Practise biodiversity questions by defining ecology terms, planning field sampling and calculating Lincoln, correlation or Simpson index values from data.
Researchers measured insect biodiversity on Acacia trees in the African savannah using the following method:
- insecticide was sprayed into each tree
- this killed the insects, which fell onto a sheet below the tree
- the dead insects were collected, identified and counted.
The researchers considered each tree to be a small, distinct ecosystem.
Discuss whether or not an individual tree can be described as a small, distinct ecosystem.
three from ref. to interactions between, biotic and abiotic (components) ;
yes tree supports, many species/community/many interactions ;
energy flow / food web, occurs on one tree ;
no idea that tree is part of larger ecosystem/interactions occur with organisms outside tree ;
part of, savannah/larger, energy flow/food web/nutrient recycling ;
3
A interactions between living and non-living or between, the community/populations of different species, and the physico-chemical environment
A idea of, discrete/self-contained/self-sustaining, group of species/community A description of three-step food chain on tree
The Venus fly trap, Dionaea muscipula, is a carnivorous plant. It has traps which catch insects.
Each trap consists of a pair of modified leaves joined by a midrib of hinge cells. The modified leaves have touch-sensitive hairs. If two hairs are touched within 20 seconds, or the same hair is touched twice in rapid succession, the trap closes.
D. muscipula grows naturally in a small region in eastern USA. Fires that destroy much of the vegetation occur in this region. Three sites in this region where there had been fires were identified and investigated.
- Site 1 had experienced a fire 2 years before.
- Site 2 had experienced a fire 10 years before.
- Site 3 had experienced a fire 30 years before.
Preliminary observations suggested that over the course of time following a fire, the biodiversity of plants had increased. However, the abundance of Venus fly trap plants had decreased and so had the light intensity available to them. There was also a decrease in the nitrogen that the plants absorbed from insects as a proportion of all the nitrogen they obtained from their environment.
Name an ecological or statistical method to measure:
the abundance of D. muscipula at each site
random sampling using frame quadrats ;
plant biodiversity at each site
Simpson's index of diversity ;
Bears are several species of mammal in the family Ursidae.
Climate change and loss of habitats due to human activity have reduced the size of some bear populations in recent years.
The scientists calculated a D value of 0.833 for the undisturbed population.
Explain what is shown by the difference in the D values between the two populations of bear.
undisturbed / higher D, has, larger / higher / more, (food), diversity / variation ;