🐛 ONGOING PROJECTS 🐛
FROM INDIVIDUALS TO COMMUNITIES:
BOTTOM-UP AND TOP-DOWN EFFECTS MEDIATING DROUGHT EFFECTS ON PLANT-HERBIVORE INTERACTIONS
*Photos from DroughtNet website |
The DroughtNet experimental trial provides an outstanding oportunity to look at climate change effects on plant-herbivore interactions in local coastal sage scrub and grassland ecosystems. This long-term experimental set up is located at the UCI campus and is part of a large international network of drought experiments. The experimenal trial includes 12 plant species and consists on a full factorial design with two factors: water avalibility (three levels - ambient, reduced precipitation and irrigated) and source population (two levels; xeric vs. mesic origin).
Here, we aim to look at (i) how drought affects insect herbivores (composition and abundance) associated to plant communties that are representative of the coastal sage scrub ecosystem of Sourthern California and (ii) whether such effects are contingent on the plant evolutionary history (source population). In order to provide insights on the bottom-up mechanisms that govern such patterns, we will measure plant traits (SLA, phenolic compounts, N and P content) and assess plant resistance to a generalist insect (i.e., Spodoptera exigua) in four of the most abundant shrub species in coastal sage scrub ecosystems, namely, Artemisa californica, Eriogonum fasciculatum, Encelia californica and Salvia melifera. In addition, aiming to explore whether top-down effects might contribute to patterns of variation in insect herbivore communities we will asess predation rates of herbivore natural enemies (e.g., birds, arthropods, reptils, mamals) at the plot level using model clay caterpillars. Results will be published in 2023. Stay tuned! |
INSULARITY EFFECTS ON TRI-TROPHIC INTERACTIONS BETWEEN OAK TREES, INSECT HERBIVORES AND BIRDS
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Islands represent natural set ups to investigate how evolutionary processes drive variation in plant-herbivore interactions. Because islands generally have lower abundance and diversity of insect herbviores, insular plants are expected to be less defended than their mainland counterparts. Such prediction is based on the relatively low abundance of big grazing mamals in islands, but has obviated the relevance of insect herbivores and the role of the third trophic level (e.g., insectivore birds) at driving herbivory preassure and concominant patterns in plant defences.
We will sample trees from four different oak species in the Channel Islands archipelago in California and their conspecific or closest congeneric populations in the mainland to test whether insularity affects herbvivory and plant defences (i.e., phenolic compounds). Importantly, we aim to test whether differences in top-down control by insectivorous birds between islands and the mainland contribute to explain insularity effects on insect herbivory and defences. To that aim we will install bird exclusions on selected branches in experimental trees and compare herbivory damage to control branches in the same tree. |
Importantly, this experimental set up will be replicated in two additional insular systems, namely the Balearic islands and the Baltic Islands. The replication of our experimental design could not be possible without the help of our collaborators in the Balearic islands, Catalonia and Sweeden. This research project has been funded by a research grant to early career researchers by the AEET (Asociación Española de Ecología Terrestre) to Carla Vázquez-González.
Results will be published in 2023.
Results will be published in 2023.