Case Study 2: Weed monitoring in a river catchment
Background information
You are employed by the Department of Conservation as a senior research
officer. Your minister (Honorable Mrs Mary Rivers) has recently
announced a weed strategy policy. The policy states that Gamba Grass
(Andropogon gayanus) and Mission Grass (Pennisetum polystachion)
are a fire hazard and must be eradicated from all public and private
lands.
![gamba](img/gamba.jpg)
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Gamba Grass Andropogon gayanus
Photo by Natalie Rossiter
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Mission Grass Pennisetum
polystachion
Photos by Colin Wilson
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Both grasses were introduced to the NT as experimental pasture
for the cattle industry. They share many similarities, including
their African origin, prolific seed production and ability to colonise
non-pastoral land. Both grasses have thrived in the tropical environment
of northern Australia. The introduction and rapid spread of Mission
and Gamba Grass has greatly increased fuel loading (tonnes per hectare
of flammable material) of the wooded savanna ecosystem common throughout
the region. This substantial increase in fuel loading, combined
with the later curing time of these grasses, has the potential for
a major change in the fire regime across the entire Top End.
Further information on Gamba and Mission Grass is provided on the
Northern Territory Fire and Rescue Service (NTFRS) web site at
http:///www.nt.gov.au/pfes/fire/Mission_Gamba_Grass.html
You have been asked to design a monitoring program for the Daly
River catchment to be used as a model for the rest of the state.
No budget has been set at this point, and part of your job is to
provide estimates of the costs involved. The time frame for the
project is set at 5 years.
There are grand plans for the future development of the catchment.
There are approximately 4,000 km2
suitable for cotton growing and other horticultural crops (mainly
mangoes and cashews). In addition, with the improvement of pastures,
more intensive cattle grazing will be possible. To give students
an idea of the extent of the proposed development, a map of part
of the catchment, classified in relation to different future land
uses, is shown.
![Future Land Clearing](img/casestudy/502dalyb3_s.gif)
Enlarged Version [107 KB]
Aims
The aims of the monitoring program are to
- provide information on current distribution of both weed species
- determine environments most at risk of infestation of both weed
species
- monitor fuel loads (specifying between native and exotic fuels)
- determine changes in composition of native plant species due
to weed infestation.
Location of catchment
The catchment covers approximately 20,000 km2,
which is equivalent to
the area of Kakadu National Park.
![daly river catchment](img/casestudy/502dalyb1_s.gif)
Enlarged Version [82.4 KB]
Much of the catchment is used for pastoralism, with some area
in conservation reserves and the remaining area is aboriginal land.
Existing vegetation
There are 11 vegetation communities present within the catchment
identified from the Northern Territory vegetation map (Wilson et
al. 1990).
![Vegetation Map](img/casestudy/502dalyb2_s.gif)
Enlarged Version [185 KB]
9 - Eucalyptus tetrodonta & E. miniata woodland,
sorghum understorey
12 - E. miniata & E. tetrodonta woodland, spinifex
understorey
13 - E. tetrodonta & E. miniata woodland with spinifex
understorey
15 - E. tectifica & E. latifolia woodland, sorghum
understorey
17 - E. dichromophloia & E. tetrodonta woodland,
grassland understorey
19 - E. terminalis & E. patellaris woodland with
grassland understorey
21 - E. tintinnans low woodland, sorghum understorey
29 - E. phoenicea woodland with spinifex understorey
44 - Terminalia arostrata woodland, grassland understorey
50 - Melaleuca minutifolia low woodland, sorghum
understorey
Blue shading - riparian forest (either Melaleuca or monsoon
forests)
References
Wilson, B.A, Brocklehurst, P.S., Clark, M.J., and Dickinson,
K.J.M. (1990). Vegetation survey of the Northern Territory. Technical
Report No. 49. Parks and Wildlife Commission of the Northern Territory,
Darwin.
![](img/line.gif)
When preparing your proposal make sure to note
the following
Length 1500-2500 words (please don't go over this limit)
In your proposal outlining and justifying the weed-monitoring
program for the minister to review, be sure to follow the basic
structure below:
1.Title
2. Table of Contents
3. Introduction
4. Methods and Justification (sub-section this as you wish).
Be sure to include
- sampling design (include seasonal timing)
- types of data to be collected
- descriptive statistics to be used
NB. you are encouraged to consider and include statistical analyses
to be used but will not be marked on this component
- proforma data sheet/s design
- outline and justify methods of data collection
5. Costs, time and staff required
- staff required
- cost and time budget for planning, sampling and report writing
6. References
- the proposal must be fully referenced
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