relation to extensive grazing conditions such as rangelands, cattle show a similar pattern as in the grasslands; when experiencing high forage allowance conditions, they explore smaller areas of the pasture each day [ 45 , 46 ], travel shorter distances, and the herd is less spread [ 41 ]. In addition, they follow less sinuous pathways during nighttime hours, and show higher avoidance of woodland areas [ 22 ], with a higher occupancy rate on open grassland [ 65 ], particularly in cold winters (greater herbage availability in open grassland) [ 22 ].…”

Predicting spatial‐temporal patterns of diet quality and large herbivore performance using satellite time series

“…Rangelands are characterized by substantial temporal and spatial variability in precipitation and temperature, both within and among years (Augustine, 2010; Knapp & Smith, 2001). This variability affects forage resources and their heterogeneous spatial–temporal distribution (Ganskopp and Bohnert 2009, Browning et al, 2018), which directly influences seasonal performance of livestock (Vavra & Raleigh, 1976) and wild ungulates (Garel et al, 2011; Owen‐Smith, 2002). Free‐ranging livestock provide a good model system for studying large herbivores since managerial control enables high‐quality and high‐frequency data collection.…”

Synchronous species responses reveal phenological guilds: implications for management

“…, Browning et al. ). Knowledge of species phenology can serve as a basis for identifying groups of species or landscape elements that exhibit similar patterns in the timing and distribution of phenophases.…”

“…Yet, data needs for specific management applications vary. Species-level phenology can inform natural resource management decisions such as timing the application of herbicides to target invasive species, optimizing water allocations for crop rotations to sustainably increase agricultural production, and managing livestock to more equitably distribute grazing pressure in large pastures with spatially and temporally variable forage production (Enquist et al 2014, Wheeler et al 2015, Browning et al 2018). Knowledge of species phenology can serve as a basis for identifying groups of species or landscape elements that exhibit similar patterns in the timing and distribution of phenophases.…”