Richard A Gill

Brigham Young University - Provo Main Campus | BYU

Invasive annual grasses can promote ecosystem state changes and habitat loss in the American Southwest. Non-native annual grasses such as Bromus spp. and Schismus spp. have invaded the Mojave Desert and degraded habitat through increased fire occurrence, severity, and shifting plant community composition. Thus, it is important to identify and chara...

1. Annual grass invasion is transforming the western United States and driving a need for restoration techniques that can both reduce exotic annual grass abundance and allow revegetation of native species. Pre‐emergent herbicides can provide control of annual grasses, but when applied concurrently with direct seeding efforts, the herbicide can also...

Invasion by exotic grasses is degrading dryland ecosystems worldwide and efforts to restore native vegetation in invaded areas have been largely unsuccessful. Control of invasive grasses with herbicide also limits restoration efforts using native seed. In this study, we evaluated two approaches that could allow for the restoration of a native speci...

Biological invasions are responsive to changing wildfire regimes related to human activities that are altering biological communities. Our objective was to investigate how fire, rodent activity, and competition among plant species modify plant community structure, invasion patterns, and vulnerability to altered fire regimes. We imposed experimental...

Wildfires destabilize biocrust, requiring decades for most biological constituents to regenerate, but bacteria may recover quickly and mitigate the detrimental consequences of burnt soils. To evaluate the short-term recovery of biocrust bacteria, we tracked shifts in bacterial community form and function in Cyanobacteria/lichen-dominated (shrub int...

Too many students reject the theory of evolution because they view it as incompatible with their religious beliefs. Some have argued that abandoning religious belief is the only way to help religious individuals accept evolution. Conversely, our data support that highlighting faith/evolution compatibility is an effective means to increase student a...

Context Exotic annual grasses are transforming native arid and semi-arid ecosystems globally by accelerating fire cycles that drive vegetation state changes. Cheatgrass (Bromus tectorum), a particularly widespread and aggressive exotic annual grass, is a key management target in national parks of the western United States due to its impacts on wild...

Polling data reveal a decades-long residual rejection of evolution in the United States, based on perceived religious conflict. Similarly, a strong creationist movement has been documented internationally, including in the Muslim world. Members of the Church of Jesus Christ of Latter-day Saints (LDS, Mormon), a generally conservative denomination,...

Post-Essay prompt and rubric. This is the essay prompt given to students at the end of the semester to determine whether change occurred. Explanations of each category are given. (DOCX)

Pre-Essay prompt and rubric. This is the essay prompt given to students at the beginning of the semester. Also included is an example of the types of statements used to categorize essays. (DOCX)

Atmospheric CO2 enrichment usually increases the aboveground net primary productivity (ANPP) of grassland vegetation, but the magnitude of the ANPP–CO2 response differs among ecosystems. Soil properties affect ANPP via multiple mechanisms and vary over topographic to geographic gradients, but have received little attention as potential modifiers of...

Background/Question/Methods Early season invasives transform native arid and semi-arid biological communities decreasing biodiversity while increasing likelihood of catastrophic fires. Landscape and climate influence spatiotemporal variation in the establishment and spread of invasive annuals. The aggressive invasive annual cheatgrass (Bromus tecto...

Resource availability and biotic interactions control opportunities for the establishment and expansion of invasive species. Studies on biotic resistance to plant invasions have typically focused on competition and occasionally on herbivory, while resource-oriented studies have focused on water or nutrient pulses. Through synthesizing these approac...

Background Acceptance of evolutionary theory varies widely and is often associated with religious background. Some have suggested there exists an additional relationship between scientific reasoning ability and the acceptance of evolutionary theory. In this study, we used structural equation modeling to test whether scientific reasoning ability pre...

Background and aimsAn advance in snowmelt timing in seasonally snow covered ecosystems has a wide range of potential impacts on plant and soil processes. Plants may respond to earlier melt through changes in phenology and altered allocation of resources to growth and reproduction, and earlier snowmelt may impact active pools of soil C such as micro...

Soil characteristics and functions are critical determinants of rangeland systems and the ecosystem services that they provide. Rangeland soils are extremely diverse, but an emerging understanding is that paradigms developed in more mesic forest ecosystems may not be applicable. Vascular plants, biological soil crusts, and the soil microbial commun...

