Human Impact on Ecosystems

By Jennifer Mu

A recent visit to a small country in the South Pacific once again reminded me how fragile nature is, how destructive human behaviors can be, how quickly an ecosystem can be altered or completely annihilated by human activities and what tremendous efforts it would take to save a devastated ecosystem.

Land of Eden 

New Zealand is the last major habitable landmass on earth settled by humans. For nearly 80 million years the land was free of mammalian predators.  Its geographic isolation created created an evolutionary path unique from the rest of the world. Adapting to life in a predator-free environment, the life forms developed no traits to protect against predation. Birds grew larger and flightless (a giant moa could reach 12 feet tall). Trees took their time to mature. Indigenous trees, such as the Kauri, took about 300 years to mature and had a lifespan of over 600 years.

Human Discovery

Then humans arrived. Polynesians (Maori) came first, along with dogs and rats. Europeans came next with Norway rats and ship rats in tow. They later imported numerous pests, including stoats and possums that still plague the land today. In less than 800 years humans destroyed the ecosystem’s indigenous biodiversity that was 80 million years in making.

New Zealand-Carving-Indigenous Woman and Man

Soon after Maori settlers arrived in New Zealand, they hunted the moa and many other large birds to extinction. Today more than 50 indigenous bird species are extinct and nearly 3,000 species of native wildlife are threatened. Deforestation, wetland drainage, introduced predators and loss of habitat through urbanization and development are some of the major contributing factors.

Human Impact

Before human arrival, forest covered more than 80 percent of New Zealand. Land clearing and logging destroyed large tracks of ancient forests and their associated biodiversity. The introduction of browsing mammals, such as deer (for sport hunting) and possums (for fur) damaged the remaining forests. Today, indigenous forests cover merely 25 percent of New Zealand’s total land area.

The devastation extended into the seas surrounding New Zealand. Large-scale sealing and whaling by early European settlers quickly diminished seal and whale populations. Outside observers called for controls. The New Zealand government protected all marine mammals 150 years later.

A Slow Road to Conservation 

People slowly realized the devastating effects of human activities on their environment. Attempts to repair the damages followed, but serious conservation measures did not occur until the mid-20th century. There were early efforts by conscientious landowners to preserve ancient forests. One example is the Riccarton Bush. If you ever visited Christchurch, you probably enjoyed taking a walk through this 15.7-acre native lowland podocarp forest. The landowner donated the forest to people of Christchurch in 1914 on condition the forest be preserved permanently in its natural state.

A predator-free fence, built in 2000, stopped further damage from possums, rats and other pests. The government responded to public concerns about dwindling bird populations and growing tourism with some early preservation measures by the government.  New Zealand created national parks and preservedscenic areas. It designated sanctuaries on mammal-free islands and relocated large numbers of endangered birds to prevent their likely extinction.

New Zealand – pasture and crops
Advocacy Brings Results

The creation of environmental advocacy groups, such as the Native Bird Protection Society and the NZ Forestry League, helped pressure the government to better protect the country’s natural heritage. By the mid-20th century, attitudes changed from exploitation to preservation. The government enacted a series of major environmental protection laws to preserve environmental resources for future generations.

A more recent effort to restore and preserve New Zealand’s native ecosystem is the creation of Zealandia in Wellington. This world-first, fully-fenced urban eco-sanctuary has an ambitious 500-year vision to restore more than 500 acres of forest and freshwater ecosystems in a former reservoir valley as closely as possible to their pre-human state.

Today, New Zealanders are proud to tell visitors about their belief in protecting and preserving their natural heritage for future generations. At the time when right-wing politicians in Washington, D.C., led by the global warming denier in the White House, are doing everything they can to reverse long-established and hard-fought federal environmental protection measures to benefit the wealthy few, I find New Zealanders’ conviction to preserve their indigenous nature for future generations refreshing and encouraging.

Courtesy of Rossmoor News July 18, 2018.  Email Jennifer Mu at


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