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The most comprehensive inventory of Colorado’s forests – ever!

Date: April 20, 2017

Results are in from Forest Inventory Analysis data collected from 2002 to 2014, reporting on growth, mortality, and many other forest characteristics


Aspen stands affected by drought in southern Colorado. Photo by J.D. Shaw.
Aspen stands affected by drought in southern Colorado. Photo by J.D. Shaw.
The current inventory of Colorado’s forest is the first to use the complete set of Forest Inventory and Analysis (FIA) plots across all ownerships and forest types. The inventory was completed at a time when Colorado forests were undergoing substantial change, primarily in the form of insect infestations in pine and spruce, but also because of drought. This report captures the current status and recent trends.

Three “statewide” forest inventories were reported for Colorado prior to release of the current inventory. The first two were periodic inventories. These were not comprehensive in terms of detail, but assessed the total forest area of Colorado (including “commercial”, “unproductive”, and “productive-reserved” classes) at over 22 million acres – the same as currently reported despite the fact that the population of the state has more than doubled since the first inventory (1959 area estimate). The 1987 report focused primarily on commercial timberlands. The first report based on annualized inventory was published in 2010. This report used data from only half of the inventory cycle (2002-2006), but reported on all ownerships and forest types. The current report uses all data collected from 2002-2013, which includes a full inventory cycle and two years of remeasurement. Using the full-cycle dataset permits greater precision of estimates, and the transition to remeasurement will provide increasing precision of trend-tracking. The most important trend is increasing mortality, resulting in reductions in the live volume of Colorado’s forests.

Colorado’s forests have sustained people for millennia. Photo by J.D. Shaw
Colorado’s forests have sustained people for millennia. Photo by J.D. Shaw

Findings

  • Between the 2002-2006 annual inventory and the current inventory (2004-2013), Colorado’s forests have transitioned from positive net growth (220 million cubic feet per year) to negative net growth (-145 million cubic feet per year).
  • Negative net growth is concentrated in the spruce-fir and lodgepole pine forest types, and exceeds the state total net growth by -75 million cubic feet per year.
  • All other forest types have shown positive net growth (123 million cubic feet per year), only partially offsetting the negative growth in spruce-fir and lodgepole pine forests.
  • While still showing positive net growth, aspen forest growth has been reduced from over 82 to 12 million cubic feet per year.

Other Publications

Benson, Robert E.; Green, Alan W. 1987. Colorado's timber resources. Resource Bulletin INT-56. Ogden, UT: U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station.

Miller, Robert L.; Choate, Grover A. 1964. The forest resource of Colorado. Resource Bulletin INT-3. Ogden, UT: U.S. Dept. of Agriculture, Forest Service, Intermountain Research Station.

Featured Publications

Thompson, Michael T. ; Shaw, John D. ; Witt, Christopher ; Werstak, Charles E. , Jr. ; Amacher, Michael C. ; Goeking, Sara A. ; DeRose, R. Justin ; Morgan, Todd A. ; Sorenson, Colin B. ; Hayes, Steven W. ; Menlove, James S. , 2017
Thompson, Michael T. ; Duda, Joseph A. ; DeBlander, Larry T. ; Shaw, John D. ; Witt, Christopher ; Morgan, Todd A. ; Amacher, Michael C. , 2010


Principal Investigators: 
Forest Service Partners: 
Michael T. Thompson (CO-PI), Chris Witt, Charles E. Werstak, Jr., Michael C. Amacher, Sara A. Goeking, R. Justin DeRose, Jim Menlove; RMRS Interior West Forest Inventory and Analysis
External Partners: 
Todd A. Morgan, Colin B. Sorenson, Steven W. Hayes; University of Montana
Research Location: 
Colorado