Herbivory Modifies the Role of Spatial Processes in a Grassland Plant Metacommunity

Area of Science:

• Ecology
• Community Ecology
• Conservation Biology

Background:

• Trophic interactions, particularly herbivory, are key drivers of biodiversity patterns in fragmented landscapes.
• Metacommunity theory predicts complex effects of herbivory on plant diversity, varying with spatial scale and habitat characteristics.

Purpose of the Study:

• To investigate the interactive effects of mammalian herbivory, habitat size, and connectivity on plant diversity in a fragmented grassland metacommunity.
• To test theoretical predictions regarding herbivory's influence on plant species coexistence and diversity-area relationships.

Main Methods:

• Field study in a naturally fragmented grassland system in Southern Finland.
• Assessed plant diversity across multiple spatial scales under varying levels of herbivory, habitat size, and connectivity.
• Statistical analyses to determine the independent and interactive effects of these factors on plant diversity.

Main Results:

• Herbivory significantly increased plant diversity across all measured scales.
• Herbivory reversed the typical diversity-area relationship, leading to a positive relationship in grazed areas and a negative one in ungrazed areas.
• Habitat connectivity showed a unimodal relationship with diversity but did not interact with herbivory.

Conclusions:

• Mammalian herbivores can promote plant coexistence and enhance biodiversity in grassland metacommunities, even across different spatial scales.
• The interplay between herbivory and habitat area is crucial for understanding plant biodiversity dynamics in fragmented ecosystems.
• Conservation strategies for fragmented grasslands should consider the role of herbivores in maintaining plant diversity.