David James wrote:
>control:
>Just a thought, but are you sure that Juncus occurs beacause of lack of
>inundation. My understanding is that it likes inundation and salt. Also,
>which came first, the Juncus or the reduced inundation?
>These control methods are recommended in Parsons & Cuthbert (1992)
(Noxious
>Weeds of Australia).
>(1) improving drainage (not appropriate at KI!)
>(2) chemical control has had mixed results.
>(3) Mechanical control has been efective, but is expensive. There are a
few
>methods, one involving a yucca cutter (Specialised subsurface plough); a
>stone-bucket designed for removing stones from paddoks, fitted to
front-end
>loader. The plants are then heaped and burned. This might be possible to
>use under stockton bridge in winter?? but not the delicate approach that
>you would like.
>Trouble is, it will recolonise from seed floating around the estuary. It
>grows slowly, so if you get an area under control it might be possible to
>keep it that way with one working bee a year until the problem can be
>approached on a catchment scale.
A little background to this site may be required for those who don't know
it. The sandspit is an artificial site created from dredge spoil when
Stockton Bridge was constructed in the late 1960's. It soon became a major
roost for many species of shorebirds but notably large numbers of godwits.
The area was colonised by Spiny Rush until it was almost completely
abandoned by the birds in the 1990's. A small number of Lesser Golden
Plover occasionally tried to roost in a small area of Salt Water Couch in
the middle of the rush. I should add that the Spiny Rush was growing in
areas that were occasionally , but regularly, inundated by high tides, ie.
they had wet feet most of the time. James obviously misinterpreted my
early comments about the degree of inundation.
As the result of a recommendation in a report I wrote on behalf of
Shortland Wetlands Shortland Wetlands Centre for the Department of Public
Works and the Kooragang Wetland Rehabilitation Project this site was
considered a priority to rehab. I suspect this had something to do with
its high public profile as much as its importance to birds. To overcome
the problems of recolonisation of the site by the weed it was decided to
increase the amount of water over the site as it was clear that the Juncus
was not growing in areas where inundation was frequent. To achieve this a
lagoon was created in the middle of the sandspit with an island. This
lagoon was designed to fill on about one third of all high tides. This,
hopefully would increase the salinity of the lagoon and further discourage
the rush while promoting saltmarsh. The entire sandspit was bulldozed and
the topsoil with the seed stock buried at the southern, higher, end of the
site.
The water in the bridge side is relatively deep (~1m) in order to
discourage people and dogs from wandering onto the island while that on the
river side is shallow (grading up from a depth of ~30cm at its deepest).
The lagoon was designed to allow a range of waders to roost in varying
depths of water across a relatively large area. A further large area of
sand separates the lagoon and the mangrove fringed river. These mangroves
have colonised the site since its establishment 25 years ago but are too
far from the lagoon to decrease the birds security through loss of line of
sight. The only areas where colonisation of the Juncus is now likely to
occur is a narrow strip and the margin of the lagoon and this is being
managed by regular working bees by the Hunter Bird Observers Club.
THe major problems with the site now (besides a somewhat inappropriate and
ugly "bird hide") is the retention of water in the lagoon on neap tides.
It very occasionally dries out but this does not appear to worry the
Eastern Curlew and Lesser Golden Plover that appear to be using the site on
most high tides (please note that I can only speak of the past two summers
- am no longer resident nearby). I suspect that the other problem relates
to the high expectations of birdwatchers who expected a return to the glory
days. Unfortunately the godwits do not, at present, appear to want to use
the site. This is probably as this species seems to be rather conservative
and once they settle on a roost site they stick to it. Thousands of godwit
still seem content to roost on the artificial retaining walls on the other
side of the river. Mind you this was their ONLY option for many years.
This highlights the sorry tale of the Hunter River estuary. This is the
most important shorebird estuary in NSW and while the foraging areas are
well reserved within Kooragang Nature Reserve degradation and loss of their
roost sites is now very much a limiting factor. The Stockton Bridge
sandspit provides them with, at least, another option. The Draft
Management Plan for Kooragang Nature Reserve recognises the loss of roost
habitat and contains several recommendations for roost habitat
rehabilitation and creation (from my initial report). It would appear,
however, that there is an unwillingness of the part of the local managers
to address these problems (the usual cries of no funds to carry out the
work). If nothing is done then it is possible that the decline of a number
of the smaller shorebird species that has been documented in this estuary
over the last 30 or so years will continue. What will the twitchers do
then???
David Geering
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