University of Queensland
Kasper Johansen
Summary | Research Objectives | Supervisors
|
Riparian zones are vital elements of the savanna landscape
(Tropical Savannas CRC, 2002), but human-induced degradation of
these environments has in many areas been considerable (Begg et
al. , 2001; Cowie & Werner, 1993; LWRRDC, 1999a). Other
than ground-based vegetation, faunal and stream surveys, there is a
significant lack of monitoring techniques able to provide regularly
updated and spatially extensive information on recognized
indicators of riparian environment condition from local to regional
scales (1–1000km2).
The research project will concentrate on developing a framework
for cost-effective monitoring of riparian zones in Australian
tropical savannas at local to regional scales using field and
remote sensing data.
The landscapes of dense grass and scattered trees that stretch
across northern Australia are characterised ecologically as
tropical savannas. Sustainable use and management of resources in
these areas are critical factors that affect the ecology and
environment (Begg et al. , 2001; NTG, 2003; Tropical
Savannas CRC, 2002).
Riparian zones are defined as the interface of terrestrial and
aquatic ecosystems and they encompass sharp gradients of
environmental factors, ecological processes, and plant communities.
Boundaries of riparian zones extend outwards to the limits of
flooding and upward into the canopy of streamside vegetation
(Gregory et al. , 1991). Riparian vegetation provides a
number of important functions including:
- nutrients to streams from litter fall;
- root masses for stream bank stability;
- shade to control water temperature and algal growth;
- large woody debris for stream channel development; and
- natural filtering preventing pollutants from entering the
waterways (Congalton et al. , 2002; Dowe, 2003; LWRRDC,
1999a; LWRRDC, 1999b).
The contribution of savanna riparian zones to biodiversity,
cultural values and the economy is disproportionate to the small
area they occupy (Tropical Savannas CRC, 2002). It is important to
maintain savanna and in-stream biodiversity, stream channel
morphology and water quality. However, savanna riparian zones are
highly vulnerable to the effects of disturbances such as weed
invasion, feral animals, fire impact, overgrazing and altered flow
regimes (Begg et al. , 2001; Finlayson & von Oertzen,
1996). Threats to riparian health are compounded by the fact that
riparian zones are the focus of much activity related to the
development of northern Australia such as grazing, agriculture,
weed invasion, tourism, and water extraction for agricultural and
domestic purposes. The concentration of land use in these habitats
is likely to increase in the future, thus increasing the need for
practical management options in riparian zones that will allow
landholders to meet their management objectives while still
maintaining riparian health (Apan et al. , 2002; Begg et
al. , 2001; Bourgeau-Chavez et al. , 2001; NTG, 2003;
Tropical Savannas CRC, 2002).
Developing practical management options for riparian zones
requires:
- a definition of riparian health;
- practical methods for assessing riparian health;
- an understanding of the effects of potentially threatening
processes on riparian health; and
- an evaluation of techniques to manage those threats (Tropical
Savannas CRC, 2002).
This research project will address all of these issues and base
the methodology on both field surveying and remote sensing.
Primary Objective
- To establish a framework for cost-effective monitoring of
riparian zones in Australian tropical savannas over local to
regional scales using field and remote sensing data.
Secondary Objectives
- To identify how environmental features (grass cover, canopy
structure, leaf angles, soils, water, exposed sandy surfaces, etc.)
and variables (phenology, water availability, weeds, fires, etc.)
within savanna riparian zones affect remotely sensed image data
spatially, spectrally, radiometrically and temporally.
- To map savanna riparian areas using field and multiple spatial
resolution image data collected for the Daly River and South
Alligator River / Barramundie Creek areas in the Northern
Territory. Field data will be integrated with the image data to map
riparian health indicators. Furthermore, field data will be used
for training and validation purposes of the multiple spatial
resolution image data.
- To monitor savanna riparian areas over time using field and
multiple spatial resolution image data collected for the Daly River
and South Alligator River in the Northern Territory. Issues related
to the use of the same and different sensors for change detection
analyses of savanna riparian areas (location and width of
wavebands, radiometry, spectral response functions, topography,
atmospheric condition, solar angle, viewing angle, geometric
coregistration, phenology, climatic factors, etc.) will be
addressed.
- To develop and validate the framework for monitoring savanna
riparian areas using field and multiple spatial resolution image
data.
Dr Stuart Phinn, University of Queensland
Robert Karfs, NTDPIE
