For the last 150 years woody plants have been expanding into grasslands and it has accelerated in the last 50 years. Why is this happening? 

This is a new project to assess the efficacy of brush/tree cutting, piling and then using prescribed fire to restore grasslands.

Elevated carbon dioxide concentrations (e[CO2]) coupled with predictions of increased drought severity and decreased in soil moisture will make life for plants difficult in the Great Plains. Are these future conditions going to favor woody plants?

Juniper has been steadily expanding in rangelands from the Great Plains to the western states. Using herbarium samples that span the last 150 years can we see to what extent nitrogen deposition has had on their growth?