Skip to main content
Advanced Search

Filters: Categories: Publication (X) > partyWithName: Susan L Phillips (X)

11 results (10ms)   

View Results as: JSON ATOM CSV
thumbnail
Biological soil crusts are an integral part of dryland ecosystems. We monitored the cover of lichens and mosses, cyanobacterial biomass, concentrations of UV-protective pigments in both free-living and lichenized cyanobacteria, and quantum yield in the soil lichen species Collema in an undisturbed Mojave Desert shrubland. During our sampling time, the site received historically high and low levels of precipitation, whereas temperatures were close to normal. Lichen cover, dominated by Collema tenax and C. coccophorum, and moss cover, dominated by Syntrichia caninervis, responded to both increases and decreases in precipitation. This finding for Collema spp. at a hot Mojave Desert site is in contrast to a similar...
thumbnail
Biological soil crusts, a community of cyanobacteria, lichens, and mosses that live on the soil surface, occur in deserts throughout the world. They are a critical component of desert ecosystems, as they are important contributors to soil fertility and stability. Future climate scenarios predict alteration of the timing and amount of precipitation in desert environments. Because biological soil crust organisms are only metabolically active when wet, and as soil surfaces dry quickly in deserts during late spring, summer, and early fall, the amount and timing of precipitation is likely to have significant impacts on the physiological functioning of these communities. Using the three dominant soil crust types found...
Soil fertility in deserts: A review on the influence of biological soil crusts and the effect of soil surface disturbance on nutrient inputs and losses, credited to Duniway, Michael C, published in 2003. Published in Desertification in the Third Millennium, on pages 245 - 252, in 2003.
thumbnail
Biological soil crusts arrest soil erosion and supply nitrogen to arid ecosys- tems. To understand their recovery from disturbance, we studied performances of Collema spp. lichens relative to four experimental treatments plus microtopography of soil pedicels, oriented north-northwest to south-southeast in crusts. At sites in Needles (NDLS) and Island in the Sky (ISKY) districts of Canyonlands National Park, lichens were transplanted to NNW, SSE, ENE, WSW, and TOP pedicel faces and exposed to a full-factorial, randomized block experiment with four treatments: nutrient addition (P and K), soil stabilization with polyacrylamide resin (PAM), added cyanobacterial fiber, and biweekly watering. After 14.5 mo (NDLS) and...
thumbnail
Biological soil crusts are an essential part of desert ecosystems throughout the world, as they are important in soil stabilization and soil fertility. Despite their importance, there have been few efforts to examine the population dynamics of the dominant species comprising these crusts or the effect of exotic plant invasions on these dynamics. In this study, we followed changes in lichen and moss cover for 8 years in plots dominated by native grasses or invaded by the exotic annual grass Bromus tectorum and across sites representing a range of land use histories. Our data showed that cover of both lichens and mosses can increase dramatically over short time periods, often going from just above 0% cover to as high...
Biological soil crusts (BSC) are a dominant feature in arid and semi-arid ecosystems. BSC stabilize soils, contribute nitrogen and carbon, enhance vascular plant nutrition, and influence local hydrologic cycles. However, these ecological roles are determined by the species composition, morphology, and physiological functioning of the BSC. These factors, in turn, can be strongly affected by land use, invasive plants, and climate change. Soil surface disturbance and/or dominance by invasive plants both result in loss of lichens and mosses, leaving cyanobacteria dominating the soil surface. This loss reduces soil stability, carbon and nitrogen contributions, surface temperatures, and soil water retention times. Climate...
thumbnail
Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion. The invasion of Bromus also resulted in a decrease in richness and a species shift in plants, microarthropods, fungi, and nematodes. However, despite the depauperate soil fauna at the invaded sites, no effects were seen on cellulose decomposition rates, nitrogen mineralization rates, or vascular plant growth. When Hilaria was planted into soils from not-invaded,...
thumbnail
Bromus tectorum is an exotic annual grass that currently dominates many western U.S. semi-arid ecosystems, and the effects of this grass on ecosystems in general, and soil biota specifically, are unknown. Bromus recently invaded two ungrazed and un-burned perennial bunchgrass communities in southeastern Utah. This study compared the soil food-web structure of the two native grassland associations (Stipa [S] and Hilaria [H]), with and without the presence of Bromus. Perennial grass and total vascular-plant cover were higher in S than in H plots, while quantities of ground litter were similar. Distribution of live and dead plant material was highly clumped in S and fairly homogenous in H. Soil food-web structure was...
thumbnail
Recently disturbed and ‘control’ (i.e. less recently disturbed) soils in the Mojave Desert were compared for their vulnerability to wind erosion, using a wind tunnel, before and after being experimentally trampled. Before trampling, control sites had greater cyanobacterial biomass, soil surface stability, threshold friction velocities (TFV; i.e. the wind speed required to move soil particles), and sediment yield than sites that had been more recently disturbed by military manoeuvres. After trampling, all sites showed a large drop in TFVs and a concomitant increase in sediment yield. Simple correlation analyses showed that the decline in TFVs and the rise in sediment yield were significantly related to cyanobacterial...
thumbnail
Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring–fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our...
thumbnail
Eolian dust (windblown silt and clay) and biological soil crusts are both important to ecosystem functioning of arid lands. Dust furnishes essential nutrients, influences hydrology, contributes to soil formation, and renders surfaces vulnerable to erosion. Biological soil crusts contribute directly to soil fertility by fixing carbon and nitrogen, and indirectly by trapping newly-deposited dust and stabilizing already-present soil. Results from crust-stabilized, unconsolidated sandy sediments on prominent rock exposures and grasslands show dust inputs have significantly increased all bio-essential nutrients in soils of SE Utah, including P, K, Mg, Na, and Ca. As plants can be P and K-limited in these soils, dust...
    map background search result map search result map Soil Biota Can Change after Exotic Plant Invasion: Does This Affect Ecosystem Processes? Wind erodibility of soils at Fort Irwin, California (Mojave Desert), USA, before and after trampling disturbance: implications for land management Global change and biological soil crusts: effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions What Makes the Desert Bloom? Contribution of Dust and Crusts to Soil Fertility on the Colorado Plateau Soil Biota in an Ungrazed Grassland: Response to Annual Grass (Bromus tectorum) Invasion Dynamics of cover, UV-protective pigments, and quantum yield in biological soil crust communities of an undisturbed Mojave Desert shrubland Soil lichen and moss cover and species richness can be highly dynamic: The effects of invasion by the annual exotic grass Bromus tectorum, precipitation, and temperature on biological soil crusts in SE Utah Response of desert biological soil crusts to alterations in precipitation frequency. Treatment effects on performance of N-fixing lichens in disturbed soil crusts of the Colorado Plateau Soil Biota Can Change after Exotic Plant Invasion: Does This Affect Ecosystem Processes? Global change and biological soil crusts: effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions What Makes the Desert Bloom? Contribution of Dust and Crusts to Soil Fertility on the Colorado Plateau Soil Biota in an Ungrazed Grassland: Response to Annual Grass (Bromus tectorum) Invasion Soil lichen and moss cover and species richness can be highly dynamic: The effects of invasion by the annual exotic grass Bromus tectorum, precipitation, and temperature on biological soil crusts in SE Utah Treatment effects on performance of N-fixing lichens in disturbed soil crusts of the Colorado Plateau Response of desert biological soil crusts to alterations in precipitation frequency. Wind erodibility of soils at Fort Irwin, California (Mojave Desert), USA, before and after trampling disturbance: implications for land management Dynamics of cover, UV-protective pigments, and quantum yield in biological soil crust communities of an undisturbed Mojave Desert shrubland