A total of 53 native Australian species (52x C3, 1x C4) were sampled from 22 plant families and 7 growth forms along a transect in WA spanning 9.56 degrees latitude and 6.85 degrees longitude. Samples were collected using the nationally-accepted AusPlots Rangelands methodology. Samples were stored to preserve isotopic signatures and analysed using standard techniques for mass spectroscopy, including internationally-calibrated standards. Technical replicates of 13% showed very low drift (0.07).
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We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging.
Purpose
This project was established to investigate the leaf stable carbon isotope response of terrestrial plants to aridity along a bioclimatic gradient known as the South West Australian Transitional Transect (SWATT) in Western Australia. The South West Australian Transitional Transect (SWATT) is an ecological infrastructure initiative developed to measure biodiversity attributes and biophysical processes. The infrastructure informs key ecosystem science questions and assists with the development and validation of ecosystem models. Many of the questions addressed by research programs using the SWATT relate to the impacts of changing climate, land use and management practice on the patterns and processes that influence the distribution of genes, species and communities. Research underpinned by SWATT data is enabling better management and provides evidence to support sustainable development, landscape restoration and increased ecosystem resilience. The program is a collaboration between TERN (Terrestrial Ecosystem Research Network) and the Western Australia Department of Biodiversity, Conservation and Attractions (DBCA).
Lineage
Isotope ratio mass spectrometry (IRMS): Leaf tissue samples from were dried in synthetic gauze bags on silica gel. Samples from species that occurred at more than seven sites (see Table SWATT_climate2.csv for locations) were selected, with the exception of one species (Grevillea hookeriana), which is only present at six sites. Leaves were ground using a ball mill (Retsch MM400 fitted with a Qiagen TissueLyser 24 adapter set). Leaves that did not grind within 3 minutes in the TissueLyzer (for example, Allocasuarina spinosissima) were ground in a 5 mL stainless steel grinding jar. For carbon and nitrogen isotope analysis, 2-2.5 mg of ground material was weighed to six significant figures into a tin capsule using an A&D BM-22 microbalance. Technical replicates for 13% of samples were run to correct for drift. Samples were combusted at 1000°C in an Elemental Analyser (EuroVector EuroEA 3000) in line with a continuous flow isotope ratio mass spectrometer (Nu Instruments Nu Horizon, University of Adelaide). Pure glycine, glutamic acid and triphenylamine (all calibrated to international C & N standards) were used as standards. A standard error of 0.07‰ was achieved. Two-point drift and size corrections based on glycine and glutamic acid standards were undertaken. Growth forms were attributed to species based on the growth forms described in the National Vegetation Attribute Manual (ESCAVI, 2003) with grasses and forbs further divided in to annual and perennial groups. Sub-specific determinations were ignored. Climate data were extracted from BIOCLIM layers modelled at 9 second resolution extracted from ANUCLIM 6.1 (Xu & Hutchinson, 2013).
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