DOI: 10.5061/dryad.x3ffbg7tt
title: Stream-breeding salamander use of headwater stream networks in managed forests of western Washington, USA

description: Stream-associated amphibians are sensitive bioindicators in headwater
 streams across the Pacific Northwest moist coniferous forests of North
 America. Much of this landscape is intensively managed for timber. Forest
 Practices (FP) rules determine harvest prescriptions on most private lands
 in Washington State and cover over 3.7 million hectares. Under these
 rules, non-fish-bearing headwater streams receive buffers on at least 50%
 of the stream length, including FP Sensitive Sites that receive 15 to
 17-meter radius no-cut patch buffers. We evaluated how torrent
 (Rhyacotriton spp.) and giant (Dicamptodon spp.) salamander relative
 abundance is influenced by headwater stream network features that
 correspond to FP Sensitive Sites. In particular, we examined how
 salamander relative abundance in the two most common FP Sensitive Sites,
 tributary junctions (TJs) and perennial initiation points (PIPs), compared
 to densities in non-Sensitive Site stream reaches, hereafter branches. We
 also evaluated salamander relative abundance and two hydrologic
 characteristics, dry channel and seeps. We analyzed data collected in 2006
 and 2007 from 17 amphibian-occupied, non-fish-bearing basins in Western
 Washington with managed forest ages 30 to 80. We found no relationship
 between torrent salamander relative abundance and PIPs and TJs or between
 giant salamander relative abundance and TJs, when compared to branches.
 Consistent with expectations, giant salamander relative abundance was less
 in PIPs than in TJs and branches, and less in first-order than second- and
 third-order streams. Conversely, torrent salamander relative abundance
 lacked a clear relationship to stream order. Giant and torrent salamander
 relative abundance showed a negative relationship with proportion of dry
 channel, but torrent salamanders were observed in short reaches of surface
 water located in predominantly dry channels. Importantly, reaches with
 seeps had 123% (CI: +103% to +146%) and 81% (CI: +49% to +121%) greater
 relative abundance of torrent and giant salamanders, respectively, than
 reaches without seeps. Current FP rules protect select side-slope seeps as
 another category of Sensitive Sites but may too narrowly define the
 criteria of seeps to protect the full range of those being utilized by
 stream-breeding salamanders. Studies focused on seeps and adjacent stream
 channel characteristics may better inform features important to
 stream-breeding salamanders.
description: Stream reaches evaluated in this study were located in 17
 amphibian-occupied non-fish-bearing stream basins in western Washington
 that were part of the Type N Experimental Buffer Treatment Study
 (McIntyre<em> et al.</em> 2018; see McIntyre<em> et
 al.</em> 2009 for detailed account of site selection process that
 screened for the following criteria). We collected salamander count data
 from streams that were sampled each year using a modified light-touch
 technique (Quinn<em> et al.</em> 2007; Lowe and Bolger 2002).
 We conducted an active search as we moved upstream, turning all moveable
 surface substrates ≥64 mm [2.5 inches] within the ordinary high-water
 mark, including in dry reaches, and within the saturated area of
 channel-connected seeps.  Amphibian observations were checked for errors
 and counted by reach type, study site and detection segement.
description: # Stream-breeding salamander use of headwater stream networks in managed
 forests of western Washington, USA
 [https://doi.org/10.5061/dryad.x3ffbg7tt](https://doi.org/10.5061/dryad.x3ffbg7tt) ## Description of the data and file structure We collected salamander count data from streams that were sampled in 2006 and 2007 using a modified light-touch technique (Quinn et al. 2007; Lowe and Bolger 2002). We conducted an active search as we moved upstream, turning all moveable surface substrates ≥64 mm [2.5 inches] within the ordinary high-water mark, including in dry reaches, and within the saturated area of channel-connected seeps. Surveys were conducted during daylight hours between June and October in 2006 and 2007. Upon capture, animals were promptly identified, measured and returned to their capture location. We designated dendritic reach types by their spatial proximity to stream network nodes (i.e., TJs and PIPs), and by extension, whether they fell within circular (17-m radius) FP Sensitive Site no-cut patch buffer criteria. Amphibian observations were grouped by site and dendritic reach type for analysis. Detection segments were used as a random effect to group similar stream segments. The stream order (*sensu* Strahler 1952) of each stream reach was verified in the field. ### Files and variables "salamandernetwork.csv" and "salamander_seep.csv" contain data used in the manuscript's analysis.  Fields, abbreviations, and units are described in the table below for each dataset.  | **dataset** | **field** | **definition** | | :------------------ | :------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | salamander\_network | basin | basin is the unique identifier for the unique site (n=17) | | salamander\_network | trib | trib is the stream tributary within the basin | | salamander\_network | order | order is the Strahler stream order (1st, 2nd, or 3rd) | | salamander\_network | detection\_seg | detection segments are used to block similar stream reaches between PIPs and TJs in first-order reaches and between all TJs of different stream orders.  PIP= perennial inititiation point; TJ= tributary junction.  | | salamander\_network | reach\_type | dendritic reach types include network nodes (PIPs and TJs) and branches | | salamander\_network | length | length of the stream reach in meters | | salamander\_network | dry2006 | length of the stream reach that was dry during sampling in 2006 | | salamander\_network | year | year of sampling effort | | salamander\_network | disp | count of giant salamanders observed in the reach  | | salamander\_network | rhsp | count of torrent salamanders observed in the reach | | salamander\_network | effort | length of survey effort in meters | | salamander\_network | prop\_dry | proportion of channel dry =(dry2006/length) | | salamander\_seep | seep\_reach | binary indicator if seep is present in reach (1) or absent (0) | | salamander\_seep | basin | basin is the unique identifier for the unique site (n=17) | | salamander\_seep | trib | trib is the stream tributary within the basin | | salamander\_seep | detection\_seg | detection segments are used to block similar stream reaches between PIPs and TJs in first-order reaches and between all TJs of different stream orders.   | | salamander\_seep | year | year of sampling effort | | salamander\_seep | length | length of the stream reach in meters | | salamander\_seep | effort | length of survey effort in meters | | salamander\_seep | disp | count of giant salamanders observed in the reach | | salamander\_seep | rhsp | count of torrent salamanders observed in the reach | ## Code/software csv files were read into RStudio and analyzed using the brms package.