We are a global network of scientists that aims to better understand the impacts of invertebrate herbivores and fungal pathogens on different aspects of plant communities. While a few studies have shown big impacts of invertebrates and fungal pathogens, we know little about how generally important they are, and how their functional composition varies across a range of different ecosystems.
A powerful tool to quantify the variation in plant consumer communities and their impact are globally coordinated experiments, using standardized measurements and replicated experiments across ecological gradients. The “Bug-Network” will be such a project and aims to explore the context dependency of biotic interactions within a coordinated research network comprised of many grassland- and shrubland sites worldwide.
A lot of theory predicts that consumer impact varies across environmental gradients. Impact is likely to depend on abiotic conditions at large spatial scales such as climate (latitude, altitude) and plant productivity, but also on abiotic and biotic drivers operating at smaller spatial scales, such as plant diversity and soil fertility (bottom-up) and predator abundance (top-down). Our understanding of how consumer communities and their impact varies across environmental gradients is surprisingly limited. Existing studies differ substantially in methodology, making generalities across large scales difficult, which calls for comparative approaches that implement standardised protocols across sites. This is particularly important if we are to understand how global change drivers, such as climate and land use change, will alter consumer communities and their functioning.
A first step in understanding how consumer impact varies along environmental gradients is to determine how consumer communities vary. In particular, it is important to understand how variation in abiotic conditions (principally climate) directly impacts consumer communities and how environmental variation alters plant communities (productivity, functional composition) and thereby indirectly affects consumers.
The second step is to understand how consumer impact changes along environmental gradients. To robustly assess impact, exclusion experiments are necessary. Only a few studies have explored the impact of certain consumer groups, such as molluscs and fungal pathogens, and we know little about whether the impact of different consumers varies along environmental gradients. Different groups of consumers may also interact and factorial exclusion are needed to test for these. In general, we could expect compensatory interactions between consumers attacking different, competing, plant species and additive interactions between consumers attacking the same plant species.
Focal research questions
- How does the functional composition of invertebrate communities vary with abiotic and biotic drivers?
- How important are direct effects of climate vs. indirect effects of changes in the plant community?
- Do insect herbivores, molluscs and fungal pathogens differ in their impact on plant communities? And do they interact with each other?
- When do invertebrate herbivores and fungal pathogens have the strongest effects on plant communities (productivity, community composition and diversity)?
Global research networks can rigorously test for general patterns and mechanisms and several, such as the NutNet or Drought-Net, have led to important advances. The goal of BugNet is to survey consumer and plant communities across sites and set-up identical above- and belowground invertebrate herbivore and fungal exclusion experiments in many parts of the world.
BugNet aims to implement a cross-site study requiring minimal investment of time and resources by each investigator. Firstly, we will conduct a comparative study to investigate how the functional composition of invertebrate communities changes along abiotic and biotic gradients. Secondly, we will initiate an experimental study to quantify plant community and ecosystem responses to invertebrate herbivores and fungal pathogens in a wide range of herbaceous-dominated ecosystems, such as desert grasslands to arctic tundra, but also heathlands or Mediterranean shrublands.
There are two ways that you can get involved in BugNet. 1) by participating in a cross-site survey by collecting data on plant- and invertebrate functional community characteristics in your study region (“comparative study”) and 2) By establishing exclusion experiments in addition, in your herbaceous-dominated study system and committing to be involved in the network for the next five years or longer (“experimental study”).