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gricultural drainage is thought to alter greenhouse gas emissions from temperate peatlands, with CH emissions reduced in favor of greater CO losses. Attention has largely focussed on C trace gases, and less is known about the impacts of agricultural conversion on NO or global warming potential. We report greenhouse gas fluxes (CH, CO, NO) from a drained peatland in the Sacramento-San Joaquin River Delta, California, USA currently managed as a rangeland (that is, pasture). This ecosystem was a net source of CH (25.8 ± 1.4 mg CH-C m d) and NO (6.4 ± 0.4 mg NO-N m d). Methane fluxes were comparable to those of other managed temperate peatlands, whereas NO fluxes were very high; equivalent to fluxes from heavily fertilized agroecosystems and tropical forests. Ecosystem scale CH fluxes were driven by 'hotspots' (drainage ditches) that accounted for less than 5% of the land area but more than 84% of emissions. Methane fluxes were unresponsive to seasonal fluctuations in climate and showed minimal temporal variability. Nitrous oxide fluxes were more homogeneously distributed throughout the landscape and responded to fluctuations in environmental variables, especially soil moisture. Elevated CH and NO fluxes contributed to a high overall ecosystem global warming potential (531 g CO-C equivalents m y), with non-CO trace gas fluxes offsetting the atmospheric 'cooling' effects of photoassimilation. These data suggest that managed Delta peatlands are potentially large regional sources of greenhouse gases, with spatial heterogeneity in soil moisture modulating the relative importance of each gas for ecosystem global warming potential. [ABSTRACT FROM AUTHOR]

In this paper, we report on the scaffold-level assembled genome for the federally endangered, California endemic crustacean Lepidurus packardi (the Vernal Pool Tadpole Shrimp). L. packardi is a key food source for other conserved California species including the California Tiger Salamander Ambystoma californiense. It faces significant habitat loss and fragmentation as vernal pools are threatened by urbanization, agricultural conversion, and climate change. This resource represents the first scaffold-level genome of any Lepidurus species. The assembled genome spans 108.6 Mbps, with 6 chromosome-length scaffolds comprising 71% of total genomic length and 444 total contigs. The BUSCO score for this genome is 97.3%, suggesting a high level of completeness. We produced a predicted gene set for this species trained on the Daphnia magna set of genes and predicted 17,650 genes. These tools can aid researchers in understanding the evolution and adaptive potential of alternative reproductive modes within this species. [ABSTRACT FROM AUTHOR]

In this review and synthesis, we argue that California is an important test case for the nation and world because terrestrial biodiversity is very high, present and anticipated threats to biodiversity from climate change and other interacting stressors are severe, and innovative approaches to protecting biodiversity in the context of climate change are being developed and tested. We first review salient dimensions of California's terrestrial physical, biological, and human diversity. Next, we examine four facets of the threat to their sustainability of these dimensions posed by climate change: direct impacts, illustrated by a new analysis of shifting diversity hotspots for plants; interactive effects involving invasive species, land-use change, and other stressors; the impacts of changing fire regimes; and the impacts of land-based renewable energy development. We examine recent policy responses in each of these areas, representing attempts to better protect biodiversity while advancing climate adaptation and mitigation. We conclude that California's ambitious 30 × 30 Initiative and its efforts to harmonize biodiversity conservation with renewable energy development are important areas of progress. Adapting traditional suppression-oriented fire policies to the reality of new fire regimes is an area in which much progress remains to be made. [ABSTRACT FROM AUTHOR]

