X-ray microtomography and Digital Volume Correlation are used to characterize the compressive behavior of fibrous materials, composed of wood fibers and thermoplastic fibers. 9-mm height and 9-mm diameter specimens are compressed uniaxially up to 30 % compression rate with an increment of 5 %. The evolution of microstructure is followed at different compression states by X-ray microtomography at a spatial resolution of 6 mu m per voxel. Digital Volume Correlation is applied on microtomographic images to obtain the 3D strain field at each loaded state. The studied material shows a heterogeneous local strain field which relates not only to the complex microstructure but also to its modifications under solicitations. Microstructural parameters such as distributions of local porosities and fiber diameters are computed at different states by mathematical morphology. Relations between morphological parameters and 3D strain field are established. In a first approach, we show that the local mechanical behavior is controlled by distributions of local porosities.