Definition: Podzols are soils with a typically ash-grey upper subsurface horizon, bleached by loss of organic matter and iron oxides, on top of a dark accumulation horizon with brown, reddish or black illuviated humus and/or reddish Fe compounds. Podzols occur in humid areas in the boreal and temperate zones and locally also in the tropics.
Definition: the biochemical pathway a plant uses to gain carbon for growth and reproduction. Plants have evolved three photosynthetic pathways, each in response to distinct environmental conditions, resulting in differences in their ecological patterns of growth and distribution.
Definition: one of three metabolic pathways for carbon fixation in photosynthesis, along with C4 and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into 3-phosphoglycerate through the following reaction:
CO2 + H2O + RuBP → (2) 3-phosphoglycerate
This reaction occurs in all plants as the first step of the Calvin–Benson cycle.