Annual cycle of Scots pine photosynthesis

Abstract

Abstract. Photosynthesis, i.e. the assimilation of atmospheric carbon to organic molecules with the help of solar energy, is a fundamental and well-understood process. Here, we connect theoretically the fundamental concepts affecting C 3 photosynthesis with the main environmental drivers (ambient temperature and solar light intensity), using six axioms based on physiological and physical knowledge, and yield straightforward and simple mathematical equations. The light and carbon reactions in photosynthesis are based on the coherent operation of the photosynthetic machinery, which is formed of a complicated chain of enzymes, membrane pumps and pigments. A powerful biochemical regulation system has emerged through evolution to match photosynthesis with the annual cycle of solar light and temperature. The action of the biochemical regulation system generates the annual cycle of photosynthesis and emergent properties, the state of the photosynthetic machinery and the efficiency of photosynthesis. The state and the efficiency of the photosynthetic machinery is dynamically changing due to biosynthesis and decomposition of the molecules. The mathematical analysis of the system, defined by the very fundamental concepts and axioms, resulted in exact predictions of the behaviour of daily and annual patterns in photosynthesis. We tested the predictions with extensive field measurements of Scots pine (Pinus sylvestris L.) photosynthesis on a branch scale in northern Finland. Our theory gained strong support through rigorous testing.

The Effect of Insect Defoliations and Seed Production on the Dynamics of Radial Growth Synchrony among Scots Pine Pinus sylvestris L. Provenances

“…The third important climatic factor for radial growth appears to be the precipitation in May of the previous year ( Figure 6B). If we assume that high precipitation is related to cloudiness, then reduced solar radiation can substantially reduce the photosynthetic efficiency of trees and thus cause the depletion of synthesized sugars, finally causing a growth reduction [92]. Climate-growth relationships were heterogeneous among some provenances; provenances RU, SU, GU, BO, and NT showed a sensitivity to long-term drought effects (SPEI6; Figure 6D; Figure S4).…”

Prediction of photosynthesis in Scots pine ecosystems across Europe by a needle-level theory

“…In order to do this in a robust way, we followed Newton's approach in discovering a way to construct equations to describe the diurnal behaviour of photosynthesis utilising knowledge of light . .a 4 a 1 = 10; a 2 = 0.065 of photosynthesis, estimated using a 3 = 2; a 4 = 1.15 × 10 −7 numeric methods (see Hari et al, 2017) and carbon reactions in photosynthesis (Hari et al, 2014(Hari et al, , 2017. First, we defined concepts and introduced the fundamental features of light and carbon reactions of photosynthesis, the action of stomata and diffusion of CO 2 (axioms).…”

“…Here, p is the rate of photosynthesis, E is transpiration rate, I is irradiation, b is a parameter called the efficiency of photosynthesis, g max is a parameter introducing stomatal conductance when stomata are fully open, r is the rate of respiration, and u opt is the optimal degree of stomatal opening obtained from as solution of the optimisation problem of stomatal behaviour (Hari et al, 2014(Hari et al, , 2017. The photosynthetic light response curve is given as f (I ) (see e.g.…”

Overview: Recent advances on the understanding of the Northern Eurasian environments and of the urban air quality in China - Pan Eurasian Experiment (PEEX) program perspective

“…Extensive measurements of Scots pine photosynthesis and modelling resulted in optimized predictions of the daily behavior and annual patterns of photosynthesis in a subarctic forest (Hari et al, 2017). The study connected theoretically the fundamental concepts affecting photosynthesis with the main environmental drivers (air temperature and light), and the theory gained strong support through empirical testing.…”