It may be that, in the absence of reforestation practices specifically designed for the special requirements of eastern Tibet, the forest does not regenerate at all. WWF fears that clearfelled forest exposes remaining Tibetan soils to frost heave, destroying seedlings as they sprout, and preventing regeneration. Long term overcutting has caused severe consequences to ecology, economy and society in the Tibetan area. It is nearly impossible to find a big tract of forest along the banks of the four primary rivers which join to become the Yangste. Especially in the Dadu River valley, where logging has continued longest, the eight timber companies assigned to its forests lack an exploitable resource and the annual harvest floated downstream in boom years, 1.5 million cubic metres.
Soil erosion is serious, floods and debris flows occur often in summer.
The siltation load dumped by the rivers increases, harming downstream dams. Also the water conserving capacity of the forests is destroyed. The 1981 flood in Sichuan can be traced to the forest reduction. Flood disaster frequency in western Sichuan has increased from once in 15 years to once in five. However, as logging expands westward within Sichuan, there is no sign of any reduction of logging to a sustainable rate, and some indications that the massive Three Gorges dam, currently under construction, has actually increased the demand for Tibetan timber, for use in dam construction formwork.