Riparian Conservation Research Articles

The Relationship between Erosion and Precipitation and the Effects of Different Riparian Practices on Soil and Total-P Losses via Streambank Erosion in Small Streams in Iowa, USA

Streambank erosion in agricultural landscapes contributes high amounts of sediment and total-P to surface water, resulting in the degradation of stream habitats and reduction in ecological services. Moreover, the implication of future climate change on bank erosion is also a growing concern. Streambank erosion rates from riparian forest buffers (RFo), grass filters (GFi), row-crops (RCr) and pastures, including fenced pastures (FPa), rotationally grazed pastures (RPa), intensive rotationally grazed pastures (IPa), and continuously grazed pastures (CPa), in three landform regions of Iowa, were measured over seven years. Bank erosion pins were measured seasonally (spring, summer and fall) in the first five years (2002–2006) and yearly for two more years (2007–2008). It was found that summer and spring seasons are the important ones since the relationships between erosion and precipitation were significantly “strong” in almost all the riparian practices, and precipitation was found to be the main factor driving streambank erosion. Streambank mean soil losses and soil total-P losses from RFo (23.3 tons km−1 yr−1 and 9.8 kg km−1 yr−1, respectively), GFi (31.1 and 9.9) and FPa (44.0 and 23.7) practices were all significantly lower than the grazing pasture practices, including RPa (142.3 and 58), CPa (255 and 105.1), IPa (234.6 and 122.7) and RCr fields (352.9 and 118.9). Also, RPa had significantly lower total-P loss than CPa, IPa and RCr practices (RFo, GFi, FPa < RPa < CPa, IPa, RCr). RCr practices had the highest streambank soil losses among all other riparian practices (RFo, GFi, FPa < RPa < IPa, CPa < RCr). The study showed that riparian conservation practices (RFo, GFi and FPa) showcased significant benefits in mitigating streambank soil loss and associated soil total-P load to streams. However, their effectiveness is highly sensitive to changing climatic conditions and the extent of spatiotemporal variations.

Socio Economic Factors Contributing to Riparian Ecosystem Degradation along Kaiti River in Makueni County

The degradation of riparian ecosystems threatens the livelihoods of communities that depend on these socio-ecological systems (SES) for their well-being. This is because; riparian ecosystems provide ecosystem services like fodder, timber, soil development, water regulation and habitat for wildlife. The riparian ecosystem in Kenya's Eastern Semi-Arid Region is one of the affected zones and information is required to understand the causes therein. This case study focussed on the Kaiti River in Makueni County to analyse the socio-economic factors leading to its riparian degradation. Data was collected between September 2018 to March 2019 using questionnaires, key informant interviews, focus group discussions and photographs. To analyse the data, SPSS version 26 interface with regression and correlation analysis was used to analyse the causes of riparian ecosystem degradation along the river. Crop farming was found to be a leading cause of degradation (R-Square =0.849, F (1, 99) =9.4495, p-value=0.0003<0.05) showing that farming accounts for 84.9% of the variations in degradation of River Kaiti riparian ecosystem. A calculated beta value implied that a unit raise in crop farming would lead to a rise in the degradation of the River Kaiti riparian ecosystem by 0.782 (p-value=0.001<0.05). The results of the study also revealed that livestock farming (R-Square =0.615, β=0.211, p-value =0.002≤0.05), lack of riparian conservation awareness (R-Square =0.573, β=-0.757, p-value= 0.002<0.05) and Commercial sand harvesting R-Square=0.659, β=0.205, p value=0.000<0.05) significantly contribute to River Kaiti riparian ecosystem degradation. Other causes significantly contributing to degradation (R-Square =0.520, β=0.212, p-value=0.001≤0.05,) were poor natural resource governance, poverty, poor infrastructure, climate change and land use changes. The study concludes that awareness creation and control of human activity in the Kaiti riparian zone would significantly reduce riparian ecosystem degradation. A multi-stakeholder approach whereby the community takes centre stage in monitoring and implementing riparian conservation measures is recommended.

