The forests of the eastern part of the Tibetan plateau. A case study from Jiuzhaigou (Zitsa Degu; NNW Sichuan)

摘要

This paper illustrates the forest vegetation of Eastern Tibet, presenting a case study from Jiuzhaigou (Tibetan: Zitsa Degu). Furthermore deforestation caused by traditional land use practices and by modern timber extraction is analysed. Jiuzhaigou Nature Reserve (103 deg 46'-104 05'E / 32 deg 55'-33 deg 20'N) is located in NNW Sichuan's Min Shan. The high mountain climate (744 mm/a, annual mean temperature 7.3 deg C at 2400 m) is subtropically influenced and typical for the moister fringe of the eastern slope of the Plateau. The following altitudinal belts have been classified: 1. The montane mixed forest belt (2000 m-2700 m), differentiated into the lower montane forest belt (2000 m-2400 m), presently dominated by a pine-oak forest, traces of a hemlock mixed forest remaining; and the upper montane forest belt (2400 m-2700 m), dominated by fir-spruce mixed forests. 2. The altomontane cloud forest belt (2700 m-3500 m), consisting of the bamboo cloud forest belt (2700 m-3200 m), dominated by bamboo-fir-spruce forests, and the Rhododendron cloud forest belt (3200 m-3500 m) with spruce forests on the sunny slopes and fir forests on the shady slope. 3. The subalpine forest belt (3500 m-3800 m), consisting of fir stands on the shady slope and juniper stands on the sunny slope. Treeline is found at 3800 m altitude.