Bulletin No. 24
The flora and fauna of radiata pine plantations in north-eastern Victoria. G.C. Suckling, E. Backen, A. Heislers, and F.G. Neumann. 1976. Forests Commission, Victoria. 58 pp.
This bulletin reports on the progress of studies of the flora and fauna of plantations of radiata pine (Pinus radiata) of several ages viz. young pine (under 10 years). intermediate-age pine (around 20 years) and mature pine (over 40 years), and of mature native peppermint forest. These studies were commenced in summer 1971-72 in north-eastern Victoria.
It was found that the establishment of pine plantations on eucalypt sites brings about the development of a new series of vegetation profiles, changing with time as the degree of canopy closure and tree height change. Shrubs, abundant in young pine plantations, become suppressed as the pines grow and subsequently almost disappear after closure of the tree canopies. Later, when the plantations reach maturity, stands are more open with fewer, larger trees, and some of the native shrub vegetation returns.
In general, the planting of pines displaces many native plants and reduces the distribution of most others. Many species abound in the early years after conversion but those remaining in later years are few and include a considerable proportion of annuals and noxious weeds.
The method of pine establishment on eucalypt sites was found to affect significantly the availability of animal habitats such as hollow logs and stumps. Manual clearing methods leave more logs and stumps suitable for mammal and bird refuge than do mechanical clearing methods.
Fourteen native mammals were recorded in mature eucalypt forest and 11 in pine plantations in north-eastern Victoria. Another 7 species were expected to occur in the eucalypt forest but were not detected during this study. The mammals absent from pine are mainly arboreal, and in some cases they are totally dependent on eucalypts for food and shelter.
Pine plantations were shown to support viable populations of many ground dwelling mammals which are either more adaptable to the pine environment or survive by relying on patches of native vegetation. The echidna and long-nosed bandicoot obtain food and shelter in plantations of all ages whereas black wallabies and wombats are abundant only in young plantations where food supply and low cover are plentiful. Small mammals such as the bush rat and brown antechinus appear well adapted to survive and reproduce within most plantations, particularly where native vegetation persists along creeks.
Seventy-one bird species were recorded in the mature eucalypt forest and 35 of these occurred regularly within pine plantations. Twenty-seven of these 35 were found breeding in one or more of the pine areas and pairs of at least 22 species occupied breeding territories located entirely within the pine.
The groups of birds best represented in pine were those species which mainly feed from the ground and the understorey of eucalypt forest. The groups of birds most poorly represented in pine were those species which feed principally from the canopy and bole of trees in eucalypt forest. The canopy feeders include many honeyeaters which feed on nectar, pollen and nectar-seeking insects from flowers of eucalypts. These food sources are generally absent in pine plantations.
Insect studies have shown that a high level of flight activity, particularly of the orders Diptera (flies), Coleoptera (beetles), Hymenoptera (mostly parasitic on other insects), Hemiptera (bugs) and Lepidoptera (moths, butterflies), occurs in stands of young and mature pine, but not markedly in the intermediate-age pine. Fewer insects in the intermediate-age pine stands implies that less food might be available for insectivores than in the younger and older stands.
Generally the Diptera (flies), Coleoptera (beetles), Hemiptera (bugs, leaf-hoppers) and Lepidoptera (moths, butterflies) were as common in pine plantations as in the eucalypt forest. The Hymenoptera (mainly parasitic wasps) seemed to favour eucalypt stands. This suggests that eucalypt forests may be entomologically more stable than pine plantations, as the greater number and variety of parasites (Hymenoptera) may more effectively control any potential insect pests.
Although vegetation species diversity was considerably reduced on sites cleared for pine establishment, it is unlikely that any species of flora or fauna within the groups studied has so far been endangered by the pine establishment programme. This situation is not expected to change in the foreseeable future because only 8.2% of native peppermint forest in north-eastern Victoria is expected to be changed to pine plantations. None of the flora or vertebrate fauna species and few of the insect species so far detected or predicted to occur in the eucalypt forests are restricted to the peppermint forests of this region. However in view of the finding of Specht et al. (1974) that peppermint forests are at present poorly represented in viable reserves in Victoria, it is important that the species which either do not occur regularly or are absent from the pine, are conserved within this region.