Bridging the Gaps: Exploring Aquatic–Terrestrial Connectivity through the Trait-Based Ecology of Riparian Predatory Arthropods

Riparian predatory arthropods represent one of the main trophic links between lotic and terrestrial ecosystems along riverine landscapes. The use of the trait-based approach promises to enhance our understanding of how these predatory communities interact with their environment through their response to various drivers of change and through their trophic interactions. We reviewed the scientific literature focused on the interaction between drivers of community change (natural and anthropogenic) and the functional traits and functional diversity components that characterize riparian ground beetles and spiders and, ultimately, on their role as cross-ecosystem trophic links. We highlight land use changes and river regulations as the strongest drivers that change the communities we study, often through various interacting mechanisms that favor the replacement of riparian specialists with generalist species, thus altering aquatic–terrestrial connectivity and the resilience of riverine arthropod consumers. Tropical regions and traits related to community responses to extreme climatic events (e.g., submersion tolerance and desiccation resistance) are less studied, while inconsistent patterns are noticed for well-studied traits, especially for spiders (e.g., their feeding preference response to aquatic subsidy availability and their body size response to flooding and bank hydrological connectivity). Future research should focus on the aforementioned drivers and knowledge gaps, along with the functional diversity changes in predatory arthropod communities along environmental and anthropogenic impact gradients, in order to improve riparian conservation.

基于水量与水质的太湖流域水生态服务供需关系及多情景评估

PDF HTML阅读 XML下载 导出引用 引用提醒 基于水量与水质的太湖流域水生态服务供需关系及多情景评估 DOI: 10.5846/stxb202112223632 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41971230）；中国科学院"美丽中国生态文明建设科技工程"专项（XDA23020201）；国家自然科学基金青年项目（41701211） Supply and demand relationship and multi-scenario assessment of water ecological services related water quantity and quality in Taihu Lake Basin Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:耦合水量供给与水质净化的水生态服务供需关系的多尺度空间量化评估，有助于刻画和识别丰水区水质性缺水问题，并丰富水生态服务研究。在构建水量供给和水质净化服务供需评估方法的基础上，利用空间分析方法在现状情景基础上分别设置提升用水效率、改善土地管理方式和优化土地利用空间配置三种优化情景，并在栅格、子流域和县域三个尺度上开展基于水量供给和水质净化的水生态服务供需关系的定量评估，分别探讨了不同情景不同尺度下的水生态服务供需变化、空间响应及其机制特征。研究结果表明：（1）太湖流域的水量供需状况显著优于水质供需状况，节水能够有效改善流域内的水量赤字，而减量施肥和优化土地利用配置能够显著改善流域内的水质赤字。（2）多尺度的水量供给与水质净化服务供需解析，有助于精准识别不同尺度下亟需治理的关键区域。（3）水量赤字区主要集中在建设用地分布区域，耕地仍是引致水质赤字的主要原因，但随着尺度的逐渐增大，水质赤字区的建设用地面积也在不断增加。（4）优化土地利用结构方案是解决水质性缺水的最有效方法，但需要突破现有政策尤其是耕地保护政策的刚性约束，故耦合提升用水效率等方法是当前治理太湖流域"水质性缺水"问题首选措施。 Abstract:It is essential to conduct supply and demand assessment of water ecological services across multiple spatial scales by integrating water quantity and quality for identifying water shortage issues caused by water pollution in humid regions. This study developed a comprehensive model that integrated water quantity and quality for quantifying the supply-demand relationships of water ecological services for the Taihu Lake Basin (TLB). This study also constructed three optimized scenarios (Water Efficiency Improvement, Fertilization Reduction, and Land Use Structure Optimization) to explore the spatial variations and key driving factors of water resources supply and demand on the grid, sub-basin, and county levels. We got the following conclusions:(1) The TLB was sufficient in water quantity, but it was deficient in water quality. Water efficiency improvement significantly reduced the demand for water resources in the TLB. Fertilization reduction and land use optimization greatly improved water quality. (2) The supply and demand assessment of water ecological services across the three spatial scales could help in identifying key areas for promoting sustainable water use in the TLB. (3) Urban land was primarily located in the regions with deficient water quantity. In comparison, croplands dominated the regions with deficient water quality, while these regions of deficient water quality were also comprised of large areas of urban land when assessed at the county level. (4) Land use optimization such as grain for green and riparian conservation was the most effective in improving water quality for the TLB, but it was at the huge cost of cropland losses. Therefore, coupling other optimization ways such as water efficiency improvement that would be the best measurement for solving pollution-caused water shortage issues in the TLB. 参考文献 相似文献 引证文献

Increasing contribution of alluvial groundwater to riparian cottonwood forest water use through warm and dry summers

