University of California Natural Reserve System

Abstract Ectotherm thermal physiology is frequently used to predict species responses to changing climates, but for amphibians, water loss may be of equal or greater importance. Using physical models, we estimated the frequency of exceeding the thermal optimum ( T opt ) or critical evaporative water loss (EWL crit ) limits, with and without shade‐ or water‐seeking behaviours. Under current climatic conditions (2002–2012), we predict that harmful thermal (> T opt ) and hydric (>EWL crit ) conditions limit the activity of amphibians during ~70% of snow‐free days in sunny habitats. By the 2080s, we estimate that sunny and dry habitats will exceed one or both of these physiological limits during 95% of snow‐free days. Counterintuitively, we find that while wet environments eliminate the risk of critical EWL, they do not reduce the risk of exceeding T opt (+2% higher). Similarly, while shaded dry environments lower the risk of exceeding T opt , critical EWL limits are still exceeded during 63% of snow‐free days. Thus, no single environment that we evaluated can simultaneously reduce both physiological risks. When we forecast both temperature and EWL into the 2080s, both physiological thresholds are exceeded in all habitats during 48% of snow‐free days, suggesting that there may be limited opportunity for behaviour to ameliorate climate change. We conclude that temperature and water loss act synergistically, compounding the ecophysiological risk posed by climate change, as the combined effects are more severe than those predicted individually. Our results suggest that predictions of physiological risk posed by climate change that do not account for water loss in amphibians may be severely underestimated and that there may be limited scope for facultative behaviours to mediate rapidly changing environments.

Summary Analogous to the spread of non‐native species, shifts in native species’ ranges resulting from climate and land use change are also creating new combinations of species in many ecosystems. These native range shifts may be facilitated by similar mechanisms that provide advantages for non‐native species and may also have comparable impacts on the ecosystems they invade. Soil biota, in particular bacteria and fungi, are important regulators of plant community composition and below‐ground ecosystem function. Compared to non‐native plant invasions, there have been relatively few studies examining how soil biota influence – or are influenced by – native species range shifts. Here, we examined how a native range‐expanding sagebrush species ( Artemisia rothrockii ) affects below‐ground abiotic conditions and microbial community structure and function using next‐generation sequencing coupled with other biotic and abiotic soil analyses. We utilized a range‐expansion gradient , together with a shrub removal experiment and structural equation models, to determine the direct and indirect drivers of these interconnected processes. Sagebrush colonization increased bacterial and archaeal richness and diversity and altered community composition across the expansion gradient. Soil organic C and N and soil moisture increased with sagebrush presence; however, results varied across the expansion gradient. We found no relationship between sagebrush and soil pH ; however, pH strongly influenced microbial richness and diversity. Microbial (substrate‐induced) respiration was influenced by soil organic N, as well as microbial diversity and functional group relative abundances, highlighting direct and indirect effects of sagebrush on microbial community structure and function. Microbial community composition of soils after 4 years of sagebrush removal was more similar to communities in shrub interspaces than underneath shrubs, suggesting microbial community resilience. Synthesis . Our results suggest that native range expansions can have important impacts on soil biological communities, soil chemistry and hydrology which can further impact below‐ground ecosystem processes such as nutrient cycling and litter decomposition. The combination of high‐throughput sequencing and structural equation modelling used here offers an exciting yet underutilized approach to understanding how both native and non‐native species’ range expansions may affect the structure and function of soil ecosystems.

Motorized UAS were introduced as a potential remote sensing tool for scientific research in the late 1970s. However, due to a variety of limitations (the weight and limited functionality of available sensors and cameras, the lack of GPS-guided autopilots and so on) these platforms had few practical applications (Przybilla and Wester-Ebbinghaus 1979; Wester-Ebbinghaus 1980; cited by Colomina and Molina 2014). For years, UAS technology was led by military needs and applications. The relatively few applications in research and agriculture included deployments in Japan for crop dusting and in Australia for meteorological studies (Colomina and Molina 2014).

