Riparian Management Research Articles

Quantifying the Variability of “Fixed-Width” Buffers on Harvested Lands in Western Oregon and Washington

Abstract In contemporary forest management, buffers of unharvested trees are left along streams to protect riparian and aquatic ecosystems. Buffer regulations often focus on specific minimum width requirements, which aid in straightforward regulation and application, but minimum widths also suggest buffered edges are uniform and contain little variability. Conceptual papers suggest that alternative buffer configurations may offer greater flexibility in landscape-level protection, increase forest complexity, and enhance aquatic and riparian biodiversity. However, before considering alternatives to fixed-width buffers, it is necessary to quantify the inherent variability in current buffer practices present on the landscape. In this study, we used aerial imagery to quantify variability of buffer widths in two hundred randomly selected recently harvested units on managed land in Oregon and Washington with both fish-bearing and non-fish-bearing sections of stream. Wider buffers on larger streams had a greater magnitude of variability, but when normalized by stream size, variation was greater in smaller streams, and overall, variation ranged from 25% to 50% of the mean width. Despite local variability, buffer widths rarely fell below 9.14 m (30 ft). The variation quantified here provides an initial measure of variability to inform future management, given emerging interest in variable retention buffers. Study Implications: In contemporary forest management, riparian and aquatic habitat protection usually relies on minimum buffer width regulations. Minimum requirements create the perception that buffered edges are uniform distances from streams containing little variability, so conceptual papers have suggested alternative buffer configurations with variable retention edges to enhance ecological benefits. However, there are several reasons why, in practice, buffer widths may vary substantially from minimum sizes within and across harvest units under current forest management, but this potential variation has not been quantified. Before considering alternative riparian management options, it is necessary to quantify and understand the inherent variability in current practices. By utilizing high-resolution aerial imagery and digital elevation models, we quantified buffer width variation. Using a set of two hundred recently harvested units, we demonstrate notable buffer width variation across managed Pacific Northwest forests. We attribute the variation in buffer widths to the presence of road crossings, tributary junctions, underlying valley slope and slope variation, and flexibility in regulations that may be overlooked in broad evaluations of strict minimum widths. Understanding fundamental information about buffer width variability provides information about current practices and provides a standard against which proposed increases in variability may be compared.

Projecting exceedance of juvenile salmonid thermal maxima in streams under climate change: A crosswalk from lab experiments to riparian restoration

Abstract Concern over rising water temperatures for freshwater ectotherms has led to application of experimentally derived thermal thresholds to stream temperature models for estimation of streams at high risk of exceeding thermal thresholds under current and future climate conditions. We optimised an approach that links field‐relevant thermal maxima experiments to corresponding stream temperature models and identifies opportunities to reduce stream temperatures through riparian tree growth. We conducted a thermal maxima experiment on cold‐water adapted juvenile Chinook (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch) that reflected natural temperatures by using incremental temperature ramping with diel fluctuations (IT‐Dmax) and refit a regionally specific stream temperature model for British Columbia, Canada to directly relate to lab‐derived thresholds. Salmon‐bearing streams across British Columbia were categorised by threshold exceedance risk (i.e., low, moderate, high, severe) based on risk tolerance scenarios for management decision making (i.e., considering a range of prediction intervals [PIs] and stream thermal sensitivities to air temperature). We linked these results directly to riparian management and restoration actions by estimating the potential for riparian tree growth to reduce threshold exceedance risk. Lab‐derived IT‐Dmax endpoints were consistently 24°C (based on the median value between the 7‐day average of the daily maximum and the mean weekly average temperature) across acclimation treatments for both species. Under current conditions, most stream reaches (99.6% using an intermediate risk tolerance scenario) were below the thermal threshold; streams with moderate to high risk of threshold exceedance were projected to increase from 0.4% to 1.5% (total linear stream length of 6,929 km) by end of century. The risk‐averse (high sensitivity, 75% PI) and risk‐tolerant (low sensitivity, 95% PI) scenarios differed by 1,107 km of streams predicted to have a moderate to severe risk of exceeding thresholds by end of century. Maximal riparian tree growth was predicted to shift 670 km of streams from moderate to low exceedance risk under end‐of‐century conditions and intermediate risk tolerance, showing the potential for mitigation from thermal impacts. Our integrative approach tackled several key considerations in identifying streams at high temperature risk for freshwater ectotherms that to date have not been addressed. Furthermore, we showcased the delineation of spatially comprehensive estimates that identify where management mitigation and a specific restoration activity may be most needed to reduce impacts of rising temperatures on rearing salmonids across an extensive region.