In semi-arid regions, riparian forests access alluvial groundwater to supplement the limited local precipitation. Understanding the sensitivity of riparian forests to variations in weather and climate, and water resources management is essential for guiding riparian conservation measures, especially on rivers impacted by dams and water withdrawal. We anticipated a seasonal trade-off in ecosystem water sources, with increasing relative groundwater use through the summer to compensate for the reduced availability of the shallow soil moisture. To test this hypothesis, we assessed the temporal patterns of alluvial groundwater uptake by a riparian cottonwood (Populus species) forest along a regulated river in southern Alberta, Canada over a three-year interval with relatively warm and dry weather, and low river flows. In support of our hypothesis, groundwater evapotranspiration, as calculated from diurnal fluctuations in the alluvial water table, displayed relative seasonal consistency until the autumnal leaf senescence period. In contrast, the ecosystem-scale evapotranspiration, measured by eddy covariance, gradually receded through the summer as precipitation inputs that fed the shallow soil layers became limited. The consistent uptake rate of alluvial groundwater by cottonwoods enables riparian forests to maintain high rates of water use and productivity in this semi-arid prairie region. We conclude the consistent groundwater use through the warm and dry summer reflected: (1) perennial river flow that replenished the floodplain aquifer; (2) adaptations of cottonwoods to the riparian hydrology and the semi-arid climate; and (3) environmental flow operations that maintained the minimum river and alluvial groundwater levels. Our study provides information on the riparian forest water sources and water use patterns that could help water managers effectively regulate river flows to support healthy downstream riparian ecosystems.

Riparian Buffers as a Critical Landscape Feature: Insights for Riverscape Conservation and Policy Renovations

Riparian zones are critical for functional integrity of riverscapes and conservation of riverscape biodiversity. The synergism of intermediate flood-induced disturbances, moist microclimates, constant nutrient influx, high productivity, and resource heterogeneity make riparian zones disproportionately rich in biodiversity. Riparian vegetation intercepts surface-runoff, filters pollutants, and supplies woody debris as well as coarse particulate organic matter (e.g., leaf litter) to the stream channel. Riparian zones provide critical habitat and climatic refugia for wildlife. Numerous conservation applications have been implemented for riparian-buffer conservation. Although fixed-width buffers have been widely applied as a conservation measure, the effectiveness of these fixed buffer widths is debatable. As an alternative to fixed-width buffers, we suggest adoption of variable buffer widths, which include multiple tiers that vary in habitat structure and ecological function, with each tier subjected to variable management interventions and land-use restrictions. The riparian-buffer design we proposed can be delineated throughout the watershed, harmonizes with the riverscape concept, thus, a prudent approach to preserve biodiversity and ecosystem functions at variable spatial extents. We posit remodeling existing conservation policies to include riparian buffers into a broader conservation framework as a keystone structure of the riverscape. Watershed-scale riparian conservation is compatible with landscape-scale conservation of fluvial systems, freshwater protected-area networks, and aligns with enhancing environmental resilience to global change. Sustainable multiple-use strategies can be retrofitted into watershed-scale buffer reservations and may harmonize socio-economic goals with those of biodiversity conservation.

Assessing Optimal Digital Elevation Model Selection for Active River Area Delineation Across Broad Regions

The Active River Area (ARA) is a spatial approach for identifying the extent of functional riparian area. Given known limitations in terms of input elevation data quality, ARA studies to date have not achieved effective computer-based ARA components delineation, limiting the efficacy of the ARA framework in terms of informing riparian conservation and management. To determine the optimal input elevation data for future ARA studies, this study tested a novel digital elevation model (DEM) smoothing algorithm and assessed ARA outputs derived from a range of DEMs for accuracy and efficiency. It was found that the tested DEM smoothing algorithm allows the ARA framework to take advantage of high-resolution LiDAR DEM and considerably improves the accuracy of high-resolution LiDAR DEM derived ARA results; smoothed LiDAR DEM in 5-m spatial resolution best balanced ARA accuracy and data processing efficiency and is ultimately recommended for future ARA delineations across large regions. The scientific findings provided by this study further enhance the efficacy of the ARA framework, and ultimately the confidence in modelled ARA outputs for application in riparian conservation and management contexts across broad geographic regions.

