Planting gardens to support insect pollinators

Abstract

Global insect pollinator declines have prompted habitat restoration efforts, including pollinator-friendly gardening. Gardens can provide nectar and pollen for adult insects and offer reproductive resources, such as nesting sites and caterpillar host plants. We conducted a review and meta-analysis to examine how decisions made by gardeners on plant selection and garden maintenance influence pollinator survival, abundance, and diversity. We also considered characteristics of surrounding landscapes and the impacts of pollinator natural enemies. Our results indicated that pollinators responded positively to high plant species diversity, woody vegetation, garden size, and sun exposure and negatively to the separation of garden habitats from natural sites. Within-garden features more strongly influenced pollinators than surrounding landscape factors. Growing interest in gardening for pollinators highlights the need to better understand how gardens contribute to pollinator conservation and how some garden characteristics can enhance the attractiveness and usefulness of gardens to pollinators. Further studies examining pollinator reproduction, resource acquisition, and natural enemies in gardens and comparing gardens with other restoration efforts and to natural habitats are needed to increase the value of human-made habitats for pollinators. Siembra jardines para dar soporte a los insectos polinizadoresResumen: La declinación mundial de insectos polinizadores ha dado pie a esfuerzos de restauración, incluyendo * email majewska@uga.edu Article impact statement: Gardens with high plant species diversity and sun exposure, more woody vegetation, and larger size benefit pollinators.

Joint Impacts of Drought and Habitat Fragmentation on Native Bee Assemblages in a California Biodiversity Hotspot

“…In our case, this ameliorating effect of fragments may potentially have arisen from the ability of at least some bees in fragments to access blooming floral resources growing in the urban landscape surrounding the fragments (see also [70]). Such a scenario would suggest a possible opportunity for enhanced urban habitat management to lessen the effects of extreme climate events in ecosystems fragmented by urban development [71,72]. An alternative, but not mutually exclusive, explanation is that reserve sites might have harbored a greater proportion of narrowly adapted species that are sensitive to various forms of environmental perturbation, whereas ecological filtering might have already eliminated sensitive species from our habitat fragments [22], such that further disturbance in the form of the drought event in 2014 might have had lesser impacts on bee diversity and functional composition in fragments.…”

Quantifying nectar production by flowering plants in urban and rural landscapes

“…Temperate pollination systems tend to be fairly generalised in nature (Memmott, 1999;Waser et al, 1996) (Garbuzov & Ratnieks, 2014;Majewska & Altizer, 2018;Matteson & Langellotto, 2011), although their prevalence in urban areas could drive changes in pollinator community composition (Seitz et al, 2020;Urbanowicz et al, 2020;Wenzel et al, 2020) and further research into nectar chemistry is needed to establish whether non-natives provide nectar of comparable nutritional quality (Tiedeken et al, 2017;Vaudo et al, 2015).…”

Behavior‐partitioned diversity reveals differential habitat values of gardens to butterfly communities

“…For example, large-scale pollinator studies (e.g. Scheper et al 2013, Majewska andAltizer 2020) often include results based on transect surveys and flower visitations, with the former and the latter representing occurrence and feeding diversity respectively. The ecological processes captured by diversity analyses might vary across sampling strategies, and mixing them into the same analyses may mask differences in their responses.…”