Factors affecting the growth of Eucalyptus delegatensis seedlings in inhibitory forest and grassland soils

Abstract

In many highland forests of Eucalyptus delegatensis in Tasmania the establishment and healthy growth of eucalypts is promoted and maintained by fire. In the absence of fire, secondary succession from eucalypt forest to rainforest occurs, during which the eucalypts decline and die prematurely. On sites that are prone to radiation frost severe reduction or removal of a tree canopy allows a sward of tussock grasses to develop, in competition with which seedlings of eucalypts decline in growth and a high proportion dies.

Eucalypt decline in Australia, and a general concept of tree decline and dieback

“…Some examples of eucalypt decline in Australia have been similarly portrayed as natural succession to rainforest (e.g. Ellis and Pennington, 1992;. Alternatively, these and other declines in Australia have been attributed to changes in biogeochemical cycles as a result of unnatural fire regimes (e.g.…”

“…Alternatively, these and other declines in Australia have been attributed to changes in biogeochemical cycles as a result of unnatural fire regimes (e.g. Mount, 1969;Ellis and Pennington, 1992;Jurskis and Turner, 2002).…”

“…Tasmanian forests declined after their natural fire regimes were disrupted (e.g. Ellis and Pennington, 1992;Jurskis et al, 2003), and burnt stands were less affected than unburnt stands (Bowling and McLeod, 1968). Mundulla yellows is a new 'disease' affecting eucalypts and other plants in highly disturbed sites across Australia (Hanold et al, 2002).…”

“…Dysfunction of tree roots as a result of changing soil conditions (e.g. Manion, 1991;Ellis and Pennington, 1992) will reduce the ability of trees to compete with understoreys as sapwood area declines because more water will be available in the soil, and the trees will be less able to use the water, and less able to cope with excessively damp soil. Understoreys flourish in declining eucalypt stands (e.g.…”

A review of eucalypt dieback associated with bell miner habitat in south-eastern Australia

“…Raison 1979;Adams and Attiwill 1986;Smith and Smith 1990;Ellis and Pennington 1992;Jurskis and Turner 2002). There is general agreement that the establishment of a dense shrubby understorey contributes to lowering the carbon/nitrogen (C/N) ratio, and to increased nitrogen mineralisation (e.g.…”