Community stewardship to protect coastal and freshwater ecosystems–pathways between recreation and stewardship intentions

Abstract Strengthening community engagement in stewardship can help to improve management of coastal and freshwater environments (blue spaces). Research suggests that recreational users of natural areas may be more willing to engage in stewardship. However, little research at a population scale has examine how recreation experiences shape psychological ingredients for stewardship. We surveyed 3271 residents of South East Queensland, Australia and quantified willingness to engage in blue space stewardship. We then quantified frequency of different types of blue space recreation, perceptions about threats to blue spaces (threat appraisal) and protective actions (coping appraisal), and satisfaction with blue spaces. We then examined pathways from recreation to stewardship intentions using mediation analysis. Results show that many types of recreation were associated with stewardship intentions. Specifically, higher frequency of social activities and nature‐appreciation activities were associated with greater intentions for individual stewardship (e.g. picking up litter, reducing use of household chemicals). Higher frequency of social activities, nature appreciation, exercise and fishing/boating was associated with stronger intentions for collective stewardship (e.g. attending a public meeting or riparian management event) Mediation analysis showed that most forms of recreation did not influence perceptions about severity of threats to blue spaces. Rather, the relationships between recreation and stewardship were mediated by greater place satisfaction, perceived vulnerability to blue space degradation, and feeling more able to contribute to waterway protection (efficacy). These findings indicate that many types of recreation (not just nature appreciation activities) can be a foundation for engaging in nature stewardship, and reinforce the importance of building efficacy when promoting stewardship. The finding that both place satisfaction and perceived vulnerability to environmental degradation suggests that there may be an optimal motivational window for stewardship: people need to connect a place with positive experiences, and have some recognition of a potential threat, but where the potential threat has not yet eroded the natural values of a place. Read the free Plain Language Summary for this article on the Journal blog.

The effects of pastoral hill country natural landscape features and land management practices on nitrate losses and its potential attenuation for improved water quality

AbstractPastoral farming on hill country landscapes influences nitrogen (N) dynamics and its losses to freshwater. This study reviewed the current literature identifying key effects of pastoral hill country landscape features and land management practices on nitrate losses to receiving waters. The review also highlighted the potential effects of inherent landscape features on nitrate attenuation pathways for better water quality outcomes. Intensive land use activities involving high rates of fertiliser application, higher stocking rates and cattle grazing, relative to sheep grazing, are more likely to increase nitrate loss, especially on lower slopes. However, soils with a high carbon (C) storage capacity such as allophanic soils potentially limit nitrate loss via denitrification in subsoil layers. Hill country seepage wetlands also offer an opportunity to attenuate nitrate loss, though their efficacy is largely impacted by hydrological variations in their inflows and outflows. By enhancing the natural nitrate attenuation capacity of seepage wetlands, mapping and strategic use of high subsoil denitrification potential, effective riparian management, efficient fertiliser and grazing practices and the incorporation of these farm management strategies into Freshwater Farm Plans (FWFPs), wider environmental and farm productivity/profitability goals, including improved water quality, would be achieved on pastoral hill country landscapes.

Experimental riparian forest gaps and increased sediment loads modify stream metabolic patterns and biofilm composition

AbstractForest management operations greatly influence stream habitats. Canopy clearing and subsequent canopy development during succession, site preparation, and ditching alter the light environment, and increase sediment inputs and nutrient exports from upland and riparian soils to streams. These physicochemical changes affect aquatic biofilms and metabolic rates, and in this study, we tested their individual and combined effects. We used 12 artificial streamside channels, together with a field survey of nine streams in and around clear‐cuts, to assess the effects of shading, substrate composition, and nutrient addition on biofilm biomass and composition, as well as metabolic rates. We found that biofilm biomass and gross primary production (GPP) were light limited in channels under 70% canopy shading. Nitrate additions at this shading level only marginally increased autotrophic biomass, while the rates of respiration increased 10‐fold when carbon was added. Open (unshaded) channels had three times higher rates of GPP compared with channels with 70% shading, and autotrophic biomass was twice as high, largely caused by the colonization of filamentous green algae. These changes to biofilm biomass, composition, and GPP were caused by differences in light alone, as temperature was not affected by the shading treatment. Notably, higher rates of GPP led to no positive effect on net ecosystem production. Further, fine‐grained substrates negatively affected GPP as compared with stone substrates in the experimental channels. In the surveyed streams, the negative effects of fine‐grained substrates exceeded the positive influence of light on biofilm biomass. Altogether, our results highlight the need for riparian management that protects headwaters from unwanted stressors by focusing on preventing sediment erosion and carbon transport in clear‐cuts, while providing variable shade conditions in second‐growth forests.

Protecting our streams by defining measurable targets for riparian management in a forestry context

Abstract Generally, governments and industry have implemented some degree of protection to reduce the impacts of forestry on aquatic ecosystems. Here, we consider the widespread application of streamside management in terms of riparian buffer retention to protect freshwaters from forestry practices across three jurisdictions with large and intensive forestry sectors (British Columbia, Finland and Sweden). This perspective was developed by working with researchers, practitioners and policymakers on mitigation measures to decrease the impacts of forestry on streams. We demonstrate that it is exceedingly rare for policies and guidelines to specify concrete objectives and measurable targets that can be assessed against riparian buffer management outcomes. Most often, policy objectives for riparian management prescribe ‘to prevent or mitigate impacts’, and this vagueness is insufficient to protect our waters. We argue that we should be clearer about the targets (outcomes) for riparian management and go beyond the simple idea that buffer presence, without further specification of its conditions, is always a successful protection strategy. One cannot measure the effectiveness of rules and guidelines without quantitative targets. Policy implications: In this paper, we suggest that locally developed and adjusted targets for riparian buffers must include quantifiable, measurable goals that specify what is supposed to be achieved and protected with respect to ecological functions, biological communities or other values. It should be relatively simple to move from current vague objectives such as ‘protect and prevent’ to a defined range of values for ecological parameters that buffers are supposed to provide. For example, these can include region‐specific shading levels and microclimate targets, large wood volumes, or riparian forest species composition. We stress that these targets must be developed through an open dialogue between agencies, practitioners, land owners and scientists. We acknowledge that there are trade‐offs between being too prescriptive and too vague. However, when excessively broad goals are the norm, we lose the capacity to effectively implement, monitor or evaluate the outcomes of protection measures.

Intermittent Prairie Streams in the Northern Great Plains: A Case of an Undervalued Ecosystem

Small (<15 m wide), intermittent prairie streams in western South Dakota, a semiarid part of the northern United States, are undervalued ecosystems because they do not exemplify the values of classic, flowing streams. However, they are valuable as wildlife corridors, aquatic habitat for drought-adapted species, and support of local grazing economies. We surveyed 90 streams in 2018–2019, collecting data on geomorphic, water chemistry, and biological properties, focusing on vegetation and grazing impacts. We developed an approach for categorizing streams by landscape position and flow regime to facilitate appropriate land management and stream restoration actions. The result was a published landowner guide to provide information on low-tech riparian management and restoration options of the four stream types we categorized. The headwaters streams and woody draws with drainage areas <26 km2 are the most abundant types and exemplify the issues described above. Large rivers, despite drainage areas exceeding 260 km2 can go dry. Management issues include invasive plant species, lack of woody riparian establishment, poor water quality, overgrazing, channel incision, and water stress from climate change. The most cost-effective management practices involve rotational grazing and practices that reduce cattle impacts. More recently, beaver dam analogs have been installed and beaver reintroduction is being considered along with reestablishment of native bison herds in place of cattle. Intermittent prairie streams present an excellent case study of an undervalued ecosystem, illustrating the challenges and opportunities of such systems. Engagement of grazing landowners can improve stewardship of these systems.

Non-rhizosphere reinforces the contributions of Feammox and anammox to nitrogen loss than rhizosphere in riparian zones

The emergence of anaerobic ammonium oxidation (anammox) coupled to iron reduction (named Feammox) refreshes the microbial pathways for nitrogen (N) loss. However, the ecological role of Feammox, compared with conventional denitrification and anammox, in microbial N attenuation in ecosystems remains unclear. Here, the specific contribution of Feammox to N loss and the underlying microbiome interactive characteristics in a riparian ecosystem were investigated through 15N isotope tracing and molecular analysis. Feammox was highlighted in the riparian interface soils and maximally contributed 14.2% of N loss. Denitrification remained the dominant contributor to N loss (68.0%–95.3%), followed by anammox (5.7%–19.1%) and Feammox (0–14.2%). The rates of Feammox and anammox significantly decreased in rhizosphere soils (0.15 ± 0.08 μg N g−1 d −1 for Feammox, 0.80 ± 0.39 μg N g−1 d −1 for anammox) compared with those in non-rhizosphere soils; however, the activities of denitrification remarkably increased in the rhizosphere (13.17 ± 3.71 μg N g−1 d −1). In rhizosphere soils, the competition between bioavailable organic matter (e.g., amino acids and carbohydrates) and ammonium for electron acceptor [i.e., Fe(III)] was the vital inducement for restricted Feammox, while the nitrite consumption boosted by heterotrophic denitrifiers was responsible for weakened anammox. The functional gene of autotrophic Acidimicrobiaceae bacterium A6, instead of heterotrophic Geobacteraceae spp., was significantly positively correlated with Feammox activity. Rare iron-reducing bacteria showed higher node degrees in the non-rhizosphere network than in the rhizosphere network. A syntrophic relationship was found between iron-reducing bacteria (e.g., Anaeromyxobacter, Geobacter) and iron-oxidizing bacteria (e.g., Sideroxydans) in the non-rhizosphere network and facilitated the Feammox pathway. This study provides an in-depth exploration of microbial driven N loss in a riparian ecosystem and introduces new insights into riparian management practices toward high-efficient N pollution alleviation.

Searching for Balance between Hill Country Pastoral Farming and Nature

Much land has been cleared of indigenous forest for pastoral agriculture worldwide. In New Zealand, the clearance of indigenous forest on hill country has resulted in high food production, but waterways have become turbid, with high nutrient and E. coli concentrations. A range of on-farm mitigations are available, but it is unclear how they should be applied catchment-wide. We have developed a catchment-scale model that integrates economics with ecosystem services to find a better balance between agriculture and nature. In the upper Wairua catchment, Northland, if three actions are prioritised—(1) keeping stock out of streams, (2) constructing flood retention bunds in first-order catchments, and (3) planting trees on highly erodible land—then sediment loads, E. coli levels, and flooding are significantly reduced. Implementing these actions would cost approximately 10% of catchment net revenue, so it is feasible with a combination of regulation and subsidy. Many catchments in New Zealand are primarily pastoral agriculture, as in other countries (in North and South America, Australasia, and the United Kingdom), and would benefit from the analysis presented here to guide development along sustainable pathways. While pastoral agriculture typically stresses waterways, with increased sedimentation and freshwater contaminants, much can be done to mitigate these effects with improved farm and riparian management.

