The decline of birds, bees and other pollinators in the world’s most diverse ecosystems may be putting plants in those areas at risk, according to new research. The finding raises concern that more may have to be done to protect Earth’s most biologically rich areas, scientists say in an article appearing in the Jan. 17 issue of the Proceedings of the National Academy of Sciences (PNAS).

The analysis shows that ecosystems with the largest number of different species, including the jungles of South America and Southeast Asia and the rich shrubland of South Africa, have bigger deficits in pollination compared to the less-diverse ecosystems of North America, Europe and Australia.

“The global pattern we observed suggests that plants in species-rich regions exhibit a greater reduction in fruit production due to insufficient pollination than plant species in regions of lower biodiversity,” said Susan Mazer, a co-author of the article and a biologist at the University of California, Santa Barbara. She and her colleagues believe such biodiversity “hotspots” are characterized by stronger competition among plant species for pollinators, such that many plant species simply don’t receive enough pollen to achieve maximum fruit and seed production.

Mazer cautioned that it is not yet possible to determine whether low pollenation observed in species-rich areas is a new phenomenon or a long-standing one. It may be a recent problem due to habitat fragmentation or destruction, she said, or it may be long term. Plant species in ecologically complex areas may be continually faced with new competitors, and therefore cannot evolve as rapidly as their environment changes. If that is true, she said, pollen limitation may be a chronic problem for species in biodiversity hotspots–a challenge they have coped with for millions of years.

“The pattern raises the alarm, however, that these species face two challenges that increase the risk of extinction: habitat destruction, which is occurring at alarming rates in the tropics, and reduced pollinator activity,” said Mazer.

The native bee population here in the Southwest has been in decline for decades — for all the usual reasons: air pollution, reduced habitat, etc..