About This Project

High up in California's coast redwoods, lichens vary in reproductive form throughout the canopy. The species I study produces different reproductive structures at varying vertical heights in any given redwood. Is this a strategy, a response to microclimatic factors, or something else entirely? I aim to answer fundamental questions about how organisms live and disperse throughout the canopy. This research will help us understand one of the world's most amazing and mysterious canopy ecosystems.

Ask the Scientists

What is the context of this research?

Lichens often grow as epiphytes (organisms that grow on plants), and they take advantage of the abundant branch and trunk space in forest canopy environments. One species, Flavoparmelia caperata, is especially widespread in the second-growth redwood forest canopy. I have observed that this lichen shows differential reproductive states depending on its height in the canopy. Why is this? What sorts of factors could drive this?

Lichens like Flavoparmelia reproduce both sexually and asexually. Their sexual reproductive structures are called apothecia, and resemble little cups on the thallus, or body, of the lichen. The lichens also have soredia, little specialized bits of the lichen body that break off to disperse. In the canopy environment, airborne dispersal is probably very important.

What is the significance of this project?

The canopy ecosystems of the world are under threat and are disappearing before they can even be truly understood. The old-growth redwood canopy is largely gone and the emerging second-growth canopy is under threat from changing environmental conditions. Higher temperatures and lower moisture content, for example, may affect where lichens can live and persist. Especially here in the southern part of the coast redwood range near Santa Cruz, California, the organisms that live in the relatively dry and hot tree crowns are at the highest risk of being pushed beyond their physical limits.

Probing what drives life in this ecosystem is a step forward in understanding the forest canopy, and in appreciating the complex dynamics of this environment before it is too late to study it.

What are the goals of the project?

In each of my study trees, I will establish a rope system that allows me to explore large areas of the inner crown. At different heights in the trees, I will observe the area covered by the lichen, the number of apothecia (sexual reproductive structures), and the area of soredia (asexual reproductive propagules).

I will install iButtons in each tree, which will continuously take and record temperature and humidity data, and I will record light exposure in different parts of the canopy.

I will also sample airborne fungal spores in my trees, to find out if the upper canopy is richer with lichen spores than lower strata.

I will combine the information from all these methods to determine which factors - height, light, microclimate - are good predictors of Flavoparmelia reproductive state.