Global change is impacting plant community composition, but the mechanisms underlying these changes are unclear. Using a dataset of 58 global change experiments, we tested the five fundamental mechanisms of community change: changes in evenness and richness, reordering, species gains and losses. We found 71% of communities were impacted by global change treatments, and 88% of communities that were exposed to two or more global change drivers were impacted. Further, all mechanisms of change were equally likely to be affected by global change treatments-species losses and changes in richness were just as common as species gains and reordering. We also found no evidence of a progression of community changes, for example, reordering and changes in evenness did not precede species gains and losses. We demonstrate that all processes underlying plant community composition changes are equally affected by treatments and often occur simultaneously, necessitating a wholistic approach to quantifying community changes.

Abstract As climate change continues to increase air temperature in high‐altitude ecosystems, it has become critical to understand the controls and scales of aquatic habitat vulnerability to warming. Here, we used a nested array of high‐frequency sensors, and advances in time‐series models, to examine spatiotemporal variation in thermal vulnerability in a model Sierra Nevada watershed. Stream thermal sensitivity to atmospheric warming fluctuated strongly over the year and peaked in spring and summer—when hot days threaten invertebrate communities most. The reach scale (~ 50 m) best captured variation in summer thermal regimes. Elevation, discharge, and conductivity were important correlates of summer water temperature across reaches, but upstream water temperature was the paramount driver—supporting that cascading warming occurs downstream in the network. Finally, we used our estimated summer thermal sensitivity and downscaled projections of summer air temperature to forecast end‐of‐the‐century stream warming, when extreme drought years like 2020–2021 become the norm. We found that 25.5% of cold‐water habitat may be lost under high‐emissions scenario representative concentration pathway (RCP) 8.5 (or 7.9% under mitigated RCP 4.5). This estimated reduction suggests that 27.2% of stream macroinvertebrate biodiversity (11.9% under the mitigated scenario) will be stressed or threatened in what was previously cold‐water habitat. Our quantitative approach is transferrable to other watersheds with spatially replicated time series and illustrates the importance of considering variation in the vulnerability of mountain streams to warming over both space and time. This approach may inform watershed conservation efforts by helping identify, and potentially mitigate, sites and time windows of peak vulnerability.

Behavior can strongly influence rates and patterns of hybridization between animal populations and species. Yet few studies have examined reproductive behaviors in natural hybrid zones within the fine-scale social context in which they naturally occur. We use radio-frequency identification tags with social network analyses to test whether phenotypic similarity in plumage and mass correlate with social behavior throughout a breeding season in a California and Gambel's quail hybrid zone. We use a novel approach to partition phenotypic variation in a way that does not confound differences between sexes and species, and we illustrate the complex ways that phenotype and behavior structure the social environment, mating opportunities, and male-male associations. Associations within the admixed population were random with respect to species-specific plumage but showed strong patterns of assortment based on sexually dimorphic plumage, monomorphic plumage, and mass. Weak behavioral reproductive isolation in this admixed population may be the result of complex patterns of phenotypic assortment based on multiple traits rather than a lack of phenotypic discrimination. More generally, our results support the utility of social network analyses for analyzing behavioral factors affecting genetic exchange between populations and species.

Abstract How aquatic primary productivity influences the carbon (C) sequestering capacity of wetlands is uncertain. We evaluated the magnitude and variability in aquatic C dynamics and compared them to net ecosystem CO 2 exchange (NEE) and ecosystem respiration ( R eco ) rates within calcareous freshwater wetlands in Everglades National Park. We continuously recorded 30-min measurements of dissolved oxygen (DO), water level, water temperature ( T water ), and photosynthetically active radiation (PAR). These measurements were coupled with ecosystem CO 2 fluxes over 5 years (2012–2016) in a long-hydroperiod peat-rich, freshwater marsh and a short-hydroperiod, freshwater marl prairie. Daily net aquatic primary productivity (NAPP) rates indicated both wetlands were generally net heterotrophic. Gross aquatic primary productivity (GAPP) ranged from 0 to − 6.3 g C m −2 day −1 and aquatic respiration ( R Aq ) from 0 to 6.13 g C m −2 day −1 . Nonlinear interactions between water level, T water , and GAPP and R Aq resulted in high variability in NAPP that contributed to NEE. Net aquatic primary productivity accounted for 4–5% of the deviance explained in NEE rates. With respect to the flux magnitude, daily NAPP was a greater proportion of daily NEE at the long-hydroperiod site (mean = 95%) compared to the short-hydroperiod site (mean = 64%). Although we have confirmed the significant contribution of NAPP to NEE in both long- and short-hydroperiod freshwater wetlands, the decoupling of the aquatic and ecosystem fluxes could largely depend on emergent vegetation, the carbonate cycle, and the lateral C flux.

