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Wildfire modifies the short- and long-term exchange of carbon between terrestrial ecosystems and the atmosphere, with impacts on ecosystem services such as carbon uptake. Dry western US forests historically experienced low-intensity, frequent fires, with patches across the landscape occupying different points in the fire-recovery trajectory. Contemporary perturbations, such as recent severe fires in California, could shift the historic stand-age distribution and impact the legacy of carbon uptake on the landscape. Here, we combine flux measurements of gross primary production (GPP) and chronosequence analysis using satellite remote sensing to investigate how the last century of fires in California impacted the dynamics of ecosystem carbon uptake on the fire-affected landscape. A GPP recovery trajectory curve of more than five thousand fires in forest ecosystems since 1919 indicated that fire reduced GPP by 157:4 ± 7:3 g C m-2 y-1(mean ± SE, n = 1926) in the first year after fire, with average recovery to prefire conditions after ~12 y. The largest fires in forested ecosystems reduced GPP by 393:8 ± 15:7 g C m-2 y-1 (n = 401) and took more than two decades to recover. Recent increases in fire severity and recovery time have led to nearly 9:9 ± 3:5 MMT CO2 (3-y rolling mean) in cumulative forgone carbon uptake due to the legacy of fires on the landscape, complicating the challenge of maintaining California's natural and working lands as a net carbon sink. Understanding these changes is paramount to weighing the costs and benefits associated with fuels management and ecosystem management for climate change mitigation. [ABSTRACT FROM AUTHOR]

Background: Shrub-dominated ecosystems in California are widespread and provide invaluable ecosystem services to surrounding human-dominated communities. Yet shrublands, especially those at the wildland-urban interface, are at risk of degradation due to increasing wildfire frequency. Strategically placed fuel breaks are an important fuel management technique for reducing fire risk to neighboring communities and natural landscapes. Fuel breaks in shrub-dominated ecosystems are typically linear features where woody biomass is reduced, thereby providing fire suppression opportunities that limit fire spread. While fuel breaks are important for tactical response to fire, they can also affect the composition and structure of shrubland habitats. To understand the ecological changes resulting from fuel treatments in southern California chaparral, we measured vegetation change associated with fuel management techniques on a recently created fuel break established around the Lake Morena community on the Cleveland National Forest. The area was initially treated with cut and pile burning, then treated with herbicide, and 2 years later was subjected to short-term grazing by 1200 goats. The purpose of this study is to (1) evaluate the compositional and structural differences associated with fuel break creation and (2) quantify compositional shifts in herbaceous and woody vegetation caused by short-duration goat grazing as a method of fuel break maintenance. Results: Plots on the fuel break and in untreated adjacent chaparral exhibited significantly different species assemblages. Total herbaceous cover (both native and non-native) was 92 times greater on the fuel break than in adjacent chaparral-dominated wildlands, and native shrub cover was 55.3 times greater in untreated adjacent chaparral than on the fuel break. Goats had a significant impact on reducing native and non-native herbaceous cover (87% reduction in cover, 92% reduction in height), but were ineffective at reducing the cover and height of most woody species such as Adenostoma fasciculatum, Eriogonum fasciculatum, Quercus berberidifolia, and Artemisia tridentata. Conclusion: Initial fuel break creation was effective at reducing native woody cover and height, simultaneously giving rise to an abundance and diversity of native and non-native herbaceous species. Targeted goat grazing was successful at reducing herbaceous biomass but was ineffective at reducing woody biomass which is often one of the most important goals for fuel management in chaparral ecosystems. In areas where control of woody biomass is the primary objective, land managers should consider grazing duration and plant species composition when contemplating goats as a tool for fuel break maintenance. [ABSTRACT FROM AUTHOR]

Large, severe fires are becoming more frequent in many forest types across the western United States and have resulted in tree mortality across tens of thousands of hectares. Conifer regeneration in these areas is limited because seeds must travel long distances to reach the interior of large burned patches and establishment is jeopardized by increasingly hot and dry conditions. To better inform postfire management in low elevation forests of California, USA, we collected 5‐yr postfire recovery data from 1,234 study plots in 19 wildfires that burned from 2004–2012 and 18 yrs of seed production data from 216 seed fall traps (1999–2017). We used these data in conjunction with spatially extensive climate, topography, forest composition, and burn severity surfaces to construct taxon‐specific, spatially explicit models of conifer regeneration that incorporate climate conditions and seed availability during postfire recovery windows. We found that after accounting for other predictors both postfire and historical precipitation were strong predictors of regeneration, suggesting that both direct effects of postfire moisture conditions and biological inertia from historical climate may play a role in regeneration. Alternatively, postfire regeneration may simply be driven by postfire climate and apparent relationships with historical climate could be spurious. The estimated sensitivity of regeneration to postfire seed availability was strongest in firs and all conifers combined and weaker in pines. Seed production exhibited high temporal variability with seed production varying by over two orders of magnitude among years. Our models indicate that during droughts postfire conifer regeneration declines most substantially in low‐to‐moderate elevation forests. These findings enhance our mechanistic understanding of forecasted and historically documented shifts in the distribution of trees. [ABSTRACT FROM AUTHOR]

Sea level rise (SLR) imposes increasing salinity and inundation stresses in salt marshes which simultaneously face invasions by exotic plant species. We aimed to improve and apply knowledge on the ecophysiological responses of halophytes to SLR to conservation management of salt marshes. In a mesocosm experiment, we measured and compared phosphoenolpyruvate carboxylase (PEPC) activity and related functional traits of the California-native Spartina foliosa , invasive S. densiflora and their hybrid S. densiflora × foliosa in response to increasing levels of salinity and inundation. S. foliosa was moderately sensitive to salinity, showing a 57% reduction in PEPC specific activity from freshwater to hypersalinity. This native species compensated for the reduction of PEPC activity with increased salinity through 80% higher enzyme activation by phosphorylation. PEPC functional trait responses of S. foliosa were mostly independent of inundation depth. In view of these results, managers should conserve undeveloped lands for accommodation space above current high tide lines to facilitate colonization of stress-tolerant S. foliosa. Our results on functional responses of PEPC traits recorded high sensitivity to salinity for S. densiflora. This was reflected by 65% lower PEPC specific activity together with increasing accumulation of free proline (+96%) and total proteins (+23%) with elevated salinity. These results suggest prioritized eradication of S. densiflora populations in brackish habitats. Measured PEPC responses support the high stress tolerance of the S. densiflora × foliosa hybrid. PEPC traits for the hybrid were mostly independent of salinity and inundation. The hybrid showed higher PEPC-specific activity than S. foliosa (+70%) and S. densiflora (+15%) in freshwater under intermediate inundation. Results suggest that eradication of the hybrid should be the highest management priority. Our study shows that the responses of key functional physiological traits to environmental stresses serve as biological indicators that can guide ecosystem management practices in a scenario of climate change. [ABSTRACT FROM AUTHOR]

