A recent study sheds light on the intricate dynamics between plants and their natural enemies, emphasizing the critical role of large herbivores in maintaining ecosystem balance. Published in the Journal of Ecology, the research underscores the potential consequences of declining interactions between plants and pests, challenging conventional notions about the role of these organisms in ecosystems.
Large herbivorous mammals such as tapirs, deer, and peccaries play a pivotal role in shaping plant-pathogen interactions. Carine Emer, co-author of the study, highlights the short-term increase in plant species richness following the absence of large mammals, attributing it to reduced pathogen spread in areas with greater species diversity.
The study, conducted at São Paulo State University’s Institute of Biosciences, unveils a significant correlation between large herbivore absence and declining pathogen abundance. Researchers point out that the extensive movements of these mammals facilitate the transfer of microorganisms between plants, a process disrupted when these animals vanish from local ecosystems.
Led by Mauro Galetti, the research builds upon two projects focusing on the ecological consequences of large herbivore decline in the Atlantic Rainforest. Galetti’s long-term experiment, involving paired open-closed forest plots across São Paulo state, provides valuable insights into the intricate web of ecological interactions within forest ecosystems.
Utilizing camera traps, researchers observed the effects of large herbivore exclusion on plant and soil dynamics, as well as on interactions such as leaf damage by insects. The findings underscore the crucial role of large mammals in soil fertilization, plant community structuring, and seed dispersal, emphasizing their significance in maintaining ecosystem health.
In their latest study, researchers analyzed leaf damage across multiple sites, categorizing it into functional groups including insect and pathogen-induced damage. Results revealed a notable decrease in total leaf damage and pathogen-induced damage in areas devoid of large herbivores, highlighting the intricate balance between herbivore presence and plant-natural enemy interactions.
Carine Emer emphasizes the evolutionary consequences of declining plant-pathogen interactions, underscoring the potential loss of biodiversity through disrupted natural selection processes. Drawing parallels with previous research, the study suggests a similar trend of declining interaction diversity in response to vegetation structure changes induced by large mammal extinction.
The study’s innovative findings call for further research in the Atlantic Rainforest and other tropical ecosystems to assess the broader implications of large herbivore extinction. Co-authors Nacho Villar and research team members Natália Melo, Valesca Ziparro, and Sergio Nazareth contributed significantly to the fieldwork and botanical identification, enriching the study’s scope and relevance.
Nacho Villar, currently affiliated with the Netherlands Institute of Ecology, echoes the need for continued research to address the multifaceted challenges posed by large mammal extinction, emphasizing the urgency of preserving these critical components of ecosystem resilience.