• A hydrologic model was developed for a snow-dominated vernal pool. • The hydrologic model was coupled to a model of the vernal pool plant community. • Climate change scenarios were simulated with the coupled models. • Climate change scenarios had shorter inundation lengths than historical period. • Model results suggest vernal pool species declines with climate change. Vernal pools are seasonal wetlands that have a high diversity of endemic and native plant species, yet they are threatened by agricultural conversion and urban development and face threats posed by climate change resulting from altered precipitation and temperature regimes. We developed an approach to investigate the potential impacts of climate change on hydrology and vegetation communities of vernal pools by creating a mass-balance hydrologic model that is coupled to a statistical model of plant community distribution. The hydrologic and vegetative models were calibrated using field measurements from a vernal pool in northeastern California that experiences snow-dominated hydrology and is larger than vernal pools in more studied areas like Central California, but representative of other northern California vernal pools. Using downscaled data from global climate models, the coupled model suggests that warmer conditions will lead to the pool being inundated for a shorter time, but with little change in maximum depth. Reduced hydroperiods suggest possible declines in vernal pool specialist species with future climate change. The coupled model is an integrated approach for understanding the impact of altered environmental conditions on unique hydrology and plant community composition of vernal pool ecosystems, but the model approach could be improved with longer term data and by applying it at more sites to broaden the applicability of the approach and to enable better process representation. [ABSTRACT FROM AUTHOR]

This study analysed threats to federally and State‐listed endangered and threatened animal taxa in California, United States, and how threats varied by taxa, habitat use, spatial extent, severity, geographical region and endemic status using threat categories from the International Union for Conservation of Nature (IUCN) Red List Threats Classification Scheme and information from scientific literature and reports.A majority of the taxa evaluated were associated with freshwater habitats and were endemic to California. The most threatened taxonomic groups were fish, followed by mammals and birds. The number of threats was mostly evenly distributed across the State's three geographical regions (i.e., North, Central and South), and no single region had a disproportionately high number of endangered animal taxa.Freshwater taxa were the most affected in nearly every threat category, suggesting that freshwater taxa are more threatened than their terrestrial and marine counterparts. In descending order, the most prominent threats across all taxa were habitat loss, invasive species, climate change and altered hydrology. Threats identified as high severity also tended to have a high spatial extent and vice versa.This study shows that the numerous freshwater faunas in California are disproportionately affected by threats also found in other freshwater systems and Mediterranean‐climate regions, highlighting the scope of the freshwater biodiversity crisis in California. Managing priorities to target the most pervasive threats to endangered freshwater taxa documented in this study will help safeguard freshwater biodiversity against human threats in California and beyond. [ABSTRACT FROM AUTHOR]

Natural climate solutions (NCS) are recognized as an important tool for governments to reduce greenhouse gas emissions and remove atmospheric carbon dioxide. Using California as a globally relevant reference, we evaluate the magnitude of biological climate mitigation potential from NCS starting in 2020 under four climate change scenarios. By mid-century NCS implementation leads to a large increase in net carbon stored, flipping the state from a net source to a net sink in two scenarios. Forest and conservation land management strategies make up 85% of all NCS emissions reductions by 2050, with agricultural strategies accounting for the remaining 15%. The most severe climate change impacts on ecosystem carbon materialize in the latter half of the century with three scenarios resulting in California ecosystems becoming a net source of carbon emissions under a baseline trajectory. However, NCS provide a strong attenuating effect, reducing land carbon emissions 41–54% by 2100 with total costs of deployment of 752–777 million USD annually through 2050. Rapid implementation of a portfolio of NCS interventions provides long-term investment in protecting ecosystem carbon in the face of climate change driven disturbances. This open-source, spatially-explicit framework can help evaluate risks to NCS carbon storage stability, implementation costs, and overall mitigation potential for NCS at jurisdictional scales. [ABSTRACT FROM AUTHOR]

