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Describe one difference between the methods used to assess species abundance in plant and in animal communities: Identify the main consideration when determining appropriate quadrat size: dentify the main consideration when determining number of quadrats: Fynlain two main disadvantages of using the ACFOR abundance scale to record information about a plant community:

Describe one difference between the methods used to assess species abundance in plant and in animal communities: Identify the main consideration when determining appropriate quadrat size: dentify the main consideration when determining number of quadrats: Fynlain two main disadvantages of using the ACFOR abundance scale to record information about a plant community:

Applications and Investigations in Earth Science (9th Edition)
Applications and Investigations in Earth Science (9th Edition)
9th Edition
ISBN:9780134746241
Author:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
Publisher:Edward J. Tarbuck, Frederick K. Lutgens, Dennis G. Tasa
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110 Quadrat-Based Estimates The simplest description of a plant community in a habitat is a list of the species that are present. This qualitative assessment of the community has the limitation of not providing any information about the relative abundance of the species present. Quick estimates can be made using abundance scales, such as the What Size Quadrat? Quadrats are usually square, and cover 0.25 m² (0.5 m x 0.5 m) or 1 m², but they can be of any size or shape, even a single point. The quadrats used to sample plant communities are often 0.25 m². This size is ideal for low-growing vegetation, but quadrat size needs to be adjusted to habitat type. The quadrat must be large enough to be representative of the community, but not so large as to take a very long time to use. A quadrat covering an area of 0.25 m² is suitable for most low growing plant communities, such as this alpine meadow, fields, and grasslands. (a) How Many Quadrats? As well as deciding on a suitable quadrat size, the other consideration is how many quadrats to take (the sample size). In species-poor or very homogeneous habitats, a small number of quadrats will be sufficient. In species-rich or heterogeneous habitats, more quadrats will be needed to ensure that all species are represented adequately. (b) Determining the number of quadrats needed Plot the cumulative number of species recorded (on the y axis) against the number of quadrats already taken (on the x axis). The point at which the curve levels off indicates. the suitable number of quadrats required. . Larger quadrats (e.g. 1 m²) are needed for communities with shrubs and trees. Quadrats as large as 4 mx 4 m may be needed in woodlands. . ACFOR scale described below. Estimates of percentage cover provide similar information. These methods require the use of quadrats. Quadrats are used extensively in plant ecology. This activity outlines some of the common considerations when using quadrats to sample plant communities. Fewer quadrats are needed in species-poor or very uniform habitats, such as this bluebell woodland. Small quadrats (0.01 m² or 100 mm x 100 mm) are appropriate for lichens and mosses on rock faces and tree trunks. Describing Vegetation Density (number of individuals per unit area) is a useful measure of abundance for animal populations, but can be problematic in plant communities where it can be difficult to determine where one plant ends and another begins. For this reason, plant abundance is often assessed using percentage cover. Here, the percentage of each quadrat covered by each species is recorded, either as a numerical value or using an abundance scale such as the ACFOR scale. The ACFOR Abundance Scale A Abundant (30% +) C = Common (20-29%) F = Frequent (10-19%) O Occasional (5-9%) R = Rare (1-4%) 1. Describe one difference between the methods used to assess species abundance in plant and in animal communities: The ACFOR scale could be used to assess the abundance of species in this wildflower meadow. Abundance scales. are subjective, but it is not difficult to determine which abundance category each species falls into. 2. Identify the main consideration when determining appropriate quadrat size: 3. Identify the main consideration when determining number of quadrats: 4. Explain two main disadvantages of using the ACFOR abundance scale to record information about a plant community:
Transcribed Image Text:110 Quadrat-Based Estimates The simplest description of a plant community in a habitat is a list of the species that are present. This qualitative assessment of the community has the limitation of not providing any information about the relative abundance of the species present. Quick estimates can be made using abundance scales, such as the What Size Quadrat? Quadrats are usually square, and cover 0.25 m² (0.5 m x 0.5 m) or 1 m², but they can be of any size or shape, even a single point. The quadrats used to sample plant communities are often 0.25 m². This size is ideal for low-growing vegetation, but quadrat size needs to be adjusted to habitat type. The quadrat must be large enough to be representative of the community, but not so large as to take a very long time to use. A quadrat covering an area of 0.25 m² is suitable for most low growing plant communities, such as this alpine meadow, fields, and grasslands. (a) How Many Quadrats? As well as deciding on a suitable quadrat size, the other consideration is how many quadrats to take (the sample size). In species-poor or very homogeneous habitats, a small number of quadrats will be sufficient. In species-rich or heterogeneous habitats, more quadrats will be needed to ensure that all species are represented adequately. (b) Determining the number of quadrats needed Plot the cumulative number of species recorded (on the y axis) against the number of quadrats already taken (on the x axis). The point at which the curve levels off indicates. the suitable number of quadrats required. . Larger quadrats (e.g. 1 m²) are needed for communities with shrubs and trees. Quadrats as large as 4 mx 4 m may be needed in woodlands. . ACFOR scale described below. Estimates of percentage cover provide similar information. These methods require the use of quadrats. Quadrats are used extensively in plant ecology. This activity outlines some of the common considerations when using quadrats to sample plant communities. Fewer quadrats are needed in species-poor or very uniform habitats, such as this bluebell woodland. Small quadrats (0.01 m² or 100 mm x 100 mm) are appropriate for lichens and mosses on rock faces and tree trunks. Describing Vegetation Density (number of individuals per unit area) is a useful measure of abundance for animal populations, but can be problematic in plant communities where it can be difficult to determine where one plant ends and another begins. For this reason, plant abundance is often assessed using percentage cover. Here, the percentage of each quadrat covered by each species is recorded, either as a numerical value or using an abundance scale such as the ACFOR scale. The ACFOR Abundance Scale A Abundant (30% +) C = Common (20-29%) F = Frequent (10-19%) O Occasional (5-9%) R = Rare (1-4%) 1. Describe one difference between the methods used to assess species abundance in plant and in animal communities: The ACFOR scale could be used to assess the abundance of species in this wildflower meadow. Abundance scales. are subjective, but it is not difficult to determine which abundance category each species falls into. 2. Identify the main consideration when determining appropriate quadrat size: 3. Identify the main consideration when determining number of quadrats: 4. Explain two main disadvantages of using the ACFOR abundance scale to record information about a plant community:
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