Oral Presentation Australian Freshwater Sciences Society Conference 2022

Peatland regulation of headwater stream water quality as a measure of peatland condition (#73)

Ewen Silvester 1 , Luke McPhan 1 , Charuni Jayasekara 2 , Aleicia Holland 1 , Samantha Grover 2 , Andre Siebers 1
  1. La Trobe University, Wodonga, VIC, Australia
  2. Applied Chemistry and Environmental Science, RMIT, Melbourne, Vic, Australia

Sub-alpine peatlands of the Australian Alps are directly associated with the water quality of headwater streams, receiving year-round supply of groundwater and modifying this water during transit through the peatland. Productive peatlands generate fixed carbon through plant growth and in doing so drive nutrient cycling processes. It is likely that the capacity of these systems to support nutrient cycling processes is directly linked to productivity and that patterns of nutrient flux across peatlands might be driven by variations in the productivity of peatlands. Here, we present data from 16 years of water quality monitoring and 6 years of local eddy-covariance flux tower measurements in a sub-alpine Australian peatland (Heathy Spur; Bogong High Plains). Our aim was to identify seasonal patterns in nutrient fluxes and compare them with patterns in peatland gross primary productivity (GPP) and ecosystem respiration (ER), and thus to investigate the utility of headwater stream water quality metrics as indicators of peatland productivity or condition. Most nutrients displayed consistent flux patterns with no change in seasonal trends from year to year, although mean nitrate (NO3-) and sulphate (SO42-) fluxes varied across years. GPP and ER also displayed seasonal trends, although the magnitude of both means and trends varied slightly across years. While there was little correlation between detrended GPP or ER and nutrient flux values themselves, the proportion of ER attributable to NO3- or SO42- metabolism did display consistent seasonal trends. Our results suggest a link between peatland productivity and nutrient cycling that may lead to a consistent multi-parameter approach to assessing peatland condition.