[Display omitted] • We explore the utility of social media and machine learning to fill gaps in mapping ecosystem services. • Social media provides a low-cost indicator for mapping cultural ecosystem services. • Machine learning improves data manipulation during ecosystem service mapping. • Variable importance in Random Forest identifies key pointers and indicators for mapping recreation. • Nature based recreation is related to environmental and landscape characteristics. Crowdsourced geotagged social media data and machine learning approaches have emerged as promising tools for mapping ecosystem services, especially cultural ecosystem services that are difficult to assess. Here, we use recreation to show how social media data, machine learning, and spatial analysis techniques can improve our understanding of human-nature interactions and the mapping of recreational ecosystem services. We extracted 80,500 photographs taken in non-urban areas of the Tahoe Central Sierra Initiative project area in California between 2005 and 2019 that were posted to the photo sharing application Flickr and used these as a proxy for recreational visits to the area. Automated image content analysis was used to identify the objects and concepts in the photographs and uncover the types of nature experiences that are important to visitors. Additionally, variable importance, a Random Forest machine learning technique, was used to examine the environmental and landscape variables that drive recreation in the area and to create a classification model that predicts the recreation potential of the entire area based on important variables. The automated image content analysis identified 1,239 unique labels linked to recreation, with mountains, hills, and rocks being the most prominent features (22%). Our Random Forest model indicates that vegetation cover, land cover, elevation, smoke days, and landscape features are major drivers of recreation in the area and are of interest to visitors in the area. The model predicted that 25.9% of the area has the potential to support recreational visits. Most of these recreation potential areas are in protected areas (77.8%), predominantly in conifer forests (66%) and within national forest boundaries, especially the Tahoe National Forest area (37.6%). These results show that recreational ecosystem services vary across landscapes and illustrate the need for improved mapping approaches to determine the provision of ecosystem services in different places. The analysis provides novel insights into the various ways social media data and machine learning techniques can be powerful components of ecosystem service research and how they hold great potential for monitoring and informing management interventions on ecosystem service provision, especially in places with limited traditional onsite visitation data. [ABSTRACT FROM AUTHOR]

Biomass estimates for shrub‐dominated ecosystems in southern California have been generated at national and statewide extents. However, existing data tend to underestimate biomass in shrub vegetation types are limited to one point in time, or estimate aboveground live biomass only. In this study, we extended our previously developed estimates of aboveground live biomass (AGLBM) based on the empirical relationship of plot‐based field biomass measurements to Landsat normalized difference vegetation index (NDVI) and multiple environmental factors to include other vegetative pools of biomass. AGLBM estimates were made by extracting plot values from elevation, solar radiation, aspect, slope, soil type, landform, climatic water deficit, evapotranspiration, and precipitation rasters and then using a random forest model to estimate per‐pixel AGLBM across our southern California study area. By substituting year‐specific Landsat NDVI and precipitation data, we created a stack of annual AGLBM raster layers for each year from 2001 to 2021. Using these AGLBM data as a foundation, we developed decision rules to estimate belowground, standing dead, and litter biomass pools. These rules were based on relationships between AGLBM and the biomass of the other vegetative pools derived primarily from peer‐reviewed literature and an existing spatial data set. For shrub vegetation types (our primary focus), rules were based on literature estimates by the postfire regeneration strategy of each species (obligate seeder, facultative seeder, obligate resprouter). Similarly, for nonshrub vegetation types (grasslands, woodlands) we used literature and existing spatial data sets specific to each vegetation type to define rules to estimate the other pools from AGLBM. Using a Python language script that accessed Environmental Systems Research Institute raster geographic information system utilities, we applied decision rules to create raster layers for each of the non‐AGLBM pools for the years 2001–2021. The resulting spatial data archive contains a zipped file for each year; each of these files contains four 32‐bit tiff files for each of the four biomass pools (AGLBM, standing dead, litter, and belowground). The biomass units are grams per square meter (g/m2). We estimated the uncertainty of our biomass data by conducting a Monte Carlo analysis of the inputs used to generate the data. Our Monte Carlo technique used randomly generated values for each of the literature‐based and spatial inputs based on their expected distribution. We conducted 200 Monte Carlo iterations, which produced percentage uncertainty values for each of the biomass pools. Results showed, using 2010 as an example, mean biomass for the study area and percentage uncertainty for each of the pools as follows: AGLBM (905.4 g/m2, 14.4%); standing dead (644.9 g/m2, 1.3%); litter (731.2 g/m2, 1.2%); and belowground (776.2 g/m2, 17.2%). Because our methods are consistently applied across each year, the data produced can be used to inform changes in biomass pools due to disturbance and subsequent recovery. As such, these data provide an important contribution to supporting the management of shrub‐dominated ecosystems for monitoring trends in carbon storage and assessing the impacts of wildfire and management activities, such as fuel management and restoration. There are no copyright restrictions on the data set; please cite this paper and the data package when using these data. [ABSTRACT FROM AUTHOR]

