Risø-R-1332(EN) Plant Respiration and Climate Change Effects

The ongoing climate changes can affect many plant physiological processes. In turn, these effects on plants may result in a feedback between the climate change and the vegetation. Plant respiration is one of the key processes in terms of an understanding of plant growth and functioning in a future climate. Plant respiration can release up to about half of the assimilated carbon by photosynthesis on a daily basis. Thus potential effects of e.g. changed air temperature and atmos-pheric [CO2] are important to investigate for predictions of respiratory release of CO2 to the atmos-phere. This is further emphasised by the fact that global terrestrial respiratory CO2 release is about ten times as high as the antropogenic contribution of CO2 to the atmosphere on an annual basis. Plants therefore constitute an important component of the global carbon cycle. Short- and long-term (direct and indirect, respectively) effects of temperature and [CO2] on plant respiration were investigated in a number of plant species. The experiments tested effects of ei-ther temperature and/or [CO2] from the level of individual respiratory enzymes, isolated mitochondria, whole-tissue (above- and below-ground tissue), and up to the whole canopy level in forests. The short-term effects of elevated atmospheric [CO2] on plant respiration appeared to be les