Intensive farming proves factor in loss of Cambodia grasslands

Around half of Cambodia’s tropical flooded grasslands have been lost in just 10 years according to new research from the University of East Anglia (UAE).

The seasonally flooded grasslands around the Tonle Sap, Southeast Asia’s largest freshwater lake, are of great importance for biodiversity as well as a vital fishing, grazing, and traditional rice farming resource for around 1.1m people.

In 1995, the grassland area spanned 3349 km2 but by 2005 it had been reduced to just 1817 km2 – a loss of 46 per cent.??Despite conservation efforts in some areas, it has continued to shrink rapidly since, with a further 19 per cent lost in four years (2005-2009).

Factors include intensive commercial rice farming with construction of irrigation channels, which is often illegal. Some areas have also been lost to scrubland where traditional, low-intensity agricultural activity has been abandoned.

The research has been led by Dr Charlotte Packman from UEA’s school of Environmental Sciences, in collaboration with the Wildlife Conservation Society Cambodia Program and BirdLife International.

“The area around the Tonle Sap lake is the largest remaining tropical flooded grassland in Southeast Asia. It is hugely important to both biodiversity and the livelihoods of some of the world’s poorest communities. Our research shows that these grasslands are disappearing at an alarming rate,” said Dr Packman.

“Rural communities have been left vulnerable to land-grabbing and privatisation of communal grasslands. Intensive commercial rice production by private companies, involving the construction of huge channels and reservoirs for irrigation, is denying local communities access to the grasslands on which their livelihoods depend and destroying a very important habitat for threatened wildlife.”

Researchers compared aerial photographs taken in 2005 with land cover maps from 1995 and 1996. They found that the greatest losses had occurred in the north and west and in inner floodplain areas. They then collected habitat information from almost 1,000 points to establish the rate of habitat change between 2005 and 2009 in the largest remaining area of grassland. This showed that grassland in the key southeast area had declined from 923km2 to 751km2 in four years.

Almost all of this loss was attributable to either intensive rice cultivation, which had risen by 666 per cent during that period, or newly constructed reservoirs.