Getting to grips with Yourka Reserve

Monday 21 December, 2009

Queensland Herbarium botanist Jeanette Kemp joined Ecological Monitoring Coordinator Jim Radford and other Bush Heritage staff in an exploration of one of Bush Heritage’s newest reserves.

Staff members Jim Radford and Clair Dougherty undertaking vegetation survey in eucalypt woodlands of Yourka Reserve, Qld. Photo Jen Grindrod.Staff members Jim Radford and Clair Dougherty surveying vegetation in eucalypt woodlands of Yourka Reserve, Qld. Photo Jen Grindrod.

Thump! We felt the jolt of the Hilux shuddering to an abrupt stop before we registered the sound of the front axle ramming into the chalky roadbed as the track gave way beneath us. Opening the doors, we tumbled out into a gaping hole in the road. The deceptively solid surface was merely a thin crust over a treacherous pothole, excavated by recent rains.

Luckily we had backup, and were pulled from impending doom before navigating an alternative route to our next survey point.

The torrential rains of the last wet season that had carved deep incisions and potholes into the tracks around Yourka Reserve had also delayed ecological surveys because much of the reserve was inaccessible until autumn. When we arrived we could see flood debris, including uprooted trees, lodged in the limbs of towering paperbarks and river she-oaks a full 20m above the creeks.

Noisy friar-bird at Yourka Reserve, Qld. Photo Wayne Lawler / EcoPix.Noisy friar-bird at Yourka Reserve, Qld. Photo Wayne Lawler / EcoPix.

The floodwaters had finally receded by late June when a team of botanists, zoologists and ornithologists from the Queensland Herbarium, Queensland Parks and Wildlife Service and Bush Heritage descended upon Yourka to undertake the reserve’s first ‘bio-blitz’.

The primary aim of the blitz was to learn more about the ecology of Yourka by gathering information from focused field surveys and investigation. An intensive mammal survey program, using infra-red motion-triggered cameras, cage traps and spotlighting, was conducted in the moist forests and woodlands in the east of the property.

Carnivorous sundew (Drosera lanata) at Yourka Reserve. Photo Jeanette Kemp.Carnivorous sundew (Drosera lanata) at Yourka. Photo Jeanette Kemp.

Although the presence of the primary target of this survey effort, the endangered northern bettong, was not confirmed, many other mammals were recorded.

Greater gliders were abundant among the tall eucalypt forests in the Cameron Creek valley; brush-tailed possums were also spotted, an encouraging sign because there is concern that this species may be declining in northern Queensland.

Rufous bettongs were widespread throughout the property; the characteristic ‘sneeze’ of the longnosed bandicoot betrayed its presence behind our camp on the Cameron Creek; and a brown bandicoot was captured by one of the cameras.

In addition, numerous native rats were trapped and an inquisitive dunnart recorded for posterity by a remote camera. Further mammal surveys are underway as we go to press.

The black-chinned honeyeater, a rare species recorded at Yourka. Photo Graeme Chapman.The black-chinned honeyeater, a rare species recorded at Yourka. Photo Graeme Chapman.

Yourka’s variety of land formations and vegetation types makes it a great place for birding. Forty-two species were added to the Yourka bird list during the blitz, bringing the total to 116 species. This is sure to rise with spring bird surveys planned for October.

Notable observations included the nearthreatened northern subspecies of the brown treecreeper and a small flock of black-chinned honeyeaters, rare in Queensland. Red-headed honeyeaters were found at the southern extremity of their range, foraging with scarlet honeyeaters among paperbarks fringing Yourka Gorge.

Raucous gatherings of noisy friar-birds, scaly-breasted and rainbow lorikeets aggregated in the open woodlands. A host of seed-eaters, such as squatter pigeons, common bronzewings, peaceful doves and red-browed firetails were common on the river flats, feasting on grass seeds that were abundant in the wake of the summer rains.

