Nitrogen Mineralization and Microbial Biomass Nitrogen Dynamics in Three Alpine Tundra Communities

• Published in: Soil Science Society of America Journal
• Main Authors: Fisk, Melany C., Schmidt, Steven K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1995
• Subjects: Soil Science; Tundra
• Online Access: http://dx.doi.org/10.2136/sssaj1995.03615995005900040012x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2136%2Fsssaj1995.03615995005900040012x; http://onlinelibrary.wiley.com/wol1/doi/10.2136/sssaj1995.03615995005900040012x/fullpdf

Abstract The alpine tundra of the Colorado Front Range supports a variety of plant communities whose distribution corresponds to their topographic position. Our objectives were to: (i) determine patterns in net N mineralization and microbial N pools among three communities, Kobresia, Acomastylis , and Carex meadows, that span a topographic gradient, and (ii) relate any patterns to soil microclimate differences among these communities. Average yearly net N mineralization rates, measured with an in situ core incubation technique, were 1.2 g N m −2 in 1991 and 1.0 g N m −2 in 1992. No differences were detected in yearly N mineralization rates among the three communities; however, net nitrification and other soil properties were found to differ among communities. Net N mineralization rates and microbial N showed strong temporal variation, and this variation was related to different variables for each community. Seasonal variation in N mineralization was related to soil water and microbial N in Kobresia meadows, to soil temperature and microbial N in Acomastylis meadows, and to soil water and temperature in Carex meadows. Seasonal changes in microbial N were related to soil water in Kobresia and Acomastylis meadows. Large fluctuations in microbial N indicate that periodic losses from the microbial pool may be important to N availability in this alpine tundra site.