Skip to main content
Advanced Search

Filters: partyWithName: Belnap, Jayne (X)

90 results (44ms)   

View Results as: JSON ATOM CSV
Desert soil surfaces are generally covered with biological soil crusts, a group of organisms dominated by cyanobacteria, lichens, and mosses. Despite their unassuming appearance, these tiny organisms are surprisingly critical to many processes in past and present desert ecosystems and are vital in creating and maintaining fertility of desert soils. They fix both carbon and nitrogen, much of which is leaked to the soils below. They stabilize soils, capture nutrient-rich dust, and can stimulate plant growth. These organisms must tolerate extreme temperatures, drought, and solar radiation, despite having relatively few wet hours for metabolic activity. Under most circumstances, they are extremely vulnerable to climate...
A physical model was developed to explain threshold friction velocities u*t for particles of the size 60?120 ?m lying on a rough surface in loose soils for semiarid and arid parts of the United States. The model corrected for the effect of momentum absorption by the nonerodible roughness. For loose or disturbed soils the most important parameter that controls u*t is the aerodynamic roughness height z 0. For physical crusts damaged by wind the size of erodible crust pieces is important along with the roughness. The presence of cyanobacteriallichen soil crusts roughens the surface, and the biological fibrous growth aggregates soil particles. Only undisturbed sandy soils and disturbed soils of all types would be expected...
Biological soil crusts are key mediators of carbon and nitrogen inputs for arid land soils and often represent a dominant portion of the soil surface cover in arid lands. Free-living soil nematode communities reflect their environment and have been used as biological indicators of soil condition. In this study, we test the hypothesis that nematode communities are successionally more mature beneath well-developed, late-successional stage crusts than immature, early-successional stage crusts. We identified and enumerated nematodes by genus from beneath early- and late-stage crusts from both the Colorado Plateau, Utah (cool, winter rain desert) and Chihuahuan Desert, New Mexico (hot, summer rain desert) at 0?10 and...
In arid and semiarid lands throughout the world, the cover of vegetation is generally sparse or absent. Open spaces between the higher plants are not bare of autotrophic life but usually covered by a community of highly specialized organisms. This soil surface floral community consists of cyanobacteria, green algae, lichens, mosses, microfungi, and other bacteria. Cyanobacterial and microfungal filaments weave throughout the top few millimeters of soil, gluing loose soil particles together to form a biological crust. These crusts occur in all hot, cool, and cold arid and semiarid regions. They may constitute up to 70% of the living cover (Belnap 1994) and have only recently been recognized as having a major influence...
Thin, vertically structured topsoil communities that become ecologically important in arid regions (biological soil crusts or BSCs) are responsible for much of the nitrogen inputs into pristine arid lands. We studied N(2) fixation and ammonium oxidation (AO) at subcentimetre resolution within BSCs from the Colorado Plateau. Pools of dissolved porewater nitrate/nitrite, ammonium and organic nitrogen in wetted BSCs were high in comparison with those typical of aridosoils. They remained stable during incubations, indicating that input and output processes were of similar magnitude. Areal N(2) fixation rates (6.5-48 micromol C(2)H(2) m(-2) h(-1)) were high, the vertical distribution of N(2) fixation peaking close to...
The net exchanges of carbon dioxide, water vapor, and energy were examined in a perennial Colorado Plateau grassland for 5 years. The study began within a multiyear drought and continued as the drought ended. The grassland is located near the northern boundary of the influence of the North American monsoon, a major climatic feature bringing summer rain. Following rain, evapotranspiration peaked above 8 mm d?1 but was usually much smaller (2?4 mm d?1). Net productivity of the grassland was low compared to other ecosystems, with peak hourly net CO2 uptake in the spring of 4 ?mol m?2 s?1 and springtime carbon gain in the range of 42 � 11 g C m?2 (based on fluxes) to 72 � 55 g C m?2 (based on carbon stocks; annual carbon...
