While walking to class during the fall semester, I can’t help but look around at all the trees that populate the campus. From early in October the leaves begin changing colors. We are far enough north that the colors are very pronounced on many of the trees. The system that leads to this color change is the death of leaves, or senescence, during the Fall and Winter. Today in Lab for an ecology class, we were given Foldscopes to construct and take samples with and I couldn’t help but think about a tree I saw every week as I walked into the lab building.

This tree, pictured above, was identified as an American Witch-Hazel, or Hamamelis virginiana. It is a deciduous tree and loses its leaves, but I wondered how this process of senescence changed interactions between the tree and its predators and the system around it. To do that, I looked at a partially dead leaf and checked for different patterns of decay and possible predation.

This picture possibly shows the interactions between several cells of the leaf. They look brown-tinged and are patchy with pigment. 

The next look into the Foldscope looks visibility more moist and succulent than the last one, which provides an interesting look at the differences between the two different states of the leaf. Neither displays signs of small-scale predation, but that is also possibly due to the poor weather conditions that this area has had recently. 
Seeing how the cell structure of the leaf changes, especially how the pigment appears to change, would indicate the loss of photosynthetic potential and possibly the loss of nutrients to herbivores around it. This is likely a primary cause for changes in the ecosystem during the winter and is just a part of the complex relationship between life forms, even in urbanized areas. I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University.