From policy to pollination: using mechanistic models to assess policy alternatives and management interventions on insect-mediated ecosystem services

Abstract

Increasing pressure on land to deliver more food and fibre with less environmental impact has dramatically increased the demand for assessing effects of present and future agri-environmental policies on ecosystem services including pollination and pest control. If we are to make clever use of these ecosystem services, it is critical to understand how they respond to our actions, which benefits we are to expect, and at which cost. This is not trivial. First, the beneficial organisms underpinning pollination and natural biological control often use multiple resources across the landscape and respond at individual, population and community level to land-use changes. Patterns emerge through complex spatiotemporal processes, with feedback loops and delayed effects that are difficult to capture using traditional regression-based models. Second, policy is filtered into changes on the ground by human decision-making processes. Both ecological and human decision-making processes can result in unexpected patterns and shortfalls compared to anticipated benefits. Here, I present ecological models for pollination and natural pest control that integrate multiple processes in a way not possible with simpler models [1]. Drawing on past and ongoing collaborative work, I present several examples of applications including the impact of flowers strips in spaces and time [1], the impact of the greening of the CAP [2], and the effects of increasing arable field sizes. On the one hand, I highlight the importance of taking into account processes such as foraging and population dynamics, on the other, show-casing applications of ecological ecosystem services models coupled with economic models, I show how farmer behaviour and costs related to interventions, can be more important for decisions and policy outcomes than ecological responses to a local management intervention. Finally, I outline remaining challenges such as handling species interactions, assessing transferability of models in space and time and handling multiple models.

References [1] Häussler J, Sahlin U, Baey C, Smith HG, Clough Y (2017) Predicting pollinator population size and pollination ecosystem service responses to enhancing floral and nesting resources. Ecology and Evolution, 7: 1898-1908. [2] Dänhardt J, Nilsson L, Hristov J, Alkan Olsson J, Brady M, Olsson P, Smith HG, Clough Y (2017) Ekologiska fokusarealer i samverkan - Utvärdering av effekter på ekosystemtjänster, jordbruk och administration. Naturvårdsverket Rapport 6773. ISBN 978-91-620-6773-1. [report to the Swedish EPA on collective implementation of ecological focus areas and impacts on ecosystem services, agriculture and administration, summary in English]