Beyond the Edge: Linking Agricultural Landscapes, Stream Networks, and Best Management Practices

Abstract

Despite much research and investment into understanding and managing nutrients across agricultural landscapes, nutrient runoff to freshwater ecosystems is still a major concern. We argue there is currently a disconnect between the management of watershed surfaces (agricultural landscape) and river networks (riverine landscape). These landscapes are commonly managed separately, but there is limited cohesiveness between agricultural landscape-focused research and river science, despite similar end goals. Interdisciplinary research into stream networks that drain agricultural landscapes is expanding but is fraught with problems. Conceptual frameworks are useful tools to order phenomena, reveal patterns and processes, and in interdisciplinary river science, enable the joining of multiple areas of understanding into a single conceptual-empirical structure. We present a framework for the interdisciplinary study and management of agricultural and riverine landscapes. The framework includes components of an ecosystems approach to the study of catchment-stream networks, resilience thinking, and strategic adaptive management. Application of the framework is illustrated through a study of the Fox Basin in Wisconsin, USA. To fully realize the goal of nutrient reduction in the basin, we suggest that greater emphasis is needed on where best management practices (BMPs) are used within the spatial context of the combined watershed-stream network system, including BMPs within the river channel. Targeted placement of BMPs throughout the riverine landscape would increase the overall buffering capacity of the system to nutrient runoff and thus its resilience to current and future disturbances.

Modeling the Ecological Impact of Phosphorus in Catchments with Multiple Environmental Stressors

“…However, despite observable reductions in nutrient concentrations that have led to an improvement in the chemical status of inland waters, a corresponding improvement in the ecological status in many catchments has not been observed (Bowes et al, 2012; Harris and Heathwaite, 2012; Sharpley et al, 2018). Understanding these links between P pollution and the ecological impact is often hampered by the disconnect between agricultural landscape‐focused research and river science (Kreiling et al, 2017), limiting our understanding of the impact of multiple stressors on the aquatic environment and our ability to predict the effects of human activity (Nõges et al, 2016). Meanwhile, catchment managers are required to address and mitigate the effect of multiple stressors in river catchments based on regulatory data, which are typically of low temporal and spatial resolution (i.e., monthly observations at catchment outlets).…”

Complex Response of Sediment Phosphorus to Land Use and Management Within a River Network

“…It is likely that the capacity of the river network to buffer against P and the ability of agricultural soils and sediments to store P has resulted in a gradual buildup and eventual release of legacy P from the soil and the sediment in both streambanks and the river channel . Thus, we further suggest that legacy P may be masking the potential positive effects of applied BMPs as poor water quality and environmental degradation continue in the Fox River watershed and in Green Bay (Kreiling et al, 2018).…”

“…However, small dams that were failing or no longer needed were removed from the watershed (WDNR, 2015), which likely caused erosion of streambank sediment (Walter & Merritts, 2008). Increases in the number of point and nonpoint sources of P also led to the eutrophication of rivers, particularly in the lower reaches of the Fox River (Kreiling et al, 2018;WDNR, 2015).…”

“…P is a major limiting nutrient in freshwaters. Elevated levels of P can stimulate autotrophic production (Withers & Jarvie, 2008), resulting in river ecosystems to become eutrophic; flipping from a "natural" to a "degraded" regime (Kreiling et al, 2018). In the Laurentian Great Lakes, for example, elevated P levels cause seasonal hypoxia and harmful algal blooms in shallow bays downstream of agricultural and urban areas (Michalak et al, 2013;Sayers et al, 2016).…”

Characterization of River Networks: A GIS Approach and Its Applications

“…These are key independent variables determining the structure and function of river channel morphology (Schumm 1977). The physical character of individual FPZs has also been shown to be associated with significantly different fish and invertebrate communities (Arthington et al 2010;Milner et al 2015), biogeochemical conditions (Kreiling et al 2018), and aquatic food web character (Thoms et al 2017). Hence these physically derived river zones have functional relevance.…”