A MONASH UNIVERSITY PERSPECTIVE Musa Kilinc and Danielle

A MONASH UNIVERSITY PERSPECTIVE Musa Kilinc and Danielle Martin School of Geography and Environmental Science

Sustainable Futures of Australian Temperate Forests: Carbon and Water Cycling J Beringer 1, R Birch 1, N D’Argent 1, M Kilinc 1, K Kurioku 1, L Hutley 2, D Mc. Guire 3, I Mc. Hugh 1, D Martin 1, S Wood 1 1 Monash University, VIC; 2 Charles Darwin University, NT; 3 Fairbanks University, Alaska

Site 2: 1926 regrowth Site 1: Oldgrowth (1730) Site 3: 1983 regrowth

OVERALL OBJECTIVES • To quantify the carbon, water and energy exchanges in a temperate forest and the factors regulating them over hourly to inter-annual time scales. • Establish the carbon, water and energy cycles of different aged forest stands and investigate how they change over successional time scales (decadal to centennial).

OBJECTIVES • Investigate the role of Mountain Ash forests on carbon stocks and fluxes. • Identify variables which may alter results. • Conclude whether younger or older eucalypt forests provide the highest rates of soil respiration, and the largest stocks of carbon.

Carbon Cycling: Contribution of Below - ground Respiration • Forest soils are responsible for storing up to 75% of forest carbon uptake (Paul et al. , 2002. • Carbon is eventually released to the atmosphere by below ground respiration Rbg (soil and root respiration). • Environmental variables: soil temperature and moisture, soil characteristics (chemical and physical properties) and stand age.

OUTLINE Three Mountain Ash sites all of different ages were selected to measure: • Below – ground Respiration (closed chamber connected to a LICOR 6200 gas analyser). • Litter - fall (litter traps) • Soil properties: chemical & physical (chemical analysis & soil bulk density) • Root biomass (dry weight) • Leaf Area Index (stems per hectare and leaf area)

Below ground Respiration

SUMMARY Rbg and Root respiration (Ra(roots)) both increase with stand – age, and litter – fall decreases with stand – age. Root biomass is also highest in site 1, where litter – fall over time is lowest (due to lower LAI).

CONCLUSIONS With the old growth forest having the highest rates of Rbg, this Mountain Ash soil is releasing the most carbon dioxide to the atmosphere out of the three sites in Wallaby Creek and is higher than many other studied terrestrial ecosystems.

• Unique site: – Eucalpytus Regnans is the tallest hardwood tree in the world – Study is based in a water catchment area – Tallest Eddy Covariance tower in the world (110 m) – Three different aged stands within the catchment

The forest ecosystem fundamentals Physical cycle - energy - sunlight - evapotranspiration Biogeochemical cycle - carbon - water - nitrogen

• The fundamentals of the carbon cycle are well understood within forests • I. e. Net uptake of the ecosystem as a whole decreases with stand age and in old growth forests, it is thought to be in equilibrium.

(Carey et al. , 2001)

Why study the terrestrial ecosystem? • An estimated terrestrial sink of 2. 3 Gt of carbon per year. • Biospheric sink is a key component of the Kyoto Protocol • Limited understanding between the coupling of these cycles

More recently… • Old forests are important carbon pools • Recent studies show that old growth forests also sequester carbon (Carey et al. , 2001; Paw U et al. , 2004) • High rates of leaf and root turnover contribute to permanent soil carbon pools [Dixon et al. , 1994; Schulze et al. , 2000].

Tower based Eddy Covariance • The basic idea of the EC method is to measure turbulent eddies and the properties being transferred (e. g. CO 2, heat, moisture, NOx), giving a mean flux across the plane (Baldocchi et al. , 1988). • Studies based on the use of tower based EC can explain temporal and diurnal local variations of fluxes. • Only on a point scale but depends on the tower footprint, based on tower height. • Results do not represent the regional scale.

Why are we here? • Airborne EC measurements are unique as it can directly measure fluxes on a regional scale…scope? • Most importantly data validation is necessary. • Compliment the data already obtained by tower based measurements, models and satellite imagery.

Thankyou