Development of nitrogen cycling in recently deglaciated watersheds

• Main Author: Malone, Edward Thomas
• Other Authors: Milner, Alexander (Sandy), Pinay, Gilles, nerc
• Format: Thesis
• Language: English
• Published: 2014
• Subjects: GB Physical geography; Glacier Bay; glacier; Alaska
• Online Access: http://etheses.bham.ac.uk//id/eprint/5338/1.hassmallThumbnailVersion/Malone14PhD.pdf; http://etheses.bham.ac.uk//id/eprint/5338/; http://etheses.bham.ac.uk//id/eprint/5338/1/Malone14PhD.pdf

Perturbation of natural environments through anthropogenic nitrogen (N) inputs and climate change significantly alter soil systems. Few pristine environments remain in which to study natural controls on the development of soil N cycling over time and thus increase our understanding of the natural development of such mechanisms. This study took place in Glacier Bay National Park and Preserve (GBNP), southeast Alaska. This area presented a unique opportunity to study microbial cycling in near pristine soil systems. Six river catchments were selected for study across a chronosequence of 200 years of primary succession. Within each watershed soil nutrient content and microbial processes where evaluated to determine a time frame for development. Samples were collected from riparian and wider catchment areas in order to investigate the effects of dominant vegetation types and slope steepness. These data were coupled with percent vegetation type generated by analysis of satellite imagery allowing the scaling up of soil variables. A key finding of this research was that vegetation type is the primary influence on nitrogen cycling processes and soil characteristics. With increasing age potential microbial activity increased in particular nitrification, which linked with the low soil NO\(_3\)- indicated a large heterotrophic microbial community in older soils.