Akasha M. Faist

Banking on the past: seed banks as a reservoir for rare and native species in restored vernal pools

We found the belowground community in the soil seed bank of restored vernal pools has been less invaded by exotic plants and is a reservoir for rare and native plant species. We also found that seed bank community structure most closely resembled the aboveground community structure from five to eight years prior to seed bank sampling rather than more recent years. The maintenance of rare and native plant species in soil seed banks, even as aboveground vegetation communities become invaded by exotic plants is an exciting finding with important implications for management and restoration efforts in annual plant communities.

Biocrusts enhance soil fertility and Bromus tectorum growth, and interact with warming to influence germination

Background and aimsBiocrusts are communities of cyanobacteria, mosses, and/or lichens found in drylands worldwide. Biocrusts are proposed to enhance soil fertility and productivity, but simultaneously act as a barrier to the invasive grass, Bromus tectorum, in western North America. Both biocrusts and B. tectorum are sensitive to climate change drivers, yet how their responses might interact to affect dryland ecosystems is unclear.MethodsUsing mesocosms with bare soil versus biocrust cover, we germinated B. tectorum seeds collected from warmed, warmed + watered, and ambient temperature plots within a long-term climate change experiment on the Colorado Plateau, USA. We characterized biocrust influences on soil fertility and grass germination, morphology, and chemistry.ResultsBiocrusts increased soil fertility and B. tectorum biomass, specific leaf area (SLA), and root:shoot ratios. Germination rates were unaffected by mesocosm cover-type. Biocrusts delayed germination timing while also interacting with the warmed treatment to advance, and with the warmed + watered treatment to delay germination.ConclusionsBiocrusts promoted B. tectorum growth, likely through positive influence on soil fertility which was elevated in biocrust mesocosms, and interacted with seed treatment-provenance to affect germination. Understanding how anticipated losses of biocrusts will affect invasion dynamics will require further investigation of how plant plasticity/adaptation to specific climate drivers interact with soil and biocrust properties.

Understory Plant Community Responses to Fuel-Reduction Treatments and Seeding in an Upland Piñon-Juniper Woodland ☆

ABSTRACT Woody plant expansion and infilling into nonwooded rangeland ecosystems have been observed worldwide. Such expansion may lead to declines in herbaceous understory plant communities and increased fuel loads in rangelands. Under the US National Fire Plan, fuel-reduction treatments have been implemented over vast expanses of western forest types to reduce the risk of catastrophic wildfire and restore historical ecosystem structure, function, and diversity. The benefits of fuel-reduction may, however, also carry inherent ecological risk such as promoting non-native species colonization. Here, we compare understory plant community responses to three commonly used fuel-reduction treatments with seeding applications in an upland piñon (Pinus edulis Engelm.)— juniper (Juniperus osteosperma [Torr.] Little) woodland on the Colorado Plateau: 1) mechanical mastication, 2) lop and slash piled then burned (pile burn), and 3) lop and scatter followed by a broadcast burn (broadcast burn). Data were collected pretreatment (2009) and one (2010), two (2011), and six (2015) growing seasons post treatment. We found while understory perennial herbaceous plant cover remained low 1 and 2 yr post treatment, it increased by > 700% in all fuel-reduction treatment plots six growing seasons post treatment. Furthermore, while we observed minor increases in invasive annual grass, Bromus tectorum L. (cheatgrass), colonization in 2010 and 2011, there were substantial increases in B. tectorum cover by 2015. B. tectorum cover varied among treatments with the greatest cover in the unseeded mastication plot at nearly 30%. Seeding applications did not increase overall seed mix species cover but enhanced seed mix species richness and, thus, may have increased resistance to B. tectorum invasion in seeded treatment plots. Our findings offer valuable insights to the ecological consequences of fuel-reduction activities in piñon-juniper woodlands through comparison of common fuel-reduction treatments and seeding applications and highlight differences in understory plant community responses to treatments across short to longer time scales.

Seed bank composition varies along invasion and inundation gradients in vernal pool wetlands

Environmental filters are well-known influences on aboveground vegetation community structure; however, less is known about their role on belowground seed banks. Understanding the influence of environmental filters on the composition of seed banks can reveal community dynamics across known environmental gradients and facilitate restoration efforts. We examined the influence of environmental filters on seed banks of vernal pools by characterizing seed density and diversity along seasonal inundation gradients. We also sampled seed banks from both naturally occurring and restored vernal pools that differed in their aboveground communities (invasive or native species dominated) in a long-term field study in Solano Co., California, USA. We found that the highest seed densities were associated with the longest inundation period and in the naturally occurring pools. Inundation gradients within a pool had little influence on seed bank diversity, yet among the pool types diversity and community metrics varied. The naturally occurring pools, regardless of invasion status, displayed a greater species richness and diversity than constructed pools. Our greenhouse germination trials did not show a strong relationship of inundation depths influencing species and total germination. Overall, we found that local position in the field along inundation gradients within a pool strongly affected soil seed bank density, while seed bank diversity varied more across pool types. Environmental filters may be limiting germination with the pool bottoms having the highest inundation and maintain the densest seed bank, but our lack of difference in the germination trials suggests alternative mechanisms other than inundation may be hindering germination.

