Forest Inventory and Analysis Highlights

The Forest Inventory and Analysis (FIA) program was originally designed as a periodic survey which inventoried forests one state at a time on a rotating basis. Beginning in 2000, the FIA program switched to an annual survey on a five-year cycle, where 1/5^th of the inventory field plots in Wisconsin were measured every year. This switched to a seven-year cycle in 2014. Every plot is re-visited every 7 years, providing valuable information at a tree level such as growth, mortality, and more.

Periodic inventories were completed in Wisconsin in 1936, 1956, 1968, 1983, 1996. Annual inventories with all five or seven years of plots measured were completed in 2004, 2009, and 2015.

Inventory highlights are available from 2012 [PDF], 2004 [PDF], and 1996 [PDF].

Definitions

Average annual mortality

Average volume of trees that died each year due to insects, diseases and other natural causes.

Average annual net growth

Gross volume between 1996 and 2004 minus mortality over that period divided by the number of growing seasons.

Average annual removals

Average volume of trees removed from growing stock each year due to timber harvests and land-use changes.

Biomass

Aboveground weight of live trees 1-inch diameter at breast height (dbh) and larger. Biomass estimates are used to address issues such as wildlife habitat, carbon storage and the availability of wood fiber for fuel.

Growing stock

All commercially valuable tree species greater than 5 inches dbh.

Poletimber

Softwood trees 5-9 inches dbh; hardwood trees 5-11 inches dbh.

Sawtimber

Softwood trees greater than 9 inches dbh; hardwood trees greater than 11 inches dbh.

Seedlings-saplings

Trees less than 5 inches in dbh.