Saline lakes worldwide are undergoing drying, and as lake levels fall and areas contract, salinities increase. There is a critical need for data on salinity impacts to guide conservation for recovery of the aquatic productivity that supports migratory and breeding birds that depend on these habitats. Brine flies are key sources of food to these birds and are adapted for life in saline waters owing to their capacity for osmotic regulation. The sublethal effects on growth, development and reproduction were determined in experiments and field observations with the alkali fly Cirrula hians from alkaline lakes of differing salinity. The cost of osmoregulation to fitness from rising salinity was exhibited in slower growth rates of larvae, smaller size at maturity of pupae, reduced adult emergence success, and lower fecundity. The results identify a salinity management range of 25 to 100 g L −1 that would optimize life history traits and productivity of this insect as a food source for birds.

Mating behaviour and the timing of reproduction can inhibit genetic exchange between closely related species; however, these reproductive barriers are challenging to measure within natural populations. Social network analysis provides promising tools for studying the social context of hybridization, and the exchange of genetic variation, more generally. We test how social networks within a hybrid population of California Callipepla californica and Gambel's quail Callipepla gambelii change over discrete periods of a breeding season. We assess patterns of phenotypic and genotypic assortment, and ask whether altered associations between individuals (association rewiring), or changes to the composition of the population (individual turnover) drive network dynamics. We use genetic data to test whether social associations and relatedness between individuals correlate with patterns of parentage within the hybrid population. To achieve these aims, we combine RFID association data, phenotypic data and genomic measures with social network analyses. We adopt methods from the ecological network literature to quantify shifts in network structure and to partition changes into those due to individual turnover and association rewiring. We integrate genomic data into networks as node-level attributes (ancestry) and edges (relatedness, parentage) to test links between social and parentage networks. We show that rewiring of associations between individuals that persist across network periods, rather than individual turnover, drives the majority of the changes in network structure throughout the breeding season, and that the traits involved in phenotypic/genotypic assortment were highly dynamic over time. Social networks were randomly assorted based on genetic ancestry, suggesting weak behavioural reproductive isolation within this hybrid population. Finally, we show that the strength of associations within the social network, but not levels of genetic relatedness, predicts patterns of parentage. Social networks play an important role in population processes such as the transmission of disease and information, yet there has been less focus on how networks influence the exchange of genetic variation. By integrating analyses of social structure, phenotypic assortment and reproductive outcomes within a hybrid zone, we demonstrate the utility of social networks for analysing links between social context and gene flow within wild populations.

Long-term field studies of relatively long-lived lizards can reveal environmental influences and ontogenetic responses over the lifetime of an individual that would not be apparent in data from short-term field studies. Hence, we initiated a long-term (31-yr) study of a population of the Coachella Fringe-Toed Lizard, Uma inornata, to determine demographic (sex, size/age, population density) and environmental (rainfall) influences on HR size of individuals. Mark-and-recapture data and observations on marked individuals provided sufficient sightings to estimate HR size using minimum convex polygons for 45 males and 40 females varying from age 0 (birth year) to age 5. Home range size was positively correlated with age and body size and was nonlinearly correlated with individual growth. Males grew faster and attained larger body size than did females and had larger HRs than did females of similar age. However, the mean body size–adjusted HR size for adult U. inornata did not differ significantly by sex. Home range size was inversely related to density in males but showed no relationship to density in females. There was a significant inverse relationship between HR size and winter rainfall preceding a field season. Within individuals, HRs shifted geographically and increased in size over sequential years as individuals grew. The location of an HR's centroid shifted between 4 and 62 m between years (mean 28 m for males, 15 m for females). Hence, combining HR data from multiple years will overestimate the actual spatial usage of an individual during any single year.

