Section a obbens p65

part of the reserve is relatively weed-free. Some very local-

ized weed incursions also occur around disturbed areas

(i.e. rabbit warrens, service track edges and an old gravel

pit/rubbish site). There are low levels of Parentucellia latifolia

and Romulea rosea scattered in the woodland areas, while

Ursinia anthemoides is scattered throughout the reserve.

These latter weeds appear innocuous, but Romulea rosea is

a serious woodland weed in the wetter wheat-belt regions

(Hussey et al. 1997).

Conservation management

Conservation reserves are generally smaller in the

inner (i.e. western) wheat-belt areas compared to more

eastern areas (CALM records). Management of small re-

serves with large  perimeter to area ratios in a fragmented

landscape is difficult (Panetta & Hopkins 1991) and has

been exacerbated by a long history of disturbance and

degradation. This includes more frequent fires, weed in-

vasions due to human intervention and habitat

modification, and also rising water-tables leading to in-

creased salinity (Hobbs 1993). In outward appearances,

Jingaring Nature Reserve seems relatively undisturbed

in comparison to other small remnants in the area. Vari-

able levels of weed incursion were found, but most native

vegetation appears relatively healthy. There were no ob-

vious signs of tree or shrub deaths that might indicate

increasing salinity, but the reserve may still be at risk due

to its low position in the landscape and its proximity to

the Avon River. Important management issues include

the protection of rare and priority flora, weed abatement,

fire management and the protection of vegetation from

inappropriate and unauthorised access (i.e. trail bikes,

horses  etc).

With two critically endangered and five priority spe-

cies, the reserve needs a high level of protection from

potential threats.  The reserve has distinct vegetation com-

munities and its geographical position makes the flora

special (as discussed previously). Weeds are a threat to the

reserve’s integrity because weeds have been shown to dis-

place native species, alter fire regimes, change local

hydrology and reduce faunal resources (Hobbs 1991;

Humphries et al. 1993; Pigott 1994; Adair 1995). Areas of

weeds targeted specifically should provide the best man-

agement results. For instance, any attempt to eradicate

weeds from the degraded creek line or boundary zones is

unlikely to produce adequate regeneration of native spe-

cies. This is because understorey seed-banks are often

depleted in long-degraded areas such as these, and/or

these areas may require specialised techniques to effect a

reasonable germination event (Arnold et al.1998; unpub-

lished personal observations). Additionally, these areas

easily become weedy again due to wind-transported

propagules and this will hinder the growth of any regen-

erated native seedlings. Ongoing weed control followed

by planting out/seeding of local understorey species may

be the only option left to rehabilitate these areas. This

requires considerable management resources and may not

produce equivalent results to the inputs needed. Most rab-

bit warrens are located in the central portion of the reserve

where regular baiting for rabbits and localized weed con-

trol should prove more successful at regenerating these

areas in the medium term (i.e. native seed rain still occur-

ring in the immediate vicinity and weed reinvasion

limited). A regular monitoring program must be imple-

mented to determine the effectiveness of management

measures and whether or not more control work is re-

quired to achieve a better outcome.

Fire is an essential part of most Australian ecosys-

tems, but too-frequent burning of fragmented landscapes

can be disastrous leading to weed invasion within small

remnants which in turn perpetuates more fire events

(Bridgewater & Kaesehagen 1979; Wycherley 1984; Hussey

& Wallace 1993; B Muir, Muir Environmental Consult-

ants,  personal communication). CALM district records

show that the reserve has not had a fire since 1980 and

likely many years prior to that date. It appears that the

localized weed invasions in the reserve are the results of

localized soil disturbance rather than too-frequent fires.

Any future fire plans should consider mosaic burns sup-

plemented with post-fire weed control if required. Grading

fire-breaks prior to mosaic burns is not recommended

due to the increased potential for weed invasion along

these breaks (i.e. increased soil disturbance) and increased

fragmentation of these small reserves. Brush-cutting nar-

row bands of vegetation may provide the necessary

fire-breaks. The potential for fire to adversely impact upon

the reserve’s rare flora must be considered. These areas

should be kept fire-free until recovery plans have been

successfully implemented which would include research

into the fire response of these species.

There has been some evidence of trail bikes and horses

using the area. The open nature of the reserve allows easy

access. A management track cuts through the centre of the

reserve and another overgrown track leads to the reserve’s

north-west corner (not shown on Fig 2). At this stage, the

damage to vegetation from vehicles and horses has been

minor. It would be advisable to erect signs that these ac-

tivities are not appropriate or authorised, and to more

clearly distinguish the area as a nature reserve.

In conclusion, the survey has highlighted aspects that

need management attention despite the reserve’s relatively

pristine appearance. It demonstrates that ‘in depth’ sur-

veys are especially useful at detecting potential issues prior

to these situations becoming real management problems.

Acknowledgements: The authors thank N Marchant and the staff of the Western

Australian Herbarium (CALM) for their assistance and support for this volun-

tary project. We also thank R Cranfield and C Yates for their help and comments

on earlier drafts of this paper.

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Journal of the Royal Society of Western Australia, 84 (2), June 2001

58