CURRENT PROJECTS:

Evaluating how habitat edges affect demographic processes, such as reproduction, will clarify population responses to fragmentation and broader effects on biodiversity. Using 2 grasses and 3 forbs that were experimentally planted in the SRS corridor project, I found that for all species, plants were less likely to be reproductive near habitat edges. For 4/5 species, even when plants were reproductive they produced fewer seeds near habitat edges (see figure). This work shows that increased edge habitat due to fragmentation decreases plant reproductive output, which may have implications for plant persistence in fragmented areas. 

Collaborators : Lars Brudvig (MSU), Ellen Damschen (UW-Madison), Josh Tewksbury (STRI), Doug Levey (NSF), Julian Resasco (CU Boulder), Nick Haddad (MSU)

Because multiple types of species interactions occur at the same time, a change in one interaction due to fragmentation has the potential to shift other interaction types. I tested how three components of habitat fragmentation (connectivity, edge amount, edge proximity) impacted three co-occurring plant-arthropod interactions (plant-pollinator, plant-florivore, plant-spider). Using the sandywoods chaffhead Carphephorus bellidifolius, I found that connectivity increased plant-pollinator and plant-spider interactions, while edge amount and proximity affected florivores. However, despite the strong effects of connectivity and edge on arthropod visitation, pollination rate was not affected. This work provides experimental evidence that multiple plant-arthropod interactions are affected by fragmentation through connectivity loss and edge effects. 

Collaborators : Thomas Smith (UW-Madison), Nick Haddad (MSU)

Species interactions can be represented in a network that describes which species interact with each other in a community. Changes in network metrics, such as nestedness or specialization, can provide insight into the structure and stability of interactions. I'm currently researching how habitat connectivity alters plant-pollinator network structure and whether network changes are driven by species turnover (changes in community composition) or interaction rewiring (behavioral changes). Understanding why plant-pollinator networks are impacted by connectivity will inform how fragmentation changes species interactions and better guide pollinator conservation. This fieldwork is ongoing! 

Collaborators : Nick Haddad (MSU)