Shifting pollinator distributions
Insects such as bees and butterflies are important for pollination of wild plants and crops. It is therefore important to understand how climate and land use changes affect pollinators. A study by researchers from the Naturalis Biodiversity Center and IBED, together with other national and international collaborators, shows how different characteristics of pollinators have influenced the distributional shifts of species in response to climate and land use change over the last 60 years. The findings were published in Scientific Reports.
Global change affects pollinator distributions
Pollinators are affected by climate and land use change. Many pollinators, especially rare and threatened species, have declined in recent decades. For instance, changes in habitat composition and fragmentation of natural areas can disrupt pollinator populations and result in local extinctions.
However, in contrast to rare species many widespread pollinators in the Netherlands have increased their geographic distributions in recent decades. This could be explained by climatic warming and recent efforts to enhance natural habitats such as grasslands and forest, and by providing more feeding and nesting resources for insect biodiversity in agricultural landscapes.
Nevertheless, the new research shows that many pollinators have shifted their distributions by moving towards the cooler north, and depending on the species, more to the east or more to the west. The magnitude of these shifts can be partly explained by the different characteristics of the species.
Species characteristics influence shifts
The researchers found that species characteristics relating to the ability of pollinators to move, reproduce and establish can partly explain the distributional shifts. ‘Generalists and specialists have responded very differently to changes in climate and land use’, says lead author Jesús Aguirre-Gutiérrez from the Naturalis Biodiversity Center. For instance, bees and butterflies which also use agricultural and urban habitats show larger range expansions over the last 60 years than species restricted to habitats only available in nature reserves.
Moreover, the nitrogen value of food plants of butterflies has a strong effect on how far species have moved to the north. 'The Netherlands is among the countries with the highest nitrogen deposition levels worldwide, and this leads to strong increases of nitrophilous plants’, explains Aguirre-Gutiérrez. This has consequences for the distribution of many butterflies because their larvae depend on specific food plants.
Consequences for pollination services?
Many crops and wild plants depend on pollination services from insects. Shifts in geographic distributions of pollinators might therefore have an influence on plant reproduction. ‘While we can now document and better predict distributional shifts of pollinators due land use and climate change, we still know very little about the subsequent consequences for plants which depend on these pollinators’, says Daniel Kissling from the University of Amsterdam. This requires more detailed studies on how multiple pollinators affect the pollination success of specific plants. ‘Nevertheless, our study makes a great step forward for the prediction of future shifts of pollinators and other animals’, highlights Kissling.
The study is a collaboration between researchers from the Naturalis Biodiversity Center, the University of Amsterdam, University of Brasilia, Butterfly Conservation (Vlinderstichting), Wageningen UR and the Helmholtz Centre for Environmental Research – UFZ.
Aguirre-Gutiérrez, J., Kissling, W.D., Carvalheiro, L.G., WallisDeVries, M.F., Franzén, M. & Biesmeijer, J.C. (2016): Functional traits help to explain half-century long shifts in pollinator distributions. Scientific Reports 6: 24451.