Endangered fairies: two new species of Caladenia (Orchidaceae; Orchidoideae; Diurideae), from the bauxite plateaux of southwestern Western Australia

Two new sympatric species of Caladenia from relatively inaccessible, high lateritic plateaux in a high rainfall area in southwestern Western Australia are described here as new to science. The species occur in a restricted area, c 100 km southeast of Perth, south of Dwellingup and northeast of Waroona. The two species co-occur and are associated with putative floral model species that they are mimicking. Caladenia lateritica mimics Conostylis setosa (Haemodoraceae) in terms of flowering time, height, colour and fragrance. Caladenia rosea mimics the flowers of Hypocalymma robustum (Myrtaceae) in terms of flowering time, colour and scent. We assume that these orchids share a pollinator with their mimics and attract the pollinator via food deception as the ‘hosts’ are sources of nectar and pollen for visiting native bees. Because the species co-occur and exhibit a remarkable evolutionary ‘arms race’, they would make an ideal model for further study of the processes driving sympatric speciation. Unfortunately, both new species are under threat from mining activities and poorly informed burning regimes.

Aspects of the biology of the European rabbit (Oryctolagus cuniculus) and rabbit haemorrhagic disease virus (RHDV) in coastal eastern Australia

A population of wild rabbits in a high-rainfall area near Sydney, New South Wales, was studied for 8 years to investigate the population biology of the rabbit in a high-rainfall area, to examine factors affecting the length of the breeding season, and to describe the biology of RHDV and a RHDV-like virus in the population. The breeding season was short, starting in June and ending in October, though some conceptions occurred in every month of the year. Supplementary feeding with grain, germinated wheat or high-protein rabbit pellets did not extend the breeding season, so predictions that the length of the breeding season and occurrence of anaemia were influenced by a lack of protein in the diet were not upheld. Myxomatosis appeared in late summer each year as in inland southern Australia. Studies of the immunostatus of the population showed that, even in the years before RHDV was released in Australia, 80–100% of adult animals were seropositive when tested with ELISA specifically designed to detect antibodies to RHDV, arguably owing to the presence of a RHDV-like virus. The proportion of seropositive animals fell when annual rainfall was below 600 mm and rose when it was above 700 mm. Presumably, in areas where rainfall is usually low the proportion of the population infected with the putative RHDV-like virus would slowly drop to a low level, providing a possible basis for the different epidemiological patterns found for RHDV in different parts of Australia.

Pasture and sheep responses to lime application in a grazing experiment in a high-rainfall area, south-eastern Australia. II. Liveweight gain and wool production

‘Managing Acid Soils Through Efficient Rotations (MASTER)’ is a long-term pasture–crop rotation experiment commenced in 1992. One of the objectives was to demonstrate the extent of crop, pasture, and animal responses to lime application on a typical acidic soil in the 500–800 mm rainfall zone of south-eastern Australia. Two types of pastures (perennial v. annual pastures) with or without lime application were established in 1992. Fifteen- to eighteen-month-old Merino hoggets were used as test animals and were changed annually. This paper reports the results of sheep responses to liming from the 4 continuous pasture treatments over 6 years from 1992 to 1997. The stocking rate was the same on all plots within a treatment during each rotation period, but was varied between treatments based on the pasture availability and sheep body condition. The most important findings from this study are that the limed treatments carried 29% and 27% more stock (up to 4 DSE/ha) than the unlimed treatments for perennial and annual pastures, respectively. As a result, the limed perennial pastures produced 27% more liveweight gain (62 kg/ha.year) and 28% more greasy wool (13 kg/ha.year) than unlimed perennial pastures, whereas the limed annual pastures produced 34% more liveweight gain (77 kg/ha.year) and 24% more greasy wool (11 kg/ha.year) than unlimed annual pastures. The significant responses to lime in liveweight and wool production were detected from the second growing season after the pastures were established. The increased sheep productivity on the limed treatment was due to a combination of increased pasture production and improved pasture quality. Perennial pastures showed a slight advantage in wool production, but not in liveweight gain. However, the seasonal variation of liveweight was greater on annual pastures than on perennial pastures. The larger variation in liveweight change could lead to more adverse effects on wool quality especially at high grazing pressures. Grazing management can be used to manipulate pasture and animal productivity to increase profits from lime use.