Abstract Pain and inflammation contribute immeasurably to reduced quality of life, yet modern analgesic and anti-inflammatory therapeutics can cause dependence and side effects. Here, we screened 1444 plant extracts, prepared primarily from native species in California and the United States Virgin Islands, against two voltage-gated K + channels - T-cell expressed Kv1.3 and nociceptive-neuron expressed Kv7.2/7.3. A subset of extracts both inhibits Kv1.3 and activates Kv7.2/7.3 at hyperpolarized potentials, effects predicted to be anti-inflammatory and analgesic, respectively. Among the top dual hits are witch hazel and fireweed; polymodal modulation of multiple K + channel types by hydrolysable tannins contributes to their dual anti-inflammatory, analgesic actions. In silico docking and mutagenesis data suggest pore-proximal extracellular linker sequence divergence underlies opposite effects of hydrolysable tannins on different Kv1 isoforms. The findings provide molecular insights into the enduring, widespread medicinal use of witch hazel and fireweed and demonstrate a screening strategy for discovering dual anti-inflammatory, analgesic small molecules.

Historical ecological research provides valuable insights for contemporary conservation management. Gaps in historical records, however, can limit the utility of that research. Future conservationists may therefore find themselves disadvantaged by the current societal trend of underinvestment in systematic collection of museum specimens and natural history information. To reduce that risk, we asked what managers and scientists could do today to better document the past and present conditions of Santa Cruz Island, California, as a means to improve both contemporary and future conservation. We focused our inquiry on the island's terrestrial fauna, which includes numerous taxa of conservation concern. Here we present recommendations for research and collection that will enhance not only the understanding of past and present ecological conditions on the island but also the records that will be accessible to future historical ecologists.

Most birds living in the temperate zones breed in spring or summer. In a variety of species, however, copulatory behavior has been observed out of season in autumn. Such activity has been proposed to represent late breeding attempts, help to maintain pair bonds during the nonbreeding season, or aid in the formation of future breeding pairs. We observed three attempted copulations (one with cloacal contact) in late November between three male and two female California Quail (Callipepla californica), a species with a flexible mating system. Given that one of the females, and at least two of the observed males, were under a year of age and, therefore, almost certainly sexually immature, we suggest that these copulation attempts could contribute to pair formation. The two males and two females, whose identities were known, spent more time associating with the individual with which they engaged in copulatory activity than with any other covey member of the opposite sex, also implying a social function of this behavior. Nevertheless, we cannot rule out the unlikely possibilities that the observed activity represented astonishingly early breeding attempts, acted as expressions of intersexual social dominance, or functioned as practice for the upcoming breeding season. Possibly, the behavior served no immediate adaptive purpose. Nevertheless, autumn copulatory activity in the California Quail may be more common than known, and we present these observations as a call for further monitoring to clarify the potential function(s) of this behavior.

Climate change is projected to cause extensive plant range shifts, and, in many cases such shifts already are underway. Most long-term studies of range shifts measure emergent changes in species distributions but not the underlying demographic patterns that shape them. To better understand species' elevational range shifts and their underlying demographic processes, we use the powerful approach of rephotography, comparing historical (1978-1982) and modern (2015-2016) photographs taken along a 1000-m elevational gradient in the Colorado Desert of Southern California. This approach allowed us to track demographic outcomes for 4263 individual plants of 11 long-lived, perennial species over the past ~36 years. All species showed an upward shift in mean elevation (average = 45 m), consistent with observed increasing temperature and severe drought in the region. We found that varying demographic processes underlaid these elevational shifts, with some species showing higher recruitment and some showing higher survival with increasing elevation. Species with faster life-history rates (higher background recruitment and mortality rates) underwent larger elevational shifts. Our findings emphasize the importance of demography and life history in shaping range shift responses and future community composition, as well as the sensitivity of desert systems to climate change despite the typical "slow motion" population dynamics of perennial desert plants.

