Even-aged stands are ones where the range of tree ages within a stand do not vary by more than 20% or so. Plantation forests are the best example of even-aged stands, as often they are created using seedlings or clones from a common set of parents. The planted trees are all the same age since they are planted at the same time.
What is an even-aged stand?
By definition, an even-aged stand is one in which the trees are within 20 percent of a given age, relative to the rotation length. Rotation length is the period of time that forest trees are grown before they are cut and a new regeneration cycle starts.
Is the stand age formulation suitable for uneven-aged stands?
Therefore, it is not suitable for uneven-aged stands, where the definition of stand age is at best ambiguous. For uneven-aged stands, a formulation based on stand density (defined by basal area) was introduced. A following system of equations, also providing compatible estimates, was used:
What is an even stand of trees?
By definition, an even-aged stand is one in which the trees are within 20 percent of a given age, relative to the rotation length. Rotation length is the period of time that forest trees are grown before they are cut and a new regeneration cycle starts. Click to see full answer.
What should the diameter distribution of an even-aged stand look like?
The diameter distribution of an even-aged stand, as we discussed in Chapter 2, Valuing and Characterizing Forest Conditions, should resemble a bell-shaped curve. This distribution will generally flatten out over time, and the range of diameters will widen, as trees either express dominance or suffer from competitive or site-related circumstances.
What are uneven-aged stands?
Uneven-aged structure means a stand has three or more age classes. This type of structure is a result of increasing species, age- and size-class diversity within a stand. Different species grow at different rates, and a distinct overstory canopy may no longer be recognizable.
What is the difference between even-aged and uneven-aged stands?
Large-scale natural disturbances, such as wildfire, have naturally favoured even-aged stands of seral species with a niche closely associated with these disturbance types. An uneven-aged stand is a mosaic of tiny even-aged clumps and scattered individuals woven together through a perpetual cycle of random disturbances.
What does even-aged mean?
By definition, an even-aged stand is one in which the trees are within 20 percent of a given age, relative to the rotation length. Rotation length is the period of time that forest trees are grown before they are cut and a new regeneration cycle starts.
What is even-aged forest and how it differ to uneven-aged forest?
When a forest has three or more age classes it is considered to be uneven-aged. complex, and may be less economically efficient than manag- ing even-aged forests. Care must be taken to remove trees without damaging trees that remain.
Where is even aged management used?
Even-aged timber management is a group of forest management practices employed to achieve a nearly coeval cohort group of forest trees. The practice of even-aged management is often pursued to minimize costs to loggers.
Why do uneven aged stands of trees offer more biodiversity?
Explanation. Uneven aged trees are like the even aged but the only difference is that uneven aged trees are cut at various time and not at the same time. This is to promote regrowth of other trees by seeding and being a shelter for those undergoing regrowth.
What are virgin trees?
Virgin forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.
What are the methods that produce an even-aged structure?
Therefore even-aged stands can be created through clearcut harvesting of trees and subsequent plantings (Fig. 4.2). Seed tree or shelterwood harvests, where a minor amount of the overstory remains to provide seed for the new stand, can be used to create an even-aged stand.
What is shelterwood tree cutting?
Shelterwood harvesting is an even-aged system used to establish and develop desirable natural regeneration. By removing a mature stand in two to three cuts over five to 20 years, more sunlight reaches the forest floor to stimulate seedling development.
What are the advantages and disadvantages of uneven-aged management relative to even-aged management?
DisadvantagesAllows almost complete control over stand establishmentSupply of seed or seedlings must come from outside of the stand to be established, unless shelter wood or seed tree reproduction methods are employedUniform growth rates and tree sizeUsually less aesthetically pleasing, depending on species composition9 more rows•Jun 1, 2018
What is clear cutting mean?
Definition of clear-cutting : the removal of all the trees in an area of forest Long considered a "trash tree" by the timber industry, the number of Pacific yews has been drastically reduced—perhaps halved—by clear-cutting, the logging practice that totally strips a targeted area.—
What is an even aged forest?
The term “even-aged forest” sometimes brings forth images of trees “grown like cabbages, ” as Aldo Leopold once described an agronomic approach to forestry. However, even-aged forests can form naturally. Crown fires, severe hurricanes, prior cultivation, and similar large-disturbance events can lead to even-aged stands as trees seed into ...
What does it mean when a tree is even aging?
By definition, an even-aged stand is one in which the trees are within 20 percent of a given age, relative to the rotation length. Rotation length is the period of time that forest trees are grown before they are cut and a new regeneration cycle starts.
How many entries are there in Shelterwood?
Shelterwood harvests may be made in two or three entries, with small trees removed in one harvest, more trees removed in a second “seed cut,” and seed trees removed in a third harvest after new seedlings are established.
How old are trees in a 100 year rotation?
For example, the trees in an even-aged stand with a 100-year rotation length might have an average age of 40 years, with some trees as young as 20 years old, and others as old as 60 years old.
Is a large tree always an old tree?
But it is important to remember that a large tree is not always an old tree and a small tree is not always a young tree. This observation is particularly true with shade-tolerant species.
Control Techniques for Commodity Production and Wildlife Objectives
Pete Bettinger, ... Donald L. Grebner, in Forest Management and Planning (Second Edition), 2017
Estimation and Projection of Stand and Forest Conditions
Pete Bettinger, ... Donald L. Grebner, in Forest Management and Planning (Second Edition), 2017
Optimization of Tree- and Stand-Level Objectives
Pete Bettinger, ... Donald L. Grebner, in Forest Management and Planning (Second Edition), 2017
Advanced Planning Techniques
Pete Bettinger, ... Donald L. Grebner, in Forest Management and Planning (Second Edition), 2017
Michael Family Forest, Texas, United States of America
The Michael Certified Family Forest management plan is designed so that any other family member can read and refer to it to understand the current ownership goals and expectantly continue good stewardship as a future legacy.
Linear Programming
Pete Bettinger, ... Donald L. Grebner, in Forest Management and Planning (Second Edition), 2017
Why is even age forest management important?
Even-aged forest management is the harvesting system of choice in many parts of the world because it is often considered to be the only method that is economically viable. Forestry operations have extremely high variable costs- per hour expenses for harvesting equipment and per kilometer expenses for log transportation compose a very large portion of the total cost to harvest a stand. Therefore, companies must obtain as much productivity as possible from their hourly equipment in order to be profitable. Uneven-aged management techniques where only certain trees are harvested, such as shelterwood systems, incur the same hourly costs while harvesting fewer trees per hour. This reality explains why in Canada, for example, 90% of forests harvested are done so by clear cut through an even-aged management system.
Is even aged timber good for biodiversity?
In some cases, the practices of even aged timber management are frequently implicated in biodiversity loss and other ecological damage . Even-aged timber management can also be beneficial to restoring natural native species succession.
