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Soil nitrogen (N) budgets are used in a global, distributed flow-path model with 0.5° × 0.5° resolution, representing denitrification and N2O emissions from soils, groundwater and riparian zones for the period 1900–2000 and scenarios for the period 2000–2050 based on the Millennium Ecosystem Assessment. Total agricultural and natural N inputs from N fertilizers, animal manure, biological N2 fixation and atmospheric N deposition increased from 155 to 345 Tg N yr−1 (Tg = teragram; 1 Tg = 1012 g) between 1900 and 2000. Depending on the scenario, inputs are estimated to further increase to 408–510 Tg N yr−1 by 2050. In the period 1900–2000, the soil N budget surplus (inputs minus withdrawal by plants) increased from 118 to 202 Tg yr−1, and this may remain stable or further increase to 275 Tg yr−1 by 2050, depending on the scenario. N2 production from denitrification increased from 52 to 96 Tg yr−1 between 1900 and 2000, and N2O–N emissions from 10 to 12 Tg N yr−1. The scenarios foresee a further increase to 142 Tg N2–N and 16 Tg N2O–N yr−1 by 2050. Our results indicate that riparian buffer zones are an important source of N2O contributing an estimated 0.9 Tg N2O–N yr−1 in 2000. Soils are key sites for denitrification and are much more important than groundwater and riparian zones in controlling the N flow to rivers and the oceans.

Riparian plants are vulnerable to acute combined nitrogen (N) and phosphorus (P) stress induced by water quality fluctuations. Here, we carried out pot experiments on Lythrum salicaria and Phragmites communis. Three N concentration levels (0 mg L−1, 0.8 mg L−1, and 20 mg L−1) and three P concentration levels (0 mg L−1, 0.03 mg L−1, and 1 mg L−1) were set up according to the actual water environment to investigate the effects of acute combined N and P stress on root morphology, photosynthesis function, and root antioxidant system. Our results revealed that the N-free treatment (0 mg N L−1) and P-free treatment (0 mg P L−1) formed deficiency stress on L. salicaria and P. communis, inhibiting root morphological growth, photosynthesis, and antioxidant capacity. Additionally, the N-free treatment improved the root potential to acquire nutrients with increases of specific root length and root length density. L. salicaria and P. communis had differences in tolerance to the high-N treatment (20 mg N L−1) and high-P treatment (1 mg P L−1). Specifically, the high-N treatment and high-P treatment caused the inhibition of root morphological and physiological traits in L. salicaria. Conversely, the high-N treatment or high-P treatment had positive effects on the root growth of P. communis. Integrated assessments of biomarker values showed that the simultaneous existence of two nutrient stresses resulted in pile-up effects and species-specific responses. These results will contribute to providing suggestions on the selection of appropriate plant species in future riparian zone construction.

PurposeThis study aims to investigate the spatial variations in soil carbon and nitrogen in the water-level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) and explore the influence of soil factors on these properties.Materials and methodsFor this research, six sampling points were selected along the WLFZ of the TGR, with the slope of the riparian zone categorized into four elevation ranges: 145–155 m, 155–165 m, 165–175 m, and above 175 m. A total of seventy-two soil samples were randomly collected to analyze the variations in soil physicochemical and biological properties along and perpendicular to the direction of river flow.Results and discussionCompared with the upstream areas, the downstream areas in the flow direction presented significantly greater soil organic carbon (SOC), microbial biomass carbon, total nitrogen (TN) contents, soil sucrase activities and soil respiration intensities. In the vertical direction, the SOC, TN and microbial biomass carbon increased with increasing elevation in the riparian zone. Notably, as the elevation of the riparian zone increases and along the flow direction, both the geometric mean diameter (GMD) and the mean weight diameter (MWD) of the soil water-stable and nonwater-stable aggregates gradually increase, whereas the fractal dimension (D) decreases, indicating an increase in stability. There was a strong positive correlation between the soil water-stable aggregates and the soil carbon and nitrogen levels.ConclusionsThe soil carbon and nitrogen contents gradually increase along the flow direction, with a distinct boundary in the midstream region, and the differences in soil physical and chemical properties are the main factors influencing these changes. The soil carbon and nitrogen contents also increased with elevation, with 165 m being a clear boundary. Above 165 m, water-stable soil aggregates have a significant effect on the soil carbon content, and soil biological properties are the primary factors driving this variation.

There is growing evidence of climate change impacts on northern ecosystems. While most climate change studies base their assessments on air temperature, spatial variation of soil temperature responses have not been fully examined as a metric of climate change. Here we examined spatial variations of soil temperature responses to an ensemble of regional climate model (RCM) projections at multiple depths in upland and riparian zones in the Swedish boreal forest. Modeling showed a stronger influence of air temperature on riparian soil temperature than was simulated for upland soils. The RCM ensemble projected a warming range of 4.7–6.0 °C in riparian and 4.3–5.7 °C in upland soils. However, soils were slightly colder in the riparian zone during winter. While the historical record showed that upland soils are about 0.4 °C warmer than the riparian soils, this may be reversed in the future as model projections showed that on an annual basis, riparian soils might be slightly warmer by 0.2 to 0.4 °C than upland soils. However, upland soils could warm up earlier (April) compared to riparian soils (May).