Urban forests provide critical ecosystem services in cities of the Western United States, including regulating thermal extremes, supporting biological diversity, and providing cultural and recreational services. However, these services may come with trade-offs such as heavy water demand in arid environments. Thus, afforestation and its effect on th...

Biotic resistance and disturbance are fundamental processes influencing plant invasion outcomes; however, the role of consumers in regulating the establishment and spread of plant invaders and how disturbance modifies biotic resistance by consumers is unclear. We document that fire in combination with experimental exclusion of rodent consumers shif...

Students frequently hold an incorrect view of evolution. There are several potential barriers that prevent religious students, specifically, from engaging evolutionary theory in the classroom. This study focuses on two hypothesized barriers on learning evolutionary theory in a highly religious model population, specifically members of The Church of...

Soil moisture in seasonally snow-covered environments fluctuates seasonally between wet and dry states. Climate warming is advancing the onset of spring snowmelt and may lengthen the summer dry state and ultimately cause drier soil conditions. The magnitude of either response may vary across elevation and vegetation types. We situated our study at...

Most hypotheses about controls over high-altitude forests, including treeline, the elevation for upright woody plants, or timberline, the upper elevation for aggregated forest, suggest that low temperature drives forest dynamics, either through effects on cell division and tree growth or indirectly through frost damage or nutrient availability. How...

We present the design and development of a new WaterML R package that provides access to the Consortium of Universities for Advancement of Hydrologic Science (CUAHSI) Hydrologic Information System (HIS) HydroServer as a means for storing and managing data. The new WaterML R package is presented in terms of its functional requirements and design, wi...

Changes in soil carbon storage could affect and be affected by rising atmospheric CO2. However, it is unlikely that soils will respond uniformly, as some soils are more sensitive to changes in the amount and chemistry of plant tissue inputs whereas others are less sensitive because of mineralogical, textural, or microbial processes. We studied soil...

Rising atmospheric CO2 concentration may change the isotopic signature of plant N by altering plant and microbial processes involved in the N cycle. CO2 may increase leaf δ(15)N by increasing plant community productivity, C input to soil, and, ultimately, microbial mineralization of old, (15)N-enriched organic matter. We predicted that CO2 would in...

Fossorial mammals may affect nutrient dynamics and vegetation in recently initiated primary successional ecosystems differently than in more developed systems because of strong C and N limitation to primary productivity and microbial communities. We investigated northern pocket gopher (Thomomys talpoides) effects on soil nutrient dynamics, soil phy...

Tree mortality because of beetle outbreaks has become substantial and widespread in conifer forests in western North America. A number of environmental and physiological factors influence patterns of mortality. Tree diversity may reduce the severity and extent of insect damage to host trees by providing associational resistance, but the existence a...

Land managers, ecologists, and global change biologists need to accurately describe net primary production (NPP) of a landscape. Their ability to accurately and precisely detect annual change in plant biomass determines how to manage a landscape, accurately describe treatment effects from an experiment, or understand how carbon is being stored in t...

Following wildfires, plant materials are direct-seeded to limit erosion and annual weed invasion. Seedlings often fail to establish because selected plant materials are not always well adapted to local soil moisture and temperature conditions. In an effort to help improve plant materials selection and to evaluate sites potential revegetation, we ha...

Much of the world’s airborne sediment originates from dryland regions. Soil surface disturbances in these regions are ever-increasing due to human activities such as energy and mineral exploration and development, recreation, suburbanization, livestock grazing and cropping. Sediment production can have significant impacts to human health with parti...

Deserts of North America are experiencing larger wildfires at shorter intervals. This increased fire frequency is attributed to increasing temperatures, droughts, and fuel buildup from non-native annual grasses Bromus rubens and Bromus tectorum. The transition from desert shrub land to annual grassland following fire may be mediated by small mammal...

Background and aims Drivers of ecosystem dynamics that are under human influence range from local, land-management decisions to global processes such as warming temperatures and N deposition. The goal of this study was to understand how multiple, potentially interacting factors influence net primary production, N mineralization, and water and soil...

