A Range Condition Dilemma

Abstract

I the late 1800's livestock grazing was unregulated along the eastern slopes of the Rocky Mountains in Alberta. To n ^ 5 protect the Saskatchewan River basin watershed the Rocky Mountains Forest Reserve (RMFR) was established in 1910. Grazing by domestic animals was prohibited. However, by 1913 grazing by livestock was recognized as a useful tool to limit forage accumulation and assist in reducing a potential fire hazard. Inadequate management policies and funding, caused water quality to continue to deteriorate because of fire and localized overgrazing. To examine the overgrazing concerns in the Rocky Mountains Forest Reserve, Land and Forest Service established the Rangeland Reference Area Program in 1949. The objectives were to assess range and monitor range trend on grasslands within the boundaries of the RMFR (Hanson 1975). To date forty-five fenced exclosures have been established in the RMFR, some dating back to 1953. These exclosures include permanently marked grazed and ungrazed transects. Species composition data has been recorded since their establishment. Recent analysis indicates that the vegetation moves through a number of vegetation states and the process closely follows the state and threshold model of succession (Laycock 1991). This created a dilemma on how the of these rangelands should be assessed because ratings for Alberta rangelands have used the old linear range condition model (Wroe et al. 1988). To examine the vegetation changes at the various reference areas over-time a combination of both ordination (DECORANA) (Gauch 1982) and cluster analysis (SAS) were used to group the inside and outside transects of different years. The groupings from cluster analysis were overlain on the site ordination and years with similar species composition were grouped into community types. Mean grazing pressure for each year was assessed by comparing annual utilization to the rated carrying capacity of the allotment. Total yearly AUM (Animal Unit Months) usage from the inception of the allotment was divided by the calculated carrying capacity (AUM) and multiplied by 100. For example a number of 100 would indicate proper utilization.