Relationship Between Riparian Buffers and Terrestrial Wildlife in the Eastern United States

When working forest stands are harvested, vegetated strips along streams are often retained as part of forestry best management practices (BMPs) to protect water quality. These riparian buffers, known as streamside management zones, when following forestry BMP recommendations, also likely provide benefits to various terrestrial wildlife species. To better understand the role of riparian buffers in contributing to biological diversity in working forest landscapes, we reviewed literature (n = 30) that reported on herpetofauna, bird, and mammal responses to riparian buffers in the eastern United States. Although few results were consistent among taxa, community composition commonly varied among riparian buffer widths. Narrower riparian buffers more commonly supported edge and disturbance-associated species whereas wider riparian buffers tended to support interior-associated species. We did not find a consistent width that supported all terrestrial wildlife species studied. Study Implications: Based on our findings, it may be most efficacious to use varying riparian buffer widths across a landscape to provide structural conditions for a diversity of wildlife species. Some interior species may be best conserved on older managed stands or other retained areas in the landscape rather than riparian buffers. Landscape context and functionality of riparian buffers as movement corridors need to be further investigated, as this is an assumed but not quantified indirect benefit for various terrestrial wildlife species and perhaps especially important for species with low vagility or low dispersal ability that require older forest or riparian areas.

Sensitivity of Riparian Buffer Designs to Climate Change—Nutrient and Sediment Loading to Streams: A Case Study in the Albemarle-Pamlico River Basins (USA) Using HAWQS

Riparian buffer zones (RBZs) provide multiple benefits to watershed ecosystems. We aimed to conduct an extensive sensitivity analysis of the RBZ designs to climate change nutrient and sediment loadings to streams. We designed 135 simulation scenarios starting with the six baselines RBZs (grass, urban, two-zone forest, three-zone forest, wildlife, and naturalized) in three 12-digit Hydrologic Unit Code watersheds within the Albemarle-Pamlico river basin (USA). Using the hydrologic and water quality system (HAWQS), we assessed the sensitivity of the designs to five water quality indicator (WQI) parameters: dissolved oxygen (DO), total phosphorous (TP), total nitrogen (TN), sediment (SD), and biochemical oxygen demand (BD). To understand the climate mitigation potential of RBZs, we identified a subset of future climate change projection models of air temperature and precipitation using EPA’s Locating and Selecting Scenarios Online tool. Analyses revealed optimal RBZ designs for the three watersheds. In terms of watershed ecosystem services sustainability, the optimal Urban RBZ in contemporary climate (1983–2018) reduced SD from 61–96%, TN from 34–55%, TP from 9–48%, and BD from 53–99%, and raised DO from 4–10% with respect to No-RBZ in the three watersheds. The late century’s (2070–2099) extreme mean annual climate changes significantly increased the projected SD and BD; however, the addition of urban RBZs was projected to offset the climate change reducing SD from 28–94% and BD from 69–93% in the watersheds. All other types of RBZs are also projected to fully mitigate the climate change impacts on WQI parameters except three-zone RBZ.

Exploring the Effects of Landscape Structure at Multiple Scales on River Water Characteristics in the Khorramabad and Chalus River basins

Background It is acknowledged that the landscape composition and configuration of land cover within a watershed could influence a watershed environmental and ecological quality. Therefore, rivers receive pollution from their surrounding landscape and the amount and intensity of this pollution are affected by the landscape structure around the river or within a watershed. Methods In this research, we estimated the relationship between landscape characteristics and water quality in two different basins. We used multiple stepwise regression analysis and redundancy analysis to explore the quantitative association between landscape metrics, at both the watershed and riparian buffer scales. Results The riparian buffer scales metrics were more effective in predicting water quality in comparison with the indices at the watershed scale. The landscape composition and configuration explained 80% of the variation in water quality at 100 m buffer, and the value decreased to 79% at 1000 m. At the 100 m buffer scale, ED of the forest, PLADJ, and MESH of urban areas in Khorramabad basin and AI of the forest, ED of urban, and SPLIT of agricultural lands were recognized as significant variables affecting the water quality in the Chalus basin. In other scales only metrics related to agriculture and urban were seen as dominant variables, indicating that these land-use classes are final determinatives in water quality changes in our study areas. Conclusion All dominant variables at each scale indicated a decreasing trend of the landscape impact on the water quality. Although in the Chalus basin human activities were insignificant, they had considerable effects on Chalus river quality, and urban and agriculture were recognized as dominant usages at all scales, implying that a large amount of forest cover cannot impede the effects of human activities in a basin.

