THE ECOSYSTEM 2 3 MEASURING BIOTIC COMPONENTS OF

THE ECOSYSTEM 2. 3 MEASURING BIOTIC COMPONENTS OF THE SYSTEM

ASSESSMENT STATEMENTS • 2. 3. 1 Construct simple keys and use published keys for the identification of organisms • 2. 3. 2 Describe and evaluate methods for estimating abundance of organisms • 2. 3. 3 Describe and evaluate methods for estimating the biomass of trophic levels in a community • 2. 3. 4 Define the term Diversity • 2. 3. 5 Apply Simpson’s diversity index and outline it’s significance

2. 3. 1 CONSTRUCT SIMPLE KEYS AND USE PUBLISHED KEYS FOR THE IDENTIFICATION OF ORGANISMS • This is one of the activities that we will be doing in class tomorrow.

2. 3. 2 DESCRIBE AND EVALUATE METHODS FOR ESTIMATING ABUNDANCE OF ORGANISMS • Lincoln Index – capturemark-release-recapture • It is essential that the marking is non-harmful, and non-conspicuous. • Movement of animals into and out of your sample area will give bad results.

2. 3. 2 DESCRIBE AND EVALUATE METHODS FOR ESTIMATING ABUNDANCE OF ORGANISMS • Quadrats- Used for nonmobile organisms. • Vary from. 25 to 1 m squares • Select quadrant size by finding smallest quadrant that has the largest diversity • Used to calculate population density – individuals of each species per unit area. • Plant coverage determined through percentage coverage.

2. 3. 2 DESCRIBE AND EVALUATE METHODS FOR ESTIMATING ABUNDANCE OF ORGANISMS • If habitat is same throughout use, random grid. • If the habitat varies, get equal samples from each type. • If there is an environmental gradient, then place quadrats at set distances. • Percentage frequency – how many quadrats a species is in.

2. 3. 3 DESCRIBE AND EVALUATE METHODS FOR ESTIMATING THE BIOMASS OF TROPHIC LEVELS IN A COMMUNITY • Samples are dried to a constant weight to remove water. • For plants you would take all the samples from a quadrat, and then multiply by the total number of quadrats. • Stated per unit area.

2. 3. 4 DEFINE THE TERM DIVERSITY • Diversity – based on number of different species, and relative numbers of individuals of each species.

2. 3. 5 APPLY SIMPSON’S DIVERSITY INDEX AND OUTLINE IT’S SIGNIFICANCE • Simpson’s Diversity Index compares the total organisms, to the total types of species. • If it is high, it suggests a stable and ancient site. • If it is low, it suggests pollution, recent colonization, or agricultural management.