You are welcome here: A practical guide to diversity, equity, and inclusion for undergraduates embarking on an ecological research experience

As we build a more diverse, equitable, and inclusive culture in the ecological research community, we must work to support new ecologists by empowering them with the knowledge, tools, validation, and sense of belonging in ecology to succeed. Undergraduate research experiences (UREs) are critical for a student's professional and interpersonal skill development and key for recruiting and retaining students from diverse groups to ecology. However, few resources exist that speak directly to an undergraduate researcher on the diversity, equity, and inclusion (DEI) dimensions of embarking on a first research experience. Here, we write primarily for undergraduate readers, though a broader audience of readers, especially URE mentors, will also find this useful. We explain many of the ways a URE benefits undergraduate researchers and describe how URE students from different positionalities can contribute to an inclusive research culture. We address three common sources of anxiety for URE students through a DEI lens: imposter syndrome, communicating with mentors, and safety in fieldwork. We discuss the benefits as well as the unique vulnerabilities and risks associated with fieldwork, including the potential for harassment and assault. Imposter syndrome and toxic field experiences are known to drive students, including students from underrepresented minority groups, out of STEM. Our goal is to encourage all students, including those from underrepresented groups, to apply for UREs, build awareness of their contributions to inclusion in ecology research, and provide strategies for overcoming known barriers.

Mentorship, equity, and research productivity: lessons from a pandemic

The coronavirus pandemic is more fully exposing ubiquitous economic and social inequities that pervade conservation science. In this time of prolonged stress on members of the research community, primary investigators or project leaders (PLs) have a unique opportunity to adapt their programs to jointly create more equitable and productive research environments for their teams. Institutional guidance for PLs pursuing field and laboratory work centers on the physical safety of individuals while in the lab or field, but largely ignores the vast differences in how team members may be experiencing the pandemic. Strains on mental, physical, and emotional health; racial trauma; familial responsibilities; and compulsory productivity resources, such as high-speed internet, quiet work spaces, and support are unequally distributed across team members. The goal of this paper is to summarize the shifting dynamics of leadership and mentorship during the coronavirus pandemic and highlight opportunities for increasing equity in conservation research at the scale of the project team. Here, we (1) describe how the pandemic differentially manifests inequity on project teams, particularly for groups that have been structurally excluded from conservation science, (2) consider equitable career advancement during the coronavirus pandemic, and (3) offer suggestions for PLs to provide mentorship that prioritizes equity and wellbeing during and beyond the pandemic. We aim to support PLs who have power and flexibility in how they manage research, teaching, mentoring, consulting, outreach, and extension activities so that individual team members' needs are met with compassion and attention to equity.

The greenhouse gas cost of agricultural intensification with groundwater irrigation in a Midwest U.S. row cropping system

Groundwater irrigation of cropland is expanding worldwide with poorly known implications for climate change. This study compares experimental measurements of the net global warming impact of a rainfed versus a groundwater-irrigated corn (maize)-soybean-wheat, no-till cropping system in the Midwest US, the region that produces the majority of U.S. corn and soybean. Irrigation significantly increased soil organic carbon (C) storage in the upper 25 cm, but not by enough to make up for the CO₂ -equivalent (CO₂ e) costs of fossil fuel power, soil emissions of nitrous oxide (N₂ O), and degassing of supersaturated CO₂ and N₂ O from the groundwater. A rainfed reference system had a net mitigating effect of -13.9 (±31) g CO₂ e m^-2  year^-1 , but with irrigation at an average rate for the region, the irrigated system contributed to global warming with net greenhouse gas (GHG) emissions of 27.1 (±32) g CO₂ e m^-2  year^-1 . Compared to the rainfed system, the irrigated system had 45% more GHG emissions and 7% more C sequestration. The irrigation-associated increase in soil N₂ O and fossil fuel emissions contributed 18% and 9%, respectively, to the system's total emissions in an average irrigation year. Groundwater degassing of CO₂ and N₂ O are missing components of previous assessments of the GHG cost of groundwater irrigation; together they were 4% of the irrigated system's total emissions. The irrigated system's net impact normalized by crop yield (GHG intensity) was +0.04 (±0.006) kg CO₂ e kg^-1 yield, close to that of the rainfed system, which was -0.03 (±0.002) kg CO₂ e kg^-1 yield. Thus, the increased crop yield resulting from irrigation can ameliorate overall GHG emissions if intensification by irrigation prevents land conversion emissions elsewhere, although the expansion of irrigation risks depletion of local water resources.

Low concentrations of silver nanoparticles in biosolids cause adverse ecosystem responses under realistic field scenario

A large fraction of engineered nanomaterials in consumer and commercial products will reach natural ecosystems. To date, research on the biological impacts of environmental nanomaterial exposures has largely focused on high-concentration exposures in mechanistic lab studies with single strains of model organisms. These results are difficult to extrapolate to ecosystems, where exposures will likely be at low-concentrations and which are inhabited by a diversity of organisms. Here we show adverse responses of plants and microorganisms in a replicated long-term terrestrial mesocosm field experiment following a single low dose of silver nanoparticles (0.14 mg Ag kg⁻¹ soil) applied via a likely route of exposure, sewage biosolid application. While total aboveground plant biomass did not differ between treatments receiving biosolids, one plant species, Microstegium vimeneum, had 32 % less biomass in the Slurry+AgNP treatment relative to the Slurry only treatment. Microorganisms were also affected by AgNP treatment, which gave a significantly different community composition of bacteria in the Slurry+AgNPs as opposed to the Slurry treatment one day after addition as analyzed by T-RFLP analysis of 16S-rRNA genes. After eight days, N₂O flux was 4.5 fold higher in the Slurry+AgNPs treatment than the Slurry treatment. After fifty days, community composition and N₂O flux of the Slurry+AgNPs treatment converged with the Slurry. However, the soil microbial extracellular enzymes leucine amino peptidase and phosphatase had 52 and 27% lower activities, respectively, while microbial biomass was 35% lower than the Slurry. We also show that the magnitude of these responses was in all cases as large as or larger than the positive control, AgNO₃, added at 4-fold the Ag concentration of the silver nanoparticles.