• Regression trees and classification techniques identified environmental indicators of stream flow at ungagged locations. • Nine out of 77 variables found with higher predictive potential of stream flow. • The predictors were accurate in estimating general annual trends of stream flow. • The nine indicators were less accurate when estimating stream flow by month. The aim of this study is to test a spatially explicit statistical model to identify indicators of natural stream flow using readily available stream, climate and landscape data. Understanding flow behavior of unmonitored streams at different temporal scales using environmental indicators is of great interest considering the logistic constraints of providing comprehensive flow instrumentation for all stream reaches in a region. Our results have applications to assess human impact in watersheds, to study environmental changes in fresh water resources, and in the management of local ecosystem. This study uses classification and regression tree analysis to identify significant explanatory variables for a predictive model of stream flow in semi-arid watersheds of southern California, USA. The study collected 77 variables with 30 years record, for a set of 48 sites, interpolated to create raster files at 30 m spatial resolution. After applying Pearson correlation analyses to eliminate redundant variables, nine variables were found to have strong positive predictive value for estimating stream flow at ungauged sites. Nine prediction rasters portraying spatial variation of stream flow for the study region at three key index months during wet, dry, and average rainfall conditions. The predictive power of the variables was tested and cross validated over a subset of data not included when building the model. Model validation by site at monthly temporal resolution showed mixed results. While some sites where accurately predicted others did not. The comparison of observed vs predicted values by month suggest that this statistically based approach is able to predict the general patterns of stream flow at the regional scale, however it may be inaccurate in estimating actual flow values by month since the models tends to under-predict monthly discharge. [ABSTRACT FROM AUTHOR]

Complex interactions between protected populations may challenge the recovery of whole ecosystems. In California, white sharks (Carcharodon carcharias) mistargeting southern sea otters (Enhydra lutris nereis) are an emergent impact to sea otter recovery, inhibiting the broader ecosystem restoration sea otters might provide. Here, we integrate and analyze tracking and stranding data to compare the phenology of interactions between white sharks and their targeted prey (elephant seals, Mirounga angustirostris) with those of mistargeted prey (sea otters, humans). Pronounced seasonal peaks in shark bites to otters and humans overlap in the late boreal summer, immediately before the annual adult white shark migration to elephant seal rookeries. From 1997 to 2017, the seasonal period when sharks bite otters expanded from 2 to 8 months of the year and occurred primarily in regions where kelp cover declined. Immature and male otters, demographics most associated with range expansion, were disproportionately impacted. While sea otters are understood to play a keystone role in kelp forests, recent ecosystem shifts are revealing unprecedented bottom‐up and top‐down interactions. Such shifts challenge ecosystem management programs that rely on static models of species interactions. [ABSTRACT FROM AUTHOR]

Positive interactions enhance biodiversity and ecosystem function, but can also exacerbate biological invasions. Facilitation of exotic invaders by exotic foundation species (invasional meltdown) has been studied extensively, but facilitation of exotic invaders by native foundation species has attracted less attention. Specifically, very few studies have examined the extent that native foundation species facilitate native and exotic competitors. Understanding the processes that mediate interactions between native and exotic species can help explain, predict, and improve management of biological invasions. Here, we examined the effects of native foundation shrubs on the relative abundance of the annual plant community - including native and exotic taxa - from 2015-2018 in a desert ecosystem at Carrizo Plain National Monument, California, USA (elevation: 723 m). Shrub effects varied by year and by the identity of annual species, but shrubs consistently enhanced the abundance of the annual plant community and facilitated both native (n=17 species) and exotic (n=4 species) taxa. However, at the provenance level, exotic annuals were facilitated 2.75 times stronger in abundance than native annuals, and exotic annuals were always more abundant than natives both near and away from shrubs. Our study reaffirms facilitation as an important process in the organisation of plant communities and confirms that both native and exotic species can form positive associations with native foundation species. However, facilitation by native foundation species can exacerbate biological invasions by increasing the local abundance of exotic invaders. Thus, the force of facilitation can have a dark side relevant to ecosystem function and management. [ABSTRACT FROM AUTHOR]

California is regularly affected by floods and droughts, primarily as a result of too many or too few atmospheric rivers (ARs). This study analyzes a 2-decade-long hourly precipitation data set from 176 California weather stations and a 3-hourly AR chronology to report variations in rainfall events across California and their association with ARs. On average, 10-40 and 60-120 hours of rainfall in southern and northern California, respectively, are responsible for more than half of annual rainfall accumulations. Approximately 10% to 30% of annual precipitation at locations across the state is from only one large storm. On average, northern California receives 25 to 45 rainfall events annually (40% to 50% of which are AR-related). These events typically last longer and have higher event-precipitation totals than those in southern California. Northern California also receives more AR landfalls with longer durations and stronger Integrated Vapor Transport (IVT). On average, ARs contribute 79%, 76%, and 68% of extreme-rainfall accumulations (i.e., top 5% events annually) in the north coast, northern Sierra, and Transverse Ranges of southern California, respectively. The San Francisco Bay Area terrain gap in the California Coast Range allows more AR water vapor to reach inland over the Delta and Sacramento Valley, and thus influences precipitation in the Delta's catchment. This is particularly important for extreme precipitation in the northern Sierra Nevada, including river basins above Oroville Dam and Shasta Dam. This study highlights differences between rainfall and AR characteristics in coastal versus inland northern California -- differences that largely determine the regional geography of flood risks and water reliability. These analyses support water resource, flood, levee, wetland, and ecosystem management within the catchment of the San Francisco Estuary system by describing regional characteristics of ARs and their influence on rainfall on an hourly time-scale. [ABSTRACT FROM AUTHOR]

This article explores high-technology entrepreneurship in Silicon Valley - an environment in which technological innovation and new enterprises have thrived during the past 30 years. In this domain, the demise of one firm typically leads to the formation of others. This process of "flexible re-cycling" can result in novel reconfiguration of knowledge and human capabilities, allowing new firms to rise from the ashes of disengaged enterprises. The versatile ecosystem of Silicon Valley facilitates the process of flexible re-cycling and can be viewed as the enduring dimension of business activity. [ABSTRACT FROM AUTHOR]