Linking instream wood recruitment to adjacent forest development in landscapes driven by stand-replacing disturbances: a conceptual model to inform riparian and stream management

Instream wood plays an important role in stream morphology and creation of fish habitat in conifer forests throughout the temperate zone. In some regions, such as the US Pacific Northwest, many streams currently have reduced amounts of instream wood due to past management activities (timber harvest, wood removal, etc.). These reductions exist against a backdrop of naturally dynamic amounts and distributions of instream wood, which likely fluctuate over time based in part on the stage of development (disturbance and succession) in adjacent riparian forests. Despite many studies on both forest development and instream wood accumulation, the linkages between these processes have not been fully described, particularly as they relate to stream restoration needs. In this paper, we combine literature on forest development, disturbance, and processes that drive instream wood recruitment to more explicitly connect the temporal dynamics of stream wood inputs with the dynamics of adjacent riparian forests. We use moist forests of the Pacific Northwest as an exemplary system, from which to draw broadly applicable patterns for landscapes influenced by stand-replacing disturbance regimes. This conceptual model highlights a U-shaped pattern of instream wood recruitment, in which instream wood is highest after a stand-replacing disturbance and during the old-growth stage, and lowest through the middle stages of forest development (currently the most abundant stages in many landscapes as a result of past forest management practices). This mid-successional period of scarce wood is likely exacerbated in streams with a history of wood removal. The U-shaped pattern suggests that, without higher-than-average levels of disturbance, many streams in landscapes dominated by mid-successional second-growth forests (∼30–80 yr old) will be deficient of instream wood until forest stands are over 200 years old. As such, the balance between the predominant riparian conservation strategy of passive restoration (e.g., unharvested riparian reserves) and the alternative of active restoration (e.g., wood additions and (or) riparian stand treatments) should be carefully considered, depending on management objectives, site context, and potential tradeoffs over time.

Urban water security: a comparative study of cities in the arid Americas

In this study we analyse how three cities in the arid Americas have addressed urban growth while facing water scarcity: Hermosillo, Mexico; Mendoza, Argentina; and Tucson, USA. We use the urban water security framework to examine five domains of water management: sociodemographic, economic, technological, ecological and governance (SETEG). Our analysis indicates that, in spite of water scarcity, urban growth has been promoted in the three cities. We argue that this expansion, although encouraged for economic development, is not sustainable in the long term. In the three cities, groundwater plays a major role in water supply, but growth has negatively affected riparian ecosystems, the health of the aquifers and access to domestic water. In order to pursue water security, several options are essential to enhance social–ecological system resilience. These include limits or reduction of urban expansion, reuse of treated effluent for riparian conservation, and community conservation efforts such as rainwater harvesting and other green infrastructure practices.

Riparian Conservation Facilitated Expansion of Gray Hawks

ABSTRACTDesert riparian ecosystems are among the most threatened biodiversity hotspots in the United States, and efforts to conserve them have been increasing. In 2010–2011 and 2014–2016, we examined shifts in the distribution, habitat characteristics, diet, nest success, and productivity of the gray hawk (Buteo plagiatus), 25 years after a Riparian National Conservation Area was established along the San Pedro River in Arizona, USA, to determine how the removal of grazing and agriculture may have affected the ecosystem. The gray hawk population increased and expanded from mesquite (Prosopis spp.)‐dominated areas that they historically occupied into areas that were dominated by grassland. In contrast with the 1990s, percent of mesquite cover in pairs' territories did not correlate with their productivity. Gray hawk diets also included more mammals in our study period, particularly in territories with more grassland. We propose that conservation measures created habitat for gray hawks in areas that were previously unsuitable by allowing grasslands to regenerate and become habitat for their prey, and that management strategies in the San Pedro Riparian National Conservation Area could serve as a model for conservation of other desert riparian ecosystems. © 2020 The Wildlife Society.

Thinking Upstream: How Do Landowner Attitudes Affect Forested Riparian Buffer Coverage?

