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Zorluk: ZorPopulation Dynamics and Ecological Sampling

An ecology student sampled the population of guinea grass (*Panicum maximum*) in a 600 m2600\text{ m}^2 pasture plot in Kaiama, Kwara State, using a 0.5 m×0.5 m0.5\text{ m} \times 0.5\text{ m} quadrat frame. The counts of grass clumps recorded from 10 randomly placed quadrats were 4, 6, 3, 7, 5, 2, 8, 4, 6, and 5. What is the estimated total population of guinea grass clumps in the entire pasture plot?

Cevap: 12000 clumps

Cevap

The estimated total population of guinea grass clumps in the pasture plot is 12,000 clumps.
To estimate total population size from quadrat samples, first determine the total area sampled (10 quadrats×0.25 m2=2.5 m210 \text{ quadrats} \times 0.25\text{ m}^2 = 2.5\text{ m}^2). Dividing the total count of organisms (50 clumps50\text{ clumps}) by this sampled area yields a population density of 20 clumps/m220\text{ clumps/m}^2. Multiplying the density by the total area of the plot (600 m2600\text{ m}^2) gives the estimated total population of 12,000 clumps12,000\text{ clumps}.

Adım Adım Çözüm

1
Determine the surface area of a single quadrat frame
Area of one quadrat = 0.5 m×0.5 m=0.25 m20.5\text{ m} \times 0.5\text{ m} = 0.25\text{ m}^2
Knowing the individual quadrat dimensions is necessary to calculate the sample area.
2
Calculate the total area sampled across all 10 quadrats
Total area sampled = 10×0.25 m2=2.5 m210 \times 0.25\text{ m}^2 = 2.5\text{ m}^2
Ten quadrats were placed, so the total sample area equals ten times the single quadrat area.
3
Find the total count of organisms recorded in all samples
Total count = 4+6+3+7+5+2+8+4+6+5=50 clumps4 + 6 + 3 + 7 + 5 + 2 + 8 + 4 + 6 + 5 = 50\text{ clumps}
Summing individual counts across all sampling frames gives the total sample size.
4
Compute the average population density per unit area
Population density = 50 clumps2.5 m2=20 clumps/m2\frac{50\text{ clumps}}{2.5\text{ m}^2} = 20\text{ clumps/m}^2
Density is defined as total count divided by total sampled area.
5
Extrapolate population density to the entire study area
Total estimated population = 20 clumps/m2×600 m2=12,000 clumps20\text{ clumps/m}^2 \times 600\text{ m}^2 = 12,000\text{ clumps}
Multiplying population density per square metre by total plot area gives the estimated overall population size.

Anahtar Kavram

Extrapolation of population size from sample quadrat density
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Konular

Population Dynamics and Ecological Sampling

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