Habitat Connectivity Index Calculator
Our biodiversity ecosystem calculator computes habitat connectivity index accurately. Enter measurements for results with formulas and error analysis.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
Graph Connectivity = Links / MaxLinks | Dispersal P = exp(-distance / dispersal)
Graph connectivity is actual links divided by maximum possible links. Dispersal probability follows a negative exponential decay with distance. The integral index combines both into a composite connectivity measure.
Worked Examples
Example 1: Forest Patch Network
Problem:15 forest patches, 25 links, mean area 80 ha, mean edge distance 800m, species dispersal 3000m.
Solution:Max links = 15x14/2 = 105\nGraph connectivity = 25/105 = 0.238\nDispersal prob = exp(-800/3000) = 0.765\nIntegral index = 0.238 x 0.765 x 100 = 18.23\nMesh size = 80 x 15 = 1200 ha
Result:Connectivity: 0.238 | Dispersal P: 0.765 | Index: 18.23 | Low
Example 2: Wetland Network
Problem:8 wetlands, 20 links, mean area 25 ha, mean edge distance 300m, species dispersal 1500m.
Solution:Max links = 8x7/2 = 28\nGraph connectivity = 20/28 = 0.714\nDispersal prob = exp(-300/1500) = 0.819\nIntegral index = 0.714 x 0.819 x 100 = 58.47\nMesh size = 25 x 8 = 200 ha
Result:Connectivity: 0.714 | Dispersal P: 0.819 | Index: 58.47 | Moderate
Frequently Asked Questions
What is habitat connectivity?
Habitat connectivity describes the degree to which the landscape facilitates animal movement and ecological flows between habitat patches. It includes structural connectivity (physical arrangement of patches) and functional connectivity (actual movement of organisms given their dispersal abilities). Well-connected landscapes allow species to access resources, find mates, recolonize after local extinction, and shift ranges in response to climate change. Loss of connectivity is a leading cause of biodiversity decline worldwide.
How is graph connectivity calculated?
Graph connectivity treats habitat patches as nodes and potential movement pathways as links in a network. The connectivity index is the ratio of actual links to the maximum possible links: C = L / (N(N-1)/2), where L is observed links and N is number of patches. A value of 1 means every patch is connected to every other patch, while 0 means complete isolation. Links are typically defined by whether the inter-patch distance is within the dispersal range of focal species.
What does the integral connectivity index represent?
The integral connectivity index (IIC) combines structural connectivity with functional connectivity by weighting graph connections by dispersal probability. Higher values indicate both many inter-patch connections and short distances between patches relative to species dispersal ability. It accounts for both the topology of the habitat network and the biological capacity of organisms to traverse gaps. Values range from 0 (completely disconnected) to 100 (fully connected with high dispersal success).
How does patch size affect connectivity?
Larger patches contribute more to landscape connectivity because they support larger populations that produce more dispersers, they are easier to locate by moving organisms, and they can serve as stepping stones for movements across the landscape. The effective mesh size metric combines patch size with connectivity to estimate the area of habitat available to an organism as a contiguous block. Small isolated patches may function as ecological traps if they attract settlers but cannot sustain viable populations.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy