Riparian Buffer Research Articles

GIS-based planning of buffer zones for protection of boreal streams and their riparian forests

Forested buffer zones with varying width have been suggested as the most promising approach for protecting boreal riparian biodiversity, reducing erosion, and minimizing nutrient leaching from managed forestry areas. Yet, less optimal fixed-width approach is still largely used, likely because of its simple design and implementation. We examined the efficiency of varying-width buffer zones based on depth-to-water (DTW) index in protecting stream riparian plant communities. We further compared the economic costs of DTW-based buffer to commonly used 5, 10 and 15 m fixed-width buffers. We also included an additional buffer based on a combination of DTW and erosion risk (Revised Universal Soil Loss Equation, RUSLE) into these comparisons to see the extent and cost of a buffer that should maximize the protection of the linked aquatic environment. Plant species richness increased with increasing soil moisture and species preferring moist conditions, nutrient-rich soils and high pH were clearly more abundant adjacent to stream in areas with high predicted soil moisture than in dry areas. Differences in species richness were paralleled by differences in community composition and higher beta diversity of plant communities in wet than in dry riparian areas. There were also several indicator species typical for moist and nutrient-rich soils for wet riparian areas. Riparian buffer zones based on DTW were on average larger than 15 m wide fixed-width buffers. However, the cost for DTW-based buffer was lower than for fixed-width buffer zones when the cost was normalized by area. Simulated selective cutting decreased the costs, but cutting possibilities were variable among streams and depended on the characteristics of forest stands. Our results thus suggest a high potential of DTW in predicting wet areas and variable-width buffer zones based on these areas in the protection of riparian biodiversity and stream ecosystems.

Spatial effects of urban green infrastructure on instream water quality assessed by chemical and sensory indicators

Urban green infrastructure has been simulated effectively and economically to reduce volume and pollutants of stormwater runoffs but its spatial effects remain unclear. A snap sampling campaign was carried out for surface water quality in the downtown waterway network of a pilot sponge city (Suzhou) in China, dividing into 7 subwatersheds according to the digital elevation map. In total, 144 sampling points were investigated and measured for chemical quality of surface water while 68 out of the sampling points had a sensory evaluation questionnaire interview for water quality with 321 respondents, in whom the native residents scored a significant spatiality of water quality. The downtown waterway network had phosphorus-limited eutrophic surface water with total nitrogen worse than Class V of the national guidelines. Chemical and sensory evaluation indexes of surface water quality had significant spatial consistency (p < 0.001). All types of green spaces (%) in subwatershed, especially along the urban waterway network (waterfront) and roadside, and in the 100 m riparian buffer zone, significantly influenced nutrient loads in surface water. Findings of the present study suggest that the 100 m riparian buffer zone would be priority areas and the waterfront and roadside should be the highly efficient spots for planning strategy on urban green infrastructure implementation to reduce nutrient loads in surface water and to improve urban landscape aesthetics.

Baseline assessment of the hydrological network and land use in riparian buffers of Pampean streams of Uruguay.

The integrated assessment of stream networks and terrestrial land use contributes a critical foundation for understanding and mitigating potential impacts on stream ecology. Riparian zone delineation and management is a key component for regulating water quality, particularly in agricultural watersheds. We present a national assessment of riparian zone land uses according to stream order for the entire hydrological network in the Uruguayan landscape in Southeastern South America. We classified over 82,500km of streams and rivers in Uruguay into seven Strahler order classes and delineated riparian buffers of 100 and 500m, depending on stream order, covering a total of 13% of the terrestrial land area in Uruguay. Natural vegetation cover in riparian zones averaged 77% among basins, whereby natural grassland dominated first and second order stream buffers at 58% and 49%, respectively. This highlighted the importance of grasslands in headwater regions of the country. Riparian forests formed corridors along larger streams, representing a mere 9% of buffers in first order streams but reaching 46% of buffers of 6th order streams. Among the six major basins of Uruguay, we found differences in the relative importance of riparian forests and crop cover in headwater stream riparian zones, as well as differences in relative crop cover within riparian zones. Results show that streams in subtropical grassland landscapes originate in open grassland environments, which has major implications for thermal regimes, carbon inputs, and stream biodiversity. Riparian buffer management should consider geographic differences among different basins and ecoregions within Uruguay.

Diverse temperate riparian buffer types promote system-level carbon sequestration in southern Ontario, Canada

Riparian buffer systems (RBSs) can sequester atmospheric carbon dioxide into terrestrial carbon (C) pools. C stocks and C sequestration potential of diverse RBSs are not adequately reported. This study, therefore, quantified: (a) C stocks in various RBSs and (b) system-level C sequestration potentials (SLCSP) [SLCSP= ΔSOC + Biomass C Pools] in southern Ontario, Canada. Results showed significant differences (p &lt; 0.05) in system-level C stocks between tree buffers (765.8 Mg C ha-1) and grass buffers (291.7 Mg C ha-1) and between natural forest buffers (935.9 Mg C ha-1) and rehabilitated buffers (595.6 Mg C ha-1), but no difference (p &gt; 0.05) between coniferous buffers (722.4 Mg C ha-1) and deciduous buffers (809.1 Mg C ha-1) were recorded. Tree buffers had higher SLCSP (633.5 Mg C ha-1) than grass buffers (126.7 Mg C ha-1). Natural forest buffers had higher SLCSP (806.7 Mg C ha1) than rehabilitated buffers (460.3 Mg C ha-1). There was no difference (p &gt; 0.05) in SLCSP between coniferous buffers (615.0 Mg C ha-1) and deciduous buffers (652.1 Mg C ha-1). Results from this study confirm that the establishment of RBSs within agricultural watersheds can significantly contribute to create new terrestrial C sinks.

Impacts of different vegetation in riparian buffer strips on runoff and sediment loss.

Buffer strips continue to feature in the management of agricultural runoff and water pollution in many countries. Existing research has explored their efficacy for reducing environmental problems in different geoclimatic settings but, the evidence on the efficacy of different vegetation treatments is less abundant than that for other buffer strip characteristics, including width, and is more contradictory in nature. With policy targets for various environmental outcomes including water or air quality and net zero pointing to the need for conversion of agricultural land, the need for robust experimental evidence on the relative benefits of different vegetation types in buffer strips is now renewed. Our experiment used a replicated plot scale facility to compare the efficacy of 12 m wide buffer strips for controlling runoff and suspended sediment loss during 15 sampled storms spanning 2017-2020. The buffer strips comprised three vegetation treatments: a deep rooting grass (Festulolium cv. Prior), a short rotation coppice willow and native broadleaved woodland trees. Over the duration of the monitoring period, reductions in total runoff, compared with the experimental control, were in the order: willow buffer strips (49%); deciduous woodland buffer strips (46%); grass buffer strips (33%). The corresponding reductions in suspended sediment loss, relative to the experimental control, were ordered: willow buffer strips (44%) > deciduous woodland buffer strips (30%) > grass buffer strips (29%). Given the 3-year duration of our new dataset, our results should be seen as providing evidence on the impacts during the establishment phase of the treatments.

Understanding the effects of forest management on streams and rivers: A synthesis of research conducted in New Brunswick (Canada) 2014–2018

Forests play a major role in maintaining healthy streams and in providing ecosystem services such as clean drinking water, flood/drought protection and biodiversity, but studies have shown that some forestry operations can compromise these benefits. To assess whether current forest management practices impact stream ecosystems, a five-year study was conducted in J.D. Irving, Limited’s Black Brook Forestry District (New Brunswick, Canada) and in other watersheds with varying forest management intensity. This study was divided into two phases, with each addressing one main research question: 1) how different intensities of forest management affect the ecological health of headwater streams and, 2) whether the changes observed in headwater streams accumulate or dissipate in larger downstream rivers. A comprehensive approach to examining these research questions was taken by measuring multiple abiotic and biotic indicators to assess the integrity of stream ecosystems (sediments, water chemistry, insect communities, leaf decomposition, fish condition, mercury concentrations). The purpose of this paper is: 1) to synthesize the results of numerous scientific articles, and 2) to present the science and management implications in terms that regulatory and industrial forest managers can use to incorporate the lessons learned into their decision making. Results in Phase I show that streams in the most intensively managed catchments had greater inputs of terrestrial materials such as sediments, and these were incorporated into food webs, resulting in more terrestrial diets of aquatic consumers. The important stream function of leaf litter breakdown was negatively influenced by increased management intensity. Management practices related to roads warrant special attention, as roads tended to be more related to changes in stream indicators than tree removal. Additionally, results suggest that wet riparian areas were more sensitive to disturbance than drier riparian areas, which has implications for riparian buffer zone configurations. Regarding Phase II, some of the effects of forest management on small streams accumulated in larger downstream rivers (e.g., sediments, use of terrestrial resources by aquatic organisms), while others dissipated (e.g., water temperature, mercury contents). Interestingly, the impacts of forest management on streams were greater in the basin with tree removal but less silviculture than in the basin with more of both, suggesting that greater overall intensity of forest practices does not necessarily translate into greater environmental impacts, for example when considering partial versus clearcut harvesting. Overall, the study suggests that while current best management practices do not eliminate all effects, they do still offer good protection of biological integrity downstream.

Growth, Nitrogen Uptake, and Nutritional Value of a Diverse Panel of Shrub Willow (Salix spp.) Genotypes in Response to Nitrogen Fertilization

Riparian buffers are a practical strategy to reduce N runoff. Shrub willows (Salix spp.) are a well-suited natural means to manage water quality due to dense aboveground biomass growth, diffuse root systems at a shallow depth, and low water- and nutrient-use efficiencies that will maximize uptake. Perennial forage crops in the margins of agricultural lands could provide biomass for fodder. The response of fifty genotypes to a single N level of fertilizer under standard conditions at a very high nutrient loading level (500 ppm N, delivered weekly) was compared with water-only controls. Irrigation with excess N caused greater aboveground growth measured as biomass, stem length, and diameter, as well as morphological properties that varied significantly by genotype, indicating a potential for selection in a breeding program. SPAD was a reliable indicator of the effect of fertilizer on foliar crude protein and showed different effects of fertilizer on N uptake and nutritional value among genotypes. We identified genotypes that display high N uptake and good relative feed value. This intentional design for environmental benefits could have a dual purpose should this potentially nutrient-dense biomass by used as fodder for small ruminants.

Effects of riparian forest and agricultural land use on stream fish diet and trophic position

AbstractTo examine agricultural impacts on stream food webs, we used gut content analysis (GCA) and stable isotope analysis (SIA) to investigate the influence of riparian forest buffers on the diet and trophic position of five stream fish species in a row‐crop agricultural watershed. Six study streams were divided into two categories (forested and agricultural) based on percentages of riparian forest and agriculture in the watershed. Results suggest alterations in riparian vegetation (forested vs. cropland) had strong impacts on instream characteristics and basal resources that affected prey abundances and fish trophic structure. Although differences varied among species, GCA revealed fish in forested streams had a more diverse diet that included greater numbers of terrestrial invertebrates and aquatic invertebrate predators, whereas fish in agricultural streams consumed more aquatic herbivores and decapods. Diet shifts of the omnivorous creek chub followed differences in basal resource biomass, with greater proportions of algae consumed in agricultural sites contrasted by greater detritus consumed in forested sites. SIA Bayesian mixing‐model results supported diet differences shown by GCA, including higher contributions of terrestrial invertebrates to fish diets in forested streams. However, the isotopic overlap of aquatic invertebrates in agricultural streams limited diet contribution comparisons. SIA indicated fish trophic position was higher in forested than agricultural streams for all species, but GCA was required to identify that greater consumption of predatory prey likely caused this widespread change in fish trophic structure. Results highlight the benefits of integrating SIA and GCA and the importance of riparian forests to stream fishes in agricultural watersheds.

Forested riparian buffer environmental variables are more important than size for species functional diversity in production forests

Retention of forested buffers around streams following forest cutting operations is a common management technique used to protect aquatic resources and conserve the surrounding ecosystem services. Species richness, or α-diversity, is commonly used as an indicator of the effects of forestry management although it provides very little information about those effects on ecosystem processes and function. Functional diversity links species traits and ecosystem function incorporating species diversity, community composition, and functional guild and is more suitable to investigate the direct and indirect effects of forestry on ecosystem function. We sampled spiders and vascular plants in buffered and unbuffered stream-forest systems in southern Sweden and used a trait-based approach to assess the effects of buffer size and environmental variables on functional diversity. We used structural equation modeling (SEM) to explore the effects of buffer size and condition on spider and vascular plant diversity. We found no effect of buffer size on the functional richness or functional redundancy for spiders or vascular plants. Buffer size had a slight effect on the α-diversity of spiders within small buffers and fully forested sites but the effect was small. Other buffer variables including canopy closure, buffer density, bare ground coverage, and soil fertility had direct effects on spider and vascular plant functional diversity. The main driver of functional richness was α-diversity, but our SEM analysis illustrated other environmental variables working jointly to drive functional diversity. Using a trait-based approach, we showed that forested buffers have a minimal overall impact on spider and vascular plant functional diversity. However, it is important to maintain high levels of α-diversity to preserve and promote both spider and plant functional richness in production forests and we suggest that forest management conserves and encourages high levels of α-diversity to increase overall functional diversity.

Capacity of River Valleys to Retain Nutrients from Surface Runoff in Urban and Rural Areas (Southern Poland)

Studies on water quality are necessary, as catchments of small watercourses are exposed to anthropogenic influences associated with agricultural activities, settlement, transport and other undertakings, leading to water pollution. There has been insufficient research performed on the valley’s ability to retain nutrients during floods, contributing to water accumulation. The main object of the study was to identify the retention capacity of river valleys under various aspects of human urbanization. To represent soil water retention, the Soil Conservation Service Curve Number (SCS-CN) method was used. Spatiotemporal autoregressive models were exploited to investigate the relationship between pollutants in precipitation and surface water in rivers. In contrast, multivariate analysis was used to identify and reveal patterns of land use for specific chemical compounds in the headwaters. The canonical-correlation analysis (CCA) showed that Mg+2 and Ca+2 cations in rainwater and surface waters play the main roles in the geochemical cycle in urban and rural areas. In the urban catchment area, the strongest relations were found for NO3−, K+ and Na+. The average NO3− concentration in urban headwater was 8.3 mg·dm−3, the highest in the study area. The relationship between NO3− concentration in headwater and rainwater was found for all study catchments using spatial autoregression (SAR). High concentrations of SO42− in surface water have been identified in urban areas. Severe water erosion raises the risk of nutrient leaching in soils prone to surface runoff. As a consequence of low soil permeability and urbanization, retention capacity is significantly reduced in areas with low soil permeability. Land development plans should take spatial retention capacity into consideration. To ensure that large reservoirs can retain water in the face of climate change, riparian buffer zones (protective zones in valleys for small water bodies as well as Nature-based Solution) are important.

A systems approach to modelling phosphorus pollution risk in Scottish rivers using a spatial Bayesian Belief Network helps targeting effective mitigation measures

Water quality remains a main reason for the failure of waterbodies to reach Good Ecological Status (GES) under the European Union Water Framework Directive (WFD), with phosphorus (P) pollution being a major cause of water quality failures. Reducing P pollution risk in agricultural catchments is challenging due to the complexity of biophysical drivers along the source-mobilisation-delivery-impact continuum. While there is a need for place-specific interventions, the evidence supporting the likely effectiveness of mitigation measures and their spatial targeting is uncertain. We developed a decision-support tool using a Bayesian Belief Network that facilitates system-level thinking about P pollution and brings together academic and stakeholder communities to co-construct a model appropriate to the region of interest. The expert-based causal model simulates the probability of soluble reactive phosphorus (SRP) concentration falling into the WFD high/good or moderate/poor status classifications along with the effectiveness of three mitigation measures including buffer strips, fertiliser input reduction and septic tank management. In addition, critical source areas of pollution are simulated on 100 × 100 m raster grids for seven catchments (12–134 km2) representative of the hydroclimatic and land use intensity gradients in Scotland. Sensitivity analysis revealed the importance of fertiliser inputs, soil Morgan P, eroded SRP delivery rate, presence/absence of artificial drainage and soil erosion for SRP losses from diffuse sources, while the presence/absence of septic tanks, farmyards and the design size of sewage treatment works were influential variables related to point sources. Model validation confirmed plausible model performance as a “fit for purpose” decision support tool. When compared to observed water quality data, the expert-based causal model simulated a plausible probability of GES, with some differences between study catchments. Reducing fertiliser inputs below optimal agronomic levels increased the probability of GES by 5%, while management of septic tanks increased the probability of GES by 8%. Conversely, implementation of riparian buffers did not have an observable effect on the probability of GES at the catchment outlet. The main benefit of the approach was the ability to integrate diverse, and often sparse, information; account for uncertainty and easily integrate new data and knowledge.

Preservation of Vegetation Diversity to Maintain the Riparian Ecosystem of the Sampean Watershed

Riparian vegetation on river borders can affect the riparian ecosystem of the watershed related to its function as a buffer zone and ecotone between water and land. A high diversity of riparian vegetation can indicate that the ecosystem of a river border is in good condition. Therefore, it is helpful to inventory the diversity of vegetation in the riparian zone, which was done in this study using the Shannon-Wiener diversity index. In this research, four plots measuring 5m x 5m, spread across upstream, middle, and downstream areas were used to analyze the types of vegetation, including trees, shrubs, and herbs. The diversity index (H’) results revealed four vegetation species at the tree level, twelve species at the shrub level, and six species at the herb level. The range of H’ values in all sample plots was 1&lt; H’ &lt;3, so the river border was shown to have moderate diversity, which indicated that the ecosystem in the Sampean watershed is relatively balanced. It is necessary to preserve the riparian buffer zone through riparian vegetation restoration management to improve the ecosystem balance of the Sampean watershed.&#x0D; Keywords: riparian vegetation, watershed, Shannon-Wiener diversity index

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.

Development of a modified thermal humidity index and its application to human thermal comfort of urban vegetation patches

ABSTRACT Extremely hot environments can trigger serious health problems. To evaluate the effects of microclimate on thermal comfort, we proposed and validated a modified thermal humidity index (MTHI) that combined air temperature and relative humidity with land surface temperature (LST). MTHI was more sensitive to microclimate changes than the general thermal humidity index that includes only T and RH, and thus the thermal comfort could be better indicated. In an urban riparian buffer study, we estimated the temporal dynamics and spatial distribution of MTHI values for 47 vegetation patches and explored how structural characteristics of patches affect the thermal comfort. The results showed that planting could significantly reduce LST and MTHI. Vegetation patches with complex vertical structures had considerably higher thermal comfort than those with simple structures. Decreasing nearest distance to river or increasing plant abundance could reduce the thermal discomfort. There were significant differences in the structure characteristics between the patches with MTHI <70 and those with MTHI >70, implying the critical thresholds of variations in thermal comfort with patch structure. Given that people always feel uncomfortable during the daytime in July, optimizing the patch structure is essential to improve the microclimate regulation services of an urban landscape.

Remote sensing indicators to assess riparian vegetation and river ecosystem health

Environmental managers need information to quickly detect which stressor combinations should be addressed to reverse river degradation across large study areas. The pivotal role of riparian vegetation in regulating thermal regimes and inputs of light, nutrients and organic matter has made it a major target of stressor-mitigation and conservation actions. However, due to the dendritic and extensive nature of river networks, field-based monitoring of local riparian conditions is expensive and time-consuming. Ongoing developments in remote sensing offer an unparalleled opportunity to address this challenge. Nonetheless, there is still a limited understanding of the capacity of remote sensing indicators to predict changes in local riparian and river conditions, urging for local calibration with in situ measurements. This study aims to evaluate the capacity of remote sensing to detect impacts on quality elements commonly used in river biomonitoring: riparian vegetation, abiotic river condition and macrophyte biomass. To this end, four remote sensing metrics were tested against field-based indicators in 50 stream locations from four river basins across the Northwest of Portugal: i) the lateral riparian continuity at reach scale (riparian forest buffer width), ii) the riparian vegetation density at reach scale (Normalized Difference Vegetation Index, NDVI100m), and iii) the land use intensification at both reach (LUI100m) and iv) segment (LUI500m) scales. We found that the combination of remote sensing variables (riparian forest buffer width and the land use intensification index) correlated with riparian vegetation quality and dissolved inorganic nitrogen concentrations. We also found that the riparian vegetation density was able to predict changes in vascular plant biomass except for bryophytes. Our study provides new insights on the capacity of satellite-based indicators to assess riparian and river health, illustrating their utility for land and water managers, to identify and monitor, at a reduced cost and time, potential changes in the riparian vegetation.

