Effects of elevated temperature and [CO_2] under different nitrogen regimes on biomass and its allocation in Quercus mongolica seedlings
Aims The cold temperate zone is very sensitive to climate change. Forests in this region provide a natural labo-ratory for studying effects of climate warming on terrestrial ecosystems. Our objective was to study the biomass responses of seedlings of a main secondary forest species, Quercus mongolica, to experimental warming and the interaction of elevated CO_2 and different nitrogen regimes to provide insights into community development under a future warmer climate.Methods We used large growth chambers to determine short-term effects of elevated temperature (+4℃) (ET)only and the combination of elevated CO_2 concentration(700 μmol CO_2·mol~(-1)) and elevated temperature(+4℃)(ECTC) under three different nitrogen regimes(15mmol·L~(-1)N (N1)),7.5mmol·L~(-1)N(N2)and no added N in soil substrate (N3)) on growth, biomass and its allocation in Q. mongolica seedlings.Important findings The ET and N1 combination generally increased growth in height and diameter, as well as biomass accumulation of the seedlings. The allocation of underground biomass of seedlings increased with the increasing of N concentration. The ETEC and N1 combination increased growth in height and underground bio-mass allocation of the seedlings, but there was no significant effect on diameter growth and total biomass of the seedlings. The C/N ratio of leaves increased with decreasing nitrogen supply, but the increases of C/N ratio under ECET was due to decreasing nitrogen concentration in the leaves and under ET was due to increasing carbon concentration in the leaves. No promotion of biomass accumulation was found under ECET and ET with lower nitrogen supply. So nitrogen supply will be an important factor with future climate change. Sufficient nitrogen supply may promote the growth of Q. mongolica seedlings, lead to changes in regeneration dynamics and increase their carbon stock under the future climate.
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万方数据
维普
