Modelling short-term variability in carbon and water exchange in a temperate Scots pine forest

11406 9 33611 2 72247 document 33611 esd-6-485-2015.pdf application/pdf efd777e9114f33779decd5a1c6761c13 MD5 1294846 2016-02-23 09:06:07 https://pure.iiasa.ac.at/id/eprint/11406/1/esd-6-485-2015.pdf 11406 1 1 application/pdf text en public

esd-6-485-2015.pdf

published 33624 2 72274 document 33624 lightbox.jpg image/png fd388b51fb3de5d278bbbfe3c4b279f0 MD5 48228 2016-02-23 09:16:42 https://pure.iiasa.ac.at/id/eprint/11406/2/lightbox.jpg 11406 2 2 image/png other Thumbnails conversion from text to thumbnail_lightbox en public

lightbox.jpg

preview.jpg

medium.jpg

small.jpg

indexcodes.txt

http://eprints.org/relation/isVersionOf https://pure.iiasa.ac.at/id/document/33611 http://eprints.org/relation/isVolatileVersionOf https://pure.iiasa.ac.at/id/document/33611 http://eprints.org/relation/isIndexCodesVersionOf https://pure.iiasa.ac.at/id/document/33611 archive 351 disk0/00/01/14/06 2016-01-15 08:53:10 2021-08-27 17:25:03 2016-01-15 08:53:10 article show 1 Vermeulen M.H. Kruijt B.J. Hickler T. Kabat P. 1953 Modelling short-term variability in carbon and water exchange in a temperate Scots pine forest pub iis_wat prog_wat The vegetation-atmosphere carbon and water exchange at one particular site can strongly vary from year to year, and understanding this interannual variability in carbon and water exchange (IAVcw) is a critical factor in projecting future ecosystem changes. However, the mechanisms driving this IAVcw are not well understood. We used data on carbon ad water fluxes from a multi-year eddy covariance study (1997.2009) in a Dutch Scots pine forest and forced a process-based cosystem model (Lund- Potsdam-Jena General Ecosystem Simulator; LPJ-GUESS) with local data to, firstly, test whether the moel can explain IAVcw and seasonal carbon and water exchange from direct environmental factors only. Initial model runs showed how correlations with estimated annual gross primary productivity (GPP) and annual actual evapotranspiration (AET), while monthly and daily fluxes showed high correlations. The model underestimated GPP and AET during winter and drought events. Secondly, we adapted the temperature inhibition function of photosynthesis to account for the observation that at this particular site, trees continue to assimilate at very low atmospheric temperatures (up to daily averages of -10 degrees C), resulting in a net carbon sink in winter. While we were able to improve daily and monthly simulations during winter by lowering the modelled minimum temperature threshold for photsynthesis, this did not increase explained IAVcw at the site. Thirdly, we implemented three alternative hypotheses concerning water uptake by plants in order revealed a strong sensitivity of the modelled fluxes during dry and warm conditions, but no single forulation was consistently superior in reproducing the data for all timescales and the overall model-data match for IAVcw could not be improved. Most probably access to deep soil water leads to higher AET and GPP simulated during the heatwave of 2003. We conclude that potosynthesis at lower temperatures than assumed in most models can be important for winter carbon and water fluxes in pine forests. Furthermore, details of the model representations of water uptake, which are often overlooked, need further attention, and deep water access should be treated explicitly. 2015-07 published Copernicus 10.5194/esd-6-485-2015 XJ-15-156 Earth System Dynamics; 6:485-503 (July 2015) [doi:10.5194/esd-6-485-2015] 141 public Earth System Dynamics 6 485-503 2190-4987 FALSE info:eu-repo/semantics/article