Alpine National Park - Ecology

Ecology

Ecologically, alpine refers to areas where the environment is such that trees are unable to grow and vegetation is restricted to dwarfed shrubs, alpine grasses and ground-hugging herbs. In Victoria this is roughly those areas above 1800 m. Below this is the Sub-Alpine Zone, an area of open forest dominated by snow-gums, with significant areas of grasslands. This zone includes basins where cold air settles, restricting tree growth. In wetter areas these basins form Sphagnum bogs, which play an important role in the water cycle.

Water enters the alps as snow or rain. Bogs and frost hollows collect the water as snow melt and run off. A key element of these bogs is Sphagnum Moss, which acts as a sponge, absorbing up to twenty times its weight in water. These bogs then release the water over summer, ensuring creeks flow throughout most of the year maintaining the alps’ creeks and streams. The greatest risk to this system is damage to the Sphagnum bogs. Trampling by feral animals (pigs, cattle, horses, humans) reduces their ability to absorb and then release water; instead of a steady release, water flows increase significantly in spring, leading to erosion and scouring of river beds, and ceases over summer and autumn, leading to localised drought. Fire can remove riparian vegetation, also increasing run-off and erosion.

Below the sub-alpine zone is the Montane Zone. On the alps southern fall, this exists as wet forest and rainforest, a consequence of the higher rainfall on this side of the park. Tall forests of Alpine Ash and Mountain Ash grow in deep soils while species like Mountain Gum are found in shallower soils or drier sites. The understory is usually shrubby, with a dense ground-layer of grasses, lilies, ferns and the like.

Rainforests are areas where the canopy cover is high, greater than 70%. The tree species are often specialists, such as Myrtle Beech in Cool Temperate Rainforest and Lilly Pilly in Warm Temperate Rainforest. Rainforest species are shade tolerant and able to regenerate below an undisturbed canopy or in small gaps created when a tree falls. Rainforest often merges with the surrounding, usually damp or wet, eucalypt forests.

These forests are home to a diverse bird life and many mammals, some of which are restricted to a particular ecological niche within the ecosystem. This can include particular vegetation for foraging, or the presence of older trees with their larger hollows, a requirement for some arboreal mammals and birds.

Rainforest species regenerate without fire and may be intolerant to fire, while other eucalypt species require fire. Fire can also affect the breeding of some mammals. Fire in Spring, for example, is considered to put juvenile Spot-tailed Quolls at risk.

The Montane Zone on the alps drier, northern fall consists of dry forest and woodland with eucalypt species such as stringybarks, boxes and peppermints. Dry forest and woodlands also surround the wet forests on the southern side of the alps. These forests provide habitat for a wide range of species.

Dry forest and woodland abut private land in many areas and as a consequence have been subject to clearing, modification and fragmentation. Thus, the major threat in these areas is fire management (protection of private assets is a key objective and so past fire regimes may not reflect environmental needs), weed invasion and lack of connectivity between patches.