Soil N2O and CH4 Emissions From Fodder Maize Production With and Without Riparian Buffer Strips of Differing Vegetation

Purpose: Nitrous oxide (N2O) and methane (CH4) are some of the most important greenhouse gases of the 21st century. Vegetated riparian buffers are primarily implemented for their water quality functions in agroecosystems and their location in the agricultural landscape allows them to intercept and process pollutants from immediately adjacent agricultural land. They recycle increase soil carbon (C), intercept nitrogen (N)-rich runoff from adjacent croplands, and are seasonally anoxic, promoting processes producing environmentally harmful gases including N2O and CH4. Against this context, the study quantified these atmospheric losses between a cropland and vegetated riparian buffers that serve it.Methods: We used the static chamber to measure N2O and CH4 emissions simultaneously with soil. Gas measurements were done simulataneously with soil and environmental variables for a 6-month period in a replicated plot-scale facility comprising of maize cropping served by three vegetated riparian buffers, namely: (i) a novel grass riparian buffer; (ii) a willow riparian buffer, and; (iii) a woodland riparian buffer. These buffered treatments were compared with a no-buffer control. Results: The no-buffer control generated the largest cumulative N2O emissions of 18 929 g ha-1 (95% confidence intervals: 524.1 - 63 643) whilst the maize crop upslope generated the largest cumulative CH4 emissions of 5 050 ± 875 g ha-1. Soil N2O and CH4-based global warming potential (GWP) were lower in the willow (1223.5 ± 362.0 and 134.7 ± 74.0 kg CO2-eq. ha-1 year-1, respectively) and woodland (1771.3 ± 800.5 and 3.4 ± 35.9 kg CO2-eq. ha-1 year-1, respectively) riparian buffers.. Conclusions: Our results suggest that maize production in general, and situations where such cropping is not undertaken in tandem with a riparian buffer strip, result in atmospheric CH4 and N2O concerns.

Event-scale flow and sediment generation responses to agricultural land cover change in lowland UK catchments

Agricultural land use can increase runoff and erosion leading to detrimental downstream impacts. This paper examines the impact of agricultural land cover change on runoff and sediment generation at event scales using a model-based approach. SHETRAN, a physically based, spatially distributed model, was applied in two southwest England catchments to represent: (a) changes in the land cover (cropland extent and spatial arrangement), (b) changes in crop type, and (c) use of riparian buffer strips. A total of 84 simulated events within a 4-year period were used to quantify flow and sediment generation impacts. We found past changes in land cover resulted in significant differences in sediment yield (p < 0.05). Linear regression showed an increase in flow and sediment yield proportional to increases in arable crop area (p < 0.001). The spatial arrangement of cropped fields and riparian buffer strips produced no significant differences in event flow or sediment yield (p > 0.05). However, buffer strip scenarios compared with the base run showed sediment load reductions in specific events, up to 20% and 15% for woodland and grass riparian buffers, respectively. When comparing crop types with and without the use of post-harvest cover crops, we observed non-significant differences (both Qv and Sy). However, large reductions in modelled sediment yields occurred for some events (e.g., up to 60% for winter cereals, 50% for maize and 74% for spring cereals). For these scenarios, examination of rainfall event magnitude emphasized the importance of ground cover in mitigating soil erosion for maize and spring cereals, but not for winter cereals. Our findings indicate that significant changes in sediment delivery at the event scale are associated with cropland extent and crop types, depending on rainfall magnitude, but not on the spatial arrangement of cropped fields or the use of riparian buffer strips.