Spelling suggestions: "subject:"biological soil trust"" "subject:"biological soil crude""
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Microbial Restoration Ecology of Biological Soil CrustsJanuary 2019 (has links)
abstract: Biological soil crusts (biocrusts) are topsoil communities of organisms that contribute to soil fertility and erosion resistance in drylands. Anthropogenic disturbances can quickly damage these communities and their natural recovery can take decades. With the development of accelerated restoration strategies in mind, I studied physiological mechanisms controlling the establishment of cyanobacteria in biocrusts, since these photoautotrophs are not just the biocrust pioneer organisms, but also largely responsible for improving key soil attributes such as physical stability, nutrient content, water retention and albedo. I started by determining the cyanobacterial community composition of a variety of biocrust types from deserts in the Southwestern US. I then isolated a large number of cyanobacterial strains from these locations, pedigreed them based on their 16SrRNA gene sequences, and selective representatives that matched the most abundant cyanobacterial field populations. I then developed methodologies for large-scale growth of the selected isolates to produce location-specific and genetically autochthonous inoculum for restoration. I also developed and tested viable methodologies to physiologically harden this inoculum and improve its survival under harsh field conditions. My tests proved that in most cases good viability of the inoculum could be attained under field-like conditions. In parallel, I used molecular ecology approaches to show that the biocrust pioneer, Microcoleus vaginatus, shapes its surrounding heterotrophic microbiome, enriching for a compositionally-differentiated “cyanosphere” that concentrates the nitrogen-fixing function. I proposed that a mutualism based on carbon for nitrogen exchange between M. vaginatus and its cyanosphere creates a consortium that constitutes the true pioneer community enabling the colonization of nitrogen-poor, bare soils. Using the right mixture of photosynthetic and diazotrophic cultures will thus likely help in soil restoration. Additionally, using physiological assays and molecular meta-analyses, I demonstrated that the largest contributors to N2-fixation in late successional biocrusts (three genera of heterocystous cyanobacteria) partition their niche along temperature gradients, and that this can explain their geographic patterns of dominance within biocrusts worldwide. This finding can improve restoration strategies by incorporating climate-matched physiological types in inoculum formulations. In all, this dissertation resulted in the establishment of a comprehensive "cyanobacterial biocrust nursery", that includes a culture collection containing 101 strains, isolation and cultivation methods, inoculum design strategies as well as field conditioning protocols. It constitutes a new interdisciplinary application of microbiology in restoration ecology. / Dissertation/Thesis / Doctoral Dissertation Liberal Studies 2019
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Bridging Post-Wildfire Communication Gaps between Managers, Researchers, and Local Communities, including a Biological Soil Crust Case StudyWhitcomb, Hilary Louise 01 August 2017 (has links)
Following a wildfire, land management agencies act quickly to protect ecosystem services. We don't currently understand how post-wildfire managers make trade-off decisions in these tight timelines, or if these decisions reflect current science. Using Brunson’s (2014) social-ecological systems multi-scalar model, surveys assessed manager opinions about post-wildfire projects, perceptions of stakeholder opinions, and ability or willingness to consider new science results. Public surveys asked local citizens their opinions about post-wildfire projects. Manager perceptions were measured through semi-structured phone interviews (n = 8) and a structured online survey (n = 256). Public surveys were mailed to 1,000 (971 deliverable, n = 152 usable) residents in rural and urban Great Basin and Mojave Desert ZIP codes. We found coarse- and fine-scale social and political opinions were associated with all post-wildfire management decisions, often creating perceived barriers to project implementation. Conversely, local citizens were more supportive of projects than managers perceived them to be. While the majority of managers and citizens supported the concept of incorporating experimental research, managers were less able to consider more specific research incorporation into actual projects. Ecologically, biological soil crusts (BSC) are emerging as an important fine-scale component of semi-arid restorations. However, even when BSCs are assessed prior to a restoration plan, it is unclear how or if this knowledge has any impact. BSCs were evaluated both socially and ecologically: all manager surveys contained questions specifically related to BSC, and a pilot greenhouse study assessed a) if seed drilling simulations on different stages of BSC may affect restoration plant establishment and b) if BSC excluded the invasive species Bromus tectorum. Similar to other new science results, managers were unlikely to be able/willing to consider BSC status in post-wildfire projects. However, our results suggest the possibility that, even when lightly burned, seeding strategy may influence native plant establishment. In ideal greenhouse conditions, B. tectorum was able to establish readily on both burned and unburned BSC.
