It’s an incredibly exciting time for tree and woodland ecology, scientists are making breakthrough discoveries that are reshaping the way we see forests, and redefining their role in our landscape. Here are five amazing new stories from the frontier of tree science.
- Trees are connected, and share nutrients.
For as long as the scientific discipline of ecology has existed the most widely held consensus has been that trees are competitive between both different species and individuals of the same species, in a constant, self-centred battle for resources such as light, water, space and nutrients.
But, in the late 1990s Dr. Suzanne Simard from the University of British Columbia made an astonishing discovery – that trees are connected by an underground ‘wood wide web’, and share nutrients. She found not only that trees of the same species ‘nurture’ and support each other’s survival, but that different species share also.
She discovered that the roots of trees in a forest are connected by a vast sprawling network of fungi known as ‘Mycorrhizas’ or ‘Mycelium’ that exchange carbon and nutrients between individual trees. ‘Hub trees’ which act like parental elders, support the growth and survival of younger trees by shading and regulating growth, and suckling saplings with nutrients through tough times.
Much work is still needed to fully understand this phenomenon, but it is believed that forests are ‘super-organisms’ much like bee or ant colonies, ‘altruistic’ structures that promote the survival of the whole to benefit the individual.
- Trees warn each other of danger
In the 1990s a zoologist named Wouter Van Hoven from Pretoria University discovered that Acacia trees browsed by herbivores such as Antelope and Giraffe triggered a chemical alarm system that warned other trees of the danger. By releasing ethelyn gas into the air, other trees within a 100 meter radius were alerted, and produced tannins in their bark and leaves that are unpalatable to herbivores.
We are starting to understand that trees all over the world communicate through airborne chemicals for a variety of different reasons, and that these tannin defence systems are widespread. Ever wondered why a caterpillar never eats the whole leaf?
Anyone familiar with the recent problem of herbivores stripping the bark of veteran Beech trees in the New Forest will no doubt wonder why it only happens to one tree amongst many. I believe the same chemical alarm system phenomenon may be taking place here too!
- Ants developed forestry before we did
In 2005/6 a scientist named Megan Elizabeth Frederickson from Stanford University discovered a species of Amazonian ant called the ‘Lemon Ant’ that uses formic acid as a natural herbicide, to kill all plants in areas of up to 1,000 square meters, leaving a monoculture clearing of between one and four tree species that the ants use as nesting habitat.
Locals call these ecological features ‘Devil’s Gardens’ and believe that a malevolent, supernatural being called Chullachaki creates them. We now know of course they are simply the product of a highly industrious species of forester ant!
- Forests help make rain
You may be aware that rain is formed as condensed clouds over the oceans, and that those clouds can only penetrate 400 miles inland without the help of a transpiring forest canopy to carry moisture further. But did you know trees release chemicals that aid the formation of clouds over land?
Trees release chemicals called ‘Terpenes’ that stick together to form ‘cloud seeds’, molecules around which condensing clouds can form. These are emitted in huge quantities over the highly-forested areas of our planet such as the northern Boreal forest. Without terpenes, we would have far less clouds, which reflect radiation back into space, and therefore global temperature would be higher, proving that trees are literally ‘cool’.
- Forests are globally linked
‘Ecoclimate teleconnections’ might not be a term you will hear being used casually in the local pub, but a study published in 2016 has proven it is an idea we need to be paying attention to.
The general thrust is that what happens in one part of the world, affects another – bringing mainstream science closer and closer into the orbit of James Lovelock’s Gaia theory. Deforestation in the Amazon for example, is driving droughts in the American mid-west. Without the trans-Atlantic dust storms of the Sahara, the Amazon rainforest would have no source of annual fertilisation.
This new science has huge implications for our understanding of global ecology, wildlife conservation and forest management, particular in relation to Climate Change – as we can no longer look at the earth’s ecosystems in isolation, but as one, interconnected whole.