DOI: 10.5061/dryad.tdz08kq2n
title: Data from: Leaf litter breakdown along an elevational gradient in Australian alpine streams

description: These data were generated to investigate the rate of leaf litter breakdown
 and how temperature and other factors such as microbial and and
 invertebrate activities were influenced over elevational and temporal
 gradients. Breakdown of allochthonous organic matter is a central step in
 nutrient cycling in stream ecosystems. There is concern that increased
 temperatures from climate change will alter the breakdown rate of organic
 matter with important consequences for ecosystem functioning of alpine
 streams. Dried leaves of Snow Gum (Eucalyptus pauciflora) and cotton
 strips were deployed in coarse (6mm) and fine (50µm) mesh size bags along
 an 820 m elevation gradient. Loss of mass in leaf litter and cotton
 tensile strength per day (k per day), fungal biomass measured as
 ergosterol concentration, invertebrate colonization of leaf litter and
 benthic organic matter (mass and composition) were determined. Both
 microbial and macroinvertebrate activities were equally important in leaf
 litter breakdown with the abundance of shredder invertebrate taxa. The
 overall leaf litter breakdown rate and loss of tensile strength in cotton
 strips (both k per day) were greater during warmer deployment periods and
 at lower elevations with significant positive relationships between mean
 water temperature and leaf breakdown and loss of tensile strength rate,
 but no differences between sites, after accounting for the effects of
 temperature. Despite considerably lower amounts of benthic organic matter
 in streams above the tree line relative to those below, shredders were
 present in coarse mesh bags at all sites. Ergosterol concentration was
 greater on leaves in coarse mesh bags than in fine mesh bags, implying
 differences in the microbial communities. The importance of water
 temperatures on the rate of leaf litter breakdown suggests potential
 effects of climate change-induced temperature increases on ecological
 processes in such streams.
description: 1) Leaf litter breakdown: dried leaves of Snow Gum (Eucalyptus
 pauciflora) were weighed and placed in streams in coarse (6mm) and fine
 (50µm) mesh size bags along an 820m elevation gradient. Final dry mass of
 leaves were taken to evaluate loss of mass and rate (k) of percentage mass
 loss calculated over the period of exposure. 2) Loss of
 cotton tensile strength: Sterile cotton strips (3x10cm) were placed in
 different mesh-sized bags with leaves with known tensile strength. Final
 tensile stength was obtained after exposure in streams and rate of tensile
 loss was calculated (k per day). Tensile strength was determined using a
 tensiometer (an Instron 4500 Uni Testing System). 3)
 Ergosterol  levels: Fungal biomass on leaves exposed in the streams were
 measured as ergosterol concentrations. Ergosterol was extracted from leaf
 samples for 30 minutes in 10ml of alkaline methanol at 80 degrees celcius.
 The ergosterol was then purified by solid phase extraction (Sep-Pak Vac RC
 tC18 500mg sorbent, Waters) after cooling. Separation of ergosterol was
 done on a high-performance liquid chromatograph (Agilent Technologies,
 1200 Series, Waldbronn, Germany) and measured with an ultraviolet detector
 (wavelength of 282nm). Using a standard calibration curve prepared with
 the chemical standard (Fluka, purity at 97%), ergosterol concentrations
 were determined and normalised to dry mass of the leaves.
 4) Invertebrate colonization of leaf litter were made from bag
 types  5) Water quality measurements were measured in
 situ at each site during sampling episodes
description: Please refer to ReadMe file.