Effect of different fire regimes on vegetation thickening in grasslands on Cape York Peninsula

Crowley G.M. (2001) "Grasslands of Cape York Peninsula - a fire-dependent habitat", in Savanna Burning—Understanding and Using Fire in Northern Australia , (eds) R. Dyer, P. Jacklyn, I. Partridge, J. Russell-Smith and R. Williams, Tropical Savannas CRC, Darwin, p.34.

This is a brief article (one page) about the interaction between grasses and woody plants, particularly tea-tree (Melaleuca spp.). It explains with a diagram how different fire regimes can affect the balance between grassland and woody plants.

In some parts of Cape York grasslands have been changing towards a thick layer of woody plants. This is known as vegetation thickening and can lead to loss of habitat for granivorous birds.

Vegetation thickening occurs because the woody plants compete with the grasses. Fires cut back tea-trees, but also stimulate growth. Any grass regrowth following an early dry season fire is soon grazed out, while tea-tree continues to grow. If there are no fires or only early dry season fires, then the grassland can be completely lost to tea-tree woodland within four or five years.

By burning later in the dry season, the tea-trees have less time to grow before the next wet season. This keeps the woody plants below grass height and gives the grass a chance to grow.