Limitation of native plant reproduction in an urban landscape



by LORENZO CIOTTI

Limitation of native plant reproduction in an urban landscape

Urban farming is normally practiced to produce income or a food supply, although in some communities the main motivation is recreation or the intelligent use of leisure time. This type of agricultural activity contributes to food security and hygiene in two ways: first, by increasing the availability of food for the inhabitants of the city; moreover, by making vegetables, fruit and meat available to urban consumers.

A common and efficient form of urban agriculture is the practice with biointensive methods. Since biointensive agriculture promotes energy-saving food production, urban and peri-urban agriculture are generally considered sustainable practices.

Pollen limitation of native plant reproduction in an urban landscape, study published on the American journal of botany, explained: "Evidence suggests that bees may benefit from moderate levels of human development. However, the effects of human development on pollination and reproduction of bee-pollinated plants are less-well understood.

Studies have measured natural variation in pollination and plant reproduction as a function of urbanization, but few have experimentally measured the magnitude of pollen limitation in urban vs. non-urban sites. Doing so is important to unambiguously link changes in pollination to plant reproduction.Previous work in the Southeastern United States found that urban sites supported twice the abundance of bees compared to non-urban sites.We tested the hypothesis that greater bee abundance in some of the same urban sites translates into reduced pollen limitation compared to non-urban sites.

We manipulated pollination to three native, wild-growing, bee-pollinated plants: Gelsemium sempervirens, Oenothera fruticosa, and Campsis radicans. Using supplemental pollinations, we tested for pollen limitation of three components of female reproduction in paired urban and non-urban sites.

We also measured pollen receipt as a proxy for pollinator visitation. We found that all three plant species were pollen-limited for some measures of female reproduction. However, opposite to our original hypothesis, two of the three species were more pollen-limited in urban relative to non-urban sites.

We found that open-pollinated flowers in urban sites received less conspecific and more heterospecific pollen on average than those in non-urban sites. These results suggest that even when urban sites have more abundant pollinators, this may not alleviate pollen limitation of native plant reproduction in urban landscapes."