Natural flood management: Lessons and opportunities from the catastrophic 2021–2022 floods in eastern Australia

AbstractNatural flood management (NFM), a nature‐based solution to flood mitigation where hydrological and biophysical processes are harnessed to reduce flow velocity, erosive energy and flood risk, is an emerging global theme of water and river management. The catastrophic 2021 and 2022 floods in eastern Australia are used to assess the hydrological properties of discrete events and to start an investigation of whether widespread changes in flood hydrology are occurring. We find that most coastal rivers in New South Wales (NSW) had a noticeable decrease in flood wave celerity (increase in flood travel time) when the 2021 and 2022 floods are contrasted with equivalent floods since the 1970s and that several also exhibit increases in flood peak attenuation. For some rivers, there is a coincident trend between these changing flood properties, riparian vegetation regrowth (regreening) and geomorphic recovery over the last +30 years. These may be the first signals that passive riparian management is counteracting some of the more severe hydrological effects of floods on these rivers and that some degree of NFM is possible. Lessons from this work are that there is an immediate opportunity to implement large‐scale NFM in coastal catchments of NSW, but this will only occur if we re‐examine current flood mitigation and adaption strategies and recognise and prioritise nature‐based solutions that include space‐to‐flood and corridors of river recovery, as essential parts of the modern flood mitigation toolkit.

Mowers versus growers: Riparian buffer management in the Southern Blue Ridge Mountains, USA

AbstractDespite long‐standing knowledge of the benefits of riparian buffers for mitigating nonpoint source pollution, many streams are unprotected by buffers. Even landowners who understand ecological values of buffers mow riparian vegetation to the streambank. Do trends in rural riparian conditions reflect the development of riparian forest science? What motivates residential riparian management actions? Using high‐resolution orthoimagery, we quantified riparian conditions and trends between 1998 and 2015 in the rural upper Little Tennessee River basin in Macon County, North Carolina and explored how landowners view riparian zone management and riparian restoration programs. Buffer composition in 2015 was as follows: no buffer (32.5%), narrow (19.3%), forested (26.7%), shrub (7.2%), and intermediate (7.0%). Relative to 1998, the greatest decrease occurred in the no buffer class (−17.7%, 46 km) and the largest increases occurred in the shrub (+72.5%, 20 km) and narrow (12.6%, 14 km) classes. Forested buffer marginally increased. Semi‐structured interview data suggest that landowners prioritize recreational and scenic aspects of riparian buffers over ecological functions such as filtration and bank stabilization. Riparian restoration programs might be made more enticing to non‐adopters if outreach language appealed to landowner priorities, design elements demonstrated intentional management, and program managers highlighted areas where ecological goals and landowner values align.

Riparian Management and Nutrients Distribution in Different Zones of Euphrates Riverbanks

Riparian Management and Nutrients Distribution in Different Zones of Euphrates Riverbanks

Forest conversion adversely affects native Macrobrachium shrimp assemblages in tropical Malaysian streams

Abstract Commodity‐driven forest conversion represents one of the most severe threats to freshwater biodiversity in Southeast Asia, notably causing population declines and the extinction of freshwater fish species. Although a variety of freshwater taxa are likely to be adversely affected by forest conversion, little is known about the impact on ecologically and economically important invertebrates such as decapod crustaceans. This study evaluated the impact of forest conversion and land‐use change on freshwater Macrobrachium shrimp species, using species richness, abundance, and environmental data collected from 20 streams across southern Peninsular Malaysia. Streams were located in three types of landscape: forest; oil palm plantation; and mixed land use, comprising young secondary forest, small‐scale plantations, patches of open and sparsely vegetated areas, and agricultural fields and clearings. Generalized linear models showed that even incomplete change from forest habitats to mixed land use and oil palm plantation resulted in significantly lower Macrobrachium native species richness and higher non‐native species abundance. Native species richness was positively correlated with canopy cover, leaf litter, substrate size, and dissolved oxygen, and was negatively correlated with water temperature and conductivity. Native species richness was also negatively correlated with non‐native species abundance, with non‐native species abundance increasing along the human disturbance gradient. These results highlight the need for riparian habitat protection to conserve native Macrobrachium and limit the spread of non‐native species. A management priority should be to maintain or restore optimum instream habitat conditions for shrimps, which would also benefit fish and other benthic macroinvertebrates. Suitable riparian management requires substantial support and funding from multiple stakeholders, but it can be aligned with other catchment‐based strategies to optimize the use of limited resources available for freshwater biodiversity conservation.