Greater sage‐grouse (Centrocercus urophasianus) have experienced considerable range contraction and reduced abundance in response to habitat loss and degradation. Translocation is a conservation action that is often used to reintroduce extirpated populations or augment existing small populations. Translocations have had limited success in restoring viable populations of sage‐grouse; a lack of success is attributed to long‐distance post‐release movements away from release sites, reduced survival, and lack of reproductive success of translocated individuals. Translocating female sage‐grouse with their chicks (brood translocation) is a technique aimed at promoting breeding area fidelity and reproduction and may be beneficial to population restoration efforts. Furthermore, the ability to capture, relocate, and release individuals while minimizing translocation‐induced loss increases the overall probability of restoration success. Accordingly, we developed a protocol to translocate female sage‐grouse and their broods simultaneously, using a delayed‐release system that included a custom release box and acclimation pen. We tested our protocol across 2 separate restoration projects in North Dakota and California during 2017–2019 with a total of 38 translocated females and 196 chicks. We successfully released 174/196 chicks (88.8%) from 32/38 (84.2%) broods. Our protocol builds on existing translocation methods used to translocate sage‐grouse and will likely prove to be a critical technique in restoring sage‐grouse populations. © 2021 The Wildlife Society. : With sage‐grouse populations experiencing significant range contraction and population declines over the past 40 years, effective and direct management techniques are needed to restore remnant populations especially on the fringe of their range. We describe and evaluate a novel method for translocating female sage‐grouse with their broods to help guide management actions aimed at restoring populations range‐wide. [ABSTRACT FROM AUTHOR]

Globally endangered ecosystems, such as ephemeral wetlands, are often critical habitat for multiple interacting imperilled species. To conserve this biodiversity, managers must consider both species‐specific resource requirements and mechanisms for endangered species coexistence under variable habitat conditions.We examined communities native to California playa pools, ephemeral wetlands that have declined by >90% from their historic extent. Specifically, we describe the diet of a federally Threatened amphibian (Ambystoma californiense), and characterise interactions between this amphibian and two federally Endangered macrocrustaceans (Branchinecta conservatio and Lepidurus packardi) across three rain years to understand how these imperilled species coexist. We examined the dietary preferences of A. californiense larvae, metamorphs, juveniles, and breeding adults, and determined how prey electivity by larval A. californiense differs between natural playa pools and human‐modified stock ponds.Within playa pools, both breeding adult and larval A. californiense preyed extensively on L. packardi, whereas fully terrestrial juveniles had relatively empty stomachs. We provide evidence for size‐moderated optimal foraging by larval A. californiense, and show that larval prey differed dramatically between playa pools and stock ponds. Additionally, an ontogenetic progression from smaller to larger prey gave the relatively large, endangered macrocrustaceans an early‐season temporal refuge, during which they reached maturity in all three rain years.Consistent with complex life cycle theory, our results suggest that ephemeral wetland habitat offers abundant food resources for A. californiense relative to terrestrial habitat. Our findings also suggest that diet flexibility facilitates the persistence of this imperilled amphibian in human‐modified stock ponds. Temporal offsets in prey maturation rates and ontogenetic shifts in predator diets are likely to facilitate coexistence among the focal endangered species.We highlight the importance of accounting for spatial and temporal variation in interspecific interactions when predicting the effects of environmental change on biodiversity, particularly in highly threatened ecosystems. [ABSTRACT FROM AUTHOR]