Little is known about the conservation of intermittent and ephemeral streams on private lands despite the importance of these waterways for ecosystem and hydrologic outcomes. Our case study of a watershed of central New York State considers landowners' attitudes toward perennial and intermittent streams on their property. We combine social science survey responses with aerial imagery to assess the underlying drivers of landowners' attitudes about their streams, and the extent to which these attitudes shape riparian conservation behaviors on their properties. We find that stream flow regularity directly and positively shapes landowners' stream attitudes, with landowners of perennially flowing streams holding their streams in higher regard than landowners with streams of intermittent flows. Landowners with forest and wetlands as the primary land cover had more riparian buffer coverage on their properties than agricultural landowners. Landowners with a weaker perceived land use efficacy also had greater buffer coverage. Our findings suggest that landowners in headwater regions do not perceive their influence on downstream water quality, and that outreach efforts should emphasize the importance and conservation of headwater streams and associated water quality outcomes.

Riparian conservation management needs habitat quality mapping

Riparian habitat quality has a significant influence on the water quality of rivers, primary resources for urban and agricultural use. River water quality deteriorates where normal ecological functioning is dis- rupted by harmful impacts from nearby land-use types. Important rivers are typically managed and protected by government-led conservation programs. These programs often lack a key tool for efficient conservation management, habitat quality mapping. The Berg River, an important water source in South Africa, was used as a case-study to assess how habitat quality mapping could broaden the current scope of river conservation programs. The river faces threats from nearby urban settlements, industrial areas, mining, encroachment, and agricultural practices. The aim of this study was to develop habitat quality and habitat degradation maps for a section of the Berg River to assess the value that mapping holds for conservation managers and spatial planners. InVEST modelling software and ArcGIS was used to produce these habitat quality maps based on land-use/land-cover and threat impact data. The resulting maps showed several specific locations of heavily threatened and degraded riparian habitat that had not specifically been included in current government con- servation management or spatial planning. Habitat quality mapping is an important tool that conservation managers and spatial planners can use to successfully address habitat degradation and protection while fac- ing resource limitations, such as lack of funding. Oversight of degraded riparian habitats will lead to further decreases in river water quality, adversely affecting human welfare and local economies.

Struktur Floristik Hutan di Kawasan Lindung Sempadan Sungai dalam Areal Hutan Tanaman Industri

This study was carried out in riparian conservation forests within a monospecific pulpwood estate in Sorek,Pelalawan District, Riau. The remaining natural forests comprised lowland rainforest (at Sei Buluh and Tolamriversides), mixed swamp forest (at Telayap riverside), and pole forest (at Rangsang riverside). The objective of thecurrent study was to describe the floristic structure of each forest type at the conservation areas in concern.Fifteen transects (width of 20 m) were established at all sites with a total length of 8.080 m. Quadrates plots of 20x 20 m were established with continue on these transect for tree sampling (dbh > 20 cm) and smaller quadrates(10 x 10 m) were nested on each one of the former for pole sampling (dbh 10 – 20 cm). The parameters used in thisstudy were Importance Value (IV), species richness (Margalef Index = R1 and Menhinick Index = R2), and Diversity Index (Shannon = H’ and Simpson = D). Results showed that in tree stratum, the largest basal area (11.25 m2ha-1) and the highest diversity was found at Telayap’s riverside (H’ = 3.70 and D = 0.98). Species richness was most profound at Tolam riverside (R1 = 10.43 and R2 = 2.83). Rangsang’s riverside possessed the highest tree density (105 individuals ha-1) but with the smallest dbh (26.5 cm). This forest was a peat-swamp forest predominating by bintangur (Calophyllum pulcherimum). At the pole stratum, the largest basal area (7.00 m2ha-1) and the highest diversity was found at Tolam riverside (H’ = 3.39 and D = 0.96). Species richness was most profound at Telayap’s riverside (R1 = 8.89 and R2 = 2.64). The highest pole density (380 individuals ha-1) was observed at Sei Buluh’s riverside, in which mempening (Quercus lucida Roxb.) was predominating. Acacia mangium was establishing very well at all sites, indicating its adaptability and potentially invasive feature.

