Linking management practices with range health in northern temperate pastures

Abstract

Little information exists on the management and range health (RH) of northern temperate pastures, where health is defined as the ability to sustain ecosystem function. We surveyed 102 pastures for RH and their associated managers during 2012–2013 across central Alberta, Canada. Pastures were generally diverse mixes of introduced grasses and contained few legumes, despite most (55%) being seeded to legumes. The majority of pastures were healthy (mean RH score = 78.8% ± 1.3%), with 2.9% having scores <50%. Criteria reducing scores were noxious weeds, bare soil, and evidence of erosion. Most pastures had a reported history of cultivation (75.5%), with those previously cultivated and seeded to introduced forage having greater stocking rates [6.18 ± 0.91 animal-unit-months (AUM) ha−1] compared with those lacking cultivation (2.14 ± 2.91 AUM ha−1). Farms with horses or mixed livestock tended to practice year-round continuous grazing and supplemental hay feeding. Stocking rates on continuous and rotationally grazed pastures were similar regardless of grazing season, with the highest stocking on pastures used year-round (19.54 ± 2.03 AUM ha−1) or throughout the dormant season (20.29 ± 3.10 AUM ha−1). Use of management inputs was variable, with manuring and harrowing common and fertilizing, over-seeding, and aerating infrequent. Herbicide use was reported on 15.7% of pastures, despite 83.3% containing noxious weeds. Use of prescribed fire was rare, although 36.3% of pastures had evidence of fire. Industrial disturbances were reported on 48.3% of pastures. Overall, these results indicate that these pastures experience complex management and the limited decline in RH is due to high stocking under year-long grazing.

Northern temperate pastures exhibit divergent plant community responses to management and disturbance legacies identified through a producer survey

“…Across all grasslands, lower health scores corresponded with increased stocking rates, reinforcing the importance of avoiding excessive grazing to conserve grasslands (Willms et al, 1985). High stocking also coincided with supplemental feeding and nutrient addition (Pyle et al, 2018 (Bork et al, 2007). In contrast, few native perennial forbs and grasses persisted in cultivated tame grasslands, where species like Bromus inermis create unsuitable environments for native plants, ultimately decreasing species richness and promoting homogeneity (Fink & Wilson, 2011;Stotz et al, 2019).…”

“…Managers were initially asked about ownership and whether the pasture had been previously cultivated. If cultivated, managers estimated when it was planted (grassland age) and how (seeding history was described in Pyle et al, 2018); cultivation status could also be classified as unknown (attributed to land-turnover or rented pasture).…”

“…European settlement has led to widespread clearing of trees and cultivation to support crop production, a process that continues (Gauthier & Wiken, 2003). In central Alberta, Canada, where this study was undertaken (see Figure 2 of Pyle, Hall, & Bork, 2018), most pastures observed (75%) were found to be previously cultivated and seeded to introduce forages. As a result, historically widespread native Festuca hallii (Vasey) Piper grasslands are considered threatened, leaving few remnants on poor-quality ecosites (Rowe, 1987).…”

“…Grazing-induced changes in composition are exacerbated under high stocking (Willms et al, 1985) and by continuous grazing (De Bruijn & Bork, 2006), which persist even after reductions in stocking (Sinkins & Otfinowski, 2012). Planted grasslands support nearly three times the livestock stocking rate of grasslands never cultivated (Pyle et al, 2018). Grazing practices are diverse and include variation in the timing and frequency (i.e.…”

“…In previous publications, we reported on the management actions and disturbances occurring across northern temperate pastures in Alberta, Canada, including their relationship with rangeland health (Pyle et al, 2018) and underlying soil conditions (Pyle et al, 2019).…”