FRST 200 Lecture Notes - Lecture 24: Pinus Taeda, Photorespiration, Photosynthesis
Document Summary
Most respiration in branches and trunk is in living bark, but also cambium and sapwood (ray parenchyma) During summer, respiration in leaves is ~10% as fast as photosynthesis. Respiration continues at night in all plant parts and in winter too -> 25-50% of fixed carbon is lost to respiration. Photosynthesis, respiration, and growth increase with temperature to a plateau. Higher temps, inhibit photosynthesis more than respiration, so growth suffers above a heat limit. Solubility of co2 relative to o2 decreases with temperature. Differe(cid:374)t spe(cid:272)ies ha(cid:448)e diff te(cid:373)p ra(cid:374)ges & opti(cid:373)a, (cid:272)orrelati(cid:374)g (cid:449)ith ha(cid:271)itat. **limited carbon gain at even -6c in some conifers. Some species show seasonal adjustment of optima (e. g. loblolly pine) Others show change in capacity e. g. red cedar. Respiration too, but in a compensating fashion (i. e. growth at lower temps results in a higher capacity = homeostasis) Important in predicting effects of climate change and impact on c sequestration.
