Keystone mutualism influences forest tree growth at a landscape scale

Area of Science:

• Ecology
• Forest Ecology
• Mutualism Studies

Background:

• Keystone interactions in terrestrial food webs are crucial for community structure and trophic cascades.
• Ant-herbivore mutualisms, specifically involving ants and phloem-feeders, are recognized as keystone interactions that can significantly alter arthropod communities.
• The influence of these interactions on plant growth is hypothesized to be modulated by herbivore community structure and bottom-up effects on plant resources.

Discussion:

• This study investigated the top-down effects of ants on hickory sapling growth within a landscape-scale, long-term ant-exclusion experiment.
• It examined how spatial variations in herbivore community structure and habitat quality influence the strength of ant-mediated cascading effects.
• The research quantified the combined impacts of ants, herbivore communities, and abiotic factors on hickory shoot growth.

Key Insights:

• Ants exert context-dependent, compensatory effects on hickory shoot growth, primarily benefiting the plants when phloem-feeding herbivores are present and chewing herbivore abundance is high.
• While landscape variables like habitat quality influenced hickory growth, they did not mediate the strength of the cascading effects initiated by ants.
• The findings indicate that ant/sap-feeder mutualisms play a significant role in regulating forest productivity by mediating the complex interactions among multiple herbivore guilds.

Outlook:

• Further research should explore the specific mechanisms by which ants mediate the effects of different herbivore guilds on plant productivity.
• Investigating the long-term consequences of these mutualisms on forest ecosystem dynamics and resilience is essential.
• Understanding these intricate relationships can inform forest management strategies aimed at enhancing ecosystem services and biodiversity.