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A Century of Change in a Ponderosa Pine Forest

Living things change constantly, as do communities of living things. In a forest, where individual trees can live for centuries and new plants replace old plants, it is not easy to visualize the changes that occur over time.

Details about "80 Years of Change in a Ponderosa Pine Forest"

Before the First Photo: In the 1900s, this was an open forest of ponderosa pine (Pinus ponderosa), typical of millions of acres of forest in the western United States. The forest contained scattered large trees and patches of young trees. Fires had burned through the grass and pine litter on the forest floor every seven years, on average, since before 1600. These fires had little impact on large trees but killed many of the young trees, although some survived. Records from the site tell us that the original forest had about 50 trees per acre and plenty of grass and lupine, an early summer wildflower that supplies nitrogen to the soil. Each time a fire burned through, it would kill the tops of the grasses and flowers, but they resprouted from underground stems, sometimes within weeks. There were few tall shrubs but many low-growing ones. Most of these also sprouted after each fire.

80 Years Poster

About the Six Photos on the Poster:

 

1909 photo

1909:

Here we see “cleanup” operations after loggers used horses to harvest about half of the trees on the site. They left half as “reserve” timber for a second cut and to provide seed for a new generation of trees. Most of the Douglas-firs were harvested, even though they were of lower economic value, to keep a native parasitic plant, western dwarf mistletoe (Arceuthobium campylopodum), from spreading through the stand.
1948

1948:

The reserve trees grew quite well for 40 years, especially during the first decade after logging and during a period of high rainfall about 30 years later. Some trees were blown down shortly after logging, but few others died. Young ponderosa pine and Douglas-fir became established. These young trees grew about one inch in diameter every three to four years.
1958 photo

1958:

To make room for the young trees to grow well, most of the undamaged Douglas-firs over 14 inches in diameter were harvested in the 1950s. Loggers also cut dead-topped and lightning-damaged trees, slow-growing old trees, trees with decay near the base, and trees leaning more than 20 degrees.
1968 photo

1968:

In 1962, some large trees were cut and patches of smaller trees were thinned. The most striking result captured in these photos is the proliferation of ponderosa pine seedlings. Ponderosa pine seedlings originate sporadically, in years after the trees produce abundant cones. They grow well in open spaces and on bare soil.
1979 photo

1979:

Lots of young Douglas-fir seedlings are growing among the pines. Douglas-fir tolerates shade and dense forest conditions better than pine, so its seedlings can grow even when the site is partly occupied by taller trees and is quite shady.
1989 photo

1989:

Ponderosa pine and Douglas-fir seedlings have developed into a dense understory. Tree branches are almost continuous from the ground into the tops of the tallest trees, so wildfires are not likely to stay in the grass and shrubs on the forest floor. Instead, they are likely to burn up into the tree crowns by way of the “ladder fuels” provided by saplings and young trees. Eighty years ago, wildfires changed the forest very little. Now they are likely to kill even the oldest, tallest trees on the site.
1997 photo

1997:

88 Years Later. Some overstory ponderosa pine were removed during 1992 selection harvesting. Patchy underburning in 1993 killed some conifers in thickets. Ground cover is kinnikinnick, dwarf huckleberry, and pine grass. The view to the left and right of the photo is much more open, similar to 1909. The stand is now multi-aged with a patch of large snags killed by beetles during the 1990s.
2009 photo

2009:

100 Years Later. Small trees killed by the 1993 underburning treatment have mostly fallen to the ground. Douglas-fir tree regeneration noted in 1979 continues to grow in patchy thickets.
2015 photo

2015:

106 Years Later. Shrub species in the understory have become more prominent. Douglas-fir regeneration evident in foreground and background.
Modified: Sep 13, 2017

Select Publications & Products

Most of the information here, and much more information on forest ecology and management in the Lick Creek area, comes from the following publication:

Smith, Helen Y.; Arno, Stephen F., eds. 1999. Eighty-eight years of change in a managed ponderosa pine forest. Gen. Tech. Rep. RMRS-GTR-23. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 55 p.