Background and aims Plant nutrient uptake is affected by environmental stress, but how plants respond to cation-nutrient stress is poorly understood. We assessed the impact of varying degrees of cation-nutrient stress on cation uptake in an experimental plant-mineral system. Methods Column experiments, with red pine (Pinus resinosa Ait.) seedlings...

Managing, archiving, and sharing large amounts of data are essential tasks in ecological laboratories, and detailed data management plans are now required by major funding agencies. Many independent research labs may lack the technical or financial resources needed to support some of the more comprehensive data management solutions that have become...

Background/Question/Methods Fire and plant invasions are reshaping deserts and often interact by changing fire frequency, species diversity, timing of resource acquisitioning, and soil chemistry. One particularly important invasive plant species in deserts of North America is Halogeton glomeratus (halogeton). The USDA has classified halogeton as...

Background/Question/Methods Fire and plant invasions are reshaping deserts and often interact by changing fire frequency, species diversity, timing of resource acquisitioning, and soil chemistry. One particularly important invasive plant species in deserts of North America is Halogeton glomeratus (halogeton). The USDA has classified halogeton as a...

The increase of aeolian dust and eroding soils is a major concern in the desert southwest. Determining soil erodibility in the field requires a portable wind tunnel, which is often too labor-, time-, and cost- intensive to be practical for most land managers. Portable wind tun- nels can be used to estimate erodibility of a soil from total sediment...

In recent years enormous amounts of digital data have become available to scientific researchers. This flood of data is transforming the way scientific research is conducted. Independent researchers are in serious need of tools that will help them managed and preserve the large volumes of data being created in their own labs. Data management will n...

Grasslands are structured by climate and soils, and are increasingly affected by anthropogenic changes, including rising atmospheric CO2 concentrations. CO2 enrichment can alter grassland ecosystem function both directly and through indirect, soil-specific effects on moisture, nitrogen availability and plant species composition, potentially leading...

Background/Question/Methods There are many factors that influence N-cycling within an ecosystem. Within this wide range of influences, recent studies have reemphasized the variability of nitrogen availability at small temporal and spatial scales. Seasonal variation, including temperature and plant community composition, is an important driver in...

Background/Question/Methods Over the past two decades, over 800,000 hectares of Engelmann spruce (Picea engelmannii) in Utah’s high country have died with little evidence of regeneration. The direct cause of death is the mountain pine beetle, but the extent and magnitude of the die-off is likely amplified by climate change. Discussions on the phy...

Background/Question/Methods In alpine and subalpine ecosystems snow depth and the timing of snowmelt drive plant development and water, nitrogen, and carbon cycles. It has been shown that early snowmelt may delay plant development and alter population dynamics, decease runoff on the scale of large watersheds, and increase fire frequency and inten...

Background/Question/Methods Forecasts predict that precipitation regimes in the western US will become more variable, with dry periods becoming more frequent and with individual rainfall events becoming more extreme. In water-limited ecosystems, increased event size may reduce soil moisture stress and increase net primary production (NPP), N mine...

Background/Question/Methods As global climates warm, rainfall regimes are being altered with future climate scenarios forecasting extended periods of drought and increased frequency of extreme rainfall events. Rainfall change will influence soil moisture dynamics; alter patterns of resource availability and physiological stress on soil bacteria;...

The interaction between windblown sediment and fluvial losses of sediments into the washes and rivers on the Colorado Plateau is poorly understood. Sediment loss often occurs from human activities such as grazing and OHV use. Previous research has focused on the impacts of suspended dust particles, and as a consequence the effects of the mass movem...

The increase of aeolian dust and eroding soils is a major concern in the desert southwest. A key wind erosion parameter that indicates when soil particles begin to detach from the soil surface is threshold friction velocity (TFV). Determining TFV in the field requires a portable wind tunnel, which is often too labor-, time-, and cost- intensive to...

Forecasts predict that precipitation regimes in the western US will become more variable, with dry periods becoming more frequent and with individual rainfall events becoming more extreme. In water-limited ecosystems, increased event size may reduce soil moisture stress and increase net primary production (NPP), N mineralization (Nmin), and soil wa...

Recent studies report increasing dust deposition on mountain snowpack resulting from disturbance of desert soils, often linked to human activities. Dust on snow surfaces causes earlier snowmelt. The consequences of early snowmelt are both biological and biogeochemical. Biological consequences may be manifest in differences in the timing of phenolog...

