Changes in biomass allocation buffer low CO2 effects on tree growth during the last glaciation.

摘要: Isotopic measurements on junipers growing in southern California during the last glacial, when ambient atmospheric [CO2] (ca) was ~180 ppm, show leaf-internal (ci) approaching modern CO2 compensation point for C3 plants. Despite this, stem growth rates were similar to today. Using a coupled light-use efficiency and tree model, we that it is possible maintain stable ci/ca ratio because both vapour pressure deficit temperature decreased under glacial conditions at La Brea, these have compensating effects ratio. Reduced photorespiration lower temperatures would partly mitigate effect of low ci gross primary production, but maintenance present-day radial also requires ~27% reduction fine root mass leaf area. Such shift due reduced drought stress Brea. The necessity changes allocation response consistent with increased below-ground allocation, apparent homoeostasis growth, as ca increases