(a) Give a brief description of the characteristics of the Northern Guinea Savanna. (b) Describe how you can estimate the density of a plant species using a...

Answer Details

(a) Characteristics of the Northern Guinea Savanna

1. The vegetation is made up of tall grasses with scattered, short, fire- and drought-resistant trees.
2. The trees are shorter and more widely spaced than in the southern (Guinea) savanna, and many have thick, fire-resistant bark and small or thorny leaves.
3. It has a longer dry season and lower total rainfall (about 1000 to 1200 mm a year) than the forest and southern savanna.
4. The grasses dry up and are often burnt during the dry season, and shed leaves reduce water loss.
5. Common plants include shea butter, locust bean and acacia trees, and common animals include antelopes, grasscutters and grasshoppers.

(Any well-explained points describing the tall-grass-with-scattered-trees structure, seasonal drought, bush fires and drought adaptations are credited.)

(b) Estimating the density of a plant species using a quadrat

1. Select the area to be studied and lay out a quadrat (a square frame of known area, e.g. 1 m by 1 m = 1 m²).
2. Throw or place the quadrat at random within the study area to avoid bias.
3. Count the number of individuals of the chosen plant species that fall inside the quadrat.
4. Repeat the sampling several times at different random positions and record each count.
5. Find the average (mean) number of the plant per quadrat.
6. Calculate the density using \[ \text{Density} = \dfrac{\text{total number of the plant counted}}{\text{total area of all the quadrats}} \] which gives the number of individuals per unit area (e.g. per m²). Multiplying by the whole area estimates the total population.