Abstract Detail


Wu, Yingtong [1], Henderson, David [2].

How high are the bugs? The vertical distribution of foliar herbivory rates in Quercus humboldtii (Andean oaks) in relation to canopy height and elevation.

Herbivory is one of the key forces structuring the distribution of biomass and biodiversity in the tropics. Canopy trees host a high diversity and abundance of herbivores. Thus, understanding the herbivory of dominant tree species is important for predicting ecosystem functions and composition in the forests. Herbivory in canopy trees is determined not only by the macro-climatic changes along elevational gradients, but is also determined by micro-habitat changes in relation to canopy height. It is yet not well-known how elevation and canopy height, these two vertical axes, interactively affect herbivory rates on canopy trees. To investigate this question, we performed a preliminary study on a keystone species, Quercus humboldtii (Andean oaks), in the cloud forests in the western cordilleras of Colombia. We collected from three sites – a primitive forest in the Farallones National Park, a secondary forest in a natural reserve surrounded by ranches, and a secondary forest on a developed hillside. At each site, we collected leaf samples from three mature trees per site; in each tree, we collected three branches from each of the three canopy zones (high-, mid-, and low-canopy), and five leaves from each branch. In total, we obtained 405 leaf samples. We measured leaf size, leaf perimeter per area, leaf fluctuating asymmetry (degree of asymmetry of leaf shape), relative branch height (absolute branch height / absolute tree height), and elevation to examine their effects on foliar herbivory rate. We used structural equation modelling for statistical analyses. The results of the structural equation modelling reveal that elevation and canopy height affect the percentage of leaf herbivory in different ways. As canopy height and elevation increase, perimeter per leaf area increases, which contributes to lower herbivory rates. As canopy height and elevation increase, leaf size decreases, and herbivory rates increase in response to reduced leaf size. However, after accounting for variation with leaf traits, elevation is positively related to herbivory rates, while canopy height is negatively related to herbivory rates. This suggests that other factors, such as the vertical distribution of parasitoid abundance and leaf chemical defense, can also affect the stratification of herbivory rates, yet these factors are not examined by our study. This preliminary study suggests that multiple abiotic and biotic interactions can interactively affect the vertical distribution of herbivory in canopy trees.

1 - University of Missouri, St. Louis, Biology Department, 1 University Blvd., St. Louis, MO, 63110, USA
2 - Biology, 1 Booking Drive, St. Louis, MO, 63130, United States

plant ecology
canopy ecology
vertical stratification.

Presentation Type: Poster
Number: PEC032
Abstract ID:145
Candidate for Awards:None

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