Physical traits 1: bark

Aspen bark is generally smooth, and unlike many other tree species, retains a strongly photosynthetic capability even into maturity.

Rough bark is produced as a defense mechanism – protection from mechanical wounds, colonization by pathogens and other types of damage. The extent to which the rough bark is produced may depend on the underlying genetics of the clone, and its susceptibility to invasion (I have yet to prove or disprove this – it’s currently only a hypothesis based on observations).

The abundance of smooth bark is one of the physical traits I investigated in five wild-growing Scottish clones over the course of this PhD. Specifically, do clones growing on the same site differ in this particular trait? Generally, yes (see fig.1 below).

Figure 1: % cover of smooth bark (with SE bars) for five aspen clones at Invertromie (RSPB Insh Marshes, nr. Kingussie, Cairngorms National Park, Scotland).

A generaized linear mixed model confirmed significant differences and separated the five clones into three groups based on these differences: red/green (BD11/BD12); grey (BD13); white/blue (BD14/BD5).

So why is this interesting? More on that in another post.

Time for the crunch…

I’ve had a bit of an absence from writing, largely due to a lot of time away in the field and lab, tying up loose ends with the research.
Now the writing process begins in earnest, and I’ll be posting some findings of my research in the coming weeks. I hope to have more pretty pictures and lots of colourful charts to delight and amuse, and maybe some (moderately) hard stats. Caveat: I’m not a statistician, only a humble biologist with aspirations…

Xanthoria parietina

X. parietina growing on 15-year-old aspen in Scotland

Aspen reproduction

Aspen clones growing at Kilmichael, nr. Lochgilphead, Argyll

In Scotland, aspen tend to reproduce mostly vegetatively from root suckers.  Flowering events are not particularly common, requiring long, hot summers in order to flower.  They are a dioecious species (male and female flowers on different trees), and produce catkins on previous years’ wood during late winter to early spring.

I was fortunate enough to see some aspen flowering at the RSPB Insh Marshes nature reserve near to Kingussie, which is a National Nature Reserve; part of the site, the Invertromie trail, has been designated an SSSI – Site of Special Scientific Interest.  Some heavy winds had damaged a few of the trees, blowing out the crowns so that for those with flowers, only a thin sliver of bark held the trees together.  Poor things.  A last-ditch effort to breed before the grim reaper shows up.

Aspen are not as widespread in Scotland as they once were, forming a major component of the original Caledonian Forest, as the Romans called it (Caledonia, not theForest bit).

Back to the root suckers.  As these are vegetatively reproductive, they tend to form varying numbers of ramets (or trees) all growing from the same rootstock, making them genetically identical.  There can be a few to many different rootstocks growing intermingled on one site, all with different genotypes creating a woodland comprising many different clones.

Aspen clones at Kilmichael, nr. Lochgilphead, Argyll

First post

Greetings and welcome to the fascinating world of lichens and aspen. I’ll be using this blog to express research findings, discuss and describe interesting publications and ultimately as a sounding board for ideas and thoughts that pop into my head over time.