Based on the work from the Saph Pani project (Hindi word meaning potable water), this book aims to study and improve natural water treatment systems, such as River Bank Filtration (RBF), Managed Aquifer Recharge (MAR), and wetlands in India, building local and European expertise in this field.

Hydrological and hydrochemical processes occurring within riparian zones in temperate mid-latitudes flatland areas have significant implications for water management by controlling nutrient transfer between the watershed and the stream system. The riparian zone in a high-order flatland stream located within a 7063-km 2 agricultural watershed in Argentina was investigated to study its hydrological connectivity to upland zones, interactions with the stream, and their implications for groundwater hydrochemistry. The analysis was based on 9-year-long time series of groundwater/stream water levels collected along a 220-m-long transect comprising six piezometers, a river stage sensor, and hydrochemical information from 37 groundwater/stream water sampling campaigns. Samples were analyzed for electrical conductivity (EC), Cl − , SO 4 +2 , (Ca +2  + Mg +2 ), pH, and redox potential (ORP). Data were interpreted using descriptive statistics, statistical tests, groundwater flux calculations, and identification of hydrological patterns and associated hydrochemical responses. The system was hydrologically controlled by shallow groundwater. Three representative landscape hydrological patterns were identified: disconnected, incipient-weakly connected, and fully connected. Groundwater hydrochemistry was closely linked to hydrological connectivity, which played an important role in the mobilization and fluxes of solutes. Overall, groundwater EC, Cl − , SO 4 +2 , and (Ca +2  + Mg +2 ) concentrations decreased from upland to lowland. For full connectivity, Cl − concentrations reduced 33%, while SO 4 +2 reduced 42%, demonstrating the system’s buffering capacity. This investigation constitutes the first attempt to formulate the riparian zone functioning in this agricultural region and has contributed to the understanding on the complex interactions between hydrologic regimes of large flatland-high-order streams and shallow groundwater systems in fine-texture sediments.

The study aims to understand the influence of pollinator visitation rate to coffee plantations located along the riparian zones of river Cauvery in Karnataka, using distance as a criterion. Plots were fixed at 10 m, 30 m and 60 m points from the edge of riparian zone towards the coffee plantations. In each of these three points, five plants were selected. In each plant, four branches with approximately six inflorescences per branch were observed for 15 minutes and the visitation rate of selected floral visitors to Coffea canephora was recorded. To understand if a riparian zone was a suitable pollinator habitat, bee colonies in the riparian zone were identified through a transect of approximately 500 m adjacent to the study plot. The total number of bee visits for Apis dorsata, Apis cerana, Tetragonula iridipennis and Apis florea was 18,100 for an observation time of 9540 minutes. A. dorsata and A. cerana were the main contributors to the total number of visits. The visitation rate of pollinators, A. cerana and A. dorsata decreased with increase in distance from the riparian zone. Additionally, colonies of A. cerana and A. dorsata were found in the riparian zones indicating riparian zones as potential pollinator habitats. A negative relationship has been observed between total species visits and distance indicating a reduction in species visits with increased distance from the riparian zone. Conservation of riparian zones increases pollination service to adjacent coffee plantations along with a multitude of other ecosystem services.

Predicting the effects of the loss of individual species on diversity represents one of the primary challenges facing community ecology. One pathway by which organisms of one species affect the distribution of species is ecosystem engineering. Changes in the dynamics of ecosystem engineers that lead to changes in the distribution of the patches of altered habitat are likely to lead to changes in diversity. I link data on the distribution of plant species found in the riparian zone of the Adirondacks (New York, USA) in patches modified by beaver and in unmodified forest patches to a model connecting the dynamics of ecosystem engineers to the dynamics of the patches that they create. These analyses demonstrate that changes in key parameters of the model, such as decreases in beaver colonization rates and rate of patch abandonment, lead to changes in species richness of up to 45% at the landscape scale, and that these changes are likely to occur over long time scales. This general approach of linking the population dynamics or behavior of a single species to changes in species richness at the landscape scale provides a means for both testing the importance of ecosystem engineering in different systems and developing scenarios to predict how changes in the dynamics of a single species are likely to affect species richness.

The plant is an important component of the riparian ecosystem, which could reflect both the environmental and functional characteristics of the riparian zone. Studies on species composition, diversity, community structure, distribution pattern, and adaptation strategies of plant communities in the riparian zone of the Three Gorges Reservoir (TGR) will help to explore the maintaining mechanism of the plant communities’ ecological function under severe water-level fluctuation. The paper reviewed the plant community characteristics, functional traits as well as their eco-physiological responses and environmental adaptations in this special ecological zone. Based on this, future research orientations in this field were also prospected, which may focus on the maintenance mechanism of the plant community, suitable plants selection and their adaptation mechanism, the relationship between plant functional traits and ecosystem functions, plant niche in the riparian zone, and the connectivity of riparian zone to the surrounding environment. The results can promote the correlational research on plant communities in the riparian zone and deepen the understanding of ecosystem services the riparian ecotone provides.

This book describes the underlying water conditions and geologies that support viable riparia, illustrates the ecological characteristics of riparia, and discusses how riparia are used by human cultures as well as how riparia can be used to sustain environmental quality.