Historical perspectives on some vegetation and soil changes in semi-arid New South Wales

Abstract

The history of settlement of the semi-arid rangelands of western New South Wales is reviewed with respect to changes in the vegetation and soil which occurred under a regime of european land management. Simple dynamics of the vegetation response to grazing are illustrated and primary archival data is explored to verify the status of traditional wisdom about three examples of perceived change; the extent of the pioneers knowledge of land degradation, the timing and causes of nineteenth century Callitris pine regrowth events, and the importance of soil compaction. In each case it is shown that the traditional wisdom surrounding these issues is partly erroneous and that folklore is in danger of becoming accepted fact. Such errors must be avoided if we are to improve range dynamics models and management.

Estimates of Historical Tree Densities in the North Lachlan River Catchment, New South Wales, Australia

“…The indication is of tree sizes including many that would be too small to be considered as corner markers. Mitchell (1991) noted that such references to dense scrubs were commonly made when Oxley made side trips away from the river and its floodplain, which tended to be more open in nature. Such observations suggest that at least in some areas, regrowth may have been occurring shortly before European settlement and that, with the densities of larger trees estimated here, the age structure of woodlands was varied.…”

“…In 1880 the New South Wales Surveyor General called for reports from his Land Commissioners and surveyors on the extent, age and significance of the pine scrub on leased lands in the western division (which begins approximately 35 km to the west of the area considered in this study and is climatically similar), after residents of the Lachlan and Murrumbidgee River valleys complained about the rapid spread of pine scrubs (Mitchell, 1991). The Commissioner concluded that a real problem existed with the growth of many young pines since grazing began (Anon., 1881in Mitchell, 1991.…”

“…In 1880 the New South Wales Surveyor General called for reports from his Land Commissioners and surveyors on the extent, age and significance of the pine scrub on leased lands in the western division (which begins approximately 35 km to the west of the area considered in this study and is climatically similar), after residents of the Lachlan and Murrumbidgee River valleys complained about the rapid spread of pine scrubs (Mitchell, 1991). The Commissioner concluded that a real problem existed with the growth of many young pines since grazing began (Anon., 1881in Mitchell, 1991. This, combined with the records of pine scrubs by Oxley in 1817 (Oxley, 1820) and the densities of large pines found by this study, suggests that although Callitris has been widespread and prominent in the landscape since before European settlement, more extensive regrowth was occurring (at least in some areas) under the existing pine-box woodlands at the time the land survey plans were being produced.…”

Prospects for the future: is there a role for virally vectored immunocontraception in vertebrate pest management?

“…Rabbit browsing in forestry plantations can cause significant damage and production losses (Gill 1992). Rabbits cause environmental damage by overgrazing and preventing regeneration of native pastures, shrubs and trees (Lange and Graham 1983;Mitchell 1991). Overgrazing can lead to soil erosion and the loss of soil fertility (Leigh et al 1987).…”

How the west was once: vegetation change in south‐west Queensland from 1930 to 1995

“…Increasing woody cover is not unique to Australia and has been widely reported and studied in arid and semi‐arid areas around the world (see review by Archer, 1995). Although widely reported some argue that woody thickening is in danger of becoming folklore rather than an empirically recorded ‘fact’ (Mitchell, 1991).…”