Theory question 103
Population EcologyThe population of some plant species found in a rainforest is presented on the table below.
Plant species | Population of plant species
Mahogany | 10
Iroko | 25
Obeche | 15
Hevea sp. | 5
Delonix sp. | 10
Use the information to answer questions 3(a) to 3(c).
(a) On the graph below, draw a bar chart with plant species on the x-axis and the population of plant species on the y-axis, using a scale of 2cm to five plants on the y-axis.
(b)(i) Identify the most dominant plant species in the habitat. (ii) Name one method of population studies that could be used to collect the data on the table.
(c) If the area of the rainforest is 1000m2, calculate the population density of Hevea sp.
(d) State four: (i) Ways of conserving endangered species (ii) benefits of conserving forests to humans
Show the model answer
(a) A bar chart with a title, labelled axes (plant species on x, population on y), the stated scale (2 cm = 5 plants, so Iroko's bar is 10 cm tall), five separate bars of equal width: Mahogany 10, Iroko 25, Obeche 15, Hevea 5, Delonix 10.
(b)(i) Iroko (largest population, 25).
(ii) Quadrat method (or line/belt transect, direct counting).
(c) Population density = number ÷ area = 5 ÷ 1000 m2 = 0.005 per m2.
(d)(i) Any four: protect their habitats in game reserves and national parks; enforce laws against poaching and illegal trade; breed them in captivity (zoos, botanical gardens) and release them; control deforestation and bush burning; public education; seed and gene banks.
(ii) Any four: supply timber, fuel wood and other products; give food and medicinal plants; protect the soil from erosion; take in carbon (IV) oxide and give out oxygen (control climate); habitat for wildlife; protect water catchments; tourism and recreation.
In the bar chart, keep gaps between the bars and label every axis.