Backed‐Up, Saturated, and Stagnant: Effect of Milldams on Upstream Riparian Groundwater Hydrologic and Mixing Regimes

AbstractHow milldams alter riparian hydrologic and groundwater mixing regimes is not well understood. Understanding the effects of milldams and their legacies on riparian hydrology is key to assessing riparian pollution buffering potential and for making appropriate watershed management decisions. We examined the spatiotemporal effects of milldams on groundwater gradients, flow directions, and mixing regime for two dammed sites on Chiques Creek, Pennsylvania (2.4 m tall milldam), and Christina River, Delaware (4 m tall dam), USA. Riparian groundwater levels were recorded every 30 min for multiple wells and transects. Groundwater mixing regime was characterized using 30‐min specific conductance data and selected chemical tracers measured monthly for about 2 years. Three distinct regimes were identified for riparian groundwaters—wet, dry, and storm. Riparian groundwater gradients above the dam were low but were typically from the riparian zone to the stream. These flow directions were reversed (stream to riparian) during dry periods due to riparian evapotranspiration losses and during peak stream flows. Longitudinal (parallel to the stream) riparian flow gradients and directions also varied across the hydrologic regimes. Groundwater mixing varied spatially and temporally between storms and seasons. Near‐stream groundwater was poorly flushed or mixed during storms whereas that in the adjacent swales revealed greater mixing. This differential groundwater behavior was attributed to milldam legacies that include: berm and swale topography that influenced the routing of surface waters, varying riparian legacy sediment depths and hydraulic conductivities, evapotranspiration losses from riparian vegetation, and runoff input from adjoining roads.

Optimizing Management Practices to Reduce Sediment Connectivity between Forest Roads and Streams in a Mountainous Watershed

Forest roads often increase runoff and sediment loss, thus greatly impacting hydrological processes in mountainous watersheds. While there has been previous investigation on best management practices (BMPs) to reduce soil erosion from forest roads, few studies have attempted to optimize BMPs based on how much they can decrease sediment connectivity between forest roads and streams. To close this gap in knowledge, we analyzed the spatial relationship between forest roads and streams, presented the spatial distribution of sediment connectivity by integrating the forest roads into the calculation of the index of connectivity (IC), determined how sediment connectivity would respond to additional BMPs through simulating scenarios, and used these data to optimize the BMPs so they would intercept the greatest sediment loads. We found that forest roads and streams in the Xiangchagou watershed in the Dabie Mountain area of China tend to occur within 180 m of each other; however, within the same buffer zones, streams are more often accompanied by forest roads. IC was greatest near road–stream crossings but smaller near streams and forest roads, and it tended to decrease as the buffer distance increased. Furthermore, we found that sediment connectivity was decreased through running a variety of scenarios that used sediment basin and riparian buffers as BMPs between forest roads and streams. Specifically, within this watershed, riparian buffers should be 64 m wide, and there should be 30 sediment basins with a minimum upslope drainage area of 2 ha. At these quantities, the BMPs in this watershed would significantly affect sediment connectivity. By contrast, beyond these thresholds, increasing the width of riparian buffers or the number of sediment basins does not lead to meaningful sediment reductions. In this way, we were able to use the mean change point method to determine the optimal sediment basin quantity (30 with corresponding minimum upslope drainage area of 2 ha) and the optimal riparian buffer width (64 m) for the Xiangchagou watershed. While these results are a first approximation in a novel research area, they can guide forest managers and stakeholders to design and optimize BMPs that control the delivery of eroded sediments associated with forest roads.