Productivity of warm deserts is highly correlated with rainfall. We analyzed body size data from a 35-yr study of Coachella Fringe-Toed Lizards, Uma inornata, to reveal precipitation-related differences among years both in growth and in the length–mass relationship (LMR). The LMR is a linear function enabling comparison of regression coefficients among groups. Adult male U. inornata were significantly larger and their maximum size differed substantially from that of females. Comparing regression coefficients of LMR between sexes revealed equal slopes, although intercepts differed slightly but significantly. We treated the sexes independently to test for seasonal and rainfall differences. Comparing seasonal differences among adults revealed that slopes were not parallel. Regression coefficients predicted that individuals weighed more in spring than in fall, which we attribute to winter rainfall. This was corroborated by recapture data. LMR slopes for extreme dry, extreme wet, and typical rainfall years were parallel, but the elevation for typical years differed significantly from both dry and wet years: they were heavier in typical years. Growth was slower in dry years than in wet or typical years. Differences in growth rates affect time to maturity. We used the production relation model of juvenile growth to estimate time to minimum reproductive size. Time to maturity is doubled during dry years in comparison with wet years (542 vs. 288 d for females, 400 vs. 200 d for males). Together, delayed maturity and predicted future increases in drought frequency and intensity imply conservation concerns for this protected species.

Abstract Interpersonal communication conflict is an inevitable part of field‐based experiences due to the many complex variables that influence human interactions, such as culture, gender, and perceived power. Moreover, in field‐based institutions (i.e., field stations and marine laboratories) privacy may be limited in terms of space and time, and physical conditions may be challenging, which can lead to more frequent and intense interpersonal conflicts. Conflicts can arise episodically or cyclically at a field‐based institution, impacting visitors and employees at all levels, that is, between students, staff, faculty, and leadership. Those who work seasonally or permanently at field‐based institutions may be able to mitigate some of the potential negative outcomes associated with unmanaged conflict by knowing when these incidents might occur, as well as how to employ meaningful conflict management strategies during these times. Thus, we propose the 10/60 model of field station experiences to define significant points of time during a field experience in which collecting feedback may be critical for avoiding communication conflict. We provide additional recommendations on best practices for soliciting feedback, as well as the importance of setting explicit communication expectations for those in leadership positions to create more inclusive and equitable spaces.

Preprint of a paper submitted to Gigascience. Abstract: The relationship between people, place, and data underpins some of the greatest challenges and opportunities of the 21st century. While there has been general enthusiasm for and work towards Findable, Accessible, Interoperable, and Reusable (FAIR) data for Open Science, only more recently have these data-centric principles been extended into dimensions important to people and place. Notably, the CARE Principles for Indigenous Data Governance, which affect collective benefit, authority to control, responsibility, and ethics. The FAIR Island Project seeks to translate these ideals into practice leveraging the institutional infrastructure provided by scientific field stations. Starting with field stations in French Polynesia as key use cases that are exceptionally well connected to international research networks, FAIR Island builds interoperability between different components of critical research infrastructure, helping connect these to societal benefit areas. The goal is not only to increase reuse of scientific data and the awareness of work happening at the field stations, but more generally to accelerate place-based research for sustainable development. FAIR Island works reflexively, aiming to scale horizontally through networks of field stations and to serve as a model for other sites of intensive long-term scientific study.

<strong class="journal-contentHeaderColor">Abstract.</strong> Post-fire changes to the transport regime of dry ravel, which describes the transport of individual particles downslope, are poorly constrained on a regional level but critical to understand as ravel may contribute to elevated sediment fluxes and associated debris-flow activity observed post-fire in the western United States. In this study, we evaluated post-fire variability in dry ravel travel distance exceedance probabilities and disentrainment rates through a series of field experiments simulating ravel with particles collected in situ. We conducted experiments between March 2021 and March 2022 on soil-mantled hillslopes in the Diablo Range of central coastal California following the Santa Clara Unit Lightning Complex fire of August 2020 with the goal of identifying a regime of &ldquo;bounded&rdquo; (light-tailed) or &ldquo;runaway&rdquo; (heavy-tailed or nonlocal) motion for different particle sizes between 3 and 35 mm. We conducted this study on both grassy south-facing slopes and oak woodland north-facing slopes. We tracked the post-fire evolution of particle transport regimes by fitting a probabilistic Lomax distribution model to the empirical travel distance exceedance probabilities of different particle sizes on a range of experimental slopes. Our experimental results indicated that a general transition from more runaway to more bounded transport occurred for our largest experimental particles (median intermediate axis of 28 mm) on south-facing slopes as vegetation recovered within the first year post-fire, while small and medium particles (median intermediate axes of 6 and 13 mm respectively) on south- or north-facing slopes and large particles on north-facing slopes did not experience notable changes in transport behavior. After the first year, seasonal variation in vegetation characteristics, such as grass density, appeared to control particle motion.

