Program A Student Profiles

1. David Forrester
2. Samantha Grover
3. Angela Newey
4. Grahame Price
5. Anna Richards
6. Stan Schymanski
7. Christine Sefton
8. Russell Turner
9. Robert Waterworth
10. Eddie Webber
11. Vanessa Wong
12. Ita Yulnafatmawita
13. Melanie Zeppel

David Forrester

Dynamics of mixed species plantations

Supervisors: Jürgen Bauhus, Annette Cowie and Ryde James

Despite the potential benefits of mixed species plantations, their current establishment in Australia is restricted, possibly due do to a perceived risk of crop failure. The success of mixed species plantations in improving productivity depends on species interactions, species composition, proportions of species and the extent to which the interactions might be influenced by growth limiting resources.

The aim of this project is to:

1. identify the growth habits and physiological characteristics in tree species that will allow an assessment of the likely competition between species;
2. to determine how the ecological interactions between nitrogen-fixing and non-nitrogen-fixing species change with resource limitations, in particular water and phosphorus limitations, which are very common in the Australian environment.

The research makes use of several field trials and a pot trial.

Preliminary results show that mixed species stands of Eucalyptus and Acacia are more productive than monocultures of either species. This is partly due to facilitation via nitrogen fixation by Acacia and accelerated cycling of nutrients in litterfall in mixed species stands.

Samantha Grover

The functions and characteristics of peat soils in subalpine mossbeds in the Australian Alps

Wellington Plain mossbed, Victorian Alps

Angela Newey

Soil Carbon Turnover Rates As A Function Of Depth In The Soil Profile

Supervisors: Dr Richard Greene, Dr Roger Gifford

Objectives:

• To identify the processes controlling soil carbon decomposition and their relative contributions, as a function of depth.
• To investigate why carbon is longer lived at depth in the soil profile and determine whether fresh litter inputs are more stable when allocated at depth in the profile than to the surface soil layers.

Current models used for greenhouse accounting purposes, to estimate carbon fluxes from below ground sources, are also based on data from just the top 20cm of soil. While there is some evidence to suggest that fluxes from deep soil layers may be insignificant relative to those of the surface layers, despite the presence of significant carbon stocks at depth, this assumption is in need of verification. Moreover, if C fluxes from deep soil layers are small as a result of greater organic matter stability at depth, an opportunity may exist whereby effective C sinks may be designed to exploit this situation for maximum sequestration potential.

This project will contribute to the parameterisation of carbon cycle models through process understanding of C dynamics at depth in the soil. This will help to improve predictions of carbon fluxes from below ground sources and inform the process of carbon sink design.

Experimental Approach:

• Changes in the ratio of naturally abundant carbon isotopes (d13C/12C) were measured in an experiment designed to trace the rate of decay of organic matter in the soil as a function of depth, in a field site where a C4 pasture had been converted to C3 pasture species. Issues with the use of this technique, relating to changes in isotopic signatures when C3 and C4 plant materials have been subjected to burning, have been identified by Evelyn Krull (CRC for GA, unpublished). The results from this experiment together with Krull's findings, identify some constraints to the use of stable isotopes in organic matter studies.
• A large scale litter-bag study is being conducted, involving burial and subsequent exhumation of 1788 litter-bags containing a range of different organic materials. The experiment investigates the effects of litter input quality and soil environmental factors on organic matter decomposition, and how these effects may vary with depth.
• A series of soil incubation/respiration experiments are being run:
  1. To investigate the relative amounts of labile and slow pool organic matter that occur at various soil depths, in certain selected soil profiles,
  2. To verify that observations from the litter-bag field study are reproducible in the lab under controlled conditions and in different soil types, and
  3. Test hypotheses regarding the underlying processes that may be causing the observed field phenomena.

Grahame Price

Carbon sequestration implications of forest health

Anna Richards

Above- and below-ground carbon dynamics in tropical mixed species forest plantations

Stan Schymanski

Ecological optimality and model parameterisation

Christine Sefton

Juvenile eucalypt leaf morphology

Supervisors: Prof. Jann Conroy, UWS, Dr Kelvin Montagu, SFNSW, Assoc. Prof. Brian Atwell, Macquarie University.

Leaves share common function yet show remarkable diversity in their form. The way in which leaf dry matter is organised is crucial for light capture, gas exchange and thus CO2 assimilation. Specific leaf area (SLA), the leaf area per unit leaf dry mass, appears to be the most useful summary parameter to measure the display of leaf dry matter. SLA (or its component parts leaf thickness and density) has been suggested to be indicative of ecological strategy. It has also been shown to correspond to resource use efficiency (water and nitrogen), leaf scale assimilation and relative growth rate. Leaf morphology varies not only between species but also within species as the result of light, nutrition, atmosphere, temperature, water availability and ontogeny. Leaf morphology is thus undoubtedly a key factor that contributes to whole plant growth. However, it is surprising that leaf morphology and anatomy has not been more intensively investigated among eucalypt species that are economically and ecologically important. The aims of my research are to establish the nature of the variation in leaf morphology and anatomy between eucalypt species and in response to changing environment. Further, how does leaf morphology contribute to growth rate, and can seedling leaf traits be used to identify long-term growth potential for use in forestry applications?