Effects of silver nanoparticle exposure on germination and early growth of eleven wetland plants

The increasing commercial production of engineered nanoparticles (ENPs) has led to concerns over the potential adverse impacts of these ENPs on biota in natural environments. Silver nanoparticles (AgNPs) are one of the most widely used ENPs and are expected to enter natural ecosystems. Here we examined the effects of AgNPs on germination and growth of eleven species of common wetland plants. We examined plant responses to AgNP exposure in simple pure culture experiments (direct exposure) and for seeds planted in homogenized field soils in a greenhouse experiment (soil exposure). We compared the effects of two AgNPs–20-nm polyvinylpyrrolidine-coated silver nanoparticles (PVP-AgNPs) and 6-nm gum arabic coated silver nanoparticles (GA-AgNPs)–to the effects of AgNO₃ exposure added at equivalent Ag concentrations (1, 10 or 40 mg Ag L⁻¹). In the direct exposure experiments, PVP-AgNP had no effect on germination while 40 mg Ag L⁻¹ GA-AgNP exposure significantly reduced the germination rate of three species and enhanced the germination rate of one species. In contrast, 40 mg Ag L⁻¹ AgNO₃ enhanced the germination rate of five species. In general root growth was much more affected by Ag exposure than was leaf growth. The magnitude of inhibition was always greater for GA-AgNPs than for AgNO₃ and PVP-AgNPs. In the soil exposure experiment, germination effects were less pronounced. The plant growth response differed by taxa with Lolium multiflorum growing more rapidly under both AgNO₃ and GA-AgNP exposures and all other taxa having significantly reduced growth under GA-AgNP exposure. AgNO₃ did not reduce the growth of any species while PVP-AgNPs significantly inhibited the growth of only one species. Our findings suggest important new avenues of research for understanding the fate and transport of NPs in natural media, the interactions between NPs and plants, and indirect and direct effects of NPs in mixed plant communities.

Environmental conditions influence the plant functional diversity effect on potential denitrification

Global biodiversity loss has prompted research on the relationship between species diversity and ecosystem functioning. Few studies have examined how plant diversity impacts belowground processes; even fewer have examined how varying resource levels can influence the effect of plant diversity on microbial activity. In a field experiment in a restored wetland, we examined the role of plant trait diversity (or functional diversity, (FD)) and its interactions with natural levels of variability of soil properties, on a microbial process, denitrification potential (DNP). We demonstrated that FD significantly affected microbial DNP through its interactions with soil conditions; increasing FD led to increased DNP but mainly at higher levels of soil resources. Our results suggest that the effect of species diversity on ecosystem functioning may depend on environmental factors such as resource availability. Future biodiversity experiments should examine how natural levels of environmental variability impact the importance of biodiversity to ecosystem functioning.

Plant trait diversity buffers variability in denitrification potential over changes in season and soil conditions

BACKGROUND

Denitrification is an important ecosystem service that removes nitrogen (N) from N-polluted watersheds, buffering soil, stream, and river water quality from excess N by returning N to the atmosphere before it reaches lakes or oceans and leads to eutrophication. The denitrification enzyme activity (DEA) assay is widely used for measuring denitrification potential. Because DEA is a function of enzyme levels in soils, most ecologists studying denitrification have assumed that DEA is less sensitive to ambient levels of nitrate (NO(3)(-)) and soil carbon and thus, less variable over time than field measurements. In addition, plant diversity has been shown to have strong effects on microbial communities and belowground processes and could potentially alter the functional capacity of denitrifiers. Here, we examined three questions: (1) Does DEA vary through the growing season? (2) If so, can we predict DEA variability with environmental variables? (3) Does plant functional diversity affect DEA variability?

METHODOLOGY/PRINCIPAL FINDINGS

The study site is a restored wetland in North Carolina, US with native wetland herbs planted in monocultures or mixes of four or eight species. We found that denitrification potentials for soils collected in July 2006 were significantly greater than for soils collected in May and late August 2006 (p<0.0001). Similarly, microbial biomass standardized DEA rates were significantly greater in July than May and August (p<0.0001). Of the soil variables measured--soil moisture, organic matter, total inorganic nitrogen, and microbial biomass--none consistently explained the pattern observed in DEA through time. There was no significant relationship between DEA and plant species richness or functional diversity. However, the seasonal variance in microbial biomass standardized DEA rates was significantly inversely related to plant species functional diversity (p<0.01).

CONCLUSIONS/SIGNIFICANCE

These findings suggest that higher plant functional diversity may support a more constant level of DEA through time, buffering the ecosystem from changes in season and soil conditions.