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Evaluation of Physicochemical Parameters in Two Different EcosystemsBrekoski, Anna M. 12 August 2022 (has links)
No description available.
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Structure and reactivity of a biological soil crust from a xeric sandy soil in Central EuropeHoppert, Michael, Reimer, Rudolph, Kemmling, Anne, Schröder, Annekatrin, Günzl, Bettina, Heinken, Thilo January 2004 (has links)
The investigation was designed to explore the structure, composition and activity of a biological soil crust on an acidic, sandy soil from a temperate climate. The crust covers several hundreds of square meters on the hilltop of a large terminal moraine. The conjugate alga <i>Zygogonium ericetorum</i> forms the essential matrix for the crust, a dense web of algal filaments with interspersed lichens and mosses. The crust is composed of three layers, with an uppermost layer consisting nearly entirely of a dense algal mat. In lower layers, a parasitic fungus, penetrating the algal cells, is another important component of the crust community. In this soil crust, photosynthetic and respiratory activity is stabilized at low water activities.
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Biological soil crusts in forested ecosystems of southern Oregon : presence, abundance and distribution across climate gradientsOlarra, Jennifer A. 14 December 2012 (has links)
In arid and semi-arid deserts, soils are commonly covered with biological soil crusts. The
study of arid biocrusts and their ecological function has become increasingly common in
the literature over the last several decades. Interestingly, no mention is made of
biological soil crusts in forested ecosystems, raising the question as to whether they exist
in these areas and if they do, why they have yet to be recognized as such? Through the
use a parallel logic, this study finds that biocrusts do indeed exist in forests, a novel
relationship in forest ecology and seeks to determine if there exist ecophysical
explanations for the abundance and distribution throughout the forest landscape.
This study examined the effects of climate variables and substrate types on the
abundance, distribution and overall cover of forest soil biocrust at fifty-two sites in
southern Oregon, U.S.A. Sites were randomly selected within established buffer zones in
the Siuslaw, Rogue-Sisikyou, Umpqua, and Fremont-Winema National Forests. The
methods of Belnap et al 2001 were tested and then modified for application in forested
ecosystems. Data were collected on the relative abundance and distribution of biocrust
morphological groups across available substrates, community biocrust morphology,
aspect, elevation and soil texture, pH and organic matter content. Site-specific data on
average annual precipitation and minimum/maximum temperatures was collected using
the PRISM Climate Model.
This study found substrate colonization by specific morphological groups mixed across
the study; though dominant communities were observed for each substrate present,
substrate availability appears to be confounded by a number of variables (climate, stand
age and structure and litter layer) not controlled for in this study. Biocrust community
morphologies varied across sites, primarily influenced by the surface texture of the
substrate and morphology of the individual. Relatively smooth surfaces (rock, bare soil)
often resulted in smooth biocrust morphologies, whereas rough surfaces (dead wood, bare
soil) tended to result in a rolling morphology. Litter layer directly influenced the relative
proportion of substrates colonized, notably affecting dead wood and mineral soil
biocrusts. Total biocrust cover increased as precipitation increased as did biocrust
preference for dead wood substrates while mineral soil remained unchanged and rock
surfaces were negatively represented. Aspect generally followed the anticipated
distribution of total biocrust cover with the highest cover on N and NW aspects and
lowest on the W aspect. Increases in elevation were negatively related to overall biocrust
cover. Soil texture was not found to be directly related to overall biocrust cover,
attributed in part to the highly adaptive nature of the biocrust community. Soil organic
matter (SOM) influenced total biocrust cover with positive correlations between total
cover and increasing SOM content. Soil pH increased as expected across the
precipitation range (17 to 159 in/yr) of the transect. Total biocrust cover was found to
trend with soil pH, but is believed to be attributed to the parallel relationship between
precipitation and pH, rather than pH alone given the relative moderate pH range (4.39 to
6.54) of the study. The distribution and abundance of forest soil biocrusts is strongly
influenced by precipitation. The confounding influence of precipitation to litter layer
depth and organic matter content (through gradients of vegetative productivity) and soil
pH further are concluded to influence substrate preference by morphological groups.
Across the variables examined, similarities between the two communities (arid and
forest) in response to climate and soil chemistry show parallel relations, justifying the
formal establishment of biological soil crust community in forested regions. The
differences between communities related to the presence of trees validate the
establishment of forest soil biocrusts as distinct community in both form and ecological
function with the forests. / Graduation date: 2013
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