Wetlands in the Jiuzhaigou World Natural Heritage site of south-west China: classification and recent changes

摘要

To understand the effects of tourism and climate change on wetlands, a study was performed at Jiuzhaigou, a destination receiving 5 million people per year. There are 21 types of wetlands in region, covering an area of 265.1 ha, with 42.8% on tufa. Wetland areas declined by 16.1% from 1983 to 1999 (autumn) and by 31.2% from 1983 to 2002 (summer) and increased by 31.8% from 1999 to 2011 (autumn) and by 60% from 2002 to 2014 (summer). Wetland changes included dissolving tufa, a reduced tufa deposit rate, collapse of tufa mats, increases in water nutrients and algae, and marshland development. Mean annual air temperature increased from 1977. Annual precipitation varied from 430 to 810mm between 1951 and 2015, exhibiting an increasing trend from 2005 onwards. The number of both heavy rain and storm events increased from 2005. The number of tourists grew slowly from 1984 to 1997, but increased quickly from 360000 in 1998 to 5.1 million in 2015. Commercial logging between 1966 and 1978 and debris flows are probably the key factors contributing to increased lake sedimentation and marshland development. Rapid tourism development with intensive bus movement and regional air pollution likely caused changes in water chemistry, which, in turn, caused tufa changes and wetland degradation. Reducing tourist numbers is likely to be effective in reducing effects on wetlands and conserving them, but research is needed to determine appropriate tourist numbers.