m01.    How much public land is there and how is it used?

Public lands make up about 42% of the nation.  Of these lands, 73% are in Alaska, 22% are in the Western US. The federal government manages 33% of these lands.  Public land is used for grazing land (54%), commercial timber (40%), and energy resources and minerals (6%).

Even though a large amount of the public land is used for commercial logging, since 1947, the US has been a net importer of wood because of population growth. Wood is used for construction (55%), for paper and cardboard (25%) and for fuel (20%). These forests are managed in two ways: Even-aged management in which a stand of trees is cut then reforested.  Crossbreeding and genetic engineering is used to improve the wood.  The goal is for a high return on the investment. Uneven-aged management cuts mature trees and the land is managed for natural regeneration.  The goal is a reasonable economic return with the area being used for many purposes such as recreation.

In uneven-aged forests, selective cutting culls the most mature trees. This lowers fire hazard, relieves overcrowding and allows trees to grow back naturally. However, it’s costly, and it may injure 1/3 to 2/3 of the trees around the one cut.

Shelterwood cutting removes all mature trees in a series of cuttings over about 17 years. This allows natural reseeding and protects seedlings until they are older. Unfortunately, it’s costly, and if too many of the mature trees are cut, natural seeding will not occur.

Seed-tree cutting removes nearly all of seed producing, leaving a few mature trees uniformly distributed. This leaves a well-mixed forest that can be used for recreation as well as natural habitat. If the best trees are left, the species will be genetically improved. On the other hand, it’s costly and if the best trees are not left to reseed, the species may decline.

In clear cutting, all trees in a given area are harvested. This is cost efficient and the land may be replanted with genetically superior species. Conversely, this leads to severe erosion and the land has no other uses while trees are growing back.

Whole-tree harvesting cuts the tree at ground level or uproots the entire tree.  All dead-and-down trees are also removed, as is any undergrowth. This is cost effective but it removes all material from the area; all the nutrients are removed which might go back into the soil. This practices also takes away all wildlife habitats.

Strip logging clear cuts a strip of trees along the contours of the land.  The area is left alone to allow for natural regeneration.  This allows for clear cutting with minimal damage.

e03.    How do pathogens and insects affect trees?

e08.    What are bioregions and biosphere reserves?

e09.    What is succession?

e13.    What is biomass?

e22.    What do we eat?

e23.    How is soil important to plants?

g08.    What are the spheres that make up the earth?

g22.    What is soil?

g23.    What are some characteristics of soil?