Final answer:
The primary timberland and economy of the North Central Plains likely involved a mix of agriculture and woodland exploitation, including timber. The exact specifics of the timberland type in the region were not detailed in the references, but adjacent regions had broadleaf forests and an economic focus on agriculture.
Step-by-step explanation:
The North Central Plains historically had a diverse economic base, with different regions specializing in various primary and secondary industries. However, the specific answer to the question about the primary timberland and economy in the North Central Plains is not explicitly provided in the provided reference material. As a result, we have to infer based on the information about surrounding regions and general historical trends. The closest region mentioned with a focus on forestry is the Eastern Woodlands, which extended from the Mississippi River basin to the Atlantic coast and had abundant broadleaf forests and other varieties of trees.
In terms of economy, agriculture has traditionally been a major part of the economy in the central United States, as the Midwest and the Great Plains are referred to as North America's breadbasket due to their high agricultural productivity. Hence, one might infer that in the North Central Plains, a mix of agriculture and woodland exploitation, including the timber industry (although not as heavily emphasized as in the Eastern Woodlands), would have been part of the historical economic activities.