Seeing the landscape for the trees: Metrics to guide riparian shade management in river catchments

摘要: Rising water temperature (Tw) due to anthropogenic climate change may have serious consequences for river ecosystems. Conservation and/or expansion of riparian shade could counter warming and buy time ecosystems adapt. However, sensitivity reaches direct solar radiation is highly heterogeneous in space time, so benefits shading are also expected be site specific. We use a network high-resolution measurements from two upland rivers the UK, conjunction with topographic modeling, assess relative significance landscape thermal behavior reaches. Trees occupy 7% study catchments (comparable UK national average) yet covers 52% area concentrated along corridors. Riparian most beneficial managing Tw at distances 5–20 km downstream source where discharge modest, flow dominated by near-surface hydrological pathways, there wide floodplain little shade, cumulative exposure times sufficient affect Tw. For studied, we find that approximately 0.5 complete necessary off-set 1°C during July (the month peak Tw) headwater site; whereas 1.1 required 25 downstream. Further research needed integrated effect future changes air temperature, sunshine duration, radiation, downward diffuse on help tree planting schemes achieve intended outcomes.