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Hilsenhoff Biotic Index Formula:
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The Hilsenhoff Biotic Index (HBI) is a measure used to assess the biological quality of soil based on the presence and abundance of macroinvertebrates and their tolerance to pollution. It provides an indication of soil health and potential contamination levels.
The calculator uses the HBI formula:
Where:
Explanation: The index is calculated by summing the products of the number of individuals and their tolerance values for each taxon, then dividing by the total number of individuals collected.
Details: HBI values help assess soil quality and pollution levels. Lower HBI values indicate cleaner, healthier soil with pollution-intolerant organisms, while higher values suggest polluted conditions with predominantly tolerant species.
Tips: Enter the number of individuals for a specific taxon, its tolerance value, and the total number of individuals collected. All values must be valid (non-negative numbers, total individuals > 0).
Q1: What do different HBI values indicate?
A: Lower HBI values (0-3.5) indicate excellent soil quality, while higher values (7.5-10) indicate severely polluted conditions.
Q2: How are tolerance values determined?
A: Tolerance values are assigned based on scientific studies of each taxon's sensitivity to pollution, typically ranging from 0 (very intolerant) to 10 (very tolerant).
Q3: What sampling methods are used?
A: Standardized soil sampling techniques are used, typically involving collection of soil cores or samples from specific depths and areas.
Q4: Are there limitations to this index?
A: HBI may be less accurate in extreme environmental conditions or when dealing with rare or poorly studied taxa with uncertain tolerance values.
Q5: How often should HBI be measured?
A: Regular monitoring (seasonally or annually) is recommended to track changes in soil quality over time and assess the effectiveness of conservation efforts.