Overview of biodiversity in Marlborough
Biodiversity is the abbreviation for the term "biological diversity" which is defined as "the variability among living organisms and the ecological complexes of which they are a part, including diversity within species, between species and of ecosystems".
New Zealand’s biodiversity gives our country a unique character and is internationally important. Many of our native species are not found anywhere else in the world and therefore make a significant contribution to global biodiversity.
Biodiversity also provides social, cultural and economic benefits through, for example, recreational opportunities, tourism, research, education, provision of ecosystem services and natural resources for primary industry, and customary and medical uses.
New Zealand’s native plants and animals (biodiversity) are internationally important and unique, but also very vulnerable because:
- Our plants and animals evolved in isolation on an island land mass for about 80 million years, prior to the arrival of humans about 700 years ago. The only mammals were bats and marine animals, so birds and insects adapted to fit most ecological niches and roles on land, with many becoming flightless and ground-dwelling and unaware of danger from mammalian predators.
- Many species of bird and reptile that had evolved in isolation over a long time period developed longer life spans and slower and less frequent breeding patterns. Some species, like the kakapo, only breed once every few years. This slow and specialised evolution and breeding pattern results in these species being vulnerable to change and disruption.
- A large proportion of the species are endemic to New Zealand, occurring nowhere else in the world. So, if they become extinct here, they are lost to the world, unlike many species in other countries. About 90% of New Zealand insects, 80% of trees, ferns and flowering plants, 25% of bird species, all 60 reptile species, four remaining frog species and two species of bat are endemic. Britain, in contrast, has only two endemic species; one plant and one animal.
- A large number of mammal species have been introduced into the New Zealand environment by humans and our native species are not generally adapted to cope with the competition for resources and heavy predation that has resulted.
700 years ago
New Zealand was one of the last large land areas on Earth to be settled by humans only 700 years ago (about 1250).
Changes were rapid as habitats were altered, vegetation cleared by fire and the introduction of numerous animal and plant species which competed with, and predated on, many of the native plants and animals which had evolved over a long period of time.
Many animal species became extinct quite quickly through predation by humans, dogs, rats, stoats and possums and other introduced species. Over 45 species of native bird have become extinct and over 1,000 species of plant, animal and fungi are considered threatened today, with further extinctions likely.
The Marlborough environment is almost two distinct areas in relation to ecology and biodiversity. The Wairau River is the approximate divider between the drier, less forested South Marlborough area (about 700,000 ha) and the wetter, more forested north Marlborough and Sounds area (about 250,000 ha). Together, these areas form a distinctive part of New Zealand's natural environment. The diversity of the region in terms of climate, geology, topography, and its central location within the country mean that a large variety of plants and animals occur here, a number at their southern or northern limits of distribution.
Marlborough, particularly its lowland environments, and the dry south-eastern areas, has been quite highly modified by human activity over the past 700 years. Early Maori fires cleared dryland forest vegetation in eastern areas and later, further clearance of land and drainage of wetland areas occurred to obtain land suitable for farming. Many bird species once common to most of New Zealand are now extinct in Marlborough (moa species, kiwi and kakapo). Other bird species like tui, bellbird and kereru are not found in large parts of the region due to limited suitable habitat. However, Marlborough has been identified as one of five centres of biodiversity in New Zealand, due to the concentration of endemic species which have evolved in the dry rocky conditions in the southern part of the region.
North Marlborough has a moister climate and steeper terrain and was less modified by human arrival. A significant amount of original forest cover remains and vigorous native regeneration is well underway on land cleared for pastoral farming from 1850 to 1940. Forest birds like tui, bellbird and kereru are common and other species like weka, a number of freshwater fish and native snails and frogs are still present. The Department of Conservation has a strong presence in the Marlborough Sounds and a number of islands are used for conservation projects to protect threatened species.
Two reports summarising the results of recent significant natural areas field work provide a more detailed overview of the ecology of both North and South Marlborough.
Links to publications and reports.
Listed here are various community restoration groups.
Invasive animals and plants probably present the largest threat to the remaining ecological values and habitats in New Zealand.
Ecosourcing means using plants grown from local seed.
There is growing interest in restoring land currently planted in Pinus radiata (pine) plantations, to native vegetation in the Marlborough Sounds.
The Marlborough Significant Natural Areas Project involves Marlborough District Council collecting information about natural areas on private land.