With the dramatic expansion of pinyon-juniper woodlands over the last century, improved understanding of how these woodlands modify infiltration properties is needed, in order for land managers to make informed decisions on how to best manage their specific resources. However, current methods for measuring soil infiltration are often limited by low sample sizes and high experimental error, due to constraints associated with remote, non agricultural settings. This thesis first presents a scheme for automating and calibrating two commercially available infiltrometers, which allows collection of a large number of precise unsaturated infiltration measurements in a relatively short period of time. Secondly, a new method to precisely determine saturated hydraulic conductivity from small intact soil cores collected in the field is demonstrated. This method removes bias due to measurement error using a multiple head linear regression approach. Finally, hundreds of fine spatial scale measurements of soil sorptivity, unsaturated hydraulic conductivity, saturated hydraulic conductivity, soil water content, and other soil descriptive measurements along radial line transects extending out from the trunk of juniper ( Juniperus osteosperma) and pinyon pine (Pinus edulis) trees. Within the subcanopy of these trees, interactions among litter material, root distributions, and hydrophobic soil significantly influence ecohydrologic properties by limiting and redirecting infiltration below the soil surface. Consequently, hydrophobicity appears to be a mechanism that promotes survival of woody vegetation in arid environments, through decreasing evaporation rates from the soil surface. We further demonstrate how differences in unsaturated infiltration and soil water content between the subcanopy and intercanopy zones are not discrete. Unsaturated infiltration was significantly lower within the subcanopy than in the intercanopy, and increased by eight-fold across a gradient extending outward from near the edge of the canopy to approximately two times the canopy radius. This gradient was not strongly related to soil moisture. In the intercanopy, increasing structural development of biological soil crust cover beyond this gradient was positivity correlated with infiltration capacity. Consequently, these results indicate that the spatial location of the trees should be considered in the assessment and modeling of woody plant and biological soil crust influence on infiltration capacity in a pinyon-juniper ecosystem.
|Advisor:||Chandler, David G.|
|Commitee:||Belnap, Jayne, Ryel, Ron|
|School:||Utah State University|
|School Location:||United States -- Utah|
|Source:||MAI 47/01M, Masters Abstracts International|
|Keywords:||Ecohydrology, Hydrology, Hydrophobicity, Infiltration, Juniper, Soils, Water repellency|
Copyright in each Dissertation and Thesis is retained by the author. All Rights Reserved
The supplemental file or files you are about to download were provided to ProQuest by the author as part of a
dissertation or thesis. The supplemental files are provided "AS IS" without warranty. ProQuest is not responsible for the
content, format or impact on the supplemental file(s) on our system. in some cases, the file type may be unknown or
may be a .exe file. We recommend caution as you open such files.
Copyright of the original materials contained in the supplemental file is retained by the author and your access to the
supplemental files is subject to the ProQuest Terms and Conditions of use.
Depending on the size of the file(s) you are downloading, the system may take some time to download them. Please be