Geology topics
Publications and source records attributed to Bryan Hopkins.
Description Water is an integral part of how we interact with the environment and live our everyday lives. This educational poster illustrates where water is in urban environments, how it moves, and different ways water is used both naturally and through human interaction. This poster is intended for eighth-grade audiences and younger.
Description Water is an integral part of how we interact with the environment and live our everyday lives. This educational poster illustrates agricultural water use, how water moves, and different ways that water is used both naturally and through human interaction. This poster is intended for eighth-grade audiences and younger.
Description The water cycle describes how water moves from Earth’s surface into the atmosphere, then back to the surface again or to below Earth’s surface. This educational poster depicts five key water-cycle processes that transport or transform water between states: evaporation, transpiration, condensation, precipitation, and infiltration. It illustrates examples of natural and human interactions with these processes. This poster is intended for eighth-grade audiences.
Woody plant encroachment can increase nutrient resources in the plant-mound zone. After a fire, this zone is often found to be water repellent. This study aimed to understand the effects of post-fire water repellency on soil water and inorganic nitrogen and their effects on plant growth of the introduced annual Bromus tectorum and native bunchgrass Pseudoroegneria spicata. Plots centered on burned Juniperus osteosperma trees were either left untreated or treated with surfactant to ameliorate water repellency. After two years, we excavated soil from the untreated and treated plots and placed it in zerotension lysimeter pots. In the greenhouse, half of the pots received an additional surfactant treatment. Pots were seeded separately with B. tectorum or P. spicata. Untreated soils had high runoff, decreased soilwater content, and elevated NO3eN in comparison to surfactant treated soils. The two plant species typically responded similar to the treatments. Above-ground biomass and microbial activity (estimated through soil CO2 gas emissions) was 16.8-fold and 9.5-fold higher in the surfactant-treated soils than repellent soils, respectably. This study demonstrates that water repellency can influence site recovery by decreasing soil water content, promoting inorganic N retention, and impairing plant growth and microbial activity.