Please enable JavaScript.
Coggle requires JavaScript to display documents.
2.5. INVESTIGATING ECOSYSTEMS (Techniques for data collection (Measuring…
2.5. INVESTIGATING ECOSYSTEMS
Knowledge and Understanding
Description and investigation of ecosystems allows for comparisons to be made between different ecosystems and for them to be monitored, modelled and evaluated overtime
Organisms in an ecosystem can be identified using keys, comparing to herbarium/specimen collections, technologies and scientific expertise
Techniques for data collection
Where to collect
quadrats
transects
What to measure
measuring abiotic or biotic factors
Measuring biotics
biomass and productivity
catching small motile animals
keys
Measuring abundance
Lincoln Index
Simpson diversity index
Quadrats
Place randomly or continuously or systematically
Map out study area, draw a grid over the study area, number each square, use random number table to identify which squares to sample
average the amount per each sample square, times by total area
Transects
sample path/line/strip along which the occurence or distribution of plants and animals in a particular study area can be recorded
Line transect: string or measuring tape laid out in direction of the environmental gradient and species touching the string or tape are recorded
Belt transect: strip of chosen width through the ecosystem - maid by laying two parallel line transects between which individuals are sampled
Transect lines can be continuous or interrupted - continuous means whole line or belt is sampled, interrupted means samples are taken at points along the line or belt systematic sampling e.g. every 5 metres
Measuring abiotic components of an ecosystem
Marine ecosystems
Salinity - determined by measuring the electrical conductivity or density of the water
pH can be measured using a pH meter/probe
temperature
Dissolved oxygen - sollubility of oxygen in water is affected by - temperature (higher the temp lower the oxygen) and water pollution
Freshwater ecosystems
Turbidity - high = cloudy water low = clear - important because it limits the depth of sunlight and therefore photosynthesis - measured using a Secchi disc
Flow velocity - speed at which water is moving and it determines which species can live within a certain area. Flow velocity varies with time, depth, position in the river - measured using floats, flow meters and impellers
Terrestrial ecosystems
Air temperature - thermometers, min-max thermometers etc
Light intensity - can be measured with electronic meters
Wind speed - anemometer
Rainfall - rain gauge
Soil - texture affects soil's drainage and water holding capacity
Soil moisture - measured by drying soil samples - record weight before and after drying
Measuring biotic components of a system
Abundance - Lincoln Index
Diversity - Simpson diversity index