Soils and Water Availability

Written by Peter Kolb, Montana State University

Soil water availability is the capacity of a soil to hold water that is available for plant use. A soil is simply a porous medium consisting of minerals, organic matter, water, and gases. The traditional definition of soil is: Soil is a dynamic natural body having properties derived from the combined effects of climate and biotic activities, as modified by topography, acting on parent materials over time.

Figure 1. Diagram

Tree Biology

Written by Peter Kolb, University of Montana

Tree physiology functions much as it does in all other plants: Their leaves absorb carbon-dioxide (CO2) from the atmosphere through little pores in their leaves called stomates and use the energy of the sun in a biochemical process called photosynthesis. This process converts carbon dioxide (CO2) and liquid water (H20) into a variety of complex sugars comprised of the basic molecular blocks of one carbon, two hydrogen, …

Forest Ecosystems

Written by Peter Kolb, University of Montana
A photo a forest landscape in the United States. Photo courtesy of Peter Kolb, University of Montana

Forest ecosystems are the combination of species, geology, topography, and climate tied together by physical and biotic processes specific to any one site, and most importantly occupied by trees as the dominant vegetation. A forest ecosystem may be as small as a tree branch microsite where mosses, insects, and microscopic organisms interact or as large as …

Tree Species

Written by Peter Kolb, Montana State University

Tree species can be identified in many ways, including by visible and genetic attributes. As with all biological organisms, tree taxonomists use the Linnaean system to differentiate between unique tree lineages (kingdom – phylum – class – order – family – genus – species). Most plant taxonomy is based on reproductive structures and trees are no different, scientifically separated in the kingdom of plants into two evolutionary phylum called angiosperms (naked seed) and …

Tree-Climate Interactions

Written by Peter Kolb, Montana State University

Tree-climate interactions essentially determine where tree species can naturally occur. The genetic processes that direct and create a certain tree species’ morphological and physiological characteristics are closely tied into the local climatic conditions through the process of natural selection. Either a tree has the ability to grow under local temperate and moisture patterns and it survives and reproduces, or it dies off. The ability to reproduce is the key element determining where tree …

Insects in Forests

Written by Peter Kolb, Montana State University

Figure 1. Some common tree-inhabiting beetles including large staghorn beetles (center), roundheaded borers (left), and a variety of much smaller bark beetles (right). Photo courtesy of Peter Kolb, Montana State University.

Insects perform many roles within forests as pollinators, herbivores, carnivores, decomposers, and food sources for other organisms. As a group, they are the most abundant and important group in the phylum Arthropoda, and by 1972 more than 900,000 species had already been …

Managed Forests

Written by Amy Grotta

Managed forests are those that people intentionally designate and manipulate to produce desired goods such as wood products and/or services such as recreational opportunities. This designation applies to “National Forests” that are managed by the U.S. Forest Service, “State Forests” that are managed by individual state agencies, “Industrial Forests” that are managed by timber industries for wood products, “Family Forests” that are managed by individual landowners and/or their families, and “Urban Forests” that are managed by …

Calculating Carbon Drawdown by Trees

Adapted from: McPherson, E.G.; J.R. Simpson,; P.J. Peper; and E. Aguaron. 2008. Urban Forestry and Climate Change. Albany, CA: USDA Forest Service, Pacific Southwest Research Station. Available at:

The Center for Urban Forest Research (CUFR) provides a tool for assessing the greenhouse gas drawdown in urban forests, the CUFR Tree Carbon Calculator (CTCC). It is the only tool approved by the Climate Action Reserve’s Urban Forest Project Protocol for quantifying carbon dioxide sequestration from greenhouse gas tree-planting …

Forest Management Types


Written by Amy Grotta

Forest ecosystems are made up of dozens of species and life forms, with sometimes complex patterns of vertical and horizontal structure. Across a large landscape, forest ecosystems are managed in a variety of ways and have many levels of human activity. Along a rough gradient from least intensive to most intensive human activity, forests may be characterized as wilderness, managed forests, wildland-urban interface, and urban forests. Each of these forest types is described in further …

Adaptive Forest Management Strategies

Adapted from: Millar, Constance I., Nathan L. Stephenson, and Scott L. Stephens, 2008. (February 5, 2008). Reframing forest and resource management strategies for a climate change context. U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. Media: millar020508.pdf

While the future impacts of climate change on forests and other natural resources remain uncertain, a variety of approaches can help foresters and forest owners prepare to manage the land in their care under changing conditions. Understanding that a range …