Tree Growth Forms Shaped by Mammals

Welcome to the Tree Growth Forms Shaped by Mammals project!

The objective of this project is to determine the global distribution and characteristics of a particular tree growth form, shaped by herbivorous mammals.

Plants often change their growth patterns when exposed to extreme environmental conditions, for example when they grow in dry places or at high altitudes. Large herbivorous animals, like deer, can also influence the growth forms of certain trees.

When these trees are heavily browsed by animals, they develop a unique growth form. The trees grow dense, sometimes thorny branches at the bottom, creating a hedge-like "cage" that protects the shoots and buds that are inside. Eventually, this allows the trees to escape the browsing animals and reproduce successfully. Because these trees transform from a defensive shape to shape more effective at producing flowers and fruits, we call these tree growth forms ‘Transformers’.

The size and shape of a cage influences the feeding habits of large herbivores. The large and densely branched structure at the bottom of the trees makes it attractive for animals to feed on, but at the same time, more difficult to take bigger bites. This allows the cage to grow in height and diameter to a point where the shoots are out of animal reach. The maximum height and diameter of the cage matches the reach of the dominant browsing animal in the area.

This study suggests that the frequency and size of the transformer trees in a landscape can tell us a lot about the type and intensity of herbivory in that area. This tree shape is seen in various systems worldwide with abundant herbivores, suggesting it is a common strategy among plants to cope with browsing by large herbivores. In general, very little is known about the global distribution and identity of transformers. By studying these growth forms, we can identify the dominant herbivores in different ecosystems and understand how important they are in controlling the vegetation. This knowledge contributes to biodiversity conservation.

In this project therefore we collect photographs and simple measurements of transformers.

This project is based on the research published in Functional Ecology journal: Churski, M., Kuijper, D. P. J., Semmelmayer, K., Bond, W. J., Cromsigt, J. P. G. M., Wang, Y., & Charles-Dominique, T. (2024). Tree growth-forms reveal dominant browsers shaping the vegetation. Functional Ecology, 38, 2027–2040. https://doi.org/10.1111/1365-2435.14623

Collecting observation protocol

1. If you see a woody plant (tree or shrub) showing one of the shapes described above take a picture. Check uploaded observations in the project for a reference.
2. If possible take a picture with a height reference; can be your friend facing the opposite direction than the camera or a walking stick.
3. Take your picture so that the entire plant fits the frame
4. If possible identify the plant species
5. If possible measure the plant cage width and height
6. If possible identify the associated mammal that could shape the plant

Thank you and enjoy the Transformers trees hunt! menos ↑