Where does fragmentation collide?

The breaking apart of a once-continuous habitat into smaller, more isolated patches, so that a landscape holds less habitat and what remains is divided by edges and gaps. Fahrig's 2003 review Effects of habitat fragmentation on biodiversity distinguished the loss of habitat area from the breaking apart of habitat, and traced how patch size, isolation, and the amount of exposed edge bear on the species a landscape can hold. The referent is a spatial pattern across land, measured in patches and edges and linked to biodiversity, not scattered free storage in a computer, a legislature split among parties, or a molecule broken in an instrument.[1]

Unit

A landscape's habitat broken into patches, scaled by patch size, isolation, and edge

Recovery means

Reconnection through corridors or habitat restoration can partly reverse it, though lost area and lost species may not return

Measured by

Quantified from maps and imagery by number and size of patches, inter-patch distance, and total edge length

The scattering of a computer's free memory or disk space into many small, noncontiguous pieces, so that space that is free in total cannot satisfy a request that needs it in one contiguous block. Randell's 1969 A note on storage fragmentation and program segmentation analysed how allocation and release of variable-size blocks leaves external gaps between them, in contrast to internal fragmentation, the unused slack left inside a fixed-size block. The referent is the layout of usable storage in a machine, measured in wasted or unusable bytes, and it has nothing to do with divided habitat, a divided parliament, or a molecule split into ions.[2]

Unit

Free storage split into noncontiguous pieces, scaled by wasted or unusable bytes

Recovery means

Compaction or garbage collection can move blocks together and coalesce free space, restoring large contiguous regions

Measured by

Assessed by the ratio of largest contiguous free block to total free space, and by counts of internal and external waste

The dispersion of a legislature or electorate among many parties rather than a few, so that seats or votes are shared out among numerous competing groups. Laakso and Taagepera's 1979 “Effective” number of parties proposed the effective number of parties, an index that weights each party by its share so that many small parties raise the count and one dominant party lowers it, giving a single figure for how divided a party system is. The referent is the structure of a competitive party system, measured from vote and seat shares, and it is unrelated to divided habitat, scattered computer memory, or a molecule broken apart.[3]

Unit

A party system's division, scaled by the share-weighted effective number of parties

Recovery means

Not applicable

Measured by

Computed from parties' vote or seat shares as the inverse of the sum of squared shares (the Laakso-Taagepera index)

The breaking apart of an energised molecular ion into smaller fragment ions inside a mass spectrometer, so that a compound yields a reproducible set of pieces, its fragmentation pattern, that helps identify it. McLafferty's 1959 Mass spectrometric analysis: Molecular rearrangements showed how ions do not merely snap at random but follow characteristic pathways, including the rearrangement now named for him, that reveal a molecule's structure. The referent is the dissociation of ions along chemical bonds, read from a mass spectrum, and it shares nothing with divided habitat, scattered memory, or a divided parliament beyond the word.[4]

Unit

A molecular ion split into product ions, read as a pattern of mass-to-charge peaks

Recovery means

Not applicable

Measured by

Recorded as a mass spectrum, where the masses and abundances of the fragment peaks form a diagnostic pattern

In archaeology, fragmentation refers to the deliberate breaking of objects and the sharing of their pieces to create links between people and places. This meaning comes from Chapman (2000) in Fragmentation in Archaeology.[5]

Unit

Recovery means

Measured by