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...
There are many reasons to be concerned about the use of non-native species or non-local genetic material in restoration efforts. An overview of these issues is presented. It is argued that site restoration is more than just successful vascular plant establishment, and that local plant material should be used whenever possible. However, it is recognized that time and money often constrain restoration efforts, and that maintenance of genetic integrity is often an issue of project scale. Published in Wildland Shrub and Arid Land Restoration Symposium, on pages 265 - 266, in 1993.
The primary purpose of this study was to examine various physiological responses (chlorophyll degradation, nitrogenase activity, and electrolyte leakage) of crusts and rock lichens on different substrates to gaseous, wet and dry deposition, both under controlled and ambient conditions. The second purpose was to collect baseline data on the elemental concent, nitrogenase activity, chlorophyll degradation, and electrolyte leakage of these crusts and selected rock lichens in ten parks on the Colorado Plateau: Arches, Bryce, Canyonlands, Capitol Reef, Colorado NM, Dinosaur, Glen Canyon NRA, Mesa Verde, Natural Bridges, and Zion.
Categories: Publication; Types: Citation
thumbnail
Biological soil crusts, composed primarily of photosynthetic cyanobacteria, algae, lichens and mosses, play a key role in many ecosystem functions of semi-arid and arid ecosystems around the world (Belnap and Lange 2001). They often cover plant interspaces in undisturbed areas (Kleiner and Harper 1972) and thus can constitute 70% or more of the living ground cover (Belnap 1995). These soil crusts are critical in the stabilization of soils and reduce both wind and water erosion (Belnap and Gillette 1997, 1998). They influence many processes that determine soil fertility, including carbon and nitrogen fixation, dust capture, and mineral chelation. They are often the dominant source of nitrogen (N) in desert ecosystems...
Categories: Publication; Types: Citation
Recent reports of net ecosysytem production >100 gCm?2 yr?1 in deserts are incompatible with existing measurements of net primary production and carbon pools in deserts. The comparisions suggest that gas exchange measurements should be used with caution and better validation if they are expected to indicate the magnitude of carbon sink in these ecosysytems. Published in Global Change Biology, volume 15, issue 6, on pages 1488 - 1490, in 2009.
We conducted a field experiment to assess effects of simulated above-average fall and spring precipitation on monoculture performance and competitive relations of the exotic annual grass Bromus tectorum and the native bunchgrass Stipa hymenoides in southeastern Utah. Between 1 October 1997 and 31 May 1998, "wet" plots received 239 mm and "dry" plots received 119 mm of water representing 175 and 87 percent of average precipitation, respectively. In monoculture, added water increased fall Bromus establishment by a factor of 1.6 but did not affect fall or winter growth. Added water adversely affected Bromus growth during early spring, but enhanced growth as soils dried during mid-spring. Overall, Bromus shoot production...
Cyanobacteria and cyanolichens dominate most desert soil surfaces as the major component of biological soil crusts (BSC). BSCs contribute to soil fertility in many ways. BSC can increase weathering of parent materials by up to 100 times. Soil surface biota are often sticky, and help retain dust falling on the soil surface; this dust provides many plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. BSCs also provide roughened soil surfaces that slow water runoff and aid in retaining seeds and organic matter. They provide inputs of newly-fixed carbon and nitrogen to soils. They are essential in stabilizing soil surfaces by linking soil particles together with filamentous sheaths, enabling soils to...
In drylands of southeastern Utah, USA, the invasive exotic grass Bromus tectorum L. occurs in distinct spatial patterns suggesting soil control of ecosystem susceptibility to invasion. To improve our understanding of these patterns, we examined performance of B. tectorum in relation to additions of water, KCl, MgO, and CaO at seventeen 1600 m2 sites distributed across a calcareous soil gradient in Canyonlands National Park. Water additions resulted in a 57% increase in B. tectorum establishment. Fall establishment was significantly correlated with silt and clay content in wet plots but not in dry plots, suggesting that texture effects on B. tectorum establishment patterns may be greater in wet years than in dry...
