POLLINATION AND POLLINATORS

Pollinators constitute a key component of global biodiversity, providing ecosystem services that are indispensable to crops and wild plants. There are many pollinator guilds worldwide, both vertebrates and invertebrates. The most important of these are insects and in particular wild and domesticated bees, which are vital to the maintenance of wild plant communities, ecosystem sustenance and, very importantly, agricultural production. The most important habitats for pollinators, especially bees, are open areas rich in flowering plants bearing conspicuous flowers with lush floral rewards, predominantly nectar and pollen. Such systems are lownutrient grasslands, in particular calcareous ones, and wood openings, all hosting a high diversity of entomophilous plants.

As a result of different anthropogenic causes, the most important being agricultural intensification associated with habitat change or loss and increased exposure to agrochemicals, there has been a continuous decline of pollinators since the early 20th century (Biesmeijer et al. 2006, Potts et al. 2010, IPBES 2016). The decline is having serious consequences on ecosystem health and food security through the productivity of pollinator-dependent agricultural crops, especially the most nutritious food stuff (Klein et al. 2007, Potts et al. 2016). This is particularly evident in agricultural landscapes where semi-natural habitats have been intentionally converted into arable land.

Image 1. A typical agroforestry system with oak trees on terraced land, western Lesvos, Greece. Although now abandoned, terraces used to be cultivated with cereals until the 1970s.

© Anastasia Dalaka

POLLINATORS AND AGROFORESTRY: THE GLOBAL EXPERIENCE

In recent years, agroforestry systems have grown in number, area, and crop yield and have been acknowledged to promote socioeconomic sustainability vis-a-vis conservation of biodiversity and ecosystem services; among them, the promotion of pollination services, the evaluation of which is still scarce (Nicholls and Altieri 2012, Sabino et al. 2022).

All the existing studies on pollination services highlight the important role pollinators play in agroforestry systems, with some of them supporting valued crops at a global scale. Cacao and coffee are two of them; they are tropical understory plants in agroforestry systems, both highly dependent on pollinators for fruit set (Arnold et al. 2018, Klein et al. 2003, Vansynghel 2022). Like in other tropical crops, the pollination services they receive depend on the local agroforestry systems and the natural habitats in surrounding landscapes (Klein et al. 2008).

In general, studies focusing on pollination services in agroforestry systems are limited. The existing ones, however, converge on the importance of these systems for pollination services and pollinator conservation in different biogeographical regions (Sabino et al. 2022 for Brazilian Legal Amazon; Image et al. 2023 and Staton et al. 2022 for silvoarable agroforestry systems comprising fruit trees in England). Using paired landscapes (agroforestry vs agricultural/non-agroforestry), Kay et al. (2018) have demonstrated the positive influence of agroforestry systems in supplying pollination services in three European biogeographical regions: Mediterranean (montados and dehesas), Continental (orchards and wooded pastures), and Atlantic agroforestry systems (chestnut soutos and hedgerow systems).