My research has involved experimentation in controlled environment glasshouses (UWS and Macquarie University) and in the field (UWS and NSW State Forests). Interspecies variation (11 species) and intraspecies response to environment (light, CO2 and temperature) was investigated in seedlings grown in glasshouses. In these experiments, whole plant growth analysis, juvenile leaf anatomy and leaf gas exchange was examined. A field trial of 12 species was established in April 2000 at the Yarramundi paddocks, UWS Richmond for comparison of field-grown and glasshouse-grown plants. Seed from State Forest Provenance trials was grown in a glasshouse trial to establish the relationship between seedling growth and leaf morphology with that of mature plantation trees, and thus infer the usefulness of seedling parameters to screen genotypes for plantation growth.

Russell Turner

Examining the use of LIDAR and Synthetic Aperture RADAR for estimating above ground woody biomass in coastal production forests

Supervisors: Prof Tony Milne, Dr Kelvin Montague

Objectives: This study aims to develop forest above-ground biomass classification models with both RADAR and LIDAR sensors using stand structure attributes, and to compare advantages and limitations of each imaging technique. This research will also explore the options for combined RADAR/LIDAR biomass modeling (or data fusion). The intention is to investigate alternative RADAR and LIDAR remote sensing technologies that have the potential to provide objective and cost effective above-ground biomass estimates on a local forest scale.

Introduction: Since the Kyoto Earth Summit (1997) there has been growing interest in remote sensing techniques for estimating above-ground biomass in Australian forests for carbon credit accounting and auditing. State Forests of NSW manage over 2.9 million ha of public forest representing a significant carbon store. As harvesting events are the prime process for varying carbon storage in these forests (both spatially and temporally) it is important to develop remote sensing techniques for biomass classification that can deal with the complex floristic and structural variation of harvested forests.

RADAR (Radio Detection and Ranging) studies have traditionally focused on microwave backscatter intensity (or return signal strength) to classify forest biomass. Backscatter is influenced by band wavelength, sensor viewing geometry, target properties and terrain characteristics (topography and soil moisture), and has been shown to saturate at high biomass levels. These constraints have limited RADAR applications to low biomass open forests on relatively flat terrain. Unfortunately, most coastal regrowth forests in NSW have high biomass levels (150 to 350 t/ha) growing in steep terrain. If imaging RADAR is to provide regional wall-to-wall biomass estimates then new techniques are required to overcome existing limitations. Alternative RADAR variables, such as band ratios, polarisation properties (scattering measures) and spatial texture, are being examined.

LIDAR (Light Detection and Ranging) offers an objective tool for mapping complex spatial variation in natural forests and woodlands. High resolution airborne laser scanners can record millions of x, y and z coordinates of forest structure from which a 3D tree canopy surface can be generated. This data can subsequently be used to infer forest parameters such as stand height, crown area, spacing and stocking.

Experimental approach: A case study site in Ourimbah State Forest was chosen as a representative example of coastal regrowth production forest in Hunter Region (NSW). It contains a diverse range of vegetation communities within a mix of harvested and unharvested stands spread across moderate to steep terrain. Following the integrated harvesting of the compartment, both intensive (2ha) and extensive (30m radius) plots were established. A range of remote sensing datasets, including SAR, LIDAR, multi-spectral video and aerial photography, have been acquired to assist in developing forest biomass classification models. This study will initially investigate independent SAR and LIDAR derived total above-ground biomass classification models in a harvested coastal hardwood forest. As a follow on, it may be possible to improve remote sensing forest biomass predictions through data fusion of SAR and LIDAR imagery either at the pixel or feature level.

Robert Waterworth

Prediction of forest growth in mid to low rainfall forest systems using process-based models

Eddie Webber

The Dynamics of Carbon Sequestration in Coarse Woody Debris of Eastern and SW Australian Forests.

Supervisors: Dr Cris Brack

Description: This study is aimed at defining the decay dynamics of coarse woody debris (CWD) in different forest types along a latitudinal gradient. The quantity of carbon (C) stored in different decay classes, and the movement of the CWD between the different decay classes, is of major importance when accounting the sequestered C in these forests. Modelling of this pool of sequestered C will lead to the formulation of management strategies for CWD in these forest types, which is currently lacking.

