DOI: 10.5061/dryad.x95x69pmd
title: Data from: Underlying geology and climate interactively shape climate change refugia in mountain streams

description: Identifying climate-change refugia is a key adaptation strategy for
 reducing global warming impacts. Knowledge of the effects of underlying
 geology on thermal regime along climate gradients and the ecological
 responses to the geology-controlled thermal regime is essential to plan
 appropriate climate adaptation strategies. In the present study, the
 dominance of volcanic rocks in the watershed is used as a landscape-scale
 surrogate for cold groundwater inputs to clarify the importance of
 underlying geology in stream ecosystems along climate gradients. First,
 using hundreds of monitoring stations distributed across multiple
 catchments, we explored the relationship between watershed geology and the
 mean summer water temperature of mountain streams along climate gradients
 in the Japanese archipelago. Mean summer water temperature was explained
 by the interaction between the watershed geology and climate in addition
 to independent effects. The cooling effect supported by volcanic rocks
 reached up to 3.3°C among study regions, which was more pronounced in
 streams with less summer precipitation or lower air temperatures. Next, we
 examined the function of volcanic streams as cold refugia under
 contemporary and future climatic conditions. Community composition
 analyses revealed that volcanic streams hosted distinct stream communities
 composed of more cold-water species compared with non-volcanic streams.
 Scenario analyses based on multiple GCMs and RCPs revealed a
 geology-related pattern of thermal habitat loss for cold-water species.
 Non-volcanic streams rapidly declined in thermally suitable habitats for
 lotic sculpins even under the lowest emission scenario (RCP 2.6). In
 contrast, most volcanic streams will be sustained below the thermal
 threshold, especially for low and mid-level emission scenarios (RCP 2.6,
 4.5). However, the distinct stream community in volcanic streams and
 geology-dependent habitat loss for lotic sculpins was not uniform and was
 more pronounced in streams with less summer precipitation or lower air
 temperatures. These findings highlight that underlying geology, climate
 variability, and their interaction should be considered simultaneously for
 effective management of climate-change refugia in mountain
 streams. 
description: <strong>Definitions
 of the variable headings</strong> 
 
 Variable Explanation Site Monitoring
 site 
 Region Monitoring
 region 
 Basin Monitoring
 basin 
 Year Monitoring year of
 water temperature WT_℃ Mean summer water
 temperature (℃) Volcanic_% Volcanic rocks in
 the watershed (%) Agri_% Agricultural lands
 in the watershed (%) CA_km2 Drainage area
 (km<sup>2</sup>) Slope_% Stream slope
 (%) 
 Elev_m Site elevation
 (m) 
 AT_℃ Mean summer air
 temperature (℃) Pricipi_mm Total summer
 precipitation (mm) Depth_cm Mean water depth
 (cm) 
 Velocity_cm/s Mean current
 velocity (cm/s) Substrate Substrate
 coarseness DO_mg/l Dissolved oxygen
 (mg/l) 
 NO3<sup>-</sup>_mg/l NO3<sup>−</sup> (mg/l) 
 *Other columns' names indicate
 species names (e.g.,<em> Potamanthus.formosus</em>).