Life Sciences Commons^™

Mimicking Biofilms: Photosynthetic Assessments Of C. Reinhardtii In 3 Physical Forms, John Michael Roesgen

Biology ETDs

Oxygenic photosynthesis supports the majority of life on Earth through the capture of energy from sunlight and the assimilation of CO₂ into basic building blocks of cells. Microalgae are fast growing and account for about half of global photosynthesis. In addition, they can be cultivated and their metabolism can be redirected to generate additional useful products ranging from biofuels to pharmaceuticals. However, the efficiency of metabolite production is severely impacted by the slow diffusion of CO₂ through water and the high energetic costs of harvesting microalgae from liquid cultures. Microalgae grow in open water, but they also form …

Evidence Of Competitive Release Following Overstory Mortality In A Semi-Arid Piñon-Juniper Woodland, Corrie D. Gonzalez

Biology ETDs

Extreme temperatures and severe drought events have led to widespread tree mortality worldwide. In semi-arid regions of the Southwest United States, these events pose a significant threat to piñon-juniper (PJ) woodlands. We studied the effects of piñon and juniper mortality on the growth and physiology of existing saplings in PJ woodlands by analyzing water status, photosynthetic activity, and tissue chemistry to gain insights into these impacts. Juniper saplings exhibited improved water status and water use efficiency in response to overstory mortality, whereas piñon saplings did not. Additionally, both piñon and juniper saplings exhibited increased photosynthetic rates, increased photosynthetic capacity, and …

The Impact Of Climate And Elevation On The Growth And Mortality Of Piñon Pine, Alice M. Fretz

Biology ETDs

The Southwestern United States is currently experiencing severe drought, resulting in the mortality of many tree species. Piñon-juniper woodlands are an extensive biome in the Southwest, and are highly vulnerable to extended periods of drought that lead to tree mortality. Specifically, Pinus edulis populations are decreasing due to increasingly arid conditions. I used dendrochronology to investigate how tree growth rings of Pinus edulis reflect severe drought in living and dead trees. I also investigated how severe drought affects Pinus edulis along an altitudinal gradient. Tree core samples were taken from currently living and dead trees, as well as from trees …

Impacts Of Long-Term Precipitation Manipulation On Hydraulic Architecture, Xylem Function, And Canopy Status In A Piñon-Juniper Woodland, Patrick J. Hudson

Biology ETDs

The Southwestern US is predicted to become hotter and drier, as global climate change forces increasing temperatures and variability in timing and size of precipitation inputs. Drought stress has become more frequent in recent decades, and resulted in massive forest mortality in piñon-juniper woodlands. During recent severe droughts (2000-2003, 2009-2012), piñon pine (Pinus edulis Englem.) suffered disproportionately high mortality compared to co-occurring one-seed juniper (Juniperus monosperma [Engelm.] Sarg.). A large-scale precipitation manipulation experiment was established in a piñon-juniper woodland in central New Mexico to test hypotheses regarding tree survival and mortality with respect to altered water regimes. Our …

A Determination Of Stelar Patterns In Various Root Divisions Of Certain Angiosperms, Serafin Ramon

Biology ETDs

Root systems from ten species of desert angiosperms were collected and examined histologically to determine the xylem patterns of the primary, secondary, and tertiary roots. The plants used in the study were Cleome serrulata Push, Croton texenis (Klotzch) Muell. Arg., Franseria acanthicarpa (Hook.) Coville, Gutierrezia microphala (D.C.) Gray, Mentzelia albicaulis Dougl., Kochia scoparia (L.), Ratibida columnaris (Sims) D. Don, Salsola kali (S. pestifer A. Nels.), Tribulus terrestris L., and Berbana macdougalii Heller.

A Distributional And Taxonomic Study Of Ratibida Columnifera Var. Columnifera, Ratiba Columnifera Var. Pucherrima, And Their Hybrids In New Mexico, Walter W. Marshall

Biology ETDs

The classification and distribution of Ratibida columnifera var. columnifera Woot. and Standl. and R. columnifera var. pulcherrima (DC.) Woot. and Standl. are complex. Some floras list R. columnifera var. pulcherrima as a purple colored form or variety of the species while other authors refer to this taxon as a separate species of Ratibida. The purpose of this study is to clarify the taxonomic status of the two forms by determining and differences in morphology, distribution, taxonomy, and ecology.

An attempt has been made to determine the route by which R. columnifera columnifera and R. columnifera pulcherrima were distributed. After this …

A Bioecological Study Of Pinyon Pine-Juniper Association At Juan Tabo In The Sandia Mountains Of New Mexico, Robert Hallett Parker

Biology ETDs

A survey of literature shows that no community or bioecological study has ever been made of the pinyon pine-juniper association as it occurs in the Upper Sonoran Life Zone in New Mexico and southern Colorado. This deficiency of knowledge relative to the pinyon pine-juniper community is in direct contrast to several studies that have been made of the same community in Arizona and Utah by the presence of dominant trees of entirely different species. Relative to the association in New Mexico, one of the dominant tress, the pinyon pine (Pinus edulis Engelm), has been investigated, but no bioecological and …