Shifted Baselines: Quantifying Past Human Influences on Andean Landscapes

Florida Institute Of Technology, Melbourne FL

Investigators

Abstract

Knowing what is natural in terms of an ecosystem, rather than simply accepting what appears to be natural, is important for all investigation of natural processes. In marine biology this concept has been summarized as "shifting baselines" in which each generation accepts a degradation of the environment and perceives it to be "natural." Carbon storage, rates of growth, vegetation succession, and potential biodiversity all are important components of ecosystem services modified by human actions. Sometimes societal changes enhance one process at the cost of another. Historically, water retention may have been paramount in a dry setting like the high Andes, but when faced with global climate change, carbon storage may become more pressing. Efforts by policy makers to grapple with climate change and loss of biodiversity increases the need for deeper understand of the trajectory of landscape change and for clearer identification of what is natural. This research project will investigate an area of very high biodiversity in the Peruvian Andes, where efforts to conserve Andean habitats to promote both biodiversity and carbon sequestration are being undertaken in a landscape that has been manipulated for millennia by humans. Present plans for high elevation carbon sequestration center around Polylepis, a tree that can grow at higher altitudes than any other. Woodlands of this tree are important habitat for endemic species. While efforts to expand forests are fueled by the belief that Polylepis was once much more abundant than present, this hypothesis has not been tested. The investigators will define "natural baselines" for ecosystems across a range of elevations, determine the natural height of tree line (important for above-ground carbon storage), and the trajectory of landscape change relative to climate change for the last 11,000 years. The researchers will analyze sediment cores from ten lakes and 200 soil cores to provide the historical data to establish these natural baselines, and they will investigate how climate change interacted with human activity to produce altered fire regimes, crop use, and forest cover. Paleoecology can, through analysis of fossil pollen and charcoal recovered from soils and lake sediments, provide detailed information about how systems have changed. The early Holocene climate (from roughly. 11,000 years to 9,000 years before the present) was quite similar to that of today, but human populations in the Andes were very low. This period therefore offers insights into the Andean ecosystem without human activity. Forming regional conservation policy with regard to local land use or even global carbon budgets requires an understanding of the trajectory of human influence on ecosystems. This project will provide new data on the timing, extent, and nature of human-induced change in Andean landscapes and provide baseline data relevant to ongoing efforts to constrain the effects of climate change through carbon sequestration while conserving biodiversity. Collaborations with scientists in complimentary disciplines (soil science, plant physiology, ecology, and remote sensing) will permit project results to be integrated into a larger prediction of appropriate policy for Andean conservation and for attempts to mitigate carbon release within Andean ecosystems.