Naturally occurring populations of most species are distributed non‐uniformly across their ranges. Observed changes in range‐wide population size are attributed to local‐scale processes such as fecundity and survival and to regional scale demographic processes such as immigration. It is often infeasible to study a species across its entire range, and we frequently make inferences on populations as a whole based on the demographic rates of a more restricted area. Extrapolating inferences about demographic processes from study areas to the entire species' range can lead to erroneous estimations, particularly when permanent emigrants contribute significantly to individual population processes. In this paper, we evaluated demographic processes and population trends at multiple scales for tricolored blackbirds (Agelaiustricolor) in California using site‐specific banding data and range‐wide citizen‐science data. First, we found that a previous estimate of statewide decline of 34% is largely driven by an estimated decline of 51.7% for the southern population. Second, we found evidence of a pseudo‐source and sink system, with the northern region acting as a sink for individuals moving from the declining southern region. The southern region is a "pseudo‐source" since it has lower rates of adult survival and an annual growth rate of r = −0.099, while still acting as a source of immigrants for the northern region. In turn, the north fits the traditional definition of a sink by an annual growth rate near zero, in addition to declining at a rate of 2.5% even though it is estimated to receive immigrants from the south at rates ranging from 8.3% to 13.2% per year. Our results suggest that the loss of wetland habitats in Southern California, coupled with increasing severity of droughts driven by changing climatic conditions, has created this pseudo‐source and sink system. Long term, tricolored blackbirds are likely to experience range contraction in the south, and the northern region is likely to undergo declines due to a loss of immigrants from the south. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Raptor Research is the property of Raptor Research Foundation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Agriculture in the Central Valley of California, one of the USA's main sources of fruits, nuts, and vegetables, is highly vulnerable to climate change impacts in the next 50 years. This interdisciplinary case study in Yolo County shows the urgency for building adaptation strategies to climate change. Climate change and the effects of greenhouse gas emissions are complex, and several of the county's current crops will be less viable in 2050. The study uses a variety of methods to assemble information relevant to Yolo County's agriculture, including literature reviews, models, geographic information system analysis, interviews with agency personnel, and a survey of farmers. Potential adaptation and mitigation responses by growers include changes in crop taxa, irrigation methods, fertilization practices, tillage practices, and land use. On a regional basis, planning must consider the vulnerability of agricultural production and the tradeoffs associated with diversified farmlands, drought, flooding of cropland, loss of habitat for wild species of concern, and urbanization. [ABSTRACT FROM AUTHOR]

We used a 30-year study of breeding Swainson's hawks (Buteo swainsoni) in northern California to examine correlates of adult apparent survival using multistate models in Program MARK. Specifically, we examined age-related patterns in adult apparent survival and how adult survival was correlated with average annual nest productivity, annual reproductive output, western juniper (Juniperus occidentalis) density around nest sites, distance to agriculture, and amount of agriculture within a territory. Annual estimates of adult survival varied from 0.85 to 0.9 (SE = 0.02). There were no indications of senescence or other patterns of age-related changes in adult apparent survival. Adult survival was inversely correlated with average reproductive output, with individuals producing >2 offspring having decreased survival, reflecting a possible tradeoff between reproduction and survival. Conversely, reproduction in any year was positively correlated with survival, providing evidence of individual quality influencing adult survival. The distance an individual had to travel to agriculture, where most individuals forage, was negatively related to survival. Primary productivity within the average Swainson's hawk territory was positively correlated with adult survival. Our results indicate that individuals may have higher survival and fitness in areas with high proportions of irrigated agriculture that provides high prey densities, particularly alfalfa. [ABSTRACT FROM AUTHOR]

Over the past two decades, watershed restoration has dramatically increased internationally. California has been at the forefront, allocating billions of dollars to restoration activities through legislation and voter-approved bonds. Yet, the implications of restoration remain ambiguous because there has been little examination of restoration accomplishments and almost no analysis of the political context of restoration. This article addresses these gaps, utilizing a case study of the Russian River basin in Northern California. We identify trends that shed light on both the ecological and the political implications of restoration at a basin scale by examining a database of 787 restoration projects implemented in the Russian River basin since the early 1980s. Although a total of over $47 million has been spent on restoration in the basin, dominant forms of restoration are limited in scope to small-scale projects that focus on technical solutions to site-specific problems. The majority of restoration efforts are devoted to road repair, riparian stabilization, and in-stream structures, accounting for 62% of all projects. These types of projects do not address the broader social drivers of watershed change such as land and water uses. We suggest that restoration can become more effective by addressing the entire watershed as a combination of social and ecological forces that interact to produce watershed conditions. [ABSTRACT FROM AUTHOR]

Wildfire risks for California under four climatic change scenarios were statistically modeled as functions of climate, hydrology, and topography. Wildfire risks for the GFDL and PCM global climate models and the A2 and B1 emissions scenarios were compared for 2005-2034, 2035-2064, and 2070-2099 against a modeled 1961-1990 reference period in California and neighboring states. Outcomes for the GFDL model runs, which exhibit higher temperatures than the PCM model runs, diverged sharply for different kinds of fire regimes, with increased temperatures promoting greater large fire frequency in wetter, forested areas, via the effects of warmer temperatures on fuel flammability. At the same time, reduced moisture availability due to lower precipitation and higher temperatures led to reduced fire risks in some locations where fuel flammability may be less important than the availability of fine fuels. Property damages due to wildfires were also modeled using the 2000 U.S. Census to describe the location and density of residential structures. In this analysis the largest changes in property damages under the climate change scenarios occurred in wildland/urban interfaces proximate to major metropolitan areas in coastal southern California, the Bay Area, and in the Sierra foothills northeast of Sacramento. [ABSTRACT FROM AUTHOR]

