Climate response of the soil nitrogen cycle in three forest types of a headwater Mediterranean catchment

Abstract

Future changes in climate may affect soil nitrogen (N) transformations, and consequently, plant nutrition and N losses from terrestrial to stream ecosystems. We investigated the response of soil N cycling to changes in soil moisture, soil temperature, and precipitation across three Mediterranean forest types (evergreen oak, beech, and riparian) by fusing a simple process-based model (which included climate modifiers for key soil N processes) with measurements of soil organic N content, mineralization, nitrification, and concentration of ammonium and nitrate. The model describes sources (atmospheric deposition and net N mineralization) and sinks (plant uptake and hydrological losses) of inorganic N from and to the 0-10cm soil pool as well as net nitrification. For the three forest types, the model successfully recreated the magnitude and temporal pattern of soil N processes and N concentrations (Nash-Sutcliffe coefficient=0.49-0.96). Changes in soil water availability drove net N mineralization and net nitrification at the oak and beech forests, while temperature and precipitation were the strongest climatic factors for riparian soil N processes. In most cases, net N mineralization and net nitrification showed a different sensitivity to climatic drivers (temperature, soil moisture, and precipitation). Our model suggests that future climate change may have a minimal effect on the soil N cycle of these forests (<10% change in mean annual rates) because positive warming and negative drying effects on the soil N cycle may counterbalance each other.

Keywords

soil nitrogen cycle; climate sensitivity; process-based model; temperature; soil water availability; climate change

Published in

Journal of Geophysical Research: Biogeosciences
2015, Volume: 120, number: 5, pages: 859-875 Publisher: AMER GEOPHYSICAL UNION

UKÄ Subject classification

Climate Research
Soil Science


Publication identifier

DOI: https://doi.org/10.1002/2014JG002791

Permanent link to this page (URI)

https://res.slu.se/id/publ/85369