http://www.charcoalfinland.fi/Helander%20et%20al.%20Trends%20in%20Plant%20Science%202012.pdf

Glyphosate in northern ecosystems.

Browning of surface waters, as a result of increasing dissolved organic carbon and iron concentrations, is a widespread phenomenon with implications to the structure and function of aquatic ecosystems. In this article, we provide an overview of the consequences of browning in relation to ecosystem services, outline what the underlying drivers and mechanisms of browning are, and specifically focus on exploring potential mitigation measures to locally counteract browning. These topical concepts are discussed with a focus on Scandinavia, but are of relevance also to other regions. Browning is of environmental concern as it leads to, e.g., increasing costs and risks for drinking water production, and reduced fish production in lakes by limiting light penetration. While climate change, recovery from acidification, and land-use change are all likely factors contributing to the observed browning, managing the land use in the hydrologically connected parts of the landscape may be the most feasible way to counteract browning of natural waters.

/pdf/browning-of-freshwaters-consequences-to-ecosystem-services-3w3ckl37tx.pdf

Browning of freshwaters: Consequences to ecosystem services, underlying drivers, and potential mitigation measures

Change in river water temperature has important consequences for the environment and people. This review provides a new perspective on the topic by evaluating changes in river water temperature for the UK over the 20th century and possible changes over the 21st century. There is limited knowledge of space-time variability in, and controls on, river temperature at the region scale and beyond over the 20th century. There is historical evidence that UK river temperature has increased in the latter part of the 20th century, but low agreement on the attribution of changes to climatic warming because river temperature is a complex, dynamic response to climate and hydrological patterns moderated by basin properties and anthropogenic impacts. Literature is scarce to evaluate changes to UK river temperature in the 21st century, but it appears as likely as not that UK river temperature will increase in the future. However, there are a number of interlinked sources of uncertainty (related to observations, scenarios,...

/pdf/river-water-temperature-in-the-united-kingdom-changes-over-2ssu7zww5i.pdf

River water temperature in the United Kingdom Changes over the 20th century and possible changes over the 21st century

Forecasting climate change effects on aquatic fauna and their habitat requires an understanding of how water temperature responds to changing air temperature (i.e., thermal sensitivity). Previous efforts to forecast climate effects on brook trout (Salvelinus fontinalis) habitat have generally assumed uniform air-water temperature relationships over large areas that cannot account for groundwater inputs and other processes that operate at finer spatial scales. We developed regression models that accounted for groundwater influences on thermal sensitivity from measured air-water temperature relationships within forested watersheds in eastern North America (Shenandoah National Park, Virginia, USA, 78 sites in nine watersheds). We used these reach-scale models to forecast climate change effects on stream temperature and brook trout thermal habitat, and compared our results to previous forecasts based upon large-scale models. Observed stream temperatures were generally less sensitive to air temperature than previously assumed, and we attribute this to the moderating effect of shallow groundwater inputs. Predicted groundwater temperatures from air-water regression models corresponded well to observed groundwater temperatures elsewhere in the study area. Predictions of brook trout future habitat loss derived from our fine-grained models. were far less pessimistic than those from prior models developed at coarser spatial resolutions. However, our models also revealed spatial variation in thermal sensitivity within and among catchments resulting in a patchy distribution of thermally suitable habitat. Habitat fragmentation due to thermal barriers therefore may have an increasingly important role for trout population viability in headwater streams. Our results demonstrate that simple adjustments to air-water temperature regression models can provide a powerful and cost-effective approach for predicting future stream temperatures while accounting for effects of groundwater.

Accounting for groundwater in stream fish thermal habitat responses to climate change.

