Field sampling protocol for foliage chemistry assessment. Applicability over varied forest sites in Australia

Photosynthetic rate is an indicator of vegetation performance as a carbon sequestration element on earth. At the same time, primary productivity is also function of photosynthetic rate and canopy cover. The photosynthetic capacity of an ecosystem is limited by the foliage pigment content due to the active participation of pigmentation in photon capture. Hence, the quantitative assessment of foliage pigment content is of high importance in order to monitor forest primary productivity and ecosystem performance in carbon sequestration. Pigment content estimation over large areas can be assessed using remote sensing data using empirical algorithms or by inverting radiative transfer models. Both techniques need accurate leaf pigment measurement for parameterisation and validation. Leaf sampling field protocols are then needed in order to collect and store leaf tissue without altering leaf pigment composition before its analysis in the laboratory. The Terrestrial Ecosystem Research Network (TERN) is a platform for researchers and land managers in Australia to work together on terrestrial ecosystem inventory and monitoring. Leaf sampling for pigment content estimation in Australian forests is then part of TERN field sites activities. This paper presents a leaf sampling field protocol used for TERN field activities during 2012. Two set of leaf samples were collected from sun exposed branches from each individual stand. The first set of samples was frozen immediately in dry ice and kept at -70 degrees Celsius for subsequent pigment quantification in the laboratory. The second set of leaves was kept under 10 degrees Celsius in humid conditions. This second set was later used for leaf spectroscopy measurement and to quantify water and dry matter content per unit area. Additionally, pertinent metadata was collected to characterise each sampled stand. The field protocol presented here has been used for leaf sampling on a broad range of study areas varying in species composition, canopy height and foliage density.