Buckling is a failure mechanism that occurs when a laminate is subjected to compression. Fibres carry tensile loads effectively whereas compressive loads are carried by the matrix so I am having trouble understanding if fibers are not really functional in compression anwyay, how does it matter how they are laid up?

I read in an article "Use a 45 degree ply on the surface of a laminate to increase its buckling resistance/strength". Can anyone explain why/how a 45 degree ply helps improve the buckling resistance of a laminate?

Lastly, are there any layup sequences optimum for a laminate that will be subjected to compression?

Imagine if all your fibres are at 0
Under compression those fibres start to bow outwards
+/- 45 helps tie them in an stops them bowing out