Species richness, heterogeneity and nitrogen contributions of roots along an arctic elevation gradient

• Main Author: Trager, Sabrina
• Other Authors: Wilson, Scott, Somers, Christopher, Gagnon, Daniel, Hardenbicker, Ulrike, Milbau, Ann, Fraser, Lauchlan
• Format: Thesis
• Language: English
• Published: Faculty of Graduate Studies and Research, University of Regina 2016
• Subjects: Arctic; Regina; Climate change
• Online Access: http://hdl.handle.net/10294/7685; http://ourspace.uregina.ca/bitstream/handle/10294/7685/Trager_Sabrina_200338509_PHD_BIOL_Spring2017.pdf

A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfilment of the Requirements For the Degree of Doctor of Philosophy in Biology, University of Regina. xv, 168 p. Roots allow interactions between plants and their belowground environment. Such interactions are especially important in ecosystems where plant biomass is dominated by roots, such as the Arctic. In contrast, we are still lacking knowledge about roots and belowground processes in many ecological topics. These belowground processes are likely to be altered by climate change. Consequently, we need to know about basic root ecological patterns and processes before we can estimate possible effects of a changing environment on belowground processes and thus whole ecosystems. The aim of my thesis was to examine three of those basic root ecological patterns and processes: plant community composition, resource heterogeneity, and root contributions to nutrient cycling. I investigated plant species richness belowground and aboveground along an arctic elevation gradient with a great variation in vegetation types. Total plant species richness exceeded aboveground richness two-fold on average, but by as much as over seven-fold in some communities. My results indicate that conventional measurements of aboveground plant richness dramatically under-estimate actual richness in all vegetation types along an elevation gradient. Consequently, measuring total plant richness (belowground and aboveground richness) along environmental gradients should be considered in future plant community studies. Further, I examined spatial root heterogeneity at resolutions ranging from 1 to 300 mm² along an elevation gradient with great variation in vegetation types. The spatial heterogeneity of fine roots varied significantly with study resolution in all vegetation types. This result suggests that roots in different vegetation types respond to or generate very fine scales of spatial heterogeneity, including scales much smaller than those that have previously ...