Effective conservation and restoration of estuarine wetlands require accurate maps of their historical and current extent, as well as estimated losses of these valued habitats. Existing coast-wide ...tidal wetland mapping does not explicitly map historical tidal wetlands that are now disconnected from the tides, which represent restoration opportunities; nor does it use water level models or high-resolution elevation data (e.g. lidar) to accurately identify current tidal wetlands. To better inform estuarine conservation and restoration, we generated new maps of current and historical tidal wetlands for the entire contiguous U.S. West Coast (Washington, Oregon, and California). The new maps are based on an Elevation-Based Estuary Extent Model (EBEEM) that combines lidar digital elevation models (DEMs) and water level models to establish the maximum historical extent of tidal wetlands, representing a major step forward in mapping accuracy for restoration planning and analysis of wetland loss. Building from this new base, we also developed an indirect method for mapping tidal wetland losses, and created maps of these losses for 55 estuaries on the West Coast (representing about 97% of historical West Coast vegetated tidal wetland area). Based on these new maps, we estimated that total historical estuary area for the West Coast is approximately 735,000 hectares (including vegetated and nonvegetated areas), and that about 85% of vegetated tidal wetlands have been lost from West Coast estuaries. Losses were highest for major river deltas. The new maps will help interested groups improve action plans for estuarine wetland habitat restoration and conservation, and will also provide a better baseline for understanding and predicting future changes with projected sea level rise.
Throughout the world, efforts are under way to restore watersheds, but restoration planning rarely accounts for future climate change. Using a series of linked models of climate, land cover, ...hydrology, and salmon population dynamics, we investigated the impacts of climate change on the effectiveness of proposed habitat restoration efforts designed to recover depleted Chinook salmon populations in a Pacific Northwest river basin. Model results indicate a large negative impact of climate change on freshwater salmon habitat. Habitat restoration and protection can help to mitigate these effects and may allow populations to increase in the face of climate change. The habitat deterioration associated with climate change will, however, make salmon recovery targets much more difficult to attain. Because the negative impacts of climate change in this basin are projected to be most pronounced in relatively pristine, high-elevation streams where little restoration is possible, climate change and habitat restoration together are likely to cause a spatial shift in salmon abundance. River basins that span the current snow line appear especially vulnerable to climate change, and salmon recovery plans that enhance lower-elevation habitats are likely to be more successful over the next 50 years than those that target the higher-elevation basins likely to experience the greatest snow-rain transition.
Based on known relationships of slope, discharge, valley confinement, sediment supply, and sediment caliber in controlling channel patterns, we developed multivariate models to predict natural ...channel patterns across the 674,500 km2 Columbia River basin, USA. We used readily available geospatial data sets to calculate reach slopes, 2 year flood discharge, and valley confinement, as well as to develop hypothesized landscape‐level surrogates for sediment load and caliber (relative slope, percent of drainage area in alpine terrain, and percent of drainage area in erosive fine‐grained lithologies). Using a support vector machine (SVM) classifier, we found that the four channel patterns were best distinguished by a model including all variables except valley confinement (82% overall accuracy). We then used that model to predict channel pattern for the entire basin and found that the spatial distribution of straight, meandering, anabranching, and braided patterns were consistent with regional topography and geology. A simple slope‐discharge model distinguished meandering channels from all other channel patterns, but did not clearly distinguish braided from straight channels (68% overall accuracy). Addition of one or more of the hypothesized sediment supply surrogates improved prediction accuracy by 4–14% over slope and discharge alone. Braided and straight channels were most clearly distinguished on an axis of relative slope, whereas braided and anabranching channels were most clearly distinguished by adding percent alpine area to the model.
Key Points
Channel pattern can be reliably predicted with a statistical model
Adding sediment supply variables improves prediction accuracy
Predicted channel patterns provide a guiding vision for river restoration
Ecologists are pressed to understand how climate constrains the timings of annual biological events (phenology). Climate influences on phenology are likely significant in estuarine watersheds because ...many watersheds provide seasonal fish nurseries where juvenile presence is synched with favorable conditions. While ecologists have long recognized that estuaries are generally important to juvenile fish, we incompletely understand the specific ecosystem dynamics that contribute to their nursery habitat value, limiting our ability to identify and protect vital habitat components. Here we examined the annual timing of juvenile coldwater fish migrating through a seasonally warm, hydrologically managed watershed. Our goal was to (1) understand how climate constrained the seasonal timing of water conditions necessary for juvenile fish to use nursery habitats and (2) inform management decisions about (a) mitigating climate-mediated stress on nursery habitat function and (b) conserving heat-constrained species in warming environments. Cool, wet winters deposited snow and cold water into mountains and reservoirs, which kept the lower watershed adequately cool for juveniles through the spring despite the region approaching its hot, dry summers. For every 1°C waters in April were colder, the juvenile fish population (1) inhabited the watershed 4–7 d longer and (2) entered marine waters, where survival is size selective, at maximum sizes 2.1 mm larger. Climate therefore appeared to constrain the nursery functions of this system by determining seasonal windows of tolerable rearing conditions, and cold water appeared to be a vital ecosystem component that promoted juvenile rearing. Fish in this system inhabit the southernmost extent of their range and already rear during the coolest part of the year, suggesting that a warming climate will truncate rather than shift their annual presence. Our findings are concerning for coldwater diadromous species in general because warming climates may constrain watershed use and diminish viability of life histories (e.g., late springtime rearing) and associated portfolio benefits over the long term. Lower watershed nurseries for coldwater fish in warming climates may be enhanced through allocating coldwater reservoir releases to prolong juvenile rearing periods downstream or restorations that facilitate colder conditions.
