DOI: 10.5061/dryad.xwdbrv1n2
title: Data from: Forestry impacts on stream flows and temperatures: A quantitative synthesis of paired catchment studies across the Pacific salmon range

description: Forestry is pervasive across temperate North America and may influence
 aquatic environmental conditions such as flows and temperatures, as well
 as important species such as Pacific salmon (Oncorhynchus spp.). While
 there have been many large-scale forestry experiments using paired
 catchment designs, these studies have yet to be quantitatively
 synthesized. Thus, it remains unclear whether forestry impacts are
 consistent, context-dependent, or unpredictable. This study aims to
 quantitatively synthesize forestry impacts on streamflow and temperature,
 through a systematic review and synthesis of paired catchment studies
 across the range of Pacific salmon. Specifically, we investigated whether
 generalizable relationships exist between forestry intensity (percent
 watershed harvested) and impacts to streamflow and temperature. We also
 examined whether watershed features (climate, hydrology, lithology) and
 harvest method mediated forestry impacts. We extracted information from 35
 unique paired-catchments from California to Alaska. Forestry had strong
 impacts on peak and low flows and maximum summer water temperatures, but
 responses were quite variable. Across all catchments, forestry elevated
 peak flows ~20% (n = 31 catchments), reduced low flows ~25% (n = 13
 catchments), and increased maximum summer temperatures ~15% (n = 35
 catchments) on average. However, these impacts were variable and were not
 predictable based on forestry intensity, thus broader stressor-response
 relationships were not supported. Forestry impacts on peak flows and
 maximum summer temperatures varied spatially. Peak flow impacts increased
 with increased northward latitude and temperature impacts decreased with
 eastward longitude. However, the magnitude of impacts were unrelated to
 other watershed attributes, which included climate (precipitation and
 aridity), rain vs. snow hydrology, elevation, and bedrock lithology.
 Harvest method and riparian buffer presence also had no detected effects
 on forestry impacts across studies and statistical models explained a low
 proportion of variation overall. Collectively, our results indicate that
 forestry can have substantial impacts on key environmental conditions;
 however, the magnitude of impact was variable and could not be clearly
 linked to easily-measured watershed characteristics. This implies that
 forestry impacts are not broadly predictable. Probabilistic risk models
 based on distributions of potential impacts may therefore be more useful
 for watershed management in data-poor situations.
description: # Data from: Forestry impacts on stream flows and temperatures: A
 quantitative synthesis of paired catchment studies across the Pacific
 salmon range
 [https://doi.org/10.5061/dryad.xwdbrv1n2](https://doi.org/10.5061/dryad.xwdbrv1n2) **Description of the data and file structure** Three .csv files have data for temperature, peak flow, and low flow respectively. Catchment names and references are consistent with table s1. Each file has the following columns: * Harvest_type - The forestry treatment method (recoded as 'clearcut' vs. 'other') * Riparian - whether a buffer was retained (temperature only) * Elevation * Lat * Long * Area_Reported_km2 - The area of catchment * PAS_pct - the percent of total precipitation as snow * Harvest_pct - the percent of the total catchment area harvested * Temp_pct, PeakFlow_pct, LowFlow_pct - the percent change in response metric * Aridity_index - Index of aridity (described in methods) * Lithology - 0/1 whether the underlying catchment lithology was permeable (described in methods) * Metric - the specific response metric used in a given study * Temp_C_change - the absolute temperature change (temperature data only)