Aboveground and belowground arthropods experience different relative influences of stochastic versus deterministic community assembly processes following disturbance

Background Understanding patterns of biodiversity is a longstanding challenge in ecology. Similar to other biotic groups, arthropod community structure can be shaped by deterministic and stochastic processes, with limited understanding of what moderates the relative influence of these processes. Disturbances have been noted to alter the relative influence of deterministic and stochastic processes on community assembly in various study systems, implicating ecological disturbances as a potential moderator of these forces. Methods Using a disturbance gradient along a 5-year chronosequence of insect-induced tree mortality in a subalpine forest of the southern Rocky Mountains, Colorado, USA, we examined changes in community structure and relative influences of deterministic and stochastic processes in the assembly of aboveground (surface and litter-active species) and belowground (species active in organic and mineral soil layers) arthropod communities. Arthropods were sampled for all years of the chronosequence via pitfall traps (aboveground community) and modified Winkler funnels (belowground community) and sorted to morphospecies. Community structure of both communities were assessed via comparisons of morphospecies abundance, diversity, and composition. Assembly processes were inferred from a mixture of linear models and matrix correlations testing for community associations with environmental properties, and from null-deviation models comparing observed vs. expected levels of species turnover (Beta diversity) among samples. Results Tree mortality altered community structure in both aboveground and belowground arthropod communities, but null models suggested that aboveground communities experienced greater relative influences of deterministic processes, while the relative influence of stochastic processes increased for belowground communities. Additionally, Mantel tests and linear regression models revealed significant associations between the aboveground arthropod communities and vegetation and soil properties, but no significant association among belowground arthropod communities and environmental factors. Discussion Our results suggest context-dependent influences of stochastic and deterministic community assembly processes across different fractions of a spatially co-occurring ground-dwelling arthropod community following disturbance. This variation in assembly may be linked to contrasting ecological strategies and dispersal rates within above- and below-ground communities. Our findings add to a growing body of evidence indicating concurrent influences of stochastic and deterministic processes in community assembly, and highlight the need to consider potential variation across different fractions of biotic communities when testing community ecology theory and considering conservation strategies.

Transforming mentorship in STEM by training scientists to be better leaders

Abstract Effective mentoring is a key component of academic and career success that contributes to overall measures of productivity. Mentoring relationships also play an important role in mental health and in recruiting and retaining students from groups underrepresented in STEM fields. Despite these clear and measurable benefits, faculty generally do not receive mentorship training, and feedback mechanisms and assessment to improve mentoring in academia are limited. Ineffective mentoring can negatively impact students, faculty, departments, and institutions via decreased productivity, increased stress, and the loss of valuable research products and talented personnel. Thus, there are clear incentives to invest in and implement formal training to improve mentorship in STEM fields. Here, we outline the unique challenges of mentoring in academia and present results from a survey of STEM scientists that support both the need and desire for more formal mentorship training. Using survey results and the primary literature, we identify common behaviors of effective mentors and outline a set of mentorship best practices. We argue that these best practices, as well as the key qualities of flexibility, communication, and trust, are skills that can be taught to prospective and current faculty. We present a model and resources for mentorship training based on our research, which we successfully implemented at the University of Colorado, Boulder, with graduate students and postdocs. We conclude that such training is an important and cost‐effective step toward improving mentorship in STEM fields.

Maintenance of Pollinator Function in Restored Vernal Pools: Gnats Filling the Role of Solitary Bees

The role of plant-pollinator interactions in influencing the success of ecological restoration projects is important and often overlooked. In our study, we examined floral visitation in an endangered vernal pool plant species, Contra Costa Goldfields (Lasthenia conjugens; Asteraceae). We observed Goldfields abundance and floral visitation in the early and late stages of an ecological vernal pool restoration project located in the Central Valley of California. After an initially high abundance at our study site in the early stages of restoration, we noted a sharp decline of this endangered species ten years later. Our floral visitor observations demonstrated that the abundance of gnats (Sciaridae) was high in the restored pools across the ten years, but was very low to nonexistent in the nearby naturally occurring pools. Solitary bee abundance was the inverse of that observed for gnats, with a very low instance of solitary bee pollinators in the restored pools, yet a higher abundance in the naturally occurring pools. With this difference in floral visitors between pool types, we found significantly more mature potentially viable seeds in the restored pools, but a general overall decline over the three observation years. The higher number of mature, potentially viable seeds in the restored pools leads us to believe that the gnats are filling the role of the solitary bees and have maintained this function over the duration of the ten-year observation period. We conclude that gnats may be acting as surrogate pollinators for Goldfields in restored pools.

Advocating for Science Writing Cooperatives in Graduate Programs

Pressure to publish “early and often” and secure grant money for research is an immediate and urgent goal upon entering a graduate program. How we respond to these pressures and our ability to meet such expectations determines our future success as scientists. As graduate students we feel that the pressure to produce high-quality science writing is not matched with the training necessary to succeed as a professional writer. Acknowledging this discrepancy between training and expectations, we formed a peer writing group for developing science writing skills. This experience so profoundly altered our approach to writing that we feel similar groups would be beneficial for every graduate student. Here, we suggest a solution for fostering superior student writing in graduate programs with minimal time investment by establishing science writing cooperatives.