Content

Introduction
Video Lecture
Supplementary Readings
Topic Quiz
Online Discussion
Assignments
Self Review

Topic Introduction

The pattern of individual tree growth is periodic over days and weeks depending on favorable temperature and moisture conditions. Tree growth pattern over years follows a typical sigmoid shaped curve. The pattern of tree growth in a stand varies between individuals because trees growing together compete for light, water and nutrients. Trees regenerating from seed start off at about the same size but some trees grow more rapidly and others more slowly. Over time the vigorous or fast growing trees suppress the slow growing trees that may become stagnant or die. Through these interactions between trees – or competition – the forest stand changes through time, it is dynamic.

Between tree competition develops as they begin to compete for aboveground resources (light) and below ground resources (moisture and nutrients). In moist environments the onset of competition usually occurs around the time of canopy closure or in drier environments, characterized by more wide-spaced trees, competition is belowground between roots for scarce moisture resources.

In woodlands the trees do not close canopy and the competition is mainly between roots for soil moisture. In a forest the trees usually achieve canopy closure at which time competition for light and tree height becomes important.

Trees in a stand differentiate in to crown classes because the growth of some trees slows more than others so that as the stand ages, a range of tree sizes develops that can be classified in to different crown classes – according to the trees relative position in the canopy.

Disturbance is a determinant of forest structure and competition between trees because forests are continually impacted by external forces to modify the structure of the stand – often through killing and felling of trees. Sources of disturbance include wind, fire, drought, water, ice and biota. There is a whole area of ecology devoted to describing and defining disturbance and our intention here is to briefly identify the interaction between trees and disturbance in creating and modifying stand structure.

Terminology and concepts definition of a stand, even-aged, mixed-age, competition, canopy, stand structure, gap formation, shifting-mosaic steady state, old growth, landscape scale.

Video Lecture

Lecture Video & Powerpoint

Topic 1.2 Lecture: Forest Regeneration and Tree Growth

[1.2 Lecture ppt to be embedded here.]

Supplementary Readings

Textbooks

Bormann, F.H., & Likens, G.E. (1981). Patterns and Process in a Forested Ecosystem. New York: Springer-Verlag.

Oliver, C.D., & Larsen, B.C. (1996). Forest Stand Dynamics (Updated ed.). New York: McGraw-Hill.

Peterken, G.F. (2001). Structural dynamics of forest stands and natural processes. In J. Evans (Eds.), The Forests Handbook (pp 83–104). Blackwell Science Ltd. ISBN 0-632-04821-2.

Article in Journals

White, P.S. (1979). Pattern, process and natural disturbance in vegetation. Botanical Review 45, 229-99

Topic Quiz

Topic Quiz 1.2

The topic quiz is designed to check your understanding of important learning concepts for this topic. The quiz contains 10 multiple choice questions. When you are ready, start the quiz at Topic Quiz 1.2.

Online Discussion

Thought-provoking Questions 1

For this activity,

You are expected to submit at least two thought provoking questions by day 5 of the week. Each question should be no longer than 75 words. Note, thought provoking question should be more analytical/critical, that spark a deep discussion about the topic.
After posting thought provoking questions, you are required to comment on at least two of their peer’s questions not exceeding 100 words by day 7 of this week.

Please see Course Schedule for detailed due dates and check out the specific requirements and grading criteria on the Thought Provoking Questions page.

Assignments

No other assignments for the week.

Topic Self-review

Reflection Questions 1.2

Please use the self-reflection questions below as a study guide to conduct self-review for the topic.

Compare and contrast the characteristics of even-aged and mixed-aged stands. Do even-aged stands eventually become mixed-aged?
As a growth and dominance strategy, what are the disadvantages of accumulating starch reserves for epicormic growth?
Should disturbances be seen as an integral component of the forest type and not an external destructive force?

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