Impacts of human actions are threatening to simplify the diverse ecosystem of world's remaining tropical forests leading to mass species loss, according to a new study released Friday by the University College London (UCL).

The UCL-led study suggest the impact of humans on these areas has been increasing for millennia, and today more than three quarters of the world's remaining tropical forests have been degraded by human actions.

The research identified three prior phases of expanding impacts, the first when hunter-gatherers moved into tropical forests and the second following the emergence of tropical agriculture, some 6,000 years ago. Under both, the overall health of tropical forests was maintained.

Today, we live in the third phase, marked by much greater impacts, with distant decision-makers directing how land is used, including permanent intensive agriculture, frontier industrial logging for timber export, cross-continental species invasions, and early climate change impacts.

The researchers term this phase the era of "Global Integration," affecting even the most remote areas.

"Earth has lost 100 million hectares of tropical forest over the last 30 years, mostly to agricultural developments," said lead author Dr. Simon Lewis.

Current trends look set to intensify without major policy changes, as global food demand is projected to double, over 25 million kilometers of road are predicted to be built by 2050, and climate change intensifies, ushering in a new phase of human dominance of tropical forests, according to the study.

"I fear a global simplification of the world's most complex forests. Deforestation, logging and road building all create fragmented patches of forest. However, as the climate rapidly changes the plants and animals living in the rainforest will need to move to continue to live within their ecological tolerances," said Dr. Lewis.

What is needed are unbroken areas of forest that link today's core tropical regions with forest areas about four degrees Celsius cooler, so as temperatures rise and rainfall patterns change species have a better chance of surviving rapid 21st century climate change, according to Lewis.

The study has been published in the journal Science. (Xinhua)