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Modelling the demand for new nitrogen fixation by terrestrial ecosystems
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bg-14-2003-2017.pdf | Published version | 3.12 MB | Adobe PDF | View/Open |
Title: | Modelling the demand for new nitrogen fixation by terrestrial ecosystems |
Authors: | Xu-Ri Prentice, IC |
Item Type: | Journal Article |
Abstract: | Continual input of reactive nitrogen (N) is required to support the natural turnover of N in terrestrial ecosystems. This “N demand” can be satisfied in various ways, including biological N fixation (BNF) (the dominant pathway under natural conditions), lightning-induced abiotic N fixation, N uptake from sedimentary substrates, and N deposition from natural and anthropogenic sources. We estimated the global new N fixation demand (NNF), i.e. the total new N input required to sustain net primary production (NPP) in nonagricultural terrestrial ecosystems regardless of its origin, using a N-enabled global dynamic vegetation model (DyNLPJ). DyN-LPJ does not explicitly simulate BNF; rather, it estimates total NNF using a mass balance criterion and assumes that this demand is met from one source or another. The model was run in steady state and then in transient mode driven by recent changes in CO2 concentration and climate. A range of values for key stoichiometric parameters was considered, based on recently published analyses. Modelled NPP and C : N ratios of litter and soil organic matter were consistent with independent estimates. Modelled geographic patterns of ecosystem NNF were similar to other analyses, but actual estimated values exceeded recent estimates of global BNF. The results were sensitive to a few key parameters: the fraction of litter carbon respired to CO2 during decomposition and plant-type-specific C : N ratios of litter and soil. The modelled annual NNF increased by about 15 % during the course of the transient run, mainly due to increasing CO2 concentration. The model did not overestimate recent terrestrial carbon uptake, suggesting that the increase in NNF demand has so far been met. Rising CO2 is further increasing the NNF demand, while the future capacity of N sources to support this is unknown. |
Issue Date: | 12-Apr-2017 |
Date of Acceptance: | 27-Feb-2017 |
URI: | http://hdl.handle.net/10044/1/54664 |
DOI: | https://dx.doi.org/10.5194/bg-14-2003-2017 |
ISSN: | 1726-4170 |
Publisher: | Copernicus Publications |
Start Page: | 2003 |
End Page: | 2017 |
Journal / Book Title: | Biogeosciences |
Volume: | 14 |
Issue: | 7 |
Copyright Statement: | © Author(s) 2017. CC Attribution 3.0 License. |
Sponsor/Funder: | AXA Research Fund |
Funder's Grant Number: | AXA Chair Programme in Biosphere and Climate Impacts |
Keywords: | Science & Technology Life Sciences & Biomedicine Physical Sciences Ecology Geosciences, Multidisciplinary Environmental Sciences & Ecology Geology NET PRIMARY PRODUCTIVITY CARBON SEQUESTRATION GLOBAL VEGETATION ELEVATED CO2 FOREST PRODUCTIVITY CLIMATE-CHANGE N-2 FIXATION SOIL PATTERNS DEPOSITION 04 Earth Sciences 05 Environmental Sciences 06 Biological Sciences Meteorology & Atmospheric Sciences |
Publication Status: | Published |
Appears in Collections: | Department of Life Sciences Faculty of Natural Sciences |