Net ecosystem productivity of boreal aspen forests under drought and climate change: Mathematical modelling with Ecosys

摘要: Abstract The net ecosystem productivity (NEP) of boreal aspen is strongly affected by comparative rates annual potential evapotranspiration ( E a ) and precipitation P ). Changes in versus during future climate change will likely determine changes NEP consequently the magnitude carbon sink/source significant part forest. We hypothesize that effects on can be modelled with soil–root–canopy hydraulic resistance scheme coupled to canopy energy balance closure determines water status thereby CO 2 uptake. As model ecosys , these schemes were used diurnal declines latent heat (LE) exchange 3-year drought (2001–2003) at Fluxnet-Canada Research Network (FCRN) southern old site (SOA). These consistent those measured eddy covariance (EC) SOA, except effluxes most nights larger EC or gap-filled from other measurements. Soil close to, but sometimes smaller than, automated surface chambers SOA. Diurnal caused model, measurements (model g C m −2 : 275 367 ± 110 2001, 82 144 ± 43 2002 23 104 ± 31 2003). Lower was attributed effluxes. Ecosys then predict biome (NBP = NEP  −  C lost disturbance) 6-year recurring droughts 100-year fire cycles under current projected IPCC SRES A1B scenario. Although NBP adversely climate, it recovered quickly non-drought years so long-term maintained 4 g C m  year −1 . rose 10, 108 126 g C m first, second third centuries droughts, indicating gradual rise sink activity aspen. However negative (C losses), gradually depleting C reserves eventually causing dieback overstory century change. This followed large decline NBP. conclude projections change, prolonged (e.g. 6 years) which would cause die back substantial amounts lost.