Answered: Discuss the difference between sampling…

Applications and Investigations in Earth Science (9th Edition)

9th Edition

ISBN:9780134746241

Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa

Chapter1: The Study Of Minerals

Section: Chapter Questions

Problem 1LR

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Discuss the difference between sampling and monitoring.

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Various methods have been devised to sample, or estimate the numbers of, arthropods on trees and shrubs. Many of these procedures were first developed for use in agricultural crops, but several have resulted from investigations on landscape ornamental pests. The objectives of sampling or monitoring are to detect the presence or absence of pests; quantify abundance of pests and their natural enemies; and follow the progress of an arthropod population through time by regular, periodic sampling. The goal of monitoring is to reach a decision as to whether, or when, a pest population requires control action. All sampling procedures share certain characteristics:

They use a common sampling unit, such as leaves, terminals, beats, or minutes.
The unit chosen must be consistent with the feeding habits of the pest population under observation. Do not select leaves as the sampling unit for scale insects that occur predominantly on twigs. Similarly, do not count aphids on the younger leaves if they occur mostly on the older leaves.
The number of samples taken must be adequate. What is "adequate" must be determined on a case-by-case basis, and by time and equipment constraints. Pests are seldom distributed uniformly over a tree or shrub. Similarly, every tree in a group of trees of that species will not be infested to the same degree. Generally, the number of samples taken from each plant at each interval is held constant over the entire sampling period, and over the entire group of plant samples.
The sampling procedure must be standardized. It helps if the same person does all the samplings. If two or more persons are involved, they should check one another in a preliminary sampling exercise to determine that their sampling methods and results are the same.
Written records of arthropod counts are kept by date, location, and person sampling, with a brief description of procedures used.