Iray Nature Shaders - Bark is a great bundle of 20 bark shaders for Iray, all taken from photographs and furnished with normal, displacement and spectral mapping, which can be applied to any item you wish to cover in bark!

Some of these great shader pre-sets include layers of moss and lichen for even more detail! 

Designed to re texture older tree models in my own runtime, to match in with some of my trees and shrubs, the bundle comes with two sets of bark shaders, one plain and one with added moss layers in the texture pre-set (Along with scaling utilities for each of the two sets as they work slightly differently).

Just select the object you wish to add the bark shader too, make sure the specific surface is selected and add the shader, then go to the scale utilities and pick one that works (many models have different UV mapping so there are different ratios to help with this. If there isnt the ratio you need you can always go to the shader tab and set the tiling to your liking there - some experimentation may be needed).

All of the shaders have high levels of displacement and are set to work with subdivision (you can convert your model to sub division inside studio if it is not already sub d). This adds to the realism of the shader and can breathe life in to an other wise flat surface.

All in all this is a great asset to have in your shader collection, adding realistic bark materials that match many of the trees and shrubs you will find in my Daz 3D store, thus enabling you to blend other items in to the scene you are creating seamlessly!