The role of soils on pollination and seed dispersal

Abstract

Ongoing environmental changes are affecting physical, chemical and biological soil components. Evidence of impacts of soil changes on pollinators' and seed dispersers' behaviour, fitness and density is scarce, but growing. Here, we reviewed information on such impacts and on a number of mechanisms that may explain its propagation, taking into account the full range of resources required by the large and diverse number of species of these two important functional groups. We show that while there is substantial evidence on the effects of soil nitrogen enrichment and changes in soil water content on the quality and quantity of floral and fruit resources, little is known on the effects of changes of other soil properties (e.g. soil pH, soil structure, other nutrients). Also, the few studies showing correlations between soil changes and pollinator and seed disperser foraging behaviour or fitness do not clearly identify the mechanisms that explain such correlation. Finally, most studies (including those with nitrogen and water) are local and limited to a small number of species, and it remains unclear how variable such effects are across time and geographical regions, and the strength of interactive effects between soil properties. Increasing research on this topic, taking into consideration how impacts propagate through species interaction networks, will provide essential information to predict impacts of ongoing environmental changes and help guide conservation plans that aim to minimize impacts on ecosystem functioning. This article is part of the theme issue 'The role of soils in delivering Nature's Contributions to People'.

Keywords: flower visitors; frugivory; pollination; seed dispersal; soil chemical and physical properties; soil microbiota.

Figure 1.

Diversity of feeding resources used by pollinators, during larval or adult stages, that can be affected by soil properties. Dashed lines represent resources used during larval stages. References used for the construction of this figure are listed in the electronic supplementary material.

Figure 2.

Pathways through which changes in soil properties (chemical, physical and biotic) may affect pollinators and seed dispersers. Blue dashed arrows represent effects on nesting and dietary resources used mostly by immature stages, orange solid arrows represent effects on dietary resources collected by adult individuals and orange thin dashed line represents direct consumption of soil by adults.