Individual variation in oak (Quercus robur) phenology results in increased caterpillar abundance and defoliation for earlier oaks, but no response of antiherbivory defense mechanisms.

Hormes, D.M. (2024) Individual variation in oak (Quercus robur) phenology results in increased caterpillar abundance and defoliation for earlier oaks, but no response of antiherbivory defense mechanisms. Master's Research Project 1, Ecology and Evolution.

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Abstract

Oaks vary consistently in budburst phenology, with earlier phenology associated with heightened caterpillar abundance during the caterpillar peak in spring. This variation may lead to differences in herbivory defense mechanisms, such as leaf toughness and phenolic content. In this field study conducted in the Netherlands, we investigated the pedunculate oak (Quercus robur). We measured caterpillar abundance, defoliation, budburst date, leaf toughness, and the concentrations of total phenolics and tannins. We hypothesized that trees with earlier budburst would display higher caterpillar abundance and defoliation, increased leaf toughness and a stronger increase in leaf toughness, and elevated concentrations of total phenolics and tannins in response to higher defoliation rates. Our findings confirmed the first hypothesis, partially supported the second, and contradicted the third. Specifically, while earlier trees exhibited higher leaf toughness, the rate of increase was uniform across all trees. Furthermore, the concentrations of total phenolics and tannins were best explained by leaf age, leaf toughness and their interaction, with young leaves with a low leaf toughness displaying the highest concentrations. Our study demonstrates that oak phenology influences leaf traits, affecting herbivore food availability. Additionally, oak phenology influences caterpillar distribution, impacting insectivore food availability. This highlights the importance of considering

Item Type:	Thesis (Master's Research Project 1)
Supervisor name:	Both, C. and Tiedge, K.J.
Degree programme:	Ecology and Evolution
Thesis type:	Master's Research Project 1
Language:	English
Date Deposited:	04 Sep 2024 13:51
Last Modified:	04 Sep 2024 13:51
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/34185

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