With many degraded environments undergoing restoration efforts, there is a growing need for the optimization of direct seeding practices. Seeds planted on wildlands are often consumed by rodents, leading to reduced plant establishment. Coating seeds in rodent aversive products may prevent seed‐predation. We tested 10 seed‐coating formulations containing products expected to deter rodents, namely: ghost and cayenne pepper powders; essential oils from bergamot, neem, and pine; methyl‐nonyl‐ketone, anthraquinone, activated carbon, beta‐cyclodextrin, and a blank coating containing no rodent deterrents to serve as a control treatment. Each treatment was applied to Pseudoroegneria spicata (bluebunch wheatgrass) seeds. These seeds germinated similarly to uncoated control seeds unless the coating contained methyl‐nonyl‐ketone which reduced germination. When seeds were offered to Ord's kangaroo rats (Dipodomys ordii), they strongly avoided the treatments in favor of uncoated control seeds. Notably, the blank coating, lacking active ingredients, still elicited 99% avoidance. However, these results indicated behavior when alternative food sources are readily available, a scenario rare in nature. To address this, a second feeding experiment was conducted to observe D. ordii's behavior under calorie‐restricted conditions. D. ordii were subjected to a fast period, then offered only one treatment. Under these conditions, many subjects chose to consume coated seeds, but to a lesser degree than subjects offered control seeds. Seeds coated in ghost pepper, neem oil, and activated carbon reduced consumption by 47–50%. Given these lab results, we would expect these treatments to increase native plant establishment following the direct seeding of wildlands by protecting seeds from rodent predation.
Background: Wildfire regimes are changing dramatically across North American deserts with the spread of invasive grasses that perpetuate invasive grass fire cycles, resulting in larger and more frequent fires. This study experimentally compared how single and repeat fires, a characteristic of invasive grass fire cycles, influence plant fuels dominated by invasive grasses, in the Great Basin and Mojave Deserts. Both study sites had an identical study design. In the summer of 2011, we experimentally burned half of each experimental block the other half remaining as an unburned control. Half of the burned plots were reburned five years later to simulate a repeat burn characteristic of increasing burn frequency. We estimated non-woody plant biomass, cover and density in plots from 2017-2020. Results: Biomass did not vary between sites, but there was higher plant cover but lower plant density at the Mojave site than the Great Basin site. Plant biomass, density and cover varied significantly across years, with stronger annual fluctuations in the Great Basin. At both desert sites, fire increased plant density and biomass compared to unburned plots but had no effect on biomass. The effect of fire on plant cover varied significantly between years for both deserts but was greater in the Great Basin than the Mojave site. Repeat fires did not amplify the initial fire effects. Conclusions: The results suggest that annual fluctuations in fine fuel production generally, and in response to fire was more responsive at the Great Basin site than the Mojave site, with no compounding effect of repeat fires.
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