**4.Changes in physical and mechanical properties**

Decaying fungi can lead to the changes in the physical and mechanical properties of wood, such as a decrease in intensity, elastic modulus, hardness, etc. Simultaneously, the toughness of wood will also deteriorate. These changes will affect the stability and service life, even the safety of wood products.

**Figure 2.**

*SEM images of wood samples biodegraded by different fungi.*

Wood decay by fungi can cause wood substrate losses, and changes in the chemical compositions, microstructures and physical and mechanical properties of wood. Among those properties, strength is a prior concern when study wood decay due to its critical significance in most structural uses. In summary, the degradation caused by fungi can damage the wood cell walls, leading to the destruction of organizational constituents and structure and the embrittlement of wood, thereby affecting its performance and service life.
