Biodiversity

“Lord Howe Island has an extraordinary diversity of landscapes and a rich array of animal and plant species.”

The biodiversity on Lord Howe Island is extraordinary!

On this tiny island in the Tasman Sea there are found 240 species of native vascular plants, over 100 moss species; hundreds of thousands of breeding seabirds from fourteen different species; around three to four thousand species of invertebrates (animals without backbones), such as snails, spiders, beetles, stick insects and ants); in the Island streams there are interesting freshwater crustaceans such as a unique shrimp species and a tiny crab Halicarcinus lacustris that is also found in Eastern Australia, New Zealand and Norfolk Island.

Then there is the marine life in the surrounding ocean – the world’s most southerly coral reef, with a great diversity of other creatures living in and on the reef. There are over 500 fish species, around seventy echinoderm species (starfish, urchins and their cousins), hundreds of mollusc species (snails, slugs and bivalves) plus hundreds of other species such as crustaceans, worms, and a myriad of other creatures.

Despite the relatively small land area of 1,463 hectares for the whole of the Lord Howe Island Group, there is an extraordinary diversity of landscapes and a rich array of microhabitats for different species to adapt and evolve.

One of the major contributing factors to Lord Howe Island’s biodiversity is the fact that the Island has mountains rising to 875 metres above sea level, creating some amazing “altitudinal” micro climates, including a unique cool and humid ‘mist forest’ on the mountain peaks.

However, there are many other equally fascinating habitats: the lowlands and hills; the many beaches – both sandy and pebbly; and sheltered, rain-forested valleys surrounded by steep mountain slopes and cliffs.

All habitats exhibit different conditions of sunlight, rainfall, humidity, exposure and soil, thereby influencing the species that can flourish there. Particularly significant, is the 6 degree temperature gradient from sea level to mountain summit providing remarkably varied climatic conditions.

Plant ecologist, John Pickard, described 26 different types of plant communities on the Island – from tall rainforest to seagrass meadows. However rainforest predominates and this falls into two sub-categories: lowland rainforest in the central and northern parts of the island; and montane rainforest in the southern mountain areas. Specific animal groups are often closely associated with each of these habitats, particularly invertebrate animals which tend to be restricted to one family or genus of plants for food.

Birds

Two hundred and eight species of birds have been recorded on Lord Howe Island, of which 32 are regular breeders today — fourteen species of seabirds, and eighteen species of landbirds.

Birds have the greatest mobility of all terrestrial creatures and form the principal fauna of small oceanic islands, including Lord Howe, which has substantial breeding populations of land and seabirds.

Plants

The flora of the Island shows close affinities with nearby islands and landmasses. The complex landscape of lowland, valley, mountain and ridge provides many microhabitats for diverse plants.

There are species of flowering plants ranging from tiny herbs to tall rainforest trees 20 metres tall. 105 of the 244 species of native vascular plants are unique to the Island.

Invertebrates

Invertebrates make up about three quarters of all living animal species. Many species found on islands are invertebrates because generally they travel across ocean distances more easily than larger animals.

Recent invertebrate surveys by staff from the Australian Museum recorded more than 1,600 species, including 157 land and freshwater snails, 515 beetle species, 27 ants, 183 spiders, 21 earthworms, 137 butterflies and moths and 71 springtails.

Fungi

Autumn rains often bring on a flush of colourful fungi that sprout from dead wood on the forest floor; although some fungi can be seen at any time of the year. What we see are the fruiting bodies or spores.

No systematic study of fungi has been done on the island, but over 80 different kinds have been photographed.

The most unusual include two species that are luminescent.

Land Vertebrates

As on all oceanic islands, vertebrate land animals, apart from birds, are rare on Lord Howe Island. There are only three native vertebrate land animals - an insect eating bat; a gecko that grows to about six centimetres in length; and a skink about ten centimetres in length.

There are no native frogs or terrestrial mammals on Lord Howe Island, as the island is too far from neighbouring land masses for these types of animals to have reached.

Marine
Life

Lord Howe's marine communities are globally unique, and contain thousands of tropical, subtropical and temperate species, including many that are found nowhere else. Because of the small human population, the marine environment is relatively pristine.

The Lord Howe Island group exhibits an unusual combination of both tropical and temperate taxa of marine flora and fauna. This includes many species at their extreme distributional limits – for example Lord Howe Island is said to have the most southerly coral reef in the world. There is also a great diversity in marine algae, fish and invertebrates.

Introduced animals

Although not settled until 1834, introductions of exotic species began in the 1820s when mariners liberated pigs and goats to provide a source of food for passing ships. Settlement brought additional vertebrate species – cats, dogs, mice, cattle, and rats.

Masked owls and Barn owls were introduced in the 1920s to eat rats; and in 1944 European Blackbirds and Song thrushes were introduced to control insect pests. There have also been accidental introductions of frog and skink species in the 1990s.

Introduced Plants

Weeds found their way onto the island in the 1830s. Some plants were introduced as food, some as ornamentals or perhaps some were introduced as seeds in bales of hay in the days when the Island relied on horses for transport and ploughing fields for farming.

Lord Howe Island has seventeen weed species listed as noxious. The 1997 review of World Heritage values of Lord Howe Island identified weeds as the major threat to the conservation of the Islands unique flora and fauna.

Biodiversity