Table 1. Attributes of habitat fragmentation studies for native bee communities.

Country	Habitat	Cause of fragmentation	No. frag.	Range   fragment   sizes	Range frag. ages	No. bee taxa	No. non-Apis bees	Reference	Author’s interpretation (from abstract)	Limitations of interpretation
Brazil	Rain forest	Experimental deforestation	4	1–100 ha	< 1 yr	16	1092	Powell and Powell (1987)	“For most [euglossine] bee species, visitation rate declined with fragment size ...”	Deforestation same season as sampling, disturbance or fragmentation effects? Bees at bait stations identified live, not collected, so two most common species confounded ‡
Brazil	Rain forest	Experimental deforestation	7	1–100 ha	5–8 yr	16	290	Becker et al. (1991)	“[Orchid bee] species richness unaffected by forest fragmentation ...” and “... bee abundance greater in 10 and 100 ha fragments than in continuous forest.”	Inefficient passive trapping method‡ and small number of fragments‡
Argentina	Dry thorn scrub	Agricultural clearing	8	0.5–21 ha	5–20 yr	43 (24*)	481	Aizen and Feinsinger (1994)	“Frequency and taxon richness of native floral visitors...declined with decreasing forest-fragment size.”	Limited taxonomic resolution,* small number of fragments,‡ application of ANOVA to data set with 84% of values at zero
Germany	Grassland	Agricultural clearing	40†	4 pots	ca. 1 month†	23	212	Stefan-Dewinter and Tscharntke (1999)	“Habitat connectivity essential to maintain ... abundant and diverse bee communities.”	Do eight potted plants constitute a “habitat island?” No relation between spatial isolation and bee body size, bee nesting needs not considered, bee species not listed
USA	Scrub desert	Urbanization	59	20 m2–2 ha	5–70 yr	59	2512	Cane et al., unpublished manuscript	“... greater densities of native bees ... in the smaller fragments” and “Fragmentation [only] dramatically affected ground-nesting [floral] specialists.”	Nesting/foraging value of urban matrix not measured,‡ pollination consequences not measured,‡ weak documentation of spatial relations of fragments‡

* Nineteen bee taxa identified only to family; only three identified to species level (9% of individuals).

† In agricultural fields adjacent to eight grassland remnants, authors placed 40 “habitat islands” (which they refer to as “fragments”) consisting of four pots, each with one radish and one mustard plant.

‡ Problem recognized by authors.