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SRI engages in its own empirical research on grassland biodiversity. Currently, we are investigating the response of the dung beetle community to the reintroduction of summertime grazing by herding animals after an 11-year absence.
Bison once roamed the West by the millions and constituted a critical part of a vast ecological web. After tens of thousands of years of predictable and cyclical grazing by these vast herds, countless plants and animals came to depend on their presence. Entire ecological suites of carnivores, scavengers, and decomposers lived and died by the presence of these herds, but the real drivers of this bison system were the dung beetles. They removed the bottleneck in the nutrient cycle by bringing energy and nutrients back into the soil for primary production, which supported these herds and the ecological systems surrounding them.
Today, bison are ecologically extinct from the vast grasslands of the American West. Although the domestic cattle that replaced them only partially resemble bison in morphology and behavior, they do have certain attributes that can partially fill the ecological vacancy left by bison. Beyond providing necessary physical disturbances to the biotic layer, cattle also notably return processed nutrients to the surface in the form of labile fecal matter, which dung beetles thrive on. We aim to answer this question: Will dung beetles, key drivers of the nutrient cycle, be coaxed back into a system with the introduction of cattle, and will primary production increase with their return?
On the Sun Ranch is a 1,000-acre pasture that has not been grazed by anything but elk in the last 11 years. Elk pellets are not suitable to the needs of dung beetles; they decompose slowly by oxidation instead. Thus, there is a bottleneck in the recycling of nutrients in this pasture. Domestic cattle, however, are scheduled to return soon to this pasture. SRI has preceded them by demarcating 15 replicated mini-pastures, each containing vegetation plots, insect traps, and elk pellet counts. We have completed one pilot season and the formal study is underway to understand how the return of cattle and dung beetles will change the pasture's biodiversity.
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