The global crises of biodiversity loss and climate change are interconnected in root cause and solutions. Targeted land conservation has emerged as a leading strategy to protect vulnerable species and buffer climate impacts, however, consistent methods to assess biodiversity and prioritize areas for protection have not yet been established. Recent landscape-scale planning initiatives in California present an opportunity to conserve biodiversity, but to enhance their effectiveness, assessment approaches should move beyond commonly used measures of terrestrial species richness. In this study, we compile publicly available datasets and explore how distinct biodiversity conservation indices - including indicators of terrestrial and aquatic species richness and of biotic and physical ecosystem condition - are represented in watersheds of the northern Sierra Nevada mountain region of California (n = 253). We also evaluate the extent to which the existing protected area network covers watersheds that support high species richness and intact ecosystems. Terrestrial and aquatic species richness showed unique spatial patterns (Spearman R = 0.27), with highest richness of aquatic species in the low-elevation watersheds of the study area and highest richness of terrestrial species in mid- and high-elevation watersheds. Watersheds with the highest ecosystem condition were concentrated in upper-elevations and were poorly correlated with those with the highest species richness (Spearman R = −0.34). We found that 28% of watersheds in the study area are conserved by the existing protected area network. Protected watersheds had higher ecosystem condition (mean rank-normalized score = 0.71) than unprotected areas (0.42), but species richness was generally lower (0.33 in protected versus 0.57 in unprotected watersheds). We illustrate how the complementary measures of species richness and ecosystem condition can be used to guide strategies for landscape-scale ecosystem management, including prioritization of watersheds for targeted protection, restoration, monitoring, and multi-benefit management. Though designed for California, application of these indices to guide conservation planning, design monitoring networks, and implement landscape-scale management interventions provides a model for other regions of the world. • Species richness and ecosystem condition are poorly correlated (Spearman R = −0.34). • Terrestrial and aquatic species richness show distinct spatial patterns (R = 0.27). • Protected areas have higher ecosystem conditions but lower species richness. • Landscape planning should include dimensions of biodiversity value and condition. [ABSTRACT FROM AUTHOR]

Finding novel ways to plan and implement landscape-level forest treatments that protect sensitive wildlife and other key ecosystem components, while also reducing the risk of large-scale, high-severity fires, can prove to be difficult. We examined alternative approaches to landscape-scale fuel-treatment design for the same landscape. These approaches included two different treatment scenarios generated from an optimization algorithm that reduces modeled fire spread across the landscape, one with resource-protection constrains and one without the same. We also included a treatment scenario that was the actual fuel-treatment network implemented, as well as a no-treatment scenario. For all the four scenarios, we modeled hazardous fire potential based on conditional burn probabilities, and projected fire emissions. Results demonstrate that in all the three active treatment scenarios, hazardous fire potential, fire area, and emissions were reduced by approximately 50 % relative to the untreated condition. Results depict that incorporation of constraints is more effective at reducing modeled fire outputs, possibly due to the greater aggregation of treatments, creating greater continuity of fuel-treatment blocks across the landscape. The implementation of fuel-treatment networks using different planning techniques that incorporate real-world constraints can reduce the risk of large problematic fires, allow for landscape-level heterogeneity that can provide necessary ecosystem services, create mixed forest stand structures on a landscape, and promote resilience in the uncertain future of climate change. [ABSTRACT FROM AUTHOR]

A methodology was developed to assess the impacts of the historic 2013-2014 drought on ecosystems of California's Central Coast region, using a combination of satellite image analysis and in situ measurements of soil moisture in predominant vegetation types of the region. According to differences in Landsat drought indices for plant water stress and vegetation green cover (NDWI and NDVI, respectively), the geographic areas within the study region that were most severely impacted by the 2013 drought were the inland Carmel Valley in northern Monterey County and the coastal zones around San Simeon Point and Cambria in northern San Luis Obispo County. An expanded area of severe vegetation moisture stress, generally indicated by relative-differenced NDWI values of >400, was detected by May 2014 in both of these same geographic areas. For more detailed examination of drought impacts, the entire study region was separated into the 3 predominant vegetation types (grasslands, shrublands, and forests) to examine changes in Landsat NDWI and NDVI in the context of differing plant community responses to severe drought. Results confirmed that higher overall drought stress in 2013 and 2014 was detected in grasslands, compared to shrublands and forests, in both years at all elevations and slopes >200 m and >5%, respectively. [ABSTRACT FROM AUTHOR]

The article discusses several lessons offered by the continuing drought in California for the management of the San Francisco Bay and Sacramento-San Joaquin Delta. A particular focus is given to the need to address ecosystem values and water supply. Also noted are the steps for drought management, including the development of a complete financing plan, and the potential effect of the drought on agriculture in the delta.

Numerous experiments have demonstrated that diverse plant communities use nitrogen (N) more completely and efficiently, with implications for how species conservation efforts might influence N cycling and retention in terrestrial ecosystems. However, most such experiments have randomly manipulated species richness and minimized environmental heterogeneity, two design aspects that may reduce applicability to real ecosystems. Here we present results from an experiment directly comparing how realistic and randomized plant species losses affect plant N use across a gradient of soil depth in a native-dominated serpentine grassland in California. We found that the strength of the species richness effect on plant N use did not increase with soil depth in either the realistic or randomized species loss scenarios, indicating that the increased vertical heterogeneity conferred by deeper soils did not lead to greater complementarity among species in this ecosystem. Realistic species losses significantly reduced plant N uptake and altered N-use efficiency, while randomized species losses had no effect on plant N use. Increasing soil depth positively affected plant N uptake in both loss order scenarios but had a weaker effect on plant N use than did realistic species losses. Our results illustrate that realistic species losses can have functional consequences that differ distinctly from randomized losses, and that species diversity effects can be independent of and outweigh those of environmental heterogeneity on ecosystem functioning. Our findings also support the value of conservation efforts aimed at maintaining biodiversity to help buffer ecosystems against increasing anthropogenic N loading. [ABSTRACT FROM AUTHOR]

A strategy for recovering endangered species during climate change is to restore ecosystem processes that moderate effects of climate shifts. In mid-latitudes, storm patterns may shift their intensity, duration, and frequency. These shifts threaten flooding in human communities and reduce migration windows (conditions suitable for migration after a storm) for fish. Rehabilitation of historic floodplains can in principle reduce these threats via transient storage of storm water, but no one has quantified the benefit of floodplain rehabilitation for migrating fish, a widespread biota with conservation and economic value. We used simple models to quantify migration opportunity for a threatened migratory fish, steelhead ( Oncorhynchus mykiss), in an episodic rain-fed river system, the Pajaro River in central California. We combined flow models, bioenergetic models, and existing climate projections to estimate the sensitivity of migration windows to altered storm patterns under alternate scenarios of floodplain rehabilitation. Generally, migration opportunities were insensitive to warming, weakly sensitive to duration or intensity of storms, and proportionately sensitive to frequency of storms. The rehabilitation strategy expanded migration windows by 16-28% regardless of climate outcomes. Warmer conditions raised the energy cost of migrating, but not enough to matter biologically. Novel findings were that fewer storms appeared to pose a bigger threat to migrating steelhead than warmer or smaller storms and that floodplain rehabilitation lessened the risk from fewer or smaller storms across all plausible hydroclimatic outcomes. It follows that statistical downscaling methods may mischaracterize risk, depending on how they resolve overall precipitation shifts into changes of storm frequency as opposed to storm size. Moreover, anticipating effects of climate shifts that are irreducibly uncertain (here, rainfall) may be more important than anticipating effects of relatively predictable changes such as warming. This highlights a need to credibly identify strategies of ecosystem rehabilitation that are robust to uncertainty. Rehabilitación de Planicies Inundables como Cerco contra la Incertidumbre Hidroclimática en un Corredor Migratorio de Oncorhynchus mykiss, Especie Amenazada [ABSTRACT FROM AUTHOR]

