Database

HREC Seed dynamics

The purpose of this study was to asses how small mammals affect plant composition, plant production, seed production, and soil nutrient levels. Twelve sites have been selected to span a broad range of conditions typical of California rangelands. At each site, we have established two 4m x 4m plots. The control plot excludes only sheep, while the exclosure plot is fenced both below- and above-ground to exclude both sheep and small mammals (the primary granivores). Throughout the growing season, we are tracking plant and litter biomass, seed production, and soil nutrients.

Seedling thinning amounts were also determine

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Project Results

The exclosure of wmall mammals had impacts that varied seasonally, and from year to year

Small mammals did not influence litter decomposition rates. They greatly decreased the number of plant seedlings early in the growing season (fall) and late in the growing season (Spring), but also led to wild fluctuations (+/- 12,000 seedlings/ m2) in seedlings across seasons. That that seedling numbers were highest in the winter when small mammals were present. Soil nitrogen availability, and to a lesser extent phosphorus availability mirrored the seedling effects. When seedling numbers were high in the presence of small mammals, soil nutrients were high.

Seasonal changes (months) and over a 2 year period

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difficult to keep small mammals excluded for a long time- build higher above-ground fences with "flashing" s they can't climb

gooatgrass cover was far lower when rodents were excluded