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United States Department of Agriculture

Agricultural Research Service

Title: Habitat Fragmentation and Native Bees: a Premature Verdict?

Author
item CANE, JAMES

Submitted to: Conservation Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2000
Publication Date: N/A

Interpretive Summary: Few studies have directly addressed the consequences of habitat fragmentation for communities of invertebrate pollinators, particulary for the most important group of pollinators, bees (Apoidea). All of these bee studies defined fragments as remnant patches of floral forage or living woody vegetation, and not by bees' nesting substrates. Several studies concluded that such habitat fragmentation was broadly deleterious, but overlooked native species in their own data that actually proliferated in fragments relative to intact habitats. Several other studies evidenced the greater densities of native bees at flowers in larger fragments relative to intact habitats, with similar species richness but sometimes dramatic shifts in species composition and abundances. Bees are typically well-adapted to habitats wherein nesting substrates and bloom are patchily distributed and spatially dissociated, provided that the coarseness of pattern does not exceed their flight vagility. Furthermore, many species live in habitats of intermediate successional stage or modest disturbance. Insightful studies of habitat fragmentation and bees will anticipate and evaluate fragmentation, alteration, and loss of nesting habitats, not just patches of forage plants.

Technical Abstract: Few studies directly address consequences of habitat fragmentation for communities of invertebrate pollinators, particularly for the most important group bees (Apoidea). The bee studies defined fragments as as remnant patches of floral forage or living woody vegetation, and not by bees' nesting substrates. Several studies concluded that habitat fragmentation was broadly deleterious, but overlooked native species in their own data that actually proliferated in fragments relative to intact habitats. Several other studies evidenced the greater densities of native bees at flowers in larger fragments relative to intact habitats, with similar species richness but sometimes dramatic shifts in species composition and abundances. Bees are typically well-adapted to habitats wherein nesting substrates and bloom are patchily distributed and spatially dissociated, provided that the coarseness of pattern does not exceed their flight vagility. Furthermore, many species live in habitats of intermediate successional stage or modest disturbance. Insightful studies of habitat fragmentation and bees will anticipate evaluate fragmentation, alteration, and loss of nesting habitats, not just patches of forage plants. Inasmuch as floral associations, floral specializations and nesting habits of bees are typically attributes of species or subgenera, authoritative determination of specimens is essential for meaningful interpretation. Study designs must anticipate and accommodate statistical problems attending bee community samples, especially non-normal data and frequent zero values.

Last Modified: 9/10/2014
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