In recent years, the use of postfire mulch treatments to stabilize slopes and reduce soil erosion in shrubland ecosystems has increased; however, the potential effects on plant recovery have not been examined. To evaluate the effects of mulching treatments on postfire plant recovery in southern California coastal sage scrub, we conducted a field experiment with three experimental treatments, consisting of two hydromulch products and an erosion control blanket, plus a control treatment. The area burned in 2007, and treatments were applied to six plot blocks before the 2008 growing season. Treatment effects on plant community recovery were analyzed with a mixed effects ANOVA analysis using a univariate repeated measures approach. Absolute plant cover increased from 13 to 90% by the end of the second growing season, and the mean relative cover of exotic species was 32%. The two hydromulch treatments had no effect on any plant community recovery response variable measured. For the erosion control blanket treatment, the amount of bare ground cover at the end of the second growing season was significantly lower ( P = 0.01), and greater shrub height was observed ( P < 0.01). We conclude that postfire mulch treatments did not provide either a major benefit or negative impact to coastal sage scrub recovery on the study area. [ABSTRACT FROM AUTHOR]

El Nin˜ o events elevate water levels, change wave direction and storm frequency, and provide an analogy to the likely impacts of climate change. Elevated sea levels intensify coastal erosion impacts affecting not only oceanfront property and recreational users, but also habitats and species that depend on the coast. This study examines physical and ecological responses to and recovery from the extreme 1997–98El Nin˜ o along beaches of Isla Vista, California, a stretch of coastline dominated by unidirectional alongshore sediment transport. Using topographic light detection and ranging (LIDAR), physical measurements, and biological surveys we quantify physical changes and assess ecological responses. We quantify short-term reductions in beach widths (.60%) and sand volumes (,80%). Although dune-backed beaches lost greater sand volumes, bluff-backed shorelines lost greater percentages of beach width. Four erosion hot spots were identified consistent with a pattern of beach reorientations. Macrophyte wrack abundance, a primary food for sandy beach ecosystems, was significantly correlated with dry sand beach width. Macroinvertebrate biomass was reduced and a decline in mean size of individuals persisted for several species. Abundance and species richness of shorebirds were lower during the El Nin˜ o. Beach segments and reorientations recovered at different times, on the basis of littoral drift direction, shoreline orientation, and wave exposure. The reorientation at the updrift beach impounded sand for .3 years after the El Nin˜ o, catalysing an erosion wave that propagated downdrift affecting downcoast beaches. Recovery of the updrift beach led to the widest beach widths shown in the historic record, whereas the downdrift beach underwent continued erosion .6 years after the El Nin˜ o. Recovery of wrack abundance and shore birds to pre-El Nin˜ o levels took .3 years. Reductions in biomass and mean size of invertebrates were detected 2 years after the event. Recovery time lines provide information for coastal managers evaluating impacts and timing of erosion mitigation alternatives. [ABSTRACT FROM AUTHOR]

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Empirical critical loads for N deposition effects and maps showing areas projected to be in exceedance of the critical load (CL) are given for seven major vegetation types in California. Thirty-five percent of the land area for these vegetation types (99,639km2) is estimated to be in excess of the N CL. Low CL values (3–8kgNha−1 yr−1) were determined for mixed conifer forests, chaparral and oak woodlands due to highly N-sensitive biota (lichens) and N-poor or low biomass vegetation in the case of coastal sage scrub (CSS), annual grassland, and desert scrub vegetation. At these N deposition critical loads the latter three ecosystem types are at risk of major vegetation type change because N enrichment favors invasion by exotic annual grasses. Fifty-four and forty-four percent of the area for CSS and grasslands are in exceedance of the CL for invasive grasses, while 53 and 41% of the chaparral and oak woodland areas are in exceedance of the CL for impacts on epiphytic lichen communities. Approximately 30% of the desert (based on invasive grasses and increased fire risk) and mixed conifer forest (based on lichen community changes) areas are in exceedance of the CL. These ecosystems are generally located further from emissions sources than many grasslands or CSS areas. By comparison, only 3–15% of the forested and chaparral land areas are estimated to be in exceedance of the NO3 − leaching CL. The CL for incipient N saturation in mixed conifer forest catchments was 17kgNha−1 yr−1. In 10% of the CL exceedance areas for all seven vegetation types combined, the CL is exceeded by at least 10kgNha−1 yr−1, and in 27% of the exceedance areas the CL is exceeded by at least 5kgNha−1 yr−1. Management strategies for mitigating the effects of excess N are based on reducing N emissions and reducing site N capital through approaches such as biomass removal and prescribed fire or control of invasive grasses by mowing, selective herbicides, weeding or domestic animal grazing. Ultimately, decreases in N deposition are needed for long-term ecosystem protection and sustainability, and this is the only strategy that will protect epiphytic lichen communities. [Copyright &y& Elsevier]

The article presents a case study on the impacts of fishing of juvenile rockfish during the breeding season of seabirds in the California Current System. The hypothesis that fishing decreases juvenile rockfish availability that limits the seabird productivity using a fisheries stock assessment approach is evaluated. The study notes that the impacts of rockfish fisheries on seabird productivity was due to ocean climate and the seabirds ability to resist the changes by prey-switching.

