Proxy Indicators of Climate Change in Echo Lake Park

Keywords: climate change, natural archives, paleoecology, tree rings, humidification, Colorado
Abstract Type: Poster Abstract

Abstract

This study evaluates whether the effects of climate changes at Echo Lake Mountain Park could be assessed using natural archives of environmental information (proxy data) extracted from sediment and tree cores recovered from a wetland and the surrounding forests. Beginning in 2017, personnel from the Denver Mountain Parks observed a noticeable decline (1 m drop) in the water level of Echo Lake, a subalpine (3230 m) glacial-aged lake in the Colorado Front Range. The decrease in the level is a serious concern for park managers due to the high biodiversity significance of its rare and globally vulnerable subalpine plants. The lake's surface area is 9.2 ha. with a drainage area of 105 ha. The water level in the lake is maintained by groundwater flow from the wetland immediately adjacent to the lake and by the direct inflow of precipitation and surface runoff. The current depth is approximately one meter, although the lake's depth fluctuates seasonally. We hypothesized that recent warmer and/or drier conditions have resulted in significant declines in the winter snowpack, early snowmelt, decreased summer precipitation, and greater evaporation from Echo Lake. Samples from sediment cores were collected for AMS radiocarbon dating and sediment analysis (loss-on-ignition, bulk density, magnetic susceptibility, and peat humidification). The sediment analysis resulted in an 11,200-year (cal PB) record of groundwater fluctuations in the wetland. Tree ring analysis from 101 cores produced a 331-year chronology sensitive to changes in early summer precipitation and temperature.