Restoration of riparian systems through clearing of invasive plant species improves functional diversity of Odonate assemblages

Riparian systems are threatened globally, but contribute disproportionately to biodiversity and ecosystem function. Restoration to reverse their loss is costly, and requires careful monitoring and evaluation. Odonates are amongst the most reliable arthropod bio-indicators for monitoring riparian ecosystems. Despite functional diversity (FD) reflecting ecosystem pattern and processes better than taxonomic diversity, Odonate FD has yet to be used in evaluating riparian conservation and restoration outcomes. We surveyed 45 sites across six river-systems in northeastern South Africa, to compare Odonate FD and standardised effect size of Odonate FD (sesFD) in riparian systems that had been invaded by alien plants, cleared of alien invasives, and sites that had never been invaded (15 sites each). Although species richness did not differ between treatments, Odonate sesFD was lower in invaded sites than those that had been cleared of alien riparian vegetation and those that had never been invaded. Clearance of 40% of alien riparian vegetation was associated with sesFD greater than that of invaded sites by almost two standard deviations. Representation of traits varied between treatments but was similar between cleared and natural sites, suggesting that invasion by alien plants directly impacts food webs, and that clearance can restore ecosystem processes and ecological services. This study confirms that Odonate FD can respond to restoration efforts. Secondary impacts of restoration to complete suites of functional groups can be anticipated to enhance ecological services and impact food webs at a range of scales.

Riparian Meadow Response to Modern Conservation Grazing Management

Riparian meadows occupy a small proportion of the public lands in the western United States but they provide numerous ecosystem services, including the production of high-quality forage for livestock grazing. Modern conservation management strategies (e.g., reductions in livestock stocking rates and adoption of new riparian grazing standards) have been implemented to better balance riparian conservation and livestock production objectives on publicly managed lands. We examined potential relationships between long-term changes in plant community, livestock grazing pressure and environmental conditions at two spatial scales in meadows grazed under conservation management strategies. Changes in plant community were not associated with either livestock stocking rate or precipitation at the grazing allotment (i.e., administrative) scale. Alternatively, both grazing pressure and precipitation had significant, albeit modest, associations with changes in plant community at the meadow (i.e., ecological site) scale. These results suggest that reductions in stocking rate have improved the balance between riparian conservation and livestock production goals. However, associations between elevation, site wetness, precipitation, and changes in plant community suggest that changing climate conditions (e.g., reduced snowpack and changes in timing of snowmelt) could trigger shifts in plant communities, potentially impacting both conservation and agricultural services (e.g., livestock and forage production). Therefore, adaptive, site-specific management strategies are required to meet grazing pressure limits and safeguard ecosystem services within individual meadows, especially under more variable climate conditions.

The influence of habitat structure on fish assemblages in Amazonian streams of Machado river basin.

Igarapés are Amazonian streams that are extremely susceptible to environmental changes. Due to the rapidly occurring riparian land use changes, and the several impacts these may have on fish assemblages, it is highly valuable to describe and understand the current relationships between these assemblages and the local environmental conditions, especially in barely know areas. In this research, we studied the taxonomic composition and fish assemblage attributes variation in three streams with different riparian conservation conditions: forest, intermediate and pasture. Samplings were performed every two months from October 2011 to September 2012, in three 1st order streams in the Machado River Basin, Rondônia. Fish were collected using trawls (seine net with a mesh size of 2 mm) and dip nets (2 mm mesh) along the entire stretch; the obtained samples were preserved and identified per site type. A total of 2 141 fish specimens belonging to 59 species, 17 families and five orders were recorded. Unlike the intermediate and pasture streams, the forest stream showed a high richness and low abundance. The forested stream exhibited the highest diversity and evenness value, and had low dominance, unlike the other streams. The variance partitioning and partial Redundancy Analysis (pRDA) indicated that assemblage composition was significantly explained by the environmental variables such as: depth, water velocity, pteridophytes and grasses, but not by spatial predictors. The non-metric multidimensional scaling (NMDS) analysis showed that intermediate and pasture streams separated from the forested stream. We concluded that both, the stream environmental variables and fish assemblage attributes were influenced by the different conservation status and land cover. Given the influence of regional processes, which have a pervasive role in local fish assemblages, land use at the watershed scale is important, especially to explain the higher richness and diversity found in forested streams.

Prioritizing Riparian Conservation: A Methodology Developed for the Santa Clara River, California