In the United States multispecies habitat conservation plans were meant to be the solution to conflicts between economic development and protection of biological diversity. Although now widely applied, questions exist concerning the scientific credibility of the conservation planning process and effectiveness of the plans. We used ants to assess performance of one of the first regional conservation plans developed in the United States, the Orange County Central-Coastal Natural Community Conservation Plan (NCCP), in meeting its broader conservation objectives of biodiversity and ecosystem-level protection. We collected pitfall data on ants for over 3 years on 172 sites established across a network of conservation lands in coastal southern California. Although recovered native ant diversity for the study area was high, site-occupancy models indicated the invasive and ecologically disruptive Argentine ant (Linepithema humile ) was present at 29% of sites, and sites located within 200 m of urban and agricultural areas were more likely to have been invaded. Within invaded sites, native ants were largely displaced, and their median species richness declined by more than 60% compared with uninvaded sites. At the time of planning, 24% of the 15,133-ha reserve system established by Orange County NCCP fell within 200 m of an urban or agricultural edge. With complete build out of lands surrounding the reserve, the proportion of the reserve system vulnerable to invasion will grow to 44%. Our data indicate that simply protecting designated areas from development is not enough. If habitat conservation plans are to fulfill their conservation promise of ecosystem-level protection, a more-integrated and systematic approach to the process of habitat conservation planning is needed. [ABSTRACT FROM AUTHOR]

The Lake Tahoe basin, located along the California and Nevada border between the Carson and Sierra Nevada mountain ranges, represents a complex forested ecosystem consisting of numerous sub-watersheds and tributaries that discharge directly to Lake Tahoe. This synthesis focuses on historical and current nutrient pools and the effects of biomass management in watersheds of the basin relative to their potential impacts on nutrient (N, P) related discharge water quality. An accumulating forest floor as a result of fire suppression has resulted in the build-up of large nutrient pools that now provide a "natural" source of long term nutrient availability to surface waters. As a consequence, stand and forest floor replacing wildfire may cause a large magnitude nutrient mobilization impact on runoff water quality. Hence, mechanical harvest and controlled burning have become popular management strategies. The most ecologically significant long-term effects of controlled fire appear to be the loss of C and N from the forest floor. Although the application of controlled fire may have some initial impact on overland/litter interflow nutrient loading, controlled burning in conjunction with mechanical harvest has the potential to improve runoff water quality by reducing N and P discharge and improving the overall health of forest ecosystems without the danger of a high intensity wildfire. [ABSTRACT FROM AUTHOR]

Abstract: Governance and planning of ecosystem and water management within the California Bay-Delta, a critical component of California''s water economy, have been characterized by a range of innovations in collaboration and conflict resolution. Despite legal mandates to incorporate environmental justice, the California Bay-Delta Authority''s (CBDA) policy-development process and the subsequent Delta Vision process have systematically marginalized the role of environmental justice in California''s water policy. We suggest that environmental justice in Bay-Delta planning can be understood as a “third party” with a tenuous seat at the CALFED water management table. As such environmental justice is a useful lens through which to assess the state''s broader commitments and capacities relative to equity as a planning principal and outcome. We interpret the fate of environmental justice within Bay-Delta planning as indicative of the inherent tensions between systems based on increasing market dominance and state legitimation and the values of environmental justice based on distributive, procedural, and cognitive justice. We construct a model of marginalization and environmental injustice in collaborative planning to illustrate these tensions. We draw upon experiences of members of the Environmental Justice Sub-Committee of CBDA''s Bay Delta Public Advisory Committee, as well as interviews with other key environmental justice interests, and a comprehensive review of internal and public CBDA documents relating to the environmental justice program including budgets and program plans, and ethnographic field work. We conclude that by learning from the mistakes of Bay-Delta planning, a positive model of collaborative, environmental justice-based planning for water and ecosystem management is possible. [Copyright &y& Elsevier]

1. Resource management agencies are often charged with managing natural resources for economic and social goals, while also protecting and conserving biodiversity and ecosystem function. However, this may not always be possible. Ecosystem-based management is frequently suggested as a way to achieve multiple objectives in resource management and requires that trade-offs among conflicting objectives be identified and an effective means to utilize these trade-offs developed. 2. We examine the relationship between area and species richness in a diverse assemblage of fishes along the US West Coast and then use parameters from this relationship as input for a model that considers trade-offs between fisheries yield and the number of species protected by different management strategies. 3. The species–area relationship ( S = cA z) for fishes along the US Pacific coast is well described by the relationship S = 16·18 A0·226. 4. There are nearly linear trade-offs between diversity and yield when fishing effort is low. However, the trade-offs become nonlinear as fishing effort increases and imposing MPAs increases both the conservation and fisheries value of the system when the system is overfished. 5. Synthesis and applications. Solving conflicts between fisheries and conservation requires attention as to how conservation benefits accrue as fishing effort is reduced. However, scientists often lack quantitative information about the trade-offs inherent in human activities such as fisheries. The approach we develop here can begin to help frame the questions to be posed and evaluate the likely consequences of different management options. [ABSTRACT FROM AUTHOR]

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, measured vegetation characteristics, quantified human activities, and evaluated ant-community responses by grouping ants into service-providing units (SPUs), defined as a group of organisms and their populations that perform specific ecosystem services, to provide an understanding of urbanization impacts on biodiversity and their delivery of ecosystem services. Species richness and abundance peaked at intermediate levels of urban development, as did the richness of 3 types of ant SPUs (aerators, decomposers, and compilers). With increasing land development aerator and decomposer ants significantly declined in abundance, whereas compiler ants significantly increased in abundance. Competing models demonstrated that precipitation was frequently among the strongest influences on ant community structure; however, urban development and human activities also had a strong, negative influence on ants, appearing in most models with ΔAICc < 2 for species richness and abundance patterns of SPUs and generalists. Response diversity was observed within SPUs, which suggests that the corresponding ecosystem services were maintained until development reached 30–40%. Our data provide evidence that ecosystem functions, such as water infiltration and soil productivity, may be diminished at sites subject to greater levels of urbanization and that conserving ant communities and the ecosystem services they provide could be an important target in land-use planning and conservation efforts. [ABSTRACT FROM AUTHOR]

The article discusses a study about the severity of fire and the subsequent response of ecosystem after the crown fires in California shrublands. This paper focuses on the large high-intensity crown fires that happened in the chaparral. The impact of these fires in ecosystem processes have been studied by managers to gather information that can help in future incidents. Surrogate measures of fire intensity through fire severity metrics are applied in looking for data. Sites during the 2003 autumn shrublands fire were investigated.

