Fig. 1

Principle of the maturation stress generation and associated strains and stress in tangential (T) and longitudinal (L) directions. Green cell, cell before maturation. a Red cell, theoretical view of the same cell after maturation if it was isolated from other cells. b Blue cell, realistic view of the cell after maturation considering that it sticks to older rigid cells. Green arrows represent maturation stress in the newly maturated cell, and growth stress increments that happen in the older cells in response to the maturation stress. Convergent arrows figure a state of compression, divergent arrows a state of tension. c Schematics of strains occurring after T or L unidirectional or LT bidirectional release of maturation stress induced by making grooves in the wood. The dashed blue rectangle represents the dimension of the measurement area at initial state, and the solid red rectangle its dimension after stress release. Strains are figured with blue arrows (their magnitude is amplified for the purpose of representation)