There exists an object that is at once a science book, a photograph album, a herbarium, a personal diary, and a historical document of the territory — all in a single notebook. It's called a tree diary. They don't teach it in school. You won't find it in any bookstore. You build it yourself, slowly, with leaves and photographs and measurements and stories. And over time, it becomes one of the most precious documents you can own.

What is a tree diary and who is it for?

A tree diary is a personal record of observations about one or more trees over time. It can be a lined notebook, a blank notebook, a waterproof field journal, or even a digital folder with photographs. The content has no fixed rules — each person builds it based on their own interests and skills. A 7-year-old child will have a diary with drawings of leaves and photographs of acorns. An adult naturalist will have sheets with biometric measurements, phenological data, and species identifications. A school will have a collective diary with contributions from dozens of students over the years. An elderly person with limited mobility will have monthly photographs of the garden tree and notes about the weather and season. All of these are valid tree diaries. The common value in all these forms is continuity: observing the same tree, in the same place, over a long period of time. This is what transforms a simple occasional observation into real knowledge.

How to start: the basic structure of a tree diary

The minimum structure of a tree diary includes: a tree presentation sheet (species, GPS location or place description, monitoring start date, full-tree photograph); monthly sheets with a photograph of the same tree (from the same position) and notes on: what has changed since last month? Are there new leaves? Is it flowering? Are there fruits? Are there signs of disease? What animals visit it? an annual measurement of trunk circumference at 1.30 meters from the ground; special events (particularly abundant flowering, a frost that damaged leaves, a bird's nest found in the branches, the first acorn that fell in autumn). Any other observation the diary author considers relevant: pressed leaves, detail photographs (bark, buds, fruits), stories of encounters with animals in the tree.

The tree diary for schools: a multi-year project

The