Riparian ecosystems perform many important ecological functions, but human activities have seriously altered and degraded these systems. To avoid continued habitat loss and associated losses in biodiversity, lands that contain intact riparian habitat can be acquired and managed for conservation values and degraded riparian areas can be restored. The Nature Conservancy (the Conservancy) is implementing a riparian conservation project on the Santa Clara River in Ventura County, California that includes both approaches. Because larger restoration projects have faster recovery rates and are more self-sustaining, the Conservancy is protecting and restoring as much contiguous riparian habitat as possible using a “conservation nodes” approach. To this end, we have begun acquisition of high-value parcels, and have developed a methodology for prioritizing additional land acquisition and restoration actions on the river. The methodology is based on quantitative measures of five criteria for 68 discrete parcels of real property contained within five nodes designated as high priority for conservation. The criteria were combined into a score for each parcel. We found that the five nodes varied in terms of their average parcel score, and in terms of the completeness of parcel acquisition. Nine of the top 20 scoring parcels have yet to be acquired by a conservation entity. We also found that the potential conservation value to be gained by restoring all of the parcels within a node varies by node. Conservation entities using this prioritization approach can phase implementation of large-scale projects by allowing restoration work to begin while acquisition efforts continue.

Damming ephemeral streams in the Sonoran Desert, Arizona, USA: biogeomorphic analysis of riparian area growth

In this study, two ephemeral streams are compared in assessing bio-geomorphic change to channels intersected by the Central Arizona Project (CAP) canal. Water and sediment are fully or partially restricted to move downstream due to the CAP canal, which acts as a dam to these streams. Upstream of traversed channels, vegetation cover has increased over time causing the development of a green-up area. Along the canal, several channels remain longitudinally connected via culvert or overchute to the downstream sections of the stream channels. The two streams examined both had longitudinal connectivity, but only one of the streams had a green-up area upstream. Field work and channel surveys reveal that this is due to the culvert’s peak discharge outflow. The stream with a developed green-up area had a culvert size that is approximately three times less than the discharge of this ephemeral stream causing the partial damming upstream during flow events. Green-up zones slowly enlarge over time as bed levels and adjacent desert surface heights increase from continual sediment deposition upstream causing the floodplain to laterally increase due to overbank flooding. It is estimated that the green-up area for the partially dammed stream will increase by approximately 1570 m2 over the next 36 years. Suggestions for urban and agricultural development are presented in this paper in relation to these dynamic green-up areas. Understanding biogeomorphic processes along dammed ephemeral streams lends valuable insight to riparian conservation efforts and future urban development plans in desert regions.

Catchment morphometric characteristics, land use and water chemistry in Pampean streams: a regional approach

The Pampean region covers a large surface in central Argentina, but despite the extensive agricultural activities and the high nutrient levels recorded in streams of the region, few authors have analysed the influence of land use on water quality. Here, we evaluated the relationships among catchment attributes (size, morphometry and land cover) and water chemistry in 23 Pampean streams in different seasons (autumn, spring and summer) and at three spatial scales: whole catchment and two scales of riparian buffers (200 and 500 m adjacent to both stream margins). Chloride concentration was positively related to catchment area and negatively related to drainage density. Nitrate level was strongly associated to cropland, but soluble phosphorus concentration showed no relationships with any type of land cover. Land cover at the buffer scale seemed to be more influential than land cover at the whole catchment for nitrogen concentration. The main impact of cropland was the increase of nitrate concentration, while cattle breeding was negatively associated to photosynthetically active radiation (PAR) in autumn and summer and to dissolved oxygen concentration in spring. Our results highlighted the importance of local land use and riparian conservation on streamwater quality.

A riparian conservation network for ecological resilience

A crucial gap exists between the static nature of the United States' existing protected areas and the dynamic impacts of 21st century stressors, such as habitat loss and fragmentation and climate change. Connectivity is a valuable element for bridging that gap and building the ecological resilience of existing protected areas. However, creating terrestrial connectivity by designing individual migration corridors across fragmented landscapes is arguably untenable at a national scale. We explore the potential for use of riverine corridors in a Riparian Connectivity Network (RCN) as a potential contributor to a more resilient network of protected areas. There is ample scientific support for the conservation value of riparian areas, including their habitat, their potential to connect environments, and their ecosystem services. Our spatial analysis suggests that they could connect protected areas and have a higher rate of conservation management than terrestrial lands. Our results illustrate that the spatial backbone for an RCN is already in place, and existing policies favor riparian area protection. Furthermore, existing legal and regulatory goals may be better served if governance requirements and incentives are aligned with conservation efforts focused on riparian connectivity, as part of a larger landscape connectivity strategy. While much research on the effectiveness of riparian corridors remains to be done, the RCN concept provides a way to improve connectivity among currently protected areas. With focused attention, increased institutional collaboration, and improved incentives, these pieces could coalesce into a network of areas for biological conservation.