Estimating the thermal response of streams to a warming climate is important for prioritizing native fish conservation efforts. While there are plentiful estimates of air temperature responses to climate change, the sensitivity of streams, particularly small headwater streams, to warming temperatures is less well understood. A substantial body of literature correlates subannual scale temperature variations in air and stream temperatures driven by annual cycles in solar angle; however, these may be a low-precision proxy for climate change driven changes in the stream energy balance. We analyzed summer stream temperature records from forested streams in the Pacific Northwest for interannual correlations to air temperature and standardized annual streamflow departures. A significant pattern emerged where cold streams always had lower sensitivities to air temperature variation, while warm streams could be insensitive or sensitive depending on geological or vegetation context. A pattern where cold streams are less sensitive to direct temperature increases is important for conservation planning, although substantial questions may yet remain for secondary effects related to flow or vegetation changes induced by climate change.

https://www.fs.fed.us/rm/pubs_other/rmrs_2014_luce_c001.pdf

Sensitivity of summer stream temperatures to climate variability in the Pacific Northwest

Many efforts to model stream temperature by using an energy budget approach have not accounted for view factors in modelling stream surface radiative exchanges, used informal approaches for computing them, or relied on calibration, which is not applicable for prediction at unmonitored sites or for predicting the effects of changes in riparian vegetation. In this paper, equations are derived for calculating view factors on the basis of geometric considerations for streams with and without riparian forest. The solutions can accommodate vegetation overhanging the stream surface. Example calculations illustrate the substantial variability of view factors across the stream width, which has implications for the estimation of view factors from point-scale radiation measurements over the stream surface, and the important influence of overhanging vegetation on view factors for narrow streams. View factors computed from the geometric model agreed well with view factors computed from hemispherical photography for streams ranging from 1 to almost 50 m wide, indicating that the model appears to be reasonably robust to deviations from the simplified geometry assumed by the model. In addition to their use in modelling stream surface energy exchanges, the solutions could also be adapted for application to energy balance and microclimate modelling in linear forest openings, such as seismic lines used in oil and gas exploration. Copyright © 2013 John Wiley & Sons, Ltd.

Geometric calculation of view factors for stream surface radiation modelling in the presence of riparian forest

Aerial application of herbicides continues to be a dominant method of vegetation control in Canadian forest management. In this paper, we describe a suite of relatively modern technologies and emphasize their potential for integrated use in optimization of aerial herbicide treatments. The potential is illustrated using several case studies involving fixed-wing applications of glyphosate-based herbicide in the boreal forest region of Ontario, Canada. Results indicate that integration of geographic information systems, differential global positioning, electronic-guidance, on-site meteorological monitoring and remote sensing can be used to effectively plan, enhance application control and provide detailed post-treatment assessment and archival data for herbicide spray programs. SprayAdvisor, a GIS-based decision support system with the capacity to directly integrate all of these elements is briefly described.

Integrating advanced technologies for optimization of aerial herbicide applications

Thermal regimes of forested headwater streams control the growth and distribution of various aquatic organisms. In a western Oregon, USA, case study we examined: (1) forested headwater stream temperature variability in space and time; (2) relationships between stream temperature patterns and weather, above-stream canopy cover, and geomorphic attributes; and (3) the predictive ability of a regional stream temperature model to account for headwater stream temperature heterogeneity. Stream temperature observations were collected at 48 sites within a 128-ha managed forest in western Oregon during 2012 and 2013. Headwater stream temperatures showed the greatest spatial variability during summer (range up to 10 
 $$^\circ$$
 C) and during cold and dry winter periods (range up to 7.5 
 $$^\circ$$
 C), but showed less spatial variability during spring, fall and wet winter periods (range between 2 and 5 
 $$^\circ$$
 C). Distinct thermal regimes among sites were identified; however, geomorphic attributes typically used in regional stream temperature models were not good predictors of thermal variability at headwater scales. A regional stream temperature model captured the mode of mean August temperatures observed across the study area, but overpredicted temperatures for a quarter of the sites by up to 2.8 
 $$^\circ$$
 C. This study indicates considerable spatial thermal variability may occur at scales not resolved by regional stream temperature models. Recognizing this sub-landscape variability may be important when predicting distributions of aquatic organisms and their habitat under climate and environment change scenarios.

https://www.fs.fed.us/pnw/pubs/journals/pnw_2017_leach001.pdf

Jason A. Leach

Papers

Geometric calculation of view factors for stream surface radiation modelling in the presence of riparian forest

Integrating advanced technologies for optimization of aerial herbicide applications

Spatial and seasonal variability of forested headwater stream temperatures in western Oregon, USA

Travel times for snowmelt‐dominated headwater catchments: Influences of wetlands and forest harvesting, and linkages to stream water quality

Lake Outflow and Hillslope Lateral Inflows Dictate Thermal Regimes of Forested Streams Draining Small Lakes