The Shrubs of Poplar Box (Eucalyptus populnea) Lands and their Biology.

Abstract

Of the 25 species of shrubs common in poplar box lands, 17 are considered to have reached the status of being a "woody weed" in New South Wales and/or Queensland. Thickening up of scrub in pastoral areas appears to have been episodic after periods of above-average rainfall. Germination of seed may occur at most times of the year if soil moisture is high. Fire promotes germination of species with hard seeds (some Acacia, Cassia and Dodonaea spp.). Increased shrub density usually follows soil disturbance if seed is present, and once established, the individuals of most apecies appear to be long-lived. Productivity of shrub communities is commensurate with rainfall. The species are well adapted to tolerate drought and they retain leaves under extreme water stress. Most species flower and set seed each year in the spring and summer period but in more arid parts of poplar box lands some species reproduce opportunistically after good rainfall. In favourable conditions most species produce copious quantities of seed. Dormancy is common in seed recently shed and loss of dormancy may occur within months or up to 3 years after seed shed. All species are subject to invertebrate and vertebrate predation and death of individuals or whole populations may sometimes result. A few species are moderately palatable to domestic livestock and native herbivores; the majority are rarely eaten even by starving animals. The regenerative ability of shrubs following fire or grazing differs amongst species and is affected by shrub size.