DOI: 10.5061/dryad.2jm63xsqv
title: Above and belowground plant traits of dominant dune grasses from Duck, Outer Banks, USA

description: We examined above and belowground traits among four prominent dune grasses
 of the Atlantic and Gulf Coasts of North America: Ammophila breviligulata,
 Panicum amarum, Spartina patens, and Uniola paniculata. Whole plant
 samples of each species were collected from the foredune at the US Army
 Engineer Research and Development Center’s Field Research Facility in
 Duck, North Carolina, USA and quantified for several above and belowground
 traits (e.g., stem height, rhizome number and length, root surface area by
 diameter class, root tensile strength, mycorrhizal percent infection).
description: Samples were collected from the U.S. Army Engineer Research and
 Development Center (ERDC) Field Research Facility (FRF) located in Duck,
 North Carolina, USA (36.1820898, -75.7512527). Whole plant samples were
 collected in June and July of 2019 by hand digging from the face of the
 main foredune ridge facing the Atlantic Ocean. Only plants that were
 located at least 0.5 m from the base of other species were collected to
 avoid interspecific interactions. Above and belowground structures were
 separated in the field. Only roots and rhizomes directly attached to the
 base of a plant were collected which typically went to a depth of ~15-20
 cm and within ~30 cm of each plant. Subsamples of the root system intended
 for mycorrhizal percent infection were preserved in 70% EtOH and those
 taken for tensile strength were preserved in 15% EtOH. Samples were placed
 on ice while in the field. Upon returning from the field, subsampled roots
 were immediately refrigerated and remaining components of plant samples
 were frozen in water until further analysis. Aboveground components were
 assessed for stem number and maximum leaf length per stem. Belowground
 components were separated into belowground stems (buried portions of
 vertical stems), rhizomes (lateral stems), and roots. Rhizomes were
 counted and measured for length, and roots were scanned using WinRHIZO.
 All above- and belowground components were then dried in an oven at 60º C
 for 48 hours and weighed for dry biomass. In WinRHIZO, roots were grouped
 into five, 0.5 mm categories of root diameter for analysis (0.0-0.5 mm,
 0.5-1.0 mm, 1.0-1.5 mm, 1.5-2.0 mm, and &gt;2.0 mm). From the WinRHIZO
 scans and biomass, root tissue density (RTD), specific root length (SRL),
 average root diameter, root surface area and root diameter distribution
 were assessed.  Subsampled tensile strength roots
 were rehydrated in distilled water for 30 minutes. Root diameter was taken
 using digital calipers. Due to lack of roots in some samples, additional
 roots were included from sampled individuals on Hog Island, part of the
 Virginia Coast Reserve Long-Term Ecological Research (LTER) Network and
 spare root samples collected from target species not directly associated
 with a sample individual. Tensile strength tests were conducted using an
 MTS Insight 30 5 Universal Testing Machine (UTM) (MTS Systems Corporation,
 Eden Prairie, MN, USA) with a 50 N load cell. MTS Advantage Wedge Action
 Grips were modified with 5 mm thick packaging foam and 220 grit sandpaper
 to prevent damage to the root sample while providing enough grip to pull
 the sample. The Testworks 4 software was then used to assess the resulting
 tensile strength data. Root samples of individual plants
 were cut into 1 cm segments and root diameter determined using the ocular
 reticle of a compound microscope. Root segments were classified into one
 of four diameter classes (0.0-0.5 mm, 0.5-1.0 mm, 1.0-1.5 mm, and 1.5-2.0
 mm). Root subsamples were placed in beaker of distilled water and gently
 agitated to remove EtOH and sediment particles. Samples were moved to hot
 10% KOH for between 5 and 15 minutes depending on species. Time in 10% KOH
 was adjusted by species to prevent disintegration of the delicate roots.
 Samples were then briefly rinsed in distilled water and moved to 3.5% HCl
 for 15 minutes. Root samples were stained overnight in 0.04% trypan blue
 and preserved in glycerin prior to mounting on slides. Species were
 assessed for hyphal, vesicular, and arbuscular colonization using a
 modified, magnified intersect method in which 5 intersections, 1 mm apart
 were assessed per 1 cm root segment.