Abstract. Post-fire changes to the transport regime of dry ravel, which describes the transport of individual particles downslope, are poorly constrained on a regional level but critical to understand as ravel may contribute to elevated sediment fluxes and associated debris-flow activity observed post-fire in the western United States. In this study, we evaluated post-fire variability in dry ravel travel distance exceedance probabilities and disentrainment rates through a series of field experiments simulating ravel with particles collected in situ. We conducted experiments between March 2021 and March 2022 on soil-mantled hillslopes in the Diablo Range of central coastal California following the Santa Clara Unit Lightning Complex fire of August 2020 with the goal of identifying a regime of “bounded” (light-tailed) or “runaway” (heavy-tailed or nonlocal) motion for different particle sizes between 3 and 35 mm. We conducted this study on both grassy south-facing slopes and oak woodland north-facing slopes. We tracked the post-fire evolution of particle transport regimes by fitting a probabilistic Lomax distribution model to the empirical travel distance exceedance probabilities of different particle sizes on a range of experimental slopes. Our experimental results indicated that a general transition from more runaway to more bounded transport occurred for our largest experimental particles (median intermediate axis of 28 mm) on south-facing slopes as vegetation recovered within the first year post-fire, while small and medium particles (median intermediate axes of 6 and 13 mm respectively) on south- or north-facing slopes and large particles on north-facing slopes did not experience notable changes in transport behavior. After the first year, seasonal variation in vegetation characteristics, such as grass density, appeared to control particle motion.

Abstract. Post-fire changes to the transport regime of dry ravel, which describes the gravity-driven transport of individual particles downslope, are poorly constrained but critical to understand as ravel may contribute to elevated sediment fluxes and associated debris flow activity observed post-fire in the western United States. In this study, we evaluated post-fire variability in dry ravel travel distance exceedance probabilities and disentrainment rates in the Diablo Range of central coastal California following the Santa Clara Unit Lightning Complex fire of August 2020. Between March 2021 and March 2022, we conducted repeat field experiments simulating ravel with in situ particles (3–35 mm diameter) on a range of experimental surface gradients (0.38–0.81) on both grassy south-facing slopes and oak woodland north-facing slopes. We characterized post-fire evolution in particle transport by fitting a probabilistic Lomax distribution model to the empirical travel distance exceedance probabilities for each experimental particle size, surface gradient, and time period. The resulting Lomax shape and scale parameters were used to identify the transport regime for each subset of simulated ravel, ranging from “bounded” (light-tailed or local) to “runaway” (heavy-tailed or nonlocal) motion. Our experimental results indicated that as vegetation recovered over the first 2 years post-fire, the behavior of small particles (median intermediate axis of 6 mm) became less similar across the experimental sites due to different vegetation structures, whereas medium and large particles (median intermediate axes of 13 and 28 mm, respectively) exhibited a general transition from more runaway to more bounded transport, and large particles became less sensitive to surface gradient. All particle sizes exhibited a decrease in the length scale of transport with time. Of all particle subsets, larger particles on steeper slopes were more likely to experience nonlocal transport, consistent with previous observations and theory. These findings are further corroborated by hillslope and channel deposits, which suggest that large particles were preferentially evacuated from the hillslope to the channel during or immediately after the fire. Our results indicate that nonlocal transport of in situ particles likely occurs in the experimental study catchment, and the presence of wildfire increases the likelihood of nonlocal transport, particularly on steeper slopes.