Natural and within-farmland biodiversity enhances crop productivity

Abstract

Running title -Weeds maximize nature benefits to crops AbstractOngoing expansion of large-scale agriculture critically threatens natural habitats and the pollination services they offer. Creating patches with high plant diversity within farmland is commonly suggested as a measure to benefit pollinators. However, farmers rarely adopt such practice, instead removing naturally occurring plants (weeds). By combining pollinator exclusion experiments with analysis of honeybee behaviour and flower-visitation webs, we found that the presence of weeds allowed pollinators to persist within sunflower fields, maximizing the benefits of the remaining patches of natural habitat to productivity of this large-scale crop. Weed diversity increased flower visitor diversity, hence ameliorating the measured negative effects of isolation from natural habitat. Although honeybees were the most abundant visitors, diversity of flower visitors enhanced honeybee movement, being the main factor influencing productivity.Conservation of natural patches combined with promoting flowering plants within crops can maximize productivity and, therefore, reduce the need for cropland expansion, contributing towards sustainable agriculture.

Indirect interactions between crops and natural vegetation through flower visitors: the importance of temporal as well as spatial spillover

“…Flower abundance is often an important predictor of indirect interactions, as a greater number of flowers equates to a greater chance of being encountered, patches containing many flowers can be more easily detected (Schiestl and Johnson, 2013), and pollinators tend to visit more inflorescences in larger patches of flowers (Goulson, 2000). That the strength of indirect effects increased with flower abundance at a greater rate for weeds and exotic plant species flowering in mango fields than for species growing in natural vegetation highlights the value of weeds in supporting flower visitors, an observation that has been noted elsewhere (Carvalheiro et al, 2011;Nel et al, 2017). This may be because (a) flowering plants in natural vegetation are more dispersed; (b) weeds flowered consistently and abundantly; and (c) weeds are in close proximity to the mango flowers, so energy expenditure to reach these flowers is minimised.…”

Honeybee health in Africa—a review

“…Indeed, genetic diversity of the honeybee population is reduced in agricultural vs. natural areas (Jaffé et al 2010). Even in agriculturally utilised land, pollination success is dependent on pollinator diversity (Carvalheiro et al 2011). Moreover, honeybees actively regulate their nutritional intake (Altaye et al 2010;Pirk et al 2010).…”

Impacts of Dryland Farm Management Systems on Weeds and Ground Beetles (Carabidae) in the Northern Great Plains

“…Weeds are often considered impediments to agricultural production due to their impacts on crop yields and interference with farming practices [5]. However, many weed species can also provide valuable ecosystem services including increasing soil organic matter, facilitating nutrient cycling, serving as propagule pools of arbuscular mycorrhizal fungi and symbiotic bacteria such as Rhizobia [6], and providing food and habitat for pollinators [7] and natural enemies [8,9]. Ground beetles are one of the most widespread, abundant, and diverse groups of insects.…”