You can spot if two trees are “friends” by looking up where their branches meet. Friends don’t grow thick branches towards each other, to better share the light. They grow thick branches away from each other, towards other trees.
In a forest, trees become a super-organism that mimics the structure of a single tree: smaller and shorter trees stay on the outside, while taller and stronger trees are on the inside.
A tree can distinguish its roots from the roots of other species, and even of other individuals of its same specie.
Most individual trees of the same species living in proximity are connected through their roots, and use the connections to balance the distribution of nourishment.
If we can read patterns in trees, we can find the way out of a forest just by reading their roots.
Conifers resist better to harsh conditions than broadleaves. For example, their vessels are narrower than those in broadleaves, which makes it harder for water to develop bubbles in freezing/de-freezing cycles.
The oldest trees on earth belong to the gymnosperm family. They include conifers and protect their seeds inside cones. It took Nature two hundred million years to evolve a new family of trees, which we call angiosperms, that develops flowers and protects its seeds inside fruits.
According to Tristan Gooley, the author of “How to read a tree”, it is far more important to recognize shapes and patterns, and their meaning, than trying to memorize the names of individual species. We can be content just by remembering tree families and their shapes.
Mespilus germanica, known as the medlar or common medlar, is a large shrub or small tree in the rose family Rosaceae. The fruit of this tree, also called medlar, has been cultivated since Roman times, is usually available in winter and eaten when bletted.
When you consider how seeds germinate in nature, it makes sense to sow seeds the same way. Winter sowing is the process of planting seeds outdoors in a container during the winter months. The container remains outdoors until the seedlings emerge in the spring. The container protects the seeds from animals and harsh weather, but the exposure to colder temperatures breaks dormancy and the seeds germinate.
Some trees like many birches can survive temperatures well below -40C
While trees have evolved amazing strategies for withstanding winter, if the cold arrives too fast for the trees to prepare, the life-sustaining sap can begin to freeze, expand, and put pressure on the bark, which can break and “explode”.
A tree doesn’t have to keep all of its cells from freezing, just the living ones which are primarily the phloem cells. This is significant, since much of a tree’s living trunk is made up of cells that are dead, such as xylem cells. These dead cells can and do freeze
Decomposing leaves add nutrients to the soil for new growth. Whole leaves take about two to three years to turn into compost.
Dormant trees have already formed buds containing flowers and leaves for next spring.
Some trees keep their dry, brown leaves throughout the winter in a process known as "marcescence". The abscission layer on these trees does not fully form until spring.
The abscission layer grows between the branch and the stem of a leaf. It causes the leaves to shed and helps to protect this sensitive area from winter cold.
We might be tempted to think that trees have a method to pump water upwards, based on how blood moves in our veins. In reality, trees can only generate a very small amount of pressure from the roots. Water is pulled up to the leaves by capillary action and transpiration.
It can take more than a century for trees to develop cavities large enough to host wildlife. Cavities provide protection from cold weather and shelter from predators.
Trees are capable of entering in a state of dormancy. In winter their metabolism slows down and they stop growing to conserve energy.
Leaves have superficial microscopic openings that allow water to evaporate and leave the trees along with oxygen. In pine needles, the openings are not on the surface, but deep inside. This, along with their reduced surface area and a special coating wax as a barrier, allows pine trees to maintain their leaves (or needles) throughout the year.
Trees protect their living cells from freezing by producing proteins called ice nucleators. They sit between the cells and are the first to freeze, attracting water. As the water leaves the cells, the concentration of sugars increases, constantly lowering their freezing temperature.
In winter, cold and dry conditions make it impossible for some trees to transport nutrients and water to their leaves. So they drop their leaves to conserve energy and resources and avoid wasting water through transpiration.
Trees cannot "move" as individuals, but they can move as a community. For example, in response to warming temperatures, European spruce has climbed 250 meters in the last fifty years, growing at higher altitudes than its usual range.
