Legacies of stream channel modification revealed using General Land Office surveys,with implications for water temperature and aquatic life

Abstract

White, SM et al 2017 Legacies of stream channel modification revealed using General Land Office surveys, with implications for water temperature and aquatic life. Elem Sci Anth, 5: 3, DOI: https://doi.org/10. 1525/elementa.192 Introduction A major challenge of the Anthropocene-the period in which human activity is the dominant influence on climate and the environment-is to solve the interrelated problems leading to irreversible damage to planetary life support systems. These intertwined problems include human population growth, overconsumption, land use, climate change, and subsequent extinctions to biodiversity and elimination of ecosystem services (Foley et al., 2005; Barnosky et al., 2016). A common approach to forecasting the effects of human activity on the environment is through modeling scenarios of land use change and climate conditions, revealing various possible futures that can be embraced, avoided, or mitigated (Moss et al., 2010;Jantz et al., 2015;Isaak et al., 2016). In order to accomplish this, a comprehensive understanding of past human activities is needed, especially when past actions propagate a legacy extending to the present (Foster et al., 2003). The integrity of rivers and streams is especially vulnerable to human activities because hydrology and water temperature are strongly influenced by climatic effects (Dittmer, 2013) and the landscapes over which they flow (Hynes, 1975; Fausch et al., 2002; Allan, 2004). Streams and rivers provide important ecosystem services including clean and abundant water supply that are difficult to valuate but nonetheless essential (Arthington et al., 2010). Degradation of riverine ecosystems represents an important loss in terms of aquatic biodiversity (Dudgeon et al., 2006) and to people that depend upon rivers for food and other cultural values (Close et al., 2002).Modifications to river ecosystems in Europe, U.S., and other locations across the globe have been well documented. The European subcontinent has experienced land use change-specifically urbanization-since 700 B.C. (Antrop, 2004); these patterns have been manifested in several ways, but primarily as landscape fragmentation (Jaeger et al., 2011) and river channelization (Jurajda, 1995) RESEARCH ARTICLELegacies of stream channel modification revealed using General Land Office surveys, with implications for water temperature and aquatic life Seth M. White * , Casey Justice * , Denise A. Kelsey * , Dale A. McCullough * and Tyanna Smith † Land use legacies can have a discernible influence in present-day watersheds and should be accounted for when designing conservation strategies for riverine aquatic life. We describe the environmental history of three watersheds within the Grande Ronde subbasin of the Columbia River using General Land Office survey field notes from the 19th century. In the two watersheds severely impacted by Euro-American land use, stream channel widths-a metric representing habitat simplification-increased from an average historical width of 16.8 m to an average present width ...

The efficacy of riparian tree cover as a climate change adaptation tool is affected by hydromorphological alterations

“…The strength and caveat of the results is that the study catchments are located within the same approximate geographic area, demonstrating a consistent effect of tree cover and hydromorphological alteration on temperature responses in catchments subject to similar meteorological drivers. The results are consistent with other studies reporting impacts of hydromorphological degradation on stream temperature dynamics (Poole & Berman, ; White et al, ). However, it would be prudent to validate the observed temperature response in geographic regions subject to different climatic conditions and landscape characteristics before wide scale management actions are implemented based on the outcomes presented here.…”

Historical and Future Stream Temperature Change Predicted by a Lidar‐Based Assessment of Riparian Condition and Channel Width

“…In reaches where channel widening has occurred, our assumption of no widening will lead us to overpredict canopy opening angle change. White et al (2017) applied a channel narrowing restoration scenario to two degraded tributaries of the Columbia River, and found water temperature reductions of 2.2°C and 0.6°C in each tributary, respectively, resulting from restoration of historical channel width alone (i.e., without increased shade from revegetation). While insightful, the analysis relied on extensive and timeconsuming mapping of historical channel conditions using notes from the General Land Office.…”

Country‐wide analysis of large wood as a driver of fish abundance in Swedish streams: Which species benefit and where?

“…Furthermore, LW has been systematically removed from large rivers to enable navigation and prevent flooding, and riparian forests have been reduced in favour of agricultural lands (Sedell & Froggatt, ; Wohl, ). Hence, the negative relationship between LW abundance and stream size is probably derived from channel changes, and from past and present land‐use and management practices in large rivers, such as snagging and forest clear‐cutting (Anlauf et al, ; Montgomery et al, ; White et al, ; Wohl, ). This is also indirectly supported by the few examples of unmanaged large river systems, where LW has been successfully retained (Bertoldi, Gurnell, & Welber, ; Gurnell et al, ).…”

“…Despite the scientific recognition of the beneficial effects of LW on riverine ecosystems, LW often remains an unwanted feature thought to disrupt the aesthetic value of riverscapes and to enhance the risk of flood damage (Chin et al, ; Chin et al, ; Piégay et al, ; Wohl, ). This perception is partly derived from a long history of management practices in rivers, where LW was deliberately removed from rivers to improve drainage, together with landscape changes and river engineering that decreased the quantities of wood found in streams over timescales of 1000 years (White, Justice, Kelsey, Mccullough, & Smith, ; Wohl, ). Furthermore, management policies led to the disappearance or reduction of old, highly productive forests in the riparian areas of many countries, which reduces the supply of LW (Lazdinis & Angelstam, ; Valett et al, ).…”