succession

Yes and no.  Shrubs rarely persist beneath a closed tree canopy, especially sagebrush.  However, deep rooted perennial grasses have been observed to persist on sites with deep soils and where restrictive layers (e.g. clay accumulation layer called an argillic), reducing water capture and storage are absent or weakly developed.  Photos of two different pinyon-juniper sites,…

The amount of lateral leader growth on understory sapling-size trees is a good indicator of understory competition between overstory trees.  Compare leader length in closed stands to trees growing in the open or at the edge of a stand or adjacent to a road. 

There is a strong inverse relationship between the tree overstory and understory including shrubs and perennial grasses and forbs. Shrubs rarely persist beneath a closed tree canopy, especially sagebrush.  However, deep rooted perennial grasses have been observed to persist where soils are moderately deep to deep and where restrictive layers (e.g. clay accumulation layer called…