Fish face many anthropogenic stressors. Authorities in marine, estuarine, and freshwater realms often share interdependent fisheries management goals, but address singular stressors independently. ...Here, we present a case study suggesting that coordinating stressor relief across management realms may synergize conservation efforts, especially to actualize restoration benefits. Major efforts are underway to restore juvenile salmon habitat across California’s Central Valley landscape, but it is unclear how fisheries and flow management will influence juvenile salmon occupancy of restored sites. Leveraging monitoring data, we find that for juvenile salmon (<55 mm) to actualize benefits of restored habitats will likely require maintaining spawner abundances and flows at or above intermediate values, especially in less-connected portions of the landscape. Furthermore, restoration efforts may prioritize more connected regions to promote use of restored areas, considering that less connected areas are often uninhabited when water and spawners are scarcer. This ecosystem-based framework that evaluates interdependencies of management decisions may be applied to realize natural productivity and enhance conservation in many systems.
River restoration plans often propose multiple rehabilitation actions to address key habitat impairments, but they rarely attempt to quantify the potential benefits of alternative sets of actions for ...targeted biota. We use geomorphic and biological analyses to estimate restoration potential under three alternative scenarios for a 64‐km section of the Trinity River, California, between the North Fork Trinity River and Lewiston Dam, which is the focus of habitat rehabilitation efforts under the Trinity River Restoration Program. The three scenarios are (1) increasing habitat quality by wood additions and alcove construction, (2) increasing habitat quantity by increasing sinuosity and side‐channel length, and (3) increasing both habitat quality and quantity. For each scenario, we used existing stream habitat and juvenile salmonid data from previous studies to estimate potential improvements in fry or pre‐smolt production. The potential increase in Oncorhynchus tshawytscha (Chinook salmon) and O. mykiss (steelhead) fry rearing capacity was 62 and 67%, respectively, for Scenario 1 (increasing habitat quality), and 36 and 44% for Scenario 2 (increasing habitat quantity). Only the most optimistic Scenario 3 (increasing both habitat quality and quantity) more than doubles potential juvenile salmonid production (112% increase in Chinook fry capacity and 107% increase in steelhead fry capacity). These quantitative predictions are useful in developing realistic restoration targets and evaluating whether proposed restoration actions can achieve the aims of a restoration program.
The effects of supplemental feeding by tourists on wild Japanese monkey's home range size and location, and troop size and composition were studied for two monkey troops, Troop A and Troop B, living ...along the Irohazaka loop road, Nikko National Park, central Japan. Changes were documented based on data gathered from 1982 to 1996 by the use of radio telemetry. Troop A's home range size shrank and changed from separate winter and summer ranges to a single, year-round home range, with its core located in a high elevation area where supplemental feeding by tourists was heavy. Troop B's home range also shrank and shifted to a lower elevation where supplemental feeding by tourists was heavy. Troop A's population size increased between the winters of 1983-1984 and 1990-1991 in conjunction with an increase in human encounter rates, and then decreased. Troop B's size increased until the winter of 1993-1994, and then decreased. The instability of troop size between 1993 and 1996 may be explained by documented factors such as a decrease in the adult sex ratio, an increase in the infant-female ratio, and an increase in juvenile mortality and/or emigration, all of which may have been influenced by supplemental feeding by tourists.
Quantifying the attributes of reference sites is a crucial problem in the restoration of ecosystems, driving both the evaluation of current conditions and the setting of management targets for ...specific points in the future. Restoration of riparian ecosystems, particularly those dominated by conifers, has become a priority because of the numerous ecosystem services they provide, including a high number of vertebrate species in population decline that utilize these structurally complex forests. By way of example, we illustrate a three-step process to assess the effects of proposed riparian ecosystem restoration efforts: (1) identify reference sites (2) quantify metrics that describe the reference sites, and (3) use models to predict the likely effects of restoration actions relative to reference conditions. To this end, we identified 117 natural, late-successional conifer dominated stands from existing forest inventories in the Pacific Northwest for the purpose of establishing reference conditions. We did this to establish quantitative metrics for structural attributes essential to the maintenance of biodiversity in these forests, and to assess whether there were any important quantitative differences between upland and riparian forests or whether upland and riparian forest reference sites could be used interchangeably. Both forest types were generally similar, but riparian stands had higher average live tree wood volumes and basal areas, suggesting they may be growing on sites that are more productive. Both riparian and upland forests had abundant large diameter (>50 cm) live trees and snags. Collectively, our data suggest that mature, late-successional conifer dominated forests have well developed structural characteristics in terms of abundant large trees in the overstory, abundant large snags, and a well-developed understory of shade-tolerant trees. We modeled the growth of young conifer stands to assess whether a common restoration treatment would accelerate development of structural characteristics typical of reference conditions. We found that left untreated, the stands followed a trajectory towards developing forest structure similar to the average reference condition. In contrast, the restoration treatment followed a developmental trajectory along the outside range of reference conditions.
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