Too much, too soon? Two Swedish case studies of short-term deadwood recruitment in riparian buffers

Forested riparian buffers are retained along streams during forest harvest to maintain a number of ecological functions. In this paper, we examine how recently established riparian buffers along northern Swedish streams provide deadwood, a key objective for riparian buffer management in Sweden. We used observational and experimental data to show that the investigated buffers provided large volumes of deadwood to streams and riparian zones shortly after their establishment, likely jeopardizing continued recruitment over the long term. Deadwood volume decreased with increasing buffer width, and the narrowest buffers tended to blow down completely. Wider buffers (~ 15 m) provided similar volumes of deadwood as narrow buffers due to blowdowns but were, overall, more resistant to wind-felling. It is clear from our study, that wider buffers are currently a safer strategy for riparian management that aims to sustain provision of deadwood and other ecological objectives continuously on the long term.

Applying the “Goldilocks Rule” to Riparian Buffer Widths for Forested Headwater Streams across the Contiguous U.S.—How Much Is “Just Right”?

Delineating riparian management zones (RMZ) around streams to protect riparian ecological functions is critical during forest management. This study compared the area dedicated to RMZ using the USFS functional-based riparian buffer approach versus individual state-defined riparian buffer allocation strategies along headwater streams across 17 states within the US. The USFS method uses a variable-width riparian buffer that seeks to capture the functions of a riparian area. Our study sought to contrast this USFS method with various state-defined RMZ guidelines. The functional approach delineated the highest percentages of the watershed area around headwater streams in most watersheds, sometimes >20% of forestland, whereas state RMZ guidelines delineated <10% of forestland around headwater streams in many watersheds. Although many state guidelines failed to identify the variable widths of functional riparian areas, some watersheds in the Great Lakes states over-allocated forestland as riparian when compared to a functional riparian delineation. The topographic and forest composition differences observed across the study area were not represented by their respective state RMZ guidelines, and these variables strongly influence the delineation of a functional RMZ.

Influence of riparian thinning on trophic pathways supporting stream food webs in forested watersheds

AbstractResource managers seek to thin second‐growth riparian forests to address multiple stream and riparian management objectives, including enhancing aquatic productivity via light‐mediated trophic pathways in watersheds of the Pacific Northwest (USA). However, such increases in aquatic productivity depend on complex food web dynamics that link riparian forests and streams. To evaluate how riparian forest thinning influences stream food webs, we conducted a replicated, manipulative field experiment in three northern California watersheds composed of second‐growth redwood forests and tracked responses across multiple trophic levels (periphyton, macroinvertebrates, amphibians, and fish) 1 year pre‐ and post‐treatment. Riparian thinning treatments increased light to the stream channel, yet we observed mixed responses by stream food webs. Thinning did not change stream periphyton biomass on natural substrates but increased periphyton accrual on ceramic tiles. Periphyton accrual appeared to be partially muted by top‐down effects from invertebrate scrapers, which were more abundant in thinned reaches. Prey in the diets of top predators—coastal giant salamanders (Dicamptodon tenebrosus) and coastal cutthroat trout (Oncorhynchus clarkii clarkii)—did not change in biomass, composition, or structure in response to thinning and instead varied more seasonally and between predators. Stable isotope analysis indicated that shifts in carbon (δ13C) signatures of stream periphyton associated with thinning were reflected to varying extents by primary consumers but did not propagate up to top predators. Top predator biomass responses varied between species, where salamander biomass remained unchanged, but cutthroat trout biomass increased slightly in thinned reaches. However, trout biomass responses were not supported by diets or isotopes and correlated weakly with changes in light associated with thinning, suggesting little evidence that responses could be attributed directly to changes in autotrophic pathways. Furthermore, we found no evidence that local trophic responses to thinning propagated into downstream reaches. Taken together, we observed that trophic pathways supporting stream food webs remained largely intact immediately after riparian thinning treatments. Collectively, these results suggest that riparian thinning does not necessarily enhance aquatic productivity in forested streams, indicating that contextual factors driving realized ecological responses should be accounted for when considering thinning as a restoration strategy for stream–riparian ecosystems.