Holistic Sustainability Assessment of Riparian Buffer Designs: Evaluation of Alternative Buffer Policy Scenarios Integrating Stream Water Quality and Costs.

Riparian buffer zones (RBZs) have been shown to be effective best management practices (BMPs) in controlling non-point source pollutants in waterbodies. However, the holistic sustainability assessment of individual RBZ designs is lacking. We present a methodology for evaluating the holistic sustainability of RBZ policy scenarios by integrating environmental and economic indicators simulated in three watersheds in the southeastern USA. We developed three unique sets of 40, 32, and 48 RBZ policy scenarios as decision management objectives (DMOs), respectively, in Back Creek, Sycamore Creek, and Greens Mill Run watersheds (Virginia and North Carolina) by combining the RBZ-widths with vegetation types (grass, urban, naturalized, wildlife, three-zone forest, and two-zone forest). We adapted the RBZ-hydrologic and water quality system assessment data of instream water quality parameters (dissolved oxygen, total phosphorus, total nitrogen, total suspended solids-sediment and biochemical oxygen demand) as environmental indicators, recently published by U.S. EPA. We calculated 20-year net present value costs as economic indicators using the RBZ's establishment, maintenance, and opportunity costs data published by the Natural Resources Conservation Service. The mean normalized net present value costs varied by DMOs ranging from 4% (grass RBZ-1.9 m) to 500% (wildlife RBZ-91.4 m) across all watersheds, due primarily to the width and the opportunity costs. The mean normalized environmental indicators varied by watersheds, with the largest change in total nitrogen due to urban RBZs in Back Creek (60-95%), Sycamore Creek (37-91%), and Greens Mill (52-93%). The holistic sustainability assessments revealed the least to most sustainable DMOs for each watershed, from least sustainable wildlife RBZ (score of 0.54), three-zone forest RBZ (0.32), and three-zone forest RBZ (0.62), respectively, for Back Creek, Sycamore Creek, and Greens Mill, to most sustainable urban RBZ (1.00) for all watersheds.

The legacy of forest logging on organic matter inputs and storage in tropical streams

AbstractRiparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear‐cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast‐growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear‐cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest‐stream interfaces.Abstract in Portuguese is available with online material.

Environmental literacy scenarios lead to land degradation and changes in riparian zones: Implications for policy in China

AbstractEnvironmental illiteracy threatens ecosystem functions globally, however, many continue to deny its existence. Knowledge deficit theory suggests that suspicions will decrease once officials and the public are presented with new facts. Despite extensive worldwide initiatives to improve riparian buffer zones, there is minimal evidence about the impact of environmental literacy metrics (ELMs) on riparian zone components (RZCs) across different land‐use types (i.e., rural, rural–urban transitional, and urban regions) within the riparian zones of dams and reservoirs. In this study, multiple statistical techniques were used to explore the extent of impacts on a 58,000 km2 area within China's Three Gorges Dam Reservoir (TGDR) area/region in 2019. Network visualization investigated RZC themes, such as plant cover, regeneration, exotics, erosion, habitat, and stresses, based on 5326 articles published over the past 121 years. Our analysis revealed the greatest lack of information regarding ELM (e.g., knowledge, attitude, and behaviour) among the general public, which, in turn, had the greatest impact on the components of plant cover in transitional regions and the least impact on regeneration in rural areas. Furthermore, the ELMs of local people had the most significant effect on RZCs, with Pearson correlation values ranging from −0.79 &lt; r &lt; 0.98 throughout the TGDR. In contrast, the ELM of government employees correlated more strongly with RZCs (−0.70 &lt; r &lt; 0.92) in transitional and rural areas. Comparatively, exposed soil, understory cover, and environmentally unfriendly activities, including pollution, were the most significant RZCs within the TGDR. Based on hierarchical methods, RZCs and ELMs differed significantly between land‐use categories. RZCs near dams and reservoirs exhibit many differences; thus, land‐use initiatives are required to raise awareness of their global impacts.