Abstract

Elevated atmospheric reactive nitrogen (NR) deposition is considered one of the key components of human induced global change, threatening biodiversity and possibly altering carbon sequestration, one of the forest’s key ecosystem services. Carbon sequestration is the net result of plant production and of soil organic matter (SOM) decomposition. Ignoring the impact of N deposition on plant growth, decomposition or any major physical, biological or anthropogenic process that alters the rate of conversion of soil organic matter to atmospheric CO2 (decomposition) will have profound implications for the global C budget and consequently climate change. Soil nitrogen cycling is predicted to change as a result of increased atmospheric N deposition and mineralization due to temperature increases. However, experimental results on the effects of increased N input on SOM decomposition in the field are inconsistent, reporting positive, negative and neutral responses of SOM to N input. We set out to test the impacts of elevated reactive nitrogen NR addition, specifically on the soil processes in the field, independently of forest production effects. Using a suite of conventional, natural abundance and isotope pool dilution methods in situ, we traced C and N transformations of soil microbial and gaseous pools and monitored concomitant changes in gross mineralization and nitrification rates, as well as enzymatic activity. Over a number of growing seasons in a spruce dominated Austrian forest we found evidence to suggest N addition significantly reduces gross N mineralization rates and enzyme activity, in-line with an emerging consensus that N deposition reduces soil fungal abundance and activity, ultimately resulting in greater stocks of soil organic carbon. Simulated elevated nitrogen deposition decelerated SOM decomposition and consequently increased soil carbon storage, an N input effect on soil processes independent of the effect of N on tree growth and forest production.

Details

Title
Functional response of an Austrian forest soil to N addition
Author
Hood-Nowotny, Rebecca 1   VIAFID ORCID Logo  ; Schmittner, Kathrin 1 ; Ziss, Elizabeth 1 ; Leitner, Simon 1 ; Watzinger, Andrea 1 ; Gorfer, Markus 2 ; Djukic, Ika 3   VIAFID ORCID Logo  ; Dirnböck, Thomas 3   VIAFID ORCID Logo 

 Institute of Soil Research, University of Natural Resources and Life Sciences (BOKU), Peter-Jordan-Straße 82, 1190 Vienna, Austria 
 AIT Austrian Institute of Technology GmbH Konrad-Lorenz-Straße 24,3430, Tulln, Austria 
 Ökosystemforschung und Umweltdatenmanagement, Umweltbundesamt GmbH, Spittelauer Lände,1090 Wien, Austria 
Publication year
2021
Publication date
Feb 2021
Publisher
IOP Publishing
e-ISSN
25157620
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2512977574
Copyright
© 2021. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.