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Articles 1 - 8 of 8
Full-Text Articles in Earth Sciences
Investigating The Roles Of Plants, Fungi, And Biocrusts In Nutrient Movement Within Dryland Ecosystems, Catherine E. Cort
Investigating The Roles Of Plants, Fungi, And Biocrusts In Nutrient Movement Within Dryland Ecosystems, Catherine E. Cort
Open Access Theses & Dissertations
In dryland ecosystems, plant productivity and microbial decomposition are often separated in space and time due to the asynchronous availability of soil moisture and organic matter inputs. It has been proposed that fungi play a key functional role in connecting these cycles by facilitating movement of water, carbon (C), and nitrogen (N) through a network of shared hyphae between plant roots and biological soil crust (biocrust) communities at the soil surface. This connection, also known as the â??fungal loop,â?? effectively re-couples processes of nutrient release and uptake between primary producers and minimizes ecosystem N losses due to leaching, erosion, and …
Temporal Trends In Dryland Soil Carbon Fluxes In Response To Artificial And Natural Pulsed Moisture Events, Briana Alyce Salcido
Temporal Trends In Dryland Soil Carbon Fluxes In Response To Artificial And Natural Pulsed Moisture Events, Briana Alyce Salcido
Open Access Theses & Dissertations
Critical zone processes in drylands play a crucial role in the global carbon cycle, and one of the most important processes is soil CO2 efflux at the interface between soils and the atmosphere, which represents a main pathway for loss of carbon. Predicting the carbon dynamics at this interface is challenging due to the complexity of belowground processes, which include both biotic (soil respiration) and abiotic (calcite precipitation) production of CO2, as well as transport processes that include both diffusive and advective components. In this study, we aimed to investigate the contribution of soil air displacement to soil CO2 efflux …
Differentiating Biotic Vs. Abiotic Co2 In The Formation Of Pedogenic Carbonate In Agriculture And Natural Dryland Soils, Valeria Isabel Molina
Differentiating Biotic Vs. Abiotic Co2 In The Formation Of Pedogenic Carbonate In Agriculture And Natural Dryland Soils, Valeria Isabel Molina
Open Access Theses & Dissertations
Drylands, characterized by low and sporadic precipitation, require irrigation for crop growth. However, irrigation practices can lead to salt accumulation in soil due to high evaporation rates and reduced leaching. In addition to loading salts to soil, irrigation promotes the accumulation of secondary calcite. In natural systems, the formation of pedogenic carbonate (secondary calcite, CaCO3) is critical, impacting the soil properties hydrologically and biogeochemically, and modifying the global carbon cycle over geological time, albeit at a lower rate. In agricultural sites, irrigation water supplies HCO3- and Ca2+, accelerating the rates of CaCO3 formation and releasing abiotic CO2. This study investigated …
Characterizing Spatial Variability In Soil Co2 Fluxes In The Chihuahuan Desert Using Geostatistical Techniques, Viridiana Orona
Characterizing Spatial Variability In Soil Co2 Fluxes In The Chihuahuan Desert Using Geostatistical Techniques, Viridiana Orona
Open Access Theses & Dissertations
Spatial variability in soil CO2 efflux across landscapes is an important feature of the â??Critical Zoneâ?? within dryland ecosystems. In dryland critical zones, resources are often distributed in patches or resource islands. Although this is particularly true in natural settings, the significance of spatial variability in CO2 efflux and its patterns also extends to dryland agriculture. In both irrigated and unirrigated systems, human management practices can significantly impact both organic and inorganic carbon cycling processes, highlighting the importance of studying CO2 efflux in these systems. We examined the spatial patterns of soil CO2 efflux and quantified the magnitude and scale …
Using Ground Penetrating Radar To Investigate Controls On Pedogenic Calcium Carbonate Distribution In Dryland Critical Zones, Nohemi Valenzuela Garay
Using Ground Penetrating Radar To Investigate Controls On Pedogenic Calcium Carbonate Distribution In Dryland Critical Zones, Nohemi Valenzuela Garay
Open Access Theses & Dissertations
Caliche or pedogenic calcium carbonate (CaCO3) layers are a common feature of arid soils, but the environmental controls on their distribution are not fully understood. Caliche layers are thought to play an important role in shallow subsurface water storage and movement, due to their water retention capacity and ability to impede vertical water transport (Hennessy et al., 1983). Therefore, caliche distribution and stability play a role in controlling water distribution in arid lands. However, due to its largely subsurface nature, caliche can be difficult to investigate and map without significant effort. I hypothesize that noninvasive geophysical methods, such as ground-penetrating …
Deciduous Shrub Encroachment Effects On Tundra Soil Properties, Daniela Aguirre
Deciduous Shrub Encroachment Effects On Tundra Soil Properties, Daniela Aguirre
Open Access Theses & Dissertations
Deciduous shrub abundance is increasing in tundra ecosystems as an effect of rising temperatures which may change tundra physical properties and, in turn, microbial communities and biogeochemical processes. Two mechanisms through which shrub presence may affect tundra ecosystems were examined in this study; the physical presence of the shrubs and effects of increasing shrub litter inputs. In a sub-arctic alpine tundra ecosystem, dominated by the deciduous shrub Betula glandulosa, both shrub presence (shrub present and removed) and litter quantity (no litter/litter removed, ambient litter, and twice ambient litter) were manipulated; multiple ecosystem properties where measured within the treatment plots over …
Effects Of Increasing Deciduous Shrub Litter On Ecosystem Functioning In Alpine Tundra, Alejandro Emmanuel Benhumea
Effects Of Increasing Deciduous Shrub Litter On Ecosystem Functioning In Alpine Tundra, Alejandro Emmanuel Benhumea
Open Access Theses & Dissertations
Rising temperatures due to global warming have resulted in rapid environmental changes in northern environments, resulting in an increase in deciduous shrub growth which has the potential to alter soil ecosystem properties and processes. In order to address some potential mechanisms by which shrubs alter ecosystem properties and processes, we designed an experiment which separated the effects of physical shrub presence and the effects of litter quantity in a fully factorial experiment on a north facing alpine plateau in the southwest Yukon, Canada. Specifically, we asked the following questions: What are effects of shrub litter, independent of shrub presence, on …
Effects Of Gradation And Moisture Content On Resistivity Of Mechanically Stabilized Earth Wall Backfill Materials, Jose Luis Arciniega
Effects Of Gradation And Moisture Content On Resistivity Of Mechanically Stabilized Earth Wall Backfill Materials, Jose Luis Arciniega
Open Access Theses & Dissertations
The service life of mechanically stabilized earth (MSE) walls depends on the corrosion rate of the metallic reinforcement used in their construction. The resistivity of the backfill aggregates needs to be measured accurately in order to estimate realistically the corrosion rate of the reinforcement. Resistivity testing is usually performed using the traditional soil box on the portion of the aggregates that passes a No. 10 or No. 8 sieve to either select or reject the backfill. For a more reasonable characterization of the corrosivity of coarse backfills, it is desirable to use their actual gradations. To that end, several resistivity …