Brief description
This data set provides the photosynthetic pathways for 4832 species recorded across plots surveyed by Australia’s Terrestrial Ecosystem Research Network (TERN) between 2011 and May 2022 (inclusive). TERN survey plots are 1 ha (100 x 100 m) permanently established sites located in a homogeneous area of terrestrial vegetation. At each plot, TERN survey teams record vegetation composition and structural characteristics and collect a range of plant samples using a point-intercept method. Species were assigned a photosynthetic pathway using literature and carbon stable isotope analysis of bulk tissue collected by TERN at the survey plots.
The data set is comprised of one data table that contains a list of each species and its photosynthetic pathway, and one metadata file which provides a data descriptor that defines data values and a list of all the peer-reviewed sources used to create this data set.
Version 1 (2020) included the photosynthetic pathways of 2428 species recorded across TERN plots surveyed between 2011 and 2017 (inclusive) and was originally published in 2020. Key updates in version 2 (2024) include an expanded species list and updated taxonomy were applicableNotes
Supplemental InformationA full list of the studies consulted is provided within the data file.
Lineage
Data Creation
Photosynthetic pathway assignment :
All TERN plant data were processed in the R statistical environment using the ‘ausplotsR’ package. A list of all vascular plant species at each TERN plot was extracted using the get_ausplots function. To assign each species a photosynthetic pathway, scientific names were first cross-referenced against well-known plant trait databases. We then conducted literature searches of the remaining unassigned species via Google Scholar with combinations of the key words “C3”, “C4”, “CAM”, “photosynthesis” and “photosynthetic pathway”. If species-specific information was not available, but the species belonged to a genus known to be exclusively C3, C4 or CAM it was assigned to that pathway (e.g. Acacia spp., Eucalyptus spp. are presumptive C3). If it was not possible to assign a photosynthetic pathway using published sources or presumptive reasoning, then that species was selected for stable carbon isotope analysis.
Stable Isotope Analysis: The carbon stable isotope values of C3 plants range from -37‰ to -20‰ δ13C (mean= ~-27‰), the values of C4 plants range from -12‰ to -16‰ δ13C (mean=~-13‰). For species where either a C3 or C4 pathway was possible, plants with δ13C values < -19‰ were designated C3, and plants with δ13C values > -19‰ were designated C4. Full CAM plants, or plants in which CAM is strongly expressed, have δ13C > -20‰. However, CAM photosynthesis almost always co-exists with the C3 pathway (C3-CAM). The δ13C of C3-CAM plants are correlated with the proportion of carbon that is obtained during light and dark periods. As a result, C3-CAM δ13C values are highly variable (approximately -13‰ to -27‰). To confirm the presence of CAM, additional measures of other physiological and biochemical variables are usually required. With this limitation in mind, for genera with previously confirmed C3-CAM potential, we tentatively denoted plants with a δ13C value > −20‰ as CAM, −21‰ to −24‰ as C3-CAM, and <−24‰ as C3.
Notes
CreditWe 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.
We acknowledge the TERN Ecosystem Surveillance field team for their work collecting the voucher specimens used in the δ13C analysis. We also acknowledge the support of TERN by the Australian government through the National Collaborative Research Infrastructure Strategy. Additional financial support for this project was provided by the AMP Foundation and the AMP Tomorrow Fund awarded to S.M., the Australian Research Council Future Fellowship (FT110100100793) awarded to F.A.M., and Australian Government Research Training Program and University of Adelaide Faculty of Sciences Divisional scholarships awarded to J.W.A.
This photosynthetic pathway data set was created by TERN to enable research examining the abundance, richness, and distribution of C4 and C3 vegetation in Australia.
Data Quality Assessment Scope
local :
dataset
Photosynthetic pathway assignments obtained from published sources have already been subject to scientific scrutiny and are well-validated. Plant δ<sup>13</sup>C were measured using well-established analytical techniques. All samples where corrected for instrument drift and normalized according to reference values using certified and calibrated standards.
Data Quality Assessment Result
local :
Quality Result
The assumption that all species within a given genus possess the same photosynthetic pathway is realistic in most circumstances. However, we identified multiple exceptions. C4 and CAM photosynthesis have independently evolved multiple times across dozens of lineages. To minimise this potential source of error, all species within a given family that are known to include C4 species were included in δ<sup>13</sup>C analysis. CAM or C3-CAM photosynthesis is particularly difficult to identify using δ<sup>13</sup>C, therefore any CAM or C3-CAM designations based on δ<sup>13</sup>C values should be considered tentative and warrant further investigation. Carbon stable isotope analysis was performed at different laboratories over multiple years. Stable carbon isotope values had average uncertainties of ≤ 0.54‰ δ<sup>13</sup>C based on repeat analysis of all the standards. The mean of the absolute difference between replicate samples (10% of all samples) was 0.22‰ δ<sup>13</sup>C.
Created: 2020-10-13
Issued: 2020-11-05
Modified: 2024-09-24
Data time period: 2011-01-01 to 2022-05-31
text: Australia, Continent-wide
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Point-of-truth metadata URL- global : 1e16257d-57ae-48dd-bbad-5701e72a9f6d
- URI : geonetwork.tern.org.au/geonetwork/srv/eng/catalog.search#/metadata/1e16257d-57ae-48dd-bbad-5701e72a9f6d
