 Station 1-2
 Plants
Soils
Station 3-5
Management
Litter Hurts
Rotten Log
Station 6-8
Plant Succession
The Living Forest
Witches Broom and Bark Beetles
Station 9-11
Effects of Trailing
Wildfire
Radio Viewpoint
Station 12-14
Forest Habitat
Abandoned Prospect
Columbus Tree
Station 15-16
Douglas-Fir Stand
Summit
Station 17-19
Pit Excavations
Fire Scar
Habitat Contrast
Station 20-22
Snags
Root System
Silver Tip Viewpoint
| Plant Succession Station 6
The old roadbed that the trail crosses was built years ago for mineral prospecting and has not been used since the 1920s. Although long abandoned, the road is still easily visible. The trees were removed before road construction. Only grasses grew when the road was first used. Shrubs began growing after the road was abandoned, and now young trees are beginning to grow. The ultimate vegetation that any site can support is known as its “climax plant community,” and the process of change toward climax is known as plant succession. Sub-climax species are known as seral species and occupy different seral stages. Because of different habitat requirements, wildlife changes according to each  seral stage. People can influence the rate of change and even reverse its direction to earlier stages of plant succession. In this case, people built a road.
Another example of artificial change is timber harvest. Land managers can simulate a certain stage of succession by cultivating plants of a specific seral stage. For example, browse for deer and elk can be created by promoting brushfields on south-facing slopes after timber is removed. This can be done by burning the area periodically to kill young trees that would eventually shade out the shrubs. Managers may also try to change the rate of succession by planting seral tree species that are less susceptible to insect and disease problems. Through succession, sites always progress to the point that they are populated with climax vegetation. However, climax vegetation is not the same for all sites. It may be a pine forest for one site and a grassland for another site. Each will vary according to the conditions of the surrounding habitat. Still, you will often see many areas with seral plants. Why do you suppose this is true? Think about it as you hike to the next station.
 The Living Forest
Station 7
A forest is composed of various plants and animals living together. Populations of each species, whether they be plant or animal, will have individuals of all ages, from infant to old. Populations of trees may even have dead trees called snags. A healthy forest will have balanced proportions of its inhabitants, and individual plants will have sufficient space to grow without competition for soil nutrients, water, and sunlight. Plant succession will proceed toward climax in the absence of natural disturbances such as fire or human disturbances such as timber harvest.
Without disturbances to maintain these balanced proportions, selected species may become too densely populated. Consequently, the chance for infestations of insects, diseases, or catastrophic wildfire will increase. These processes retard plant succession from achieving climax vegetation. Habitat is “home” for any living thing and provides food, shelter (also known as  cover), water, and living space. Generally, the diverse forest vegetation provides food and cover for the variety of wildlife that inhabits the forest. For example, ruffed grouse and deer primarily eat buds and twigs, whereas finches and sparrows eat seeds. Red squirrels cache tree cones for later use during harsh winters. Standing trees provide habitat for insects and spiders, which are eaten by chickadees. Three-toed woodpeckers and black-backed woodpeckers feed almost exclusively on bark and wood-boring beetles. Nearly all infant birds need animal protein from insects to grow. Forest plants provide security cover for animals to rest or roost, escape cover from predators including people, protective cover from extreme weather, and reproductive cover for giving birth and rearing young. Each animal species has its unique habitat requirements and relies upon different plant species to provide its needs.
|
Witches Broom & Bark Beetles
 Station 8
Parasitic insects and diseases can infect trees in the forest. A parasite is a living organism that lives on or in another organism called a ”host.” Parasites derive their nourishment from their hosts and return nothing. Insects and disease can kill a tree or weaken it and slow its growth. Weakened trees are less able to compete with healthy trees and can be crowded out. They are also more susceptible to infestation by other parasites. Infestations can thin a timberstand or eliminate the climax vegetation and the plant succession cycle is repeated. In this way, vegetation diversity is maintained and we will continue to see seral vegetation. Wildfire also causes vegetation to diversify.
As you stand at this station, take a look around. Can you find an example of a parasite infecting a tree? The large Douglas-fir below the trail and the other trees in this area have deformities that appear as multi-branched broom-like growths on otherwise normal tree branches. The deformity is called witches broom, and is caused by dwarf mistletoe, a parasitic plant. The branched formation is caused by the tree’s own disease-combating defenses. The tree tries to cure itself by rushing nutrients to the infected area, much as white blood cells are rushed to human wounds. This rush of nutrients causes the sporadic growth pattern. Dwarf mistletoe is a serious parasite in many western conifers and can cause great economic losses. A parasitic insect found in the area is the bark beetle.
Since the start of the trail, you have probably noticed many dead ponderosa pine trees. They were killed by a tiny beetle that enters the tree and feeds just under the bark. The feeding action of the beetle eventually will girdle the tree, cutting off the flow of nutrients,  immediately killing it. Bark beetles are a common and serious pest. They usually attack weakened or dying trees. Many of the dead pine trees you see on Mineral Ridge were killed in the 1980s after several years of warm, dry weather made the trees vulnerable to beetle attack. As you proceed up the trail, see how many ponderosa pine trees you can find that may have been killed by the bark beetle.
|
>