Copyright of Condor is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

1. Ephemeral wetland habitats provide a useful model system for studying how life-history patterns enable populations to persist despite high environmental variation. One important life-history trait of both plants and crustaceans in such habitats involves hatching/germination of only some of the eggs/seeds at any time. This bet-hedging leads to the development of a bank composed of dormant propagules of many ages. 2. The San Diego fairy shrimp, Branchinecta sandiegonensis (Crustacea: Anostraca), a dominant faunal element of ephemeral ponds in San Diego, California, is a suitable organism for studying the consequences of highly fluctuating environmental conditions. As a result of large-scale habitat loss, the species is also endangered, and this motivated our specific study towards understanding the hatching dynamics of its egg bank for planning conservation efforts such as pool restoration and re-creation. 3. We formulated a matrix population model using egg age within the bank to study the relationship between adult survival and reproduction, and survival in and hatching from the egg bank. As vital rates for fairy shrimp are only poorly known, we generated 48 matrices with parameters encompassing ranges of likely values for the vital rates of B. sandiegonensis. We calculated population growth rates and eigenvalue elasticities both for a static model and a model with periodic reproductive failure. 4. The model shows that in good filling events, population growth rate is very high and the egg bank is increased dramatically. While population growth rate is insensitive to long-term survival in the egg bank in our static deterministic model, it becomes sensitive to survival in the egg bank when a regime of periodically failed reproductive events is imposed. 5. Under favourable conditions, it was best for shrimp to hatch from eggs as soon as possible. However, under a regime where failed reproductive events were common, it was best to hatch after several pool fillings . Because conditions change from favourable to unfavourable unpredictably, variation in age within the egg bank appears to be critical for the persistence of the population. This attribute needs to be carefully considered when restoring or creating new pools for conservation purposes. [ABSTRACT FROM AUTHOR]

This article explores the prospects for establishing an environmental accounting system along the U.S.-Mexico border. After reviewing the rationale for environmental accounting and developing an accounting framework, three studies from the San Diego-Tijuana region are presented. In the first study, we estimate the total proportion of government expenditures made to defend the environment against human-induced changes in San Diego. This study reveals that defensive expenditures absorb 1.23 percent of total economic output and more than 21 percent of local government expenditures. The second study focuses on a smaller area along the border where the environmentally sensitive Tijuana Estuary on the U.S. side connects to the heavily populated Canon de los Laureles on the Mexican side. Expenditures made in Mexico aim to protect against threats to human health and safety, while those in the U.S. target the preservation of recreational resources and ecosystem health. Our third study estimates the value of agriculture land losses in San Diego between 1990 and 1995. Using an average price estimate for agricultural output and discount rates ranging from 0 to 5 percent, we find that the present value of the losses ranges from 0.18 percent to 1.8 percent of the total economy. Many of the areas lost to urban development are close to the existing urban area, suggesting the possibility of secondary impacts, such as increased air-pollution emissions resulting from longer transportation distance to market. [ABSTRACT FROM AUTHOR]

