Grazing Protection Influences Soil Mesofauna in Ungrazed and Grazed Riparian and Upland Pastures

The influence of grazing protection caused by streambank fencing on soil mesofauna density is unknown. Our objective was to determine if grazing protection (ungrazed vs. grazed), location (upland vs. riparian pasture), and seasonal (spring vs. fall) treatment effects associated with streambank fencing had a significant influence on soil mesofauna distribution and density. We collected five intact soil cores (0-5 cm depth) in June and October of 2012 from within four treatments consisting of ungrazed and grazed riparian and upland pastures associated with streambank fencing along an 800-m reach of the Lower Little Bow River in southern Alberta, Canada. Soil mesofauna were extracted and densities of Acari (mites) taxa, Collembola (springtails) taxa, and other mesofauna were determined. Grazing protection resulted in a significant (P ≤ 0.05) negative response of Astigmata mite densities for the upland pasture, and a positive response for Oribatida mites and total Collembola, and Hypogastruridae and Onychiuridae springtails for both pastures. Location and season had a significant influence on Acari and Collembola taxa, but the effects were dependent on interaction effects. We conclude that grazing protection influenced certain soil mesofauna in pastures associated with streambank fencing, and this may influence decomposition of soil organic matter, nutrient cycling, and soil structure in associated pastures.