|Title||Micobial biomass and population densities of non-sorted circles and small patterned ground features along a climatic gradient from low to high arctic|
|Publication Type||Conference Proceedings|
|Year of Publication||2006|
|Authors||Rivera-Figueroa, F, González, G, Gould, WA, Cantrell, SA, Perez, J|
|Publisher||American Geophysical Union, Fall Meeting|
|Conference Location||San Francisco, CA|
Non-sorted circles are small patterned-ground features that occur in arctic soils as a result of intensive frost heave action. This tundra feature has been extensively described. However, little is known about the ecological relationships between this pattern and above- and belowground organisms. In this study, we compare the biomass and populaton densities of microbes in non-sorted circles and the vegetated surrounding soils (inter-circles) in the High Arctic. We collected soil samples during the summer of 2004 and 2005 on Banks and Prince Patrick and Ellef Ringnes Islands, Canada. Soil samples (0-10 cm) were gathered from non- sorted circles and inter-circles along a topographic sequence: dry (ridge), mesic (mid slope) and wet (valley) and along three transects in zonal (mesic) sites on each island. We estimated total microbial biomass and bacterial population densities using substrate induce respiration (SIR) and the most probable number method (MPN), respectively. We also isolated soil fungi using Rose Bengal and Saboraud Dextrose culture media. We are in the process of analyzing the catena samples using a terminal restriction fragment length polymorphism (TRFLP) technique of PCR-amplified 16S rRNA. Based on the SIR trials, the average microbial biomass at the mid slope position in the Banks site (Green Cabin) was 0.49 mg C g-1 dry soil in the non- sorted circles and 0.95 mg C g-1 dry soil in the inter-circles. At Prince Patrick Island (Mould Bay) the microbial biomass was 0.54 mg C g-1 dry soil in the non-sorted circles and 0.74 mg C g-1 dry soil in the inter-circles. In Ellef Ringnes (Isachsen) the microbial biomass was 0.09 mg C g-1 dry soil in the non- sorted circles and 0.14 mg C g-1 dry soil in the inter-circles. At the mesic site at Green Cabin, bacteria vary from 2.92 x 106 cell g-1 dry soil in the non-sorted circles to 6.74 x 106 cell g-1 dry soil in the inter-circles. At Mould Bay the range was 7.67 x 105 cells g-1 dry soil in the non-sorted circles to 7.33 x 106 cells g-1 wt soil in the inter-circles and at Isachsen, the range was from 5.9 x 106 cells g-1 dry soil to 1.36 x 107(non-sorted circles and inter-circles, respectively). SIR and MPN results also vary along the topographic sequence. We have found that there are differences in soil microbial biomass and bacterial population densities between non-sorted circles and inter-circles at the three study sites. Based on SIR, the non-sorted circles tend to have less microbial biomass than the inter-circles areas. The same trend was observed with the MPN trials, were the bacterial population densities are lower in the non-sorted circles than the inter-circles. According to the TRFLPs and the number of fungi isolates, the bacterial and fungal communities differ between non-sorted circles and inter-circles ecosystems. We isolated a higher number of fungal colonies at the inter-circles than in the non-sorted circles in the three islands.