Map of Yourka Reserve boundaries in context of Wet Tropics World Heritage Area

Large flocks of the comical and acrobatic apostle-bird, families of greycrowned babblers and a dawn chorus led by bush stone curlews were sights and sounds to gladden the soul. Wet tropic species like Victoria’s riflebird, bridled honeyeater and lemon-bellied flycatcher could be ticked off in the hills along the eastern margins of the property.

The real gems, however, were uncovered by the botanists. Yourka is proving to be a botanical wonderland, even for local experts, who had previously been unable to explore the area thoroughly. There are substantial areas of deep weathered white or red sandy soils on low rises and plains.

The poor nutrient status of these soils and ephemeral nature of the rains have encouraged the development of a heath-like flora that is species rich, particularly in miniature annuals, but also in low shrubby heath plants that are otherwise uncommon in the tropical north.

The blitz gave us a tantalising sample of the array of exciting ground species to be found, including tiny delicate trigger plants (Stylidium) less than 1 cm tall, a stunning carnivorous sundew (Drosera lanata) shaped like a manyarmed starfish, and a miniaturised herb (Mitrasacme phascoides) known from only a handful of specimens in Cape York.

Greater glider at Yourka Reserve. Photo Wayne Lawler/EcoPix.
Greater glider at Yourka Reserve. Photo Wayne Lawler/EcoPix.

Finding this plant at Yourka means that its range is extended by nearly  300 km. Many more annual species, too dry to be identified this time round, will be looked at again in the wet season.

A long-unburnt example of heathy vegetation was discovered, supporting grasstrees with complete skirts of dead foliage, as well as piles of litter on the ground. In one of these litter piles we found a poorly known orchid, later identified by the Queensland Herbarium as the green truffle orchid (Arthrochilus dockrillii). This is only the tenth record of this species, and it extends the known range south by 10–20 km.

The edges of incised creeks reveal a hardened layer beneath the weathered sands, and it is this habitat which is revealing several interesting shrubby heath species, including a probable undescribed boronia, the hopbush Dodonaea uncinata (listed as Rare under the Queensland Nature Conservation Act ), and a shrub from the Rutaceae family (Cryptandra debilis) which has a very restricted range (200 x 70 km) – the Yourka specimen extends its previously known range by 30 km.

Grasstree habitat at Yourka Reserve, Qld. Photo Jeanette Kemp.Grasstree habitat at Yourka Reserve, Qld. Photo Jeanette Kemp.

The blitz enabled field checking of the existing vegetation mapping done by the Queensland Herbarium and the Wet Tropics Management Authority. This provided useful data for Herbarium staff who are refining the mapping, while at the same time providing a basis for Bush Heritage staff to produce a more detailed map to use for fire planning and general management.

Herbarium staff were excited by a vegetation assemblage which could be considered as a new vegetation type. If officially recognised, its entire known distribution may be restricted to Yourka Reserve.

This vegetation type occurs on pale deep-weathered soils, and is dominated by the Queensland peppermint (E. exserta), the restricted-range bloodwood (Corymbia abergiana), and two species of she-oak, including the hairy she-oak (Allocasuarina inophloia), which outside Yourka is rarely found in such extensive communities.

A shrubby, heathy layer includes a rare hopbush (Dodonaea uncinata), as well as wattles, grevilleas, sedges and many interesting ephemeral herbs.

Overall the blitz has contributed to a current plant list of 308 species including four listed as threatened under the Queensland Nature Conservation Act, and an additional 11 species that are very poorly known and/or collected.

Processing of the plant specimens is not yet complete, and may still reveal more interesting finds.

While the bio-blitz revealed many of Yourka’s secrets, we have just scratched the surface. Reptiles, amphibians, fish and invertebrates were not included in the surveys and many of the regional ecosystems on Yourka are poorly surveyed. Much work remains to be done and we look forward to uncovering more exciting finds.

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