In recent days, when importing a pier extract into a clean image, it has shown up as:

environment that has no content or a parent. In the default pier install, the localEnvironment is nil.This can be fixed by running:
PRKernel instances anyOne root localEnvironment parent ifNil: [ PRKernel instances anyOne root localEnvironment: (PRPathLookup start: PRKernel instances anyOne root path: '/system/templates/environment') ].
In a similar manner, the missing CSS can be resolved with:
PRKernel instances anyOne root localStyleSheet: (PRPathLookup start: PRKernel instances anyOne root path: '/system/components/StyleSheet').
Another solution is to have the settings setup so the environment is taken from /template - this is how recent Pier installs are setup. Older versions were set to use the above /system/templates/environment.
Comments
After some testing, using
/templatesdoes not always work.