This article, both theoretical and methodological in nature, argues the potential merits of using a net benefits’ framework as a tool to aid policy makers in their efforts to compare Salton Sea restoration alternatives and inform the public as to the potential magnitude and distribution of trade-offs associated with each alternative. A net benefits’ approach can provide a more accurate comparison and evaluation of the potential net returns from public spending on Salton Sea restoration than what would be provided under the suggested criteria of current legislative mandates. Furthermore, a net benefits’ framework provides a more lucid and systematic accounting framework by which to enumerate the full array of benefits and costs of each alternative for policy analysis. Finally, net benefits’ analysis serves to add transparency to the decision-making process so that the public gains an understanding of how its scarce resources, including both financial and natural capital, are being appropriated. Additionally, we illustrate and emphasize the importance of estimating the non-market values associated with many of the ecosystem services provided by the Salton Sea and describe the major techniques that do so. [ABSTRACT FROM AUTHOR]

Restoration of natural systems depends, in part, on reconstructing historic landscapes to serve as reference ecosystems. The most effective historic landscape reconstruction relies on multiple lines of evidence at different temporal and spatial scales. This study analyzes original Public Land Survey (PLS) records and compares the results with previous work that relied on dendroecology and aerial photograph evidence of vegetation change. Notations in the land survey regarding the location of prairie-woody vegetation ecotones in the Bald Hills of Redwood National Park were transcribed into a geographic information system. Sugihara and Reed (1987) measured the degree of coniferous forest encroachment into prairies and oak woodlands, estimating a 29 percent loss in the spatial extent between 1850 and 1983. The location of 1875-1882 land survey records of ecotones provides evidence that transects across the prairies might have narrowed by as much as 44 percent. Furthermore, this study found evidence of both oak woodland and coniferous forest encroachment into prairies, and that the diminishment of prairies further inland might result primarily from the expansion of oak woodland. A reconstruction of the historic landscape that relies on both field and archival evidence is the best approach to defining reference ecosystems. [ABSTRACT FROM AUTHOR]

Ecological observations sustained over decades often reveal abrupt changes in biological communities that signal altered ecosystem states. We report a large shift in the biological communities of San Francisco Bay. first detected as increasing phytoplankton biomass and occurrences of new seasonal blooms that began in 1999. This phytoplankton increase is paradoxical because it occurred in an era of decreasing wastewater nutrient inputs and reduced nitrogen and phosphorus concentrations, contrary to the guiding paradigm that algal biomass in estuaries increases in proportion to nutrient inputs from their watersheds. Coincidental changes included sharp declines in the abundance of bivalve mollusks, the key phytoplankton consumers in this estuary, and record high abundances of several bivalve predators: Bay shrimp, English sole, and Dungeness crab. The phytoplankton increase is consistent with a trophic cascade resulting from heightened predation on bivalves and suppression of their filtration control on phytoplankton growth. These community changes in San Francisco Bay across three trophic levels followed a state change in the California Current System characterized by increased upwelling intensity, amplified primary production, and strengthened southerly flows. These diagnostic features of the East Pacific "cold phase" lead to strong recruitment and immigration of juvenile flatfish and crustaceans into estuaries where they feed and develop. This study, built from three decades of observation, reveals a previously unrecognized mechanism of ocean-estuary connectivity. Interdecadal oceanic regime changes can propagate into estuaries, altering their community structure and efficiency of transforming land-derived nutrients into algal biomass. [ABSTRACT FROM AUTHOR]

The article reports that delta smelt fish was listed as endangered species in Delta Region, California. According to the article, these small fish, native to the San Joaquin River Delta, are bred and farmed out to fisheries biologists throughout the region who are racing to understand their life cycle, feeding habits and vulnerabilities. Historically, millions of the fish swam in this river, however a survey of juvenile smelt conducted in June 2007 found only 37, down from 884 found a year earlier.

Despite increasing attention to the human dimension of conservation projects, a rigorous, systematic methodology for planning for ecosystem services has not been developed. This is in part because flows of ecosystem services remain poorly characterized at local-to-regional scales, and their protection has not generally been made a priority. We used a spatially explicit conservation planning framework to explore the trade-offs and opportunities for aligning conservation goals for biodiversity with six ecosystem services (carbon storage, flood control, forage production, outdoor recreation, crop pollination, and water provision) in the Central Coast ecoregion of California, United States. We found weak positive and some weak negative associations between the priority areas for biodiversity conservation and the flows of the six ecosystem services across the ecoregion. Excluding the two agriculture-focused services—crop pollination and forage production—eliminates all negative correlations. We compared the degree to which four contrasting conservation network designs protect biodiversity and the flow of the six services. We found that biodiversity conservation protects substantial collateral flows of services. Targeting ecosystem services directly can meet the multiple ecosystem services and biodiversity goals more efficiently but cannot substitute for targeted biodiversity protection (biodiversity losses of 44% relative to targeting biodiversity alone). Strategically targeting only biodiversity plus the four positively associated services offers much promise (relative biodiversity losses of 7%). Here we present an initial analytical framework for integrating biodiversity and ecosystem services in conservation planning and illustrate its application. We found that although there are important potential trade-offs between conservation for biodiversity and for ecosystem services, a systematic planning framework offers scope for identifying valuable synergies. [ABSTRACT FROM AUTHOR]

Collaborative approaches to environmental and natural resource management are on the rise in the United States. This article examines collaborative governance in four high-profile and large-scale ecosystems: the Northwest Power and Conservation Council's Fish and Wildlife Program in the Columbia River Basin, the Chesapeake Bay Program, the CALFED Bay-Delta Program in California's San Francisco Bay/Sacramento-San Joaquin River Delta, and the Florida Everglades Restoration Program. We compare the governance structures of these four institutional arrangements by examining how collaboration occurs or is organized at three different levels of decision making: constitutional, collective choice (or policymaking), and operational (or implementation). This includes an examination of governance and advisory bodies as well as coordinating and monitoring structures. [ABSTRACT FROM AUTHOR]

The article reports on the role of the Pacific salmon in transporting marine-derived nutrient to adjacent forest ecosystems with significant effects on plant and wildlife production. A study on two California wine country rivers showed that Mokelumne River Chinook salmon transported biomass and nitrogen similar to Pacific Northwest salmon streams while those from Calaveras River were much less. The study suggests that abundant salmon continues to provide essential ecological services with high economic value, particularly in impaired watersheds. The loss of the Pacific salmon could not only affect the stream and riparian vegetation ecosystem function, but can also create local economy disruption where agriculture and salmon streams coexist.

