Forestry experts are urging local authorities to monitor a potential epidemic of plant diseases and pests, which could decimate the nation's trees.

Summer is expected to be the worst time with more than 14 million hectares of woodland under threat, experts from the State Forestry Administration (SFA) warned in their latest report.

Based on last year's situation and climate change so far this year, they made it clear that caterpillars are increasing in areas south of the Yangtze River, areas between the Yangtze and the Huaihe river areas, the middle and lower reaches of the Yangtze, southern parts of North China and most parts of Northwest China.

Spring spanworms insects, which devour the leaves of poplars - will threaten forests in Northwest China and parts of the Inner Mongolia Autonomous Region.

Outbreaks of other moths in forested areas surrounding farmland and urban green belt are also possible.

Leaf-eating insects such as the massive caterpillars have been observed in some areas as the SFA predicted earlier this year.

They have already damaged some forests in Central and East China - including Hubei, Hunan, Jiangxi, Zhejiang and Anhui provinces - with insects particularly prevalent around the Three Gorges Dam site in Hubei.

Up to 98 percent of forests in Northwest and North China suffer the onslaught of such insects.

Massive cypress tussock moths have struck more than 244,600 hectares of forests in Southwest China's Sichuan Province, causing the bark of many poplars to rot. This has also been seen in Northeast and North China.

Experts attributed the tree damage to the high frequency of caterpillars, which have been hatching because of the warm winters over the past four decades.

Other causes include the photokinesis of insects around massive construction sites like the Three Gorges Dam.

Warm winters have cut the death rate of eggs and pupae of insects while massive construction with strong lighting induces them to gather in such places.

More than 8,000 types of plagues of pests and rats have been reported throughout the country. Of which, a quarter has been proven to be dangerous for forests.

"The problem has become one of the major factors restricting the further development of forestry industry," SFA's experts say, viewing the plague as "smokeless forest fires."

Plant diseases and insect cause damage to about 14 million hectares of forests annually, ruining 17 million cubic meters of timber valued at 5 billion yuan (US$602 million).

Calling on local authorities to earmark special funds to fight these pests immediately, SFA experts say they hope chemical pesticides can be used reasonably.

Random use of such pesticides throughout forest zones is one of the major causes of the worsening plague of insects in recent years.

The natural balance of forestry ecosystems have been also damaged through the poisoning of many natural enemies of insects, SFA experts added.

( China Daily April 23, 2002)