Origami with leaves

Things have really started to green up over the last few days; the vibrant fresh greens of new growth add a sense of life to a previously dull canvas. Look closely and you will see that there is a clear succession to much of this greening. Trees in particular provide an opportunity to spot which species come into leaf first and which are more sluggish. Over the last few days the rowan in my garden has come into leaf, while the hazel is only just bursting through from its buds. The buds of beech on the other hand, remain firmly sealed, the leaves inside yet to put in appearance.

Many of the newly emerged leaves clearly have quite a bit of growing still to do; look at those of horse chestnut for instance, miniature versions of their final form. On the other hand, the beech leaves will emerge almost fully-formed, raising the question of just how they can be packed into such a small bud. It seems that the key to this trick lies in the way in which the new leaves are folded. Researchers have discovered that the angle between the mid-rib of the leaf and the lateral veins that emerge from it determines how the leaf will unfold. This angles varies between different tree species, ranging from 10 degrees to almost 90; the bigger the angle the more compactly a leaf can be folded and, hence, crammed into a smaller bud. However, this space-saving option comes at a price, since the larger the angle the more slowly the leaf expands. Beech has an angle of roughly 40 degrees (ranging from 50 near the stalk to 30 near the tip), allowing it to expand to its full area that much more rapidly. This strategy lies behind the long leaf buds that you see on beech, each containing a virtually fully-formed leaf, folded ready for rapid deployment.

That we know all this is down to work carried out by a team of scientists working in Japan. They have spent time studying the mechanics of leaf emergence, even using paper to replicate the nature of the unfolding process. An understanding of the principles of leaf emergence and, in particular, how you cram a large flat object into a much smaller three dimensional space, has value elsewhere in science by highlighting how we might overcome particular design problems. This area of science is known as biomimetics and has been used to look to nature for solutions to design issues relating to as wide a range of subjects as folding tents through to deploying the solar panels of satellites and other space-craft. The mechanics of nature are something that we can all learn from.

I can't see the trees for the wood

Spurred on by Richard Mabey’s new book ‘Beechcombings: The narratives of trees’, I have re-evaluated my relationship with woodland. I was raised on the Surrey-Sussex border, amid the verdant growth of deciduous woodland that extends over a large part of the Wealden landscape. Trees provided me with tools for play; they supported the insects and birds with which I became fascinated, yet all the time they remained a backdrop to my progression towards maturity. They were such an integral part of my childhood that I took them for granted and ignored them, relegating them to the role of scenery, in front of which I played out my youth.

Richard’s book has made me realise the extent to which I have underplayed the beauty and value of trees. I am not as confident in their identification as I am with birds, insects and other wildlife and, by not knowing them, perhaps I appreciate them far less than I should. When I first left Surrey I was struck by how open a landscape could be, perhaps no more so than in the fenlands of Norfolk. Separation from the woodland within which I had been so comfortable, and the feeling of loss that came with it, underlined the importance of woodland to me. However, it was the woodland (this community of mixed species and forms) that I missed, and I still did not have a relationship with individual species of tree. This has changed, a response to reading of Richard’s own experiences with woodland, of his strong bond with the beech and the role that particular trees have played in the lives of other people across the country. Even though individual trees, because of their size and longevity, genuinely do provide a backdrop to our lives, it is possible (perhaps even essential) that we also regard them as living organisms.

In this age of regimented and man-made materials, we are becoming increasingly divorced from natural products, like wood, and the inherent variation in quality and end use towards which such products may be put. The varying qualities of different woods, how they can be worked, how they burn and what they are best suited for, help define the qualities of the trees themselves – for example, the sturdy oak, the flexible willow. To properly understand them, you need to appreciate these qualities and take time to study the form of individual trees within the landscape. Many will have decades of history associated with them and knowing this (plus knowing that this history will continue to accumulate long after you are gone) soon brings the tree out from the background and into the central focus. It becomes a living individual, just like you.