Mechanistic Simulations Suggest Riparian Restoration Can Partly Counteract Climate Impacts to Juvenile Salmon

AbstractClimate change is reducing summertime water availability and elevating water temperature, placing human consumptive needs in competition with needs of coldwater fishes. We worked with natural resource managers in the Snoqualmie River (Washington, USA) to develop riparian management scenarios, and used a process‐based modeling system to examine how a threatened population of Chinook salmon (Oncorhynchus tschawytscha) may respond to climate change and whether riparian restoration could reduce climate effects. Linking models of global climate, regional hydrology, water temperature, and fish, we projected that streams would become warmer year‐round and drier during summer, further stressing salmon. Climate change accelerated egg emergence, increased juvenile growth and survival, and accelerated outmigration of sub‐yearling migrants. Growth was depressed for salmon remaining instream during summer (potential yearling migrants). Riparian restoration counteracted ~10% of summer increases in water temperature, and affected salmon similarly regardless of whether riparian buffers were partially or fully restored, whereas riparian degradation further warmed streams. Riparian restoration fully mitigated climate change effects on potential yearling migrant size, but only minimally affected sub‐yearling migrants (assessment metrics changed <2%). Our results will be useful for watershed managers in aligning priorities for fish and humans and our framework can be applied elsewhere.

Going with the flow? The role of intention in riparian zone management

Going with the flow? The role of intention in riparian zone management

Vegetation Affecting Water Quality in Small Streams: Case Study in Hemiboreal Forests, Latvia

Riparian forests are important ecosystems located along the margins of freshwaters. Riparian zones provide many ecosystem services, such as nutrient modification, erosion and temperature control, leading to improvements in water quality in adjacent water ecosystems. In many areas, riparian forest management is restricted to improve adjacent water quality. The potential influence of forest management on water quality of small streams was assessed by analysing species composition and structural diversity in riparian forests. We collected data in riparian forests along 15 streams in the eastern Baltics (Latvia) with different water quality classes. We used detrended correspondence analysis and indicator species’ analysis to determine relationships between woody plants and understory vegetation. We also used ADONIS and ANOSIM analysis to determine possible factors that affect species composition. Our results suggested that water quality is affected by ground vegetation, which in turn was altered by stand density and total yield. Site-specific decision making in management is required in riparian forests to ensure the required conditions in the streams, because species composition differs between sites, dominant tree species and stand parameters (density, total yield, stand age). Introduction of Betula pubescens Ehrh. in coniferous stands is favourable to ensure litter fall quality and provide shade for streams during summer.

Exploring water quality management with a socio-hydrological model: a case study from Burkina Faso

ABSTRACT Models that can integrate aspects of society such as institutions, perceptions and behaviours with aspects of the natural system such as rainfall, runoff and water quality may help us understand and manage complex human–water systems. In this paper, a socio-hydrological model is developed for the Black Volta (Mouhoun) watershed in Burkina Faso. The model captures the relationships between the awareness of water quality issues and capacity of local organizations, land use in the riparian zone, agricultural practices and suspended sediment concentration as an indicator of water quality. Scenarios are generated for the current situation and for plausible pathways to achieve improved water quality through different riparian land management strategies. Scenario comparison show how water quality improvements are generated if institutional support, resources and capacity of local level organizations are substantially increased compared to current levels.