The objective of this study was to characterize the community structure and activity of N2-fixing microorganisms in mature and poorly developed biological soil crusts from both the Colorado Plateau and Chihuahuan Desert. Nitrogenase activity was approximately 10 and 2.5 times higher in mature crusts than in poorly developed crusts at the Colorado Plateau site and Chihuahuan Desert site, respectively. Analysis of nifH sequences by clone sequencing and the terminal restriction fragment length polymorphism technique indicated that the crust diazotrophic community was 80 to 90% heterocystous cyanobacteria most closely related to Nostoc spp. and that the composition of N2-fixing species did not vary significantly between...
The episodic nature of water availability in arid and semiarid ecosystems has significant consequences on belowground carbon and nutrient cycling. Pulsed water events directly control belowground processes through soil wet-dry cycles. Rapid soil microbial response to incident moisture availability often results in almost instantaneous C and N mineralization, followed by shifts in C/N of microbially available substrate, and an offset in the balance between nutrient immobilization and mineralization. Nitrogen inputs from biological soil crusts are also highly sensitive to pulsed rain events, and nitrogen losses, particularly gaseous losses due to denitrification and nitrate leaching, are tightly linked to pulses of...
Chlorophyll degradation and electrolyte leakage were measured for the umbilicate desert lichen Rhizoplaca melanophthalma (Ram.) Leuck. & Poelt in the vicinity of a coal-fired power plant near Page, Arizona. Patterns of lichen damage indicated by chlorophyll degradation were similar to those indicated by electrolyte leakage. Regression analyses of chlorophyll degradation as well as electrolyte leakage on distance from the power plant were significant (p < 0.001), suggesting that lichen damage decreased with increasing distance from the power plant. Mean values for both variables at the two sites closest to the power plant (7 and 12 km) differed significantly from values for the two sites farthest from the plant (21...
Categories: Publication; Types: Citation, Journal Citation; Tags: The Bryologist
This guide is primarily based on characteristics that can be observed in the field with the naked eye or a hand lens. Descriptions reflect ?typical? field appearance in North American drylands. The keys are constructed for dry material, while the full-page descriptions include colors when moist. Microscopic characteristics are included when they are necessary to aid in identification. Published by U.S. Government Printing Office, in 2007.
thumbnail
The Colorado Plateau is located in the interior, dry end of two moisture trajectories coming from opposite directions, which have made this region a target for unusual climate fluctuations. A multi-decadal drought event some 850 years ago may have eliminated maize cultivation by the first human settlers of the Colorado Plateau, the Fremont and Anasazi people, and contributed to the abandonment of their settlements. Even today, ranching and farming are vulnerable to drought and struggle to persist. The recent use of the Colorado Plateau primarily as rangeland has made this region less tolerant to drought due to unprecedented levels of surface disturbances that destroy biological crusts, reduce soil carbon and nitrogen...
Soil surfaces dominated by cyanobacteria and cyanolichens (such as Collema sp.) are widespread in deserts of the world. The influence of these biological soil crusts on the uptake of bioessential elements is reported for the first time for six seed plants of the deserts of Utah. This sample almost doubles the number of species for which the influence of biological soil crusts on mineral uptake of associated vascular plants is known. These new case studies, and others previously published, demonstrate that cyanobacterial or cyanobacteria- Collema crusts significantly alter uptake by plants of many bioessential elements. In studies now available, these crusts always increase the N content of associated seed plants....
map background search result map search result map Nitrogen deposition and UV stressor impacts in Canyonlands National Park as affected by climatic pulse events Sensitivity of the Colorado Plateau to Change: Climate, Ecosystems, and Society Nitrogen deposition and UV stressor impacts in Canyonlands National Park as affected by climatic pulse events Sensitivity of the Colorado Plateau to Change: Climate, Ecosystems, and Society