Use of a rope, helmet, and harness are the minimum requirements to ensure the safety of the climber. Other equipment can also be used depending on the experience and skill of the tree climber. Some tree climbers take special hammocks called "Treeboats" and Portaledges with them into the tree canopies where they can enjoy a picnic or nap, or spend the night.
Tree climbing is an "on rope" activity that puts together many different tricks and gear originally derived from rock climbing and caving. These techniques are used to climb trees for many purposes, including tree care (arborists), animal rescue, recreation, sport, research, and activism.
The three big sources of tree damage are biotic (from living sources), abiotic (from non-living sources) and deforestation (cutting trees down). Biotic sources would include insects which might bore into the tree, deer which might rub bark off the trunk, or fungi, which might attach themselves to the tree.
Abiotic sources include lightning, vehicles impacts, and construction activities. Construction activities can involve a number of damage sources, including grade changes that prevent aeration to roots, spills involving toxic chemicals such as cement or petroleum products, or severing of branches or roots. People can damage trees also.
Both damage sources can result in trees becoming dangerous, and the term "hazard trees" is commonly used by arborists, and industry groups such as power line operators. Hazard trees are trees which due to disease or other factors are more susceptible to falling during windstorms, or having parts of the tree fall.
The process of finding the danger a tree presents is based on a process called the quantified tree risk assessment.
Trees are similar to people. Both can take a lot of some types of damage and survive, but even small amounts of certain types of trauma can result in death. Arborists are very aware that established trees will not tolerate any appreciable disturbance of the root system. Even though that is true, most people and construction professionals do not realize how easily a tree can be killed.
One reason for confusion about tree damage from construction involves the dormancy of trees during winter. Another factor is that trees may not show symptoms of damage until 24 months or longer after damage has occurred. For that reason, persons who do not know about caring for trees may not link the actual cause with the later damaged effect.
Various organizations have long recognized the importance of construction activities that may damage tree health. This can result in monetary losses due to tree damage and replacement costs. As a result, standard methods of tree management for building activities are well established and tested.
The tree has always been a cultural symbol. Common icons are the World tree, for instance Yggdrasil, and the tree of life. The tree is often used to represent nature or the environment itself. A common mistake (wrong thing) is that trees get most of their mass from the ground. In fact, 99% of a tree's mass comes from the air.
A Wish Tree (or wishing tree) is a single tree, usually distinguished by species, position or appearance, which is used as an object of wishes and offerings. Such trees are identified as possessing a special religious or spiritual value. By tradition, believers make votive offerings in order to gain from that nature spirit, saint or goddess fulfillment of a wish.
Tree worship refers to the tendency of many societies in all of history to worship or otherwise mythologize trees. Trees have played a very important role in many of the world's mythologies and religions, and have been given deep and sacred meanings throughout the ages. Human beings, seeing the growth and death of trees, the elasticity of their branches, the sensitiveness and the annual (every year) decay and revival of their foliage, see them as powerful symbols of growth, decay and resurrection. The most ancient cross-cultural symbolic representation of the universe's construction is the 'world tree'.
The tree, with its branches reaching up into the sky, and roots deep into the earth, can be seen to dwell in three worlds - a link between heaven, the earth, and the underworld, uniting above and below. It is also both a feminine symbol, bearing sustenance; and a masculine, phallic symbol - another union.
For this reason, many mythologies around the world have the concept of the World tree, a great tree that acts as an "Axis mundi", holding up the cosmos, and providing a link between the heavens, earth and underworld. In European mythology the best known example is the tree Yggdrasil from Norse mythology.
The world tree is also an important part of Mesoamerican mythologies, where it represents the four cardinal directions (north, south, east, and west). The concept of the world tree is also closely linked to the motif of the Tree of life.
In literature, a mythology was notably developed by J.R.R. Tolkien, his Two Trees of Valinor playing a central role in his 1964 "Tree and Leaf". William Butler Yeats describes a "holy tree" in his poem "The Two Trees" (1893).
There are many types of trees. Here is a list of some of them:
Tragedy
In theatre, a tragedy as defined by Aristotle is a play that ends badly for the hero or heroine or others. A tragedy is usually about a person who has many good qualities, but also has one poor quality (called a "tragic flaw") that causes trouble for him, and maybe his family or friends.
Often in a tragedy, there is one possible event that the hero fears and tries to prevent, but no matter what he does, it makes this thing more and more sure to happen. Tragedies originated in Ancient Greek theatre, where they were performed at religious festivals. The three most famous Greek tragedy writers were Aeschylus, Sophocles and Euripides. Later famous writers include Shakespeare and Jean Racine.
Sometimes the word tragedy is also used to mean something with a bad outcome in real life e.g. crime or death.
Taxonomy
Taxonomy is a branch of science. It is about the laws and principles of classifying things, especially classifying organisms. From one type of taxonomy, many classifications might be produced.
The best-known kind of taxonomy is used for the classification of lifeforms (living and extinct). Each organism has a scientific name. This name is part of the biological classification of that species. The name is the same all over the world, so scientists from different places can understand each other. In addition, a species has a position in the tree of life. Thus the crow is "Corvus corone", a member of the Corvidae family, and they are passerine birds. That is well agreed, but the classification of some groups is not agreed at present, and often several classifications are being discussed.
Living things are classified into three domains: bacteria, archaea and eukaryotes. The highest rank in a domain is the kingdom. Each kingdom has many smaller groups in it, called phyla. Each phylum has more smaller groups in it, called classes. This pattern looks like branches on a tree with smaller branches growing from them. Each species is put into a group because of what it does, how and what it eats, special body parts, and so on. At the end of the pattern, the groups (genera) are very small. Then each species in the genus is given its own name.
When someone writes about a living thing and its formal scientific name, they write the genus and species name. This is known as binomial nomenclature, because it uses two names for each organism. The first is the genus name, and the second is the species in that genus. The scientific name of the domestic cat is "Felis catus". Sometimes it is enough to write "F. catus".
These are the major groups (ranks) used in taxonomy:
Kingdom --> Phylum --> Class --> Order --> Family --> Genus --> Species
Some mnemonics (sayings to help a person remember something):