Climate change is likely to cause nonlinear responses in ecosystem function and threshold changes in species composition. Here we report aboveground net primary productivity (ANPP) responses to a continuous CO2 concentration gradient (250 to 500 μL L-1,) in experimental grassland communities on three soils differing in water holding capacity and ot...

Continuous monitoring of canopy architecture and greenness is an economic challenge to researchers doing plot studies. Important questions could be answered by inexpensive but robust spectral sensors. We show here how light emitting diodes (LEDs) can be used as low-cost, narrow band spectral sensors. The wavelengths they sense are not exactly those...

Background/Question/Methods Rising atmospheric CO2 concentrations are expected to alter grassland ecosystem structure and function, and may have contributed to the current level of woody encroachment. But critical questions remain regarding 1) how much change in productivity or species composition may occur with near-future increases in CO2, comp...

Background/Question/Methods Literature suggests that as atmospheric CO2 rises, soil carbon will cycle more rapidly as plants input greater amounts of labile carbon into the soil. This labile carbon may stimulate the decomposition of more slowly-cycling soil organic matter through microbial priming. We test these hypotheses in a prairie exposed to...

Rising atmospheric CO2 concentrations can alter carbon and nutrient cycling and microbial processes in terrestrial ecosystems. One of the primary ways microbes interact with soil organic matter is through the production of extracellular enzymes, which break down complex organic molecules and release nutrients into the soil. We conducted a meta-anal...

Climate change has the potential to change the distribution of upper treeline in alpine systems. Two elements of climate change---rising low temperatures and changes in precipitation event size--are likely to influence the physiological ecology of treeline species. Rising low temperatures will influence plant carbon status, likely increasing respir...

Human activities have resulted in well-documented increases in atmospheric carbon dioxide concentration and mean annual temperature, with forecast future increases of between 1.1 and 6.4 oC. These increased temperatures will alter patterns of atmospheric circulation and influence hydrologic processes. For ecologists the challenge lies in the abilit...

The effect of low nutrient availability on plant-consumer interactions during early succession is poorly understood. The low productivity and complexity of primary successional communities are expected to limit diversity and abundance of arthropods, but few studies have examined arthropod responses to enhanced nutrient supply in this context. We in...

Background/Question/Methods Increasing atmospheric CO2 has been shown to significantly affect terrestrial ecosystems through increased primary production. This response is thought to be mitigated by changes to the soil microbial community, which can alter nutrient availability in these systems. In this study we examine the effects of a unique fie...

Background/Question/Methods Numerous studies have indicated that increases in atmospheric CO2 have the potential to decrease nitrogen availability through the process of progressive nitrogen limitation (PNL). The timing and magnitude of PNL in field experiments is varied due to numerous ecosystem processes. Here we examined the responsiveness of...

Background/Question/Methods Rising atmospheric CO2 will have direct effects on ecosystems in addition to consequences for climate. We investigated belowground response of a prairie ecosystem to a preindustrial-to-future (250-500ppm) gradient of CO2. Three soil types are represented throughout the gradient, allowing us to ask how soil type influen...

Background/Question/Methods It is widely recognized that average global temperatures have risen significantly within the past century, and more sharply within the past decade. A unique element of rising temperatures that confirms the role of greenhouse gasses is that the average difference between day and night temperatures has become smaller. Si...

Background/Question/Methods The National Research Council has identified active learning as a priority for improving science literacy, while most introductory science courses tend to be taught as large lecture courses that often reinforce students' passive attitudes toward learning. Active learning increases information retention, critical thinki...

Since the days of the IBP, there has been a strong emphasis on research about the biogeochemistry of shortgrass steppe ecosystems (e.g., Clark, 1977; Woodmansee, 1978). A major theme has been seeking to understand spatial and temporal patterns and controls of biogeochemical pools and fluxes at scales that span from several centimeters to hundreds o...

Vascular plants and associated microbial communities affect the nutrient resources of terrestrial ecosystems by impacting chemical weathering that transfers elements from primary minerals to other ecosystem pools, and chemical denudation that transports weathered elements out of the system in solution. We performed a year-long replicated flow-throu...

