Principles of Vegetation Measurement & Assessment
and Ecological Monitoring & Analysis

 

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Module 5 - Measuring Plant Density

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Lesson Instructions

  1. Read through the Overview and Learning Objectives.

  2. Complete the Required Reading.

  3. Read and review the Web Lessons (1-3).
  4. Visit suggested Internet Sites in the lectures.
  5. Check the schedule for the required Assignment.
  6. Complete assignment and submit by Blackboard.
     
    Content Summary Assignment due by Midnight on Tuesday, September 25.

    Data Summary
    Assignment due by Midnight on Tuesday, October 02.

ReadingSuggested Further Reading:

 

Density, Chapter 5 (pp 137-192) Measurements of Terrestrial Vegetation by Charles Bonham (Wiley)

 

Suggested Internet Sites:

Learning Materials

Reading

Required Reading:

 

Slides Web Lessons

  • Lesson 1 - What is Density?

  • Lesson 2 - Plot-based or Quadrat Techniques

  • Lesson 3 - Plotless or Distance-Based Techniques

 

Assignment:

What this Lesson Covers

Overview

A myriad of protocols exist for measuring vegetation.  It seems field technicians are always trying to create a "better mouse trap" or find the "silver bullet" that describes vegetation in miraculously new and clever ways.  Don't get lost in acronyms and details.  Remember, there are only a handful of attributes you can measure about a plant:

  • Frequency - Was the plant there or not?

  • Density - How many plants were there?

  • Biomass - How much did the plants weigh?

  • Cover - How much space did they occupy?

  • Structure - How tall were the plants and how were branches and leaves arranged?

  • Plant Species or Type - What kind of plant was it?

In this module we will focus on how to measure Plant Density and give decision guidelines for when to measure density instead of other plant attributes.

Learning Objectives

After this module you will be able to:

  • Understand the various definitions of density. 

  • Explain the difference between density, cover, and abundance.

  • Understand the advantages and challenges in using density for characterizing vegetation.

  • Understand how we measure density using plot or quadrat-based techniques

  • Understand how we measure density using plotless or distance-based techniques

additional references

  • Bonham, C.D. 1989. Density. pp. 137-197. In: Measurements for Terrestrial Vegetation. John Wiley & Sons, New York.

  • Cottom, G. and J.T. Curtis. 1956. The use of distance measures in phyto-sociological sampling. Ecology 37:451-460.

  • Dix, R.L. 1961. An application of the point-centered quarter method to the sampling of grassland vegetation. Journal of Range Management 14:63-69.

  • Hutchings, S.S. and M.J. Morris. 1959. Use of distance measures for determining plant density in semi-arid vegetation. Proc. 9th Intl. Bot. Cong. Vol 2:174.

  • Laycock, W.A. 1985. Density as a method for monitoring rangeland vegetation. Symp. on Rangeland Monitory. Soc. for Range Manage. Ann. Meeting. Salt Lake City, UT.

  • Lyon, J.L. 1968. An evaluation of density sampling in a shrub community. Journal of Range Management 18:205-211.

  • Mueller-Dombois, D. and H. Ellenberg. 1974. The count-plot method and plotless sampling techniques. pp. 93-135. In: Aims and Methods on Vegetation Ecology. John Wiley & Sons, New York.

  • Oldenmeyer, J.L. and W.L. Regelin. 1980. Comparison of 9 methods for estimating shrub density and saplings in Alaska. Journal of Wildlife Management 44:662-666.