It is currently unclear whether observed pelagic ecosystem responses to ocean warming, such as a mid-1970s change in the eastern North Pacific, depart from typical ocean variability. We report variations in planktonic foraminifera from varved sediments off southern California spanning the past 1400 years. Increasing abundances of tropical/subtropical species throughout the 20th century reflect a warming trend superimposed on decadal-scale fluctuations. Decreasing abundances of temperate/subpolar species in the late 20th century indicate a deep, penetrative warming not observed in previous centuries. These results imply that 20th-century warming, apparently anthropogenic, has already affected lower trophic levels of the California Current. [ABSTRACT FROM AUTHOR]

Demonstrates the sophistication and complexity of past resource management systems that shaped the ecology of temperate wildlands using the management of diverse array of shrub species for California Indian basketry. Use of fire and pruning to shape ecosystem structure and reduce the occurrence of insects and diseases; Ecological rationale for indigenous management.

Recent legislation designed to reduce air pollution has restricted Californian rice-farmers from burning rice stubble after harvest. Intentional flooding of fields during winter to speed straw decomposition is becoming increasingly common as growers seek alternatives to burning residual straw. The potential for flooded fields to act as a surrogate for destroyed wetland habitat may be an additional benefit in a region that hosts a large proportion of North Americaߣs wintering waterbirds. We investigated the degree to which waterbirds use flooded fields and whether the method of flooding affects their use. Specifically, we tested whether waterbird use (a) was greater in intentionally flooded fields than in unflooded fields, (b) differed among flooded fields receiving different straw manipulations and (c) varied with water depth. Intentionally flooded rice fields received significantly greater use by 24 of 31 species studied. Only great blue herons Ardea herodias and sandhill cranes Grus Canadensis were significantly more common in unflooded fields. Geese densities did not differ between flooded and unflooded fields. We found no differences in the densities of most species in flooded fields that received different straw manipulations to improve decomposition rates. Exceptions included several small shorebirds which occurred at highest densities in fields where straw was incorporated into the soil. Species differed in their use of different water depths. For 14 species we tested whether preferred depths, suggested in the literature, received disproportionately higher use. Most of these species were more likely to be encountered within the suggested depth ranges. Depth, however, was a poor predictor of bird density. Depths of 15–20 cm resulted in frequent use by the greatest number of species. We conclude that flooding rice fields increased suitable habitat for most, but not all, species studied. Different straw manipulation methods had little effect on most species. Water depth, however, was important in determining species occurrence. During the first half of the winter, water depths were greater than the median depths used by most species. [ABSTRACT FROM AUTHOR]

The article focuses on a pest management program developed during 1970-1975 for Berkeley, California's 30,000 street trees. Key components in the program were a public education effort and the importation of host-specific parasitic Hymenoptera to control various species of aphids. In Berkeley, prior to introduction of the program the insecticide usage levels had prevailed for 10-15 years. Comments are made on the importance of developing trained ecosystem managers for urban problems and creating a place for such professionals in municipal governments.

• We synthesize three years of research in urban community gardens in Central Coast, California. • Global social and environmental change factors impact management and delivery of ecosystem services. • Garden regulations and management decisions by gardeners determine the ecological complexity of gardens. • Ecological complexity can affect the ecosystem service, such as food provision, coming from gardens. • Active management can increase social-ecological outcomes that feedback to the larger system. Urban community gardens are vital green spaces threatened by global social and environmental change factors. Population growth has reduced the amount of space available in cities, and climate change challenges plant growth thresholds. Urban community gardens provide dynamic socio-ecological systems to study how such social and environmental change factors affect the management and delivery of ecosystem services. They provide spaces where urban citizens purposefully interact with nature and receive multiple benefits. In this paper, we synthesize the results of three years of research in a case study of urban community gardens across the Central Coast of California and present a framework showing how both social and environmental change factors at the regional scale affect the ecological make-up of urban community gardens, which in turn affect the ecosystem services coming from such systems. Our study reveals that global environmental change felt at the regional level (e.g., increased built environment, climate change) interact with social change and policy (e.g., population growth, urbanization, water use policy), thus affecting regulations over garden resources (e.g., water availability) and management decisions by gardeners (e.g., soil management, crop planting decisions). These management decisions at the plot-scale, determine the ecological complexity and quality of the gardens and affect the resulting ecosystem services that come from these systems, such as food provision for both humans and urban animals. A greater understanding of how environmental and social change factors drive the management processes of urban community gardens is necessary to design policy support systems that encourage the continued use and benefits arising from such green spaces. Policies that can support urban community gardens to maintain ecological complexity and increase biodiversity through active management of soil quality and plant diversity have the potential to increase social and environmental outcomes that feedback to the larger environmental and social system. [ABSTRACT FROM AUTHOR]

Features a case study on the ecosystem alteration of the Salton Sea in California. Background on the Salton Sea; Discussion on Salton Sea's problems; Possible solutions.

The article argues that in order for ecosystem service to be a viable option for conservation efforts, it must be understood that it has limitations and that there are opportunity costs. The author looks at the cases of almond farmers in California and coffee farmers in India. It is noted that the almond farmers are reliant on honeybees to pollinate their crops although bees are losing habitat and are falling in numbers. In India coffee plants are pollinated by bees that live in certain native trees but these are being replaced by other trees and land is being cleared to grow more crops.

The article reports that the state officials in Nevada and California are concerned over the discovery of quagga mussels in the Lake Mead, Nevada and downstream in the Colorado River, due to their ability to cause ecological and economic damage. Quagga mussels along with the Zebra mussels are known to clog intake pipes of power plants, coat the hulls of boats, and damage ecosystems. An emergency task force of the National Park Service and state agencies have suspended the Park Service boats, and private boats are being inspected more frequently. But mussels are reported to have already spread downstream. On 17 January, divers found quagga mussels in Lake Havasu, near the intake to the Colorado River Aqueduct. The Metropolitan Water District is planning to use copper sulfate to kill them.