The influence of soil color on seedbed microclimate and seedling demographics of a perennial bunchgrass

Authors: Boyd, Chad; Davies, Kirk; Lemos, Jarod

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2017
Publication Date: 8/7/2017
Citation: Boyd, C.S., Davies, K.W., Lemos, J.A. 2017. The influence of soil color on seedbed microclimate and seedling demographics of a perennial bunchgrass. Rangeland Ecology and Management. 70(5):621-624. https://doi.org/10.1016/j.rama.2017.03.004.
DOI: https://doi.org/10.1016/j.rama.2017.03.004

Interpretive Summary: Perennial bunchgrasses are critical to maintaining sagebrush plant communities and previous research indicates that blackened soils beneath burned sagebrush canopies have increased seeding success. We investigated the potential of using soil colorants to increase emergence and survival of bluebunch wheatgrass seedlings. Results indicate that in years with adequate moisture, increased soil temperature associated with black soils can promote increased seedling emergence and survival, but white colored soils had highest emergence and survival when soil water was limiting. Our work suggests that artificial soil colorants can influence emergence and survival of bluebunch wheatgrass and this concept could be combined with existing seeding technologies (e.g., drill seeding) to help ameliorate low success rates typical of perennial bunchgrass seedings in the sagebrush steppe.

Technical Abstract: Perennial bunchgrasses are critical to maintaining sagebrush plant communities but seeding of native bunchgrasses following fire has met with only limited success. Previous research indicates that blackened soils beneath burned sagebrush canopies have increased seeding success for perennial bunchgrasses when compared to interspace locations. We investigated soil moisture and temperature across white, neutral, and black soils and tested the relationship between soil color and seedling demographics for seeded bluebunch wheatgrass. We used a randomized block design with three treatments and five replications conducted in a Wyoming big sagebrush community in southeast Oregon. The study site was roto-tilled prior to establishing 50 x 50 cm plots in each of two years. We installed soil temperature/moisture probes at two cm depth in each plot. Plots were seeded in November of each year with 250 viable bluebunch wheatgrass seeds. Plots were then covered in a < 1mm layer of white, brown, or black aquarium sand and sand was re-applied as needed over time. We counted emergent seedlings weekly from snowmelt through May of the year following planting. Soil moisture during the emergence period (March – May) was highest for white soils and lowest for black or neutral soils (p < 0.05); soil temperature was highest for black or neutral soils and lowest for white soils (p < 0.05). Year one was characterized by a warm and dry emergence period and year two was relatively cool and moist. Emergent seedling density was highest (p < 0.05) for white soils; surviving seedling density (on June 1) was highest (p < 0.05) for white soils in year one and black soils in year two. Black soils had greater success in a year with lower soil temperatures and adequate soil moisture. When soil moisture is limited, increased soil temperature on black soils led to seedling desiccation and death.