Skip to main content

Blank, Robert R

The hypotheses that weeds increase soil nutrient availability and differentially alter soil nutrient dynamics were tested in the greenhouse by comparing and contrasting plant-soil relationships among Bromus tectorum L. (cheatgrass, downy brome), Lepidium latifolium L. (perennial pep-perweed, tall whitetop), and Centaurea solstitialis L. (yellow starthistle). These species are highly invasive and produce dense stands that reduce or eliminate native species. A high resource (HR) soil and a low resource (LR) soil were evaluated. To simulate declining soil resources, individual plants were grown in the same pots, harvested, then replanted for a total of three growth cycles. Aboveground mass was greatest in the HR soil...
Categories: Publication; Types: Citation, Journal Citation; Tags: Soil Science
Invasion of western United States rangelands by Bromus tectorum (cheatgrass) is an environmental and economic concern. To increase understanding of soil factors that affect growth and site invasibility by cheatgrass, the invasion of a Krascheninnikovia lanata (winterfat) community in the Honey Lake Valley of northeastern CA has been monitored for a 5 year period. Overall, sites invaded by cheatgrass have greater soil-solution ortho-P, and Mg+2, greater mineralization potential for NO3 -, greater phosphatase and amidase enzyme activities, and greater numbers of microbial cells than nearby non-invaded sites. Complementary greenhouse studies indicate that non-invaded soil is inhibitory to the growth of cheatgrass;...
Pinyon and juniper have been expanding into sagebrush (Artemisia tridentata) ecosystems since settlement of the Great Basin around 1860. Herbaceous understory vegetation is eliminated as stand densities increase and the potential for catastrophic fires increases. Prescribed fire is increasingly used to remove trees and promote recovery of sagebrush ecosystems. We quantified the effects of prescribed fire, vegetation type, and time following fire on soil KCl extractable nitrogen and NaHCO3 extractable phosphorus in a pinyon?juniper woodland and its associated sagebrush ecosystem immediately before and for 4 years after a spring prescribed burn. Potassium chloride extractable NH4+ and total inorganic-N increased immediately...
Numerous basins of the intermountain area often have extensive playa surfaces that are nearly devoid of vegetation. Margins of these playas support sparse communities dominated by chenopod shrubs Allenrolfea occidentalis (iodine bush) and Sacrobatus vermiculatus (black greasewood). These plants establish and persist in an environment where halomorphic soils induce extreme osmotic stress and atmospheric precipitation is very low and erratic and occurs largely during the winter when temperatures are too low for growth. We measured net CO2 assimilation rates, leaf conductances, transpiration rates, water-use efficiencies, and stem xylem potentials for these two C3 species. Data were collected in above-average (1991)...
Few studies have examined plant?soil relationships in competitive arenas between exotic and native plants in the western United States. A pair-wise competitive design was used to evaluate plant?soil relationships between seedlings of the exotic annual grasses Bromus tectorum and Taeniatherium caput-medusae and the native perennial grasses Elymus elymoides and Pseudoroegneria spicata. Two soils were tested: an arid soil (argid) occupied by E. elymoides and presently invaded by B. tectorum and a high elevation, high organic matter, soil (aquept) where none of the tested species would typically occur. Plant growth proceeded for 85 days at which time above-ground biomass and tissue nutrient concentrations were quantified....
View more...
ScienceBase brings together the best information it can find about USGS researchers and offices to show connections to publications, projects, and data. We are still working to improve this process and information is by no means complete. If you don't see everything you know is associated with you, a colleague, or your office, please be patient while we work to connect the dots. Feel free to contact sciencebase@usgs.gov.