Surveying of CWD will be done at Atherton Tableland (tropical rainforest) and Rockhampton (eucalypt woodland) in Queensland, southern Tasmania (eucalypt plantations), and in SW Western Australia (eucalypt plantations). Due to the slow rate of decomposition of CWD, and the short duration of this project, CWD decomposition will be surveyed using the chronosequence method. This method involves the surveying of CWD of different ages at the one time.

CWD will be surveyed in the field with the use of the line-intersect method. This will give a volume of CWD (per hectare) for each decay class. CWD samples of different decay classes will be analysed in the lab for density and chemical constituents. The density of the lab samples will be used to calculate the mass (per hectare) of CWD at each location, based on decay class. The line transects are triangular, with each side being 100 m long (total transect length of 300 m). This triangular arrangement is necessary in order to account for any orientation bias, especially in areas with high gradients.

Vanessa Wong

The effect of salinity and sodicity on soil carbon stocks and fluxes

Ita Yulnafatmawita

The Influence of Organic Matter on Soil Structural Stability and CO2 Release during Cultivation

Supervisors : H.B.So1), N.W.Menzies1), and R.C.Dalal2) (1). Univ. of Queensland, 2) CRC-GA, QDNR)

Abstract: This project aims to investigate the role of OM in improving soil structural stability and also the function of structured soils in protecting SOM against oxidation. How strong the OM binds soil particles/aggregates, where it can be found within aggregates, what type of the OM presents, and how long it can stay in each aggregate fraction were assessed. Seven (7) soils with different textures, clay mineralogy, as well as land use were investigated. Soil aggregates were fractionated into 3 different sizes (>20, 2-20, and <2 um) using 3 rates of energy application of 0.04, 0.06, and 0.20 Jg-1 soil (Fig. 1). For each soil type, fifteen soil separates were obtained in this process. It was assumed that aggregates collected after application of specific rate of energy, had bonding energy which was greater than or the same as the energy level applied.

Generally, the result showed that most soils have high %OC in smaller aggregate sizes, either in the 2-20 or <2 um, and low in aggregates >20 um, except for the Ferrosols (ORP and ORF). In ORP soil (Fig. 2), the <2 um fractions had the lowest OC contents, lower than the OC of the bulk soil. The fractions >20 and 2-20 um had higher OC contents than the bulk soil, and the highest absolute OC value was found in aggregates >20 um. The reverse occurs with the Black Earth (BE) soil (Fig. 2), aggregates >20 um had the lowest OC contents, which decreased with increasing energy levels. Although some aggregates <2 um had higher OC content than that of 2-20 um, the absolute highest value of the OC was found at aggregates 2-20 um.

The susceptibility of SOM in each fraction to oxidation was measured under laboratory conditions through CO2 emission using Licor-6400 (Fig. 3). For both soils, BE & ORP, CO2 emission from aggregates <2 um was greater than that from the aggregates >20 and 2-20 um, as well as from unfractionated bulk soil. Low CO2 emission rate at 2-20 um fraction was also found at both soils. The higher rates of CO2 emission from those fractionated soils compared to the bulk soils indicate that SOM was not sufficiently exposed to oxygen until they were broken into <2 um size fractions, where some of the SOM would have been found on the outer surfaces of these fractions. Therefore, it appears that SOM is partly protected within soil aggregates. The implication of these findings is that excessive cultivation will increase the rate of SOM degradation significantly.

Figure 1: Energy levels used to break bulk soil aggregates	Figure 2: OC content (%wt) of ORP and BE soil fractions

Figure 3: CO2 release measurement using Licor-6400 at laboratory

Melanie Zeppel

Tree growth, water use and dryland salinity

Supervisors:Professor Derek Eamus, DR Brad Murray and DR Craig Barton

My project aims to:

1. compare tree growth, carbon accumulation and water use between a remnant forest and plantation forest in the same locality,
2. establish relationships among tree growth, tree water use, leaf area, and basal area, and (c) compare tree growth and water use between saline and non-saline areas.

By comparing growth and water use of native vegetation and planted forests in a common location, we shall significantly improve our ability to apply a scientific understanding to the problems of land management brought about through changes in land use.

This project will determine seasonal tree growth and water use patterns over a three-year period. The information on species survival and growth under different salinity conditions will also provide pertinent information for greenhouse accounting. Knowledge of amounts and change in carbon stocks resulting from salinisation is fundamental to emissions accounting and a national carbon inventory.

Relevance and Significance to the CRC of Greenhouse Accounting: This project is relevant to the CRC's investigations on dryland salinity and the effects on carbon sequestration. This project will determine seasonal tree growth and water use patterns over a three-year period. The information on species survival and growth under different salinity conditions will also provide pertinent information for greenhouse accounting. Therefore, this project contributes to the overall vision of the CRC to provide research outputs for greenhouse emissions accounting at the national and project level. Knowledge of amounts and change in carbon stocks resulting from salinisation is fundamental to emissions accounting and a national carbon inventory.