1. Recent legislation in California, USA, has restricted traditional open-field burning of rice straw residues, leading farmers to adopt alternative methods of straw disposal such as post-harvest flooding of rice fields. These changes may benefit wildlife because winter-flooded fallow rice fields provide foraging habitat to migratory waterfowl. In turn, the foraging activity of waterfowl may help to increase rice straw decomposition, providing a reciprocal benefit to farmers. We examined the effects of waterfowl foraging activity on straw decomposition and nitrogen mineralization following rice harvest in a fallow flooded soil. 2. Experimental plots (25 m2 ) were established on a silty clay soil and were subjected to two post-harvest treatments: wet-rolled or untilled. Mallard ducks Anas platyrhynchos were placed in one-half of the experimental plots, following a split-plot design, for a 3-week period, at a density equivalent to 33 birds ha-1 over a season of 180 days to approximate regional abundance data. 3. Waterfowl foraging activity increased residual surface straw decomposition by 78% in untilled plots and 18% in wet-rolled plots compared with the respective unforaged plots. Average straw diameter in foraged plots was reduced to one-third that of unforaged plots. 4. Waterfowl foraging and field tillage reduced nitrogen (N) concentrations in the surface straw residue remaining at the end of the winter fallow period. Below-ground organic residue was not affected by waterfowl foraging, indicating that ducks did not incorporate the straw. There were no apparent additions of carbon (C) or N to the soil as a result of waterfowl activity. 5. We conclude that waterfowl foraging can substantially increase straw decomposition in flooded, fallow, rice fields. Accordingly, rice producers should consider agronomic practices that attract waterfowl, such as winter flooding, to maximize the decomposition of rice straw residue. At the upper end of... [ABSTRACT FROM AUTHOR]

Population growth, climate change, aging infrastructure, and changing societal values alter how water must be managed in the 21st Century. O'Shaughnessy Dam, located in Yosemite National Park, has been identified as a possible candidate for dam removal. It is a component of San Francisco's Hetch Hetchy System and is operated for water supply and hydropower. This article describes a spatially scaled approach to analyze water reliability without O'Shaughnessy Dam, but with improved water conveyance between the Hetch Hetchy System and existing reservoirs and aqueducts at the watershed, regional Bay Area, and statewide scales. It broadens previous research to highlight larger scale implications of removing O'Shaughnessy Dam and evaluates the role of improved water conveyance for water management. CALifornia Value Integrated Network, a large-scale hydro-economic model evaluates intertied water management using estimated urban and agricultural water demands for year 2050 with 72-year historical and warm, dry hydrologic conditions. Results suggest that O'Shaughnessy Dam can be removed with additional conveyance at any spatial scale while maintaining water reliability. With a warm, dry climate, water reliability, and storage decline, indicating removing O'Shaughnessy Dam may have less effect on water management than climate change when conveyance is improved between the Hetch Hetchy System and nearby systems. Improving water conveyance can sometimes substitute for water storage in storage-rich watersheds. [ABSTRACT FROM AUTHOR]

Thousands of species of bees are in global decline, yet research addressing the ecology and status of these wild pollinators lags far behind work being done to address similar impacts on the managed honey bee. This knowledge gap is especially glaring in natural areas, despite knowledge that protected habitats harbor and export diverse bee communities into nearby croplands where their pollination services have been valued at over $3 billion per year. Surrounded by ranches and farmlands, Pinnacles National Park in the Inner South Coast Range of California contains intact Mediterranean chaparral shrubland. This habitat type is among the most valuable for bee biodiversity worldwide, as well as one of the most vulnerable to agricultural conversion, urbanization and climate change. Pinnacles National Park is also one of a very few locations where extensive native bee inventory efforts have been repeated over time. This park thus presents a valuable and rare opportunity to monitor long-term trends and baseline variability of native bees in natural habitats. Fifteen years after a species inventory marked Pinnacles as a biodiversity hotspot for native bees, we resurveyed these native bee communities over two flowering seasons using a systematic, plot-based design. Combining results, we report a total of 450 bee species within this 109km2 natural area of California, including 48 new species records as of 2012 and 95 species not seen since 1999. As far as we are aware, this species richness marks Pinnacles National Park as one of the most densely diverse places known for native bees. We explore patterns of bee diversity across this protected landscape, compare results to other surveyed natural areas, and highlight the need for additional repeated inventories in protected areas over time amid widespread concerns of bee declines., Competing Interests: The authors have declared that no competing interests exist.