Sampling and studying ecosystems 0.0 / 5 ? BiologyEcology, ecosystems and environmental biologyA2/A-levelOCR Created by: Steff06Created on: 05-06-16 17:06 Describe a quadrat 1m square and string across every 10cm, separating it into 100 squares. 1 of 14 What can we record with a quadrat? Either the distribution or abundance of each species. 2 of 14 What is distribution? The presence or absence of each species. 3 of 14 What is abundance? Estimating or counting the number of individuals. 4 of 14 When it is difficult to count individuals, what do ecologists tend to estimate? Estimate percentage cover. 5 of 14 What will improve the estimate? Using a point frame. 6 of 14 How is a point frame used? Each needle should be lowered downwards and species recorded that the tip touches. 7 of 14 How can we avoid biasing the sample? Randomly position the quadrats across the habitat using random numbers to plot coordinates. Taking samples at regular distances. 8 of 14 How do ecologists work out how many quadrats are needed? Carry out pilot study with random samples and plot cumulative frequency against quadrat number. Where curve levels off. 9 of 14 How do you work out what size the quadrats should be? Plot quadrat area on x axis against no. of species you find in each one. Read where curve levels off. 10 of 14 What is the equation used to estimate the population size of a species? Mean no. of individual of species in each quadrat/fraction of total habitat area covered by quadrat. 11 of 14 How is a transect used? Line taken across a habitat/stretched out tape measure. Take samples at regular intervals along tape. 12 of 14 How is a line transect used? Taken at regulation intervals, make a note of which species are touching the tape. 13 of 14 How is a belt transect used? At regular intervals, place quadrat next to the line (interrupted belt) and study each or move the quadrat along the line (continuous belt transect). 14 of 14
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