Changes in lacustrine environment due to anthropogenic activities over 240 years in Jiuzhaigou National Nature Reserve, southwest China

Abstract

Jiuzhaigou National Nature Reserve in southwest China is listed as a World Natural Heritage Site and has numerous alpine and subalpine travertine lakes. Over the past 240 years, agricultural expansion, tourism enhancement and other human activities have resulted in land use and land cover change. In this study, sediment cores from three lakes in Jiuzhaigou were collected to track the nature and intensity of these human activities in Jiuzhaigou as well as determine the influences of human activities on the lacustrine environment. Total organic carbon (TOC), total phosphorus (TP), total nitrogen (TN), carbon to nitrogen ratio (C/N), biogenic silica (BSi), heavy metal elements and other indicators were used to trace the evolution of the lacustrine sedimentary environment in Jiuzhaigou. The increased intensity in agricultural activities, large-scale deforestation, unsustainable tourism and other activities was clearly identified in the lake sediment records. Ecological restoration and decreased travel disturbance would reduce the levels of the various eutrophic substances and heavy metal elements in the lacustrine environment. Studying and understanding the response of lacustrine environment to human activities is of great significance for the protection and sustainable use of water and landscapes in the mountain lakes of Jiuzhaigou.