Anthropogenic disturbance of tropical forests threatens pollination services to açaí palm in the Amazon river delta

Abstract

The açaí palm Euterpe oleracea Mart. in the Amazon river delta has seen rapid expansion to meet increased demand for its fruit. This has been achieved by transforming lowland forest habitats (floodplains) into simplified agroforests and intensive plantation in upland areas. As açaí palm makes an important contribution to the economy and food security of local communities, identifying management approaches that support biodiversity and ecosystem processes that underpin fruit production on açaí farms is essential. We compared flower‐visitor communities and açaí fruit production in floodplain forests and upland plantations, across gradients of local management intensity (i.e. açaí density per ha) and surrounding forest cover. The relative contribution of biotic pollination and degree of pollen limitation were assessed using insect exclusion and hand‐pollination experiments. We found that açaí flower visitors are highly diverse (c. 200 distinct taxa) and had variable responses to disturbance. Bee visitation was higher in floodplains and positively related to surrounding forest cover, but other flower visitors, including specialised curculionid beetles, were unresponsive to changes in surrounding forest cover. However, intensive management practices (i.e. high açaí palm densities) in floodplains and uplands had contrasting effects on flower‐visitor communities, with flower‐visitor richness being lower on intensively managed floodplain farms and ant densities being higher on intensive upland farms. Pollination experiments revealed açaí palm to be highly dependent on biotic pollination. Fruit set in open‐pollinated inflorescences was positively related to flower‐visitor richness and specialised curculionid beetle visitation, whereas the presence of ants on inflorescences had a negative effect. Synthesis and applications. Our study shows that pollinators are essential for açaí fruit production, but that intensive farming practices have eroded the relationship between surrounding forest cover and ecosystem function in floodplains (i.e. conversion of native forest into simplified agroforests) and increased the frequency of antagonistic interactions in uplands (e.g. high ant densities). These findings underline the value of extensive management practices, such as the maintenance of other tree species within farms and adjacent unmanaged forest patches, to ensure the long‐term sustainability of açaí fruit production in the Amazon river delta.

A dataset of multi-functional ecological traits of Brazilian bees

“…Planetary decline and non-random loss of biodiversity have been reported in response to anthropogenic-driven actions 13 . Factors implicated in bee species decline include habitat loss due to landscape change, competition with invasive species for resources, emergent species (including pathogens), pesticides and climate change 12,[14][15][16] . Linking ecosystem functioning to biodiversity conservation is fundamental in determining the aims of policies and strategies for species and ecosystem conservation in the long term 17 .…”

“…Pollination success is related to pollinator species occurrence and availability 16 , but it also depends on the biological community assembly 17,[20][21][22] and on the relationship between flower traits (e.g., size and morphology) and the body size of its visitors 23 . Castilla et al 24 showed that pollinator body size contributes to plant seed viability but is apparently not related to long-distance genetic flow.…”

Environmental and social consequences of the increase in the demand for ‘superfoods’ world‐wide

“…Further, the resulting changes unleashed by açaí on forest structure also translate into important impacts on some of the ecosystem services the crop relies on (e.g. pollination, Campbell et al, 2018), which ultimately threaten the long‐term sustainability of its production. As the demand for açaí products continues to increase, research has concluded that the exploitation of açaí is not, at present, a model that merges forest conservation and rural development (Weinstein & Moegenburg, n.d.).…”

“…Thus, superfoods are not only fulfilling the dietary concerns of consumers but also their ethical ones (Loyer, 2016). However, the growing demand for many of these products, means that in many instances, they are no longer produced following traditional practices, but rather revert to intensive agricultural production practices, with important social and environmental impacts (Campbell et al, 2018). Further, in order to reach consumers, superfoods are processed, packaged and distributed, which means that their recollection/cultivation, transportation and packaging are an important source of GHG emissions (Vermeulen, Campbell, & Ingram, 2012).…”

Effects of ants (Hymenoptera: Formicidae) on flying insect visitor behaviour and fruit production in açaí palm (Euterpe oleracea Martius)

“…The unisex flowers of E. oleracea do not preclude visitation by any specific insect group (although larger insects are uncommon due to low nectar rewards per flower) and so are visited by a diverse array of bees, beetles, flies, wasps and ants. Many of these insects are considered 'potential pollinators', by virtue of visiting both sexual morphs (Campbell et al 2018), and being known pollen vectors. For example, Bezerra et al (unpublished data) found 72 of 74 insect taxa (including ants) collected on female inflorescences carried E. oleracea pollen grains, although native bees (stingless bees and sweat bees) carried at least eight times more pollen than other taxa and are likely the palm's main pollinators.…”