Phenotypic plasticity is the term used to describe the plants’ ability to adapt their shape and shrink or grow their size based on their environment and on the availability of nutrients.
Plants are decentralized organisms. They are made up of modules that distribute functions throughout their bodies, unlike animals, which concentrate specific functions in specific organs.
Trees, like all plants, are capable of simultaneously perceiving light, temperature, gravity, chemical gradients, electric fields, touch, sound... and more. Their heightened sensitivity compensates for their inability to move.
Plants represent more than 80 per cent of the biomass on Earth, a total of 450 billion tons. Humans account for 0.6 billion tons, less than 0.01 per cent. In other words, if all life on earth had your weight, humans will approximately be lighter than one of the banknotes you carry with you.
Depending on the species, roots extend horizontally a minimum of 2.5 to 3 times the width of the crown.
Trees are nurturers. They nurture each other and they nurture us.
Trees, like us, cannot remain healthy under continuous stress. For a tree, compacted soil, limited space for the root system, air pollution and disrupted lighting patterns are all cause of stress.
“Almost all the trees we plant in our cities come from forests somewhere in the world. What does that mean for the tree? How do our present planning and management strategies affect tree health and resilience?” @Naomi Zurcher, Connecting trees with people
Root explore the underground based on the temperature of the soil and on the availability of oxygen, water and nutrients.
An individual forest tree’s root system begins with the development of at least one order root in each of the four cardinal directions, forming the root system’s perennial framework.
Forests occur over millennia. They are a process of succession and evolution.
A forest is a complex-adaptive ecosystem formed by flora, funga, fauna, soil… and trees. A complex-adaptive ecosystem managed with linear, extractive, industrial practices loses its capacity to support biodiversity and, in the long run, to host life.
Tree growth is the combined interaction of genetic potential and its ability to deliver on that potential, driven by the surrounding environment.
Trees have living cells in their outermost structure (buds, roots, leaves) and use dead cells as their core structure. This is opposite of how we are structured: we are supported by living cells and use dead cells (hair, nails, and the skin surface) to protect us from the environment.
Forest trees live in extended cooperative communities below ground. They share resources and information in cooperation with symbiotic fungi. This association (mychorriza) drives plant population and community biology.
The Ginko biloba, the Maidenhair tree and conifers are the first trees to appear as plants that produce unenclosed seeds, or “naked” sees.
In a tree, the crown architecture determines how light is captures and distributed for photosynthesis. The shape of the crown varies according to species and age.
Branches that don’t produce more resources than they use, die. However they will only shed when all their resources have been reabsorbed into the tree.
Trees can vary the architecture that they inherit from their specie to adapt to the environment. They may change the size of their leaves to respond to variations in temperature, or increase the amount of wood in parts that need it most, to support their weight.
The earlier examples of vascular plants dates back approximately 420 million years. The form that we recognize as tree evolved during 360 million years.
“There can be no life without soil and no soil without life; they have evolved together” – Charles Kellog
Soil can take millennia to evolve to the point where it can support a forest community.
Trees and plants are the only organisms on earth that produce their own nourishment. Directly or indirectly, they feed all forms of life.
Trees produce their own food and the material they need to grow. This is why they cannot grow beyond their possibilities.
When we sweat, our body temperature goes down. When trees sweat, the water cycle starts, and the environment around them cools down.
"Se la conoscenza del tutto (dell'unità) viene divisa in due e spiegata e successivamente queste due metà sono divise ulteriormente in tre o quattro e analizzate, non siamo affatto più vicini a capire il tutto rispetto a prima. Eppure, quando facciamo ciò siamo preda dell'illusione secondo cui la nostra conoscenza è aumentata."
M. Fukuoka, Sowing seeds in the desert
Trees are the longest living organisms on Earth and never die of old age. Some of the oldest living trees, such as the bristlecone pines and giant sequoias in California, are 4,000-5,000 years old.