Tag: Krista McGuire

Tropical land use change effect on soil microbial function

Presenter(s): Sky Ramirez-Doble

Faculty Mentor(s): Krista McGuire & Stephanie Ostresh

Oral Session 1 O

70% of remaining tropical forests, sites with high biodiversity, primary productivity, and CO2 exchange, are being converted into agricultural or logged areas. Tropical agricultural sites have been found with altered levels of soil carbon, nitrogen, and microbial composition; however, anthropogenic effects on soil and litter microbial functional potential are poorly understood. To help reveal the relationship between an altered soil and litter chemistry and microbial functionality, total soil and litter carbon and nitrogen concentrations were correlated with the presence of key decomposition macromolecules in litter and soil in the three most abundant tree species in El Yunque National Forest: Prestoea montana var. acuminate, Casearia arborea, and Dacryodes excelsa. Through a series of statistical tests, we were able to determine if (1) tree species and land use create distinct physical and chemical zones that alter microbial composition and functional potential, (2) differential carbon and nitrogen availability across land use reflects the dominant tree species present, and (3) high land use areas are correlated to earlier successional species such as Casearia arborea and low land use are correlated with late successional species such as Dacryodes excelsa. My research will provide insight into the anthropogenic effects of tropical agriculture.

Effect of Root Symbionts on Inga laurina (Fabaceae) in Disturbed Tropical Forests

Presenter(s): Charles Paulino

Faculty Mentor(s): Krista McGuire & Stephanie Ostresh

Poster 84

Session: Social Sciences & Humanities

Succession in tropical forests is an important yet poorly understood topic in ecology. Dynamic principles are at play that are dictated by resource availability, inter and intraspecific competition, and environmental conditions at affect community structure and function. In this experiment I aim to investigate the physiochemical outputs of Inga laurina(Sw.) Willd., a mid-successional tree, in both early and mid-successional forest plots using Carbon-Nitrogen analysis. Since the roots of I. laurna can be colonized by arbuscular mycorrhizal (AM) fungi andnitrogen- fixing Rhizobium sp. bacteria, I hypothesize: H1: net Nitrogen output into the environment will be higher in the early-successional plot than the mid-successional plot where environmental conditions favor N-fixing bacteria; H2: if H1 is true, than AM fungal root colonization will be higher in mid-successional stage than early-succession, where environmental conditions are favorable for fungal symbionts.

Linking mycorrhizal fungal diversity with pathogen abundances in a vineyard agroecosystem.

Presenter(s): Emily Hill—Biology

Faculty Mentor(s): Krista McGuire

Soil microbes are becoming increasingly recognized as significant contributors to agroecosystem processes due to their functions as decomposers, mutualists and pathogens . Monoculture cropping systems are known to harbor high abundances of microbial pathogens specific to the species of plants or animals in cultivation; for this reason, pesticides and fungicides are widely applied across all farming systems, including those that practice sustainable management techniques . However, application of fungicides also negatively affects mutualists such as arbuscular mycorrhizal (AM) fungi, which provide beneficial ecosystem services such as soil stability, nutrient cycling and amelioration of biotic and abiotic stressors . Despite the ecological and economic stress caused

by the widespread application of pesticides and fungicides, the effects of these agricultural management practices on soil microbial communities remain largely uncharacterized . Here, we aim to understand how various ecological and environmental factors influence shifts in soil microbial community composition and pathogen abundance in vineyard agroecosystems across Oregon . Viticulture is a perennial crop system in which Vitis vinifera is cultivated for wine production . In Oregon, there is a long history of different viticultural practices implemented across distinct growing regions delineated by climate, soils and topography . Vitis plants are highly reliant on AM fungi, which provide both nutritional and nonnutritional benefits to their hosts including uptake and transfer of limiting nutrients and increased resistance to pathogens . Ecological patterns are thus expected to emerge between AM fungal composition and diversity, and the abundances of soilborne pathogens specific to Vitis plants . This project will elucidate these ecological relationships across growing regions and management practices by comparing the AM fungal composition with the abundances of microbial pathogens .