Measuring and monitoring field-scale hydrology is important to understanding the fate of water in the vadoze zone, especially in concert with pedological information. Historically, single point measurements of hydrologic and pedological information have been straightforward to obtain, while monitoring widely distributed locations over time has been...

Human communities in the Intermountain West depend heavily on subalpine rangelands because of their importance in providing water for irrigation and forage for wildlife and livestock. In addition, many constituencies are looking to managed ecosystems to sequester carbon in plant biomass and soil C to reduce the impact of anthropogenic CO2 on climat...

Vascular plants and associated microbial communities produced biofilm coatings increase weathering by extending contact periods of minerals with low pH liquids. We performed an experiment to isolate the effects of ectomycorrhiza-forming fungi and ectomycorrhiza- helper bacteria on chemical weathering and chemical denudation (i.e. chemical erosion),...

Wetlands are dynamic habitats with many unique, important functions including filtering sediments and providing diverse habitats for fish and wildlife. Wetlands in the western United States are particularly important because they offer habitat for a number of protected runs of endangered fish species. Historically, livestock grazing has altered wet...

In the two decades following the 1980 eruption of Mount St. Helens in Washington State, the N2-fixing colonizer Lupinus lepidus is associated with striking heterogeneity in plant community and soil development. We report on differences in nutrient availability and plant tissue chemistry between older, dense patches (core) of L. lepidus and more rec...

The interaction between nitrogen cycling and carbon sequestration is critical in predicting the consequences of anthropogenic increases in atmospheric CO2 (hereafter, Ca). The progressive N limitation (PNL) theory predicts that carbon sequestration in plants and soils with rising Ca may be constrained by the availability of nitrogen in many ecosyst...

The species–time relationship (STR) describes how the species richness of a community increases with the time span over which the community is observed. This pattern has numerous implications for both theory and conservation in much the same way as the species–area relationship (SAR). However, the STR has received much less attention and to date on...

The mountain lands of the intermountain west are vital to the wellbeing of human communities in the adjacent valleys, providing these communities with water, important summer forage for wildlife and domestic livestock, and possibly the sequestration of anthropogenic carbon. In this work, I build on a 90-year old grazing experiment in mountain meado...

AimUse a regression model that relates climatic variables to the relative abundances of shrubs, C4 and C3 grasses to project the plant functional type composition of temperate grasslands and shrublands within North and South America in response to climate change.LocationThe temperate zone grassland and shrubland regions of North and South America.M...

Carbon sequestration in soil organic matter may moderate increases in atmospheric CO(2) concentrations (C(a)) as C(a) increases to more than 500 micromol mol(-1) this century from interglacial levels of less than 200 micromol mol(-1) (refs 1 6). However, such carbon storage depends on feedbacks between plant responses to C(a) and nutrient availabil...

We used minirhizotrons to determine patterns of root longevity andturnover for the perennial bunchgrass Bouteloua gracilisinthe shortgrass steppe of eastern Colorado, USA. We hypothesized that rootlongevity would be partially controlled by root diameter, following previouslyobserved patterns in woody plants. In addition, we hypothesized that roottu...

In many temperate and annual grasslands, above-ground net primary productivity (NPP) can be estimated by measuring peak above-ground biomass. Estimates of below-ground net primary productivity and, consequently, total net primary productivity, are more difficult. We addressed one of the three main objectives of the Global Primary Productivity Data...

The distribution and turnover of plant litter contribute to soil structure, the availability of plant nutrients, and regional budgets of greenhouse gasses. Traditionally, studies of decomposition have focused on the upper soil profile. Other work has shown that temperature, precipitation, and soil texture are important determinates of patterns of d...

In many temperate and annual grasslands, above-ground net primary productivity (NPP) can be estimated by measuring peak above-ground biomass. Estimates of below-ground net primary productivity and, consequently, total net primary productivity, are more difficult. We addressed one of the three main objectives of the Global Primary Productivity Data...

Root turnover is a critical component of ecosystem nutrient dynamics and carbon sequestration and is also an important sink for plant primary productivity. We tested global controls on root turnover across climatic gradients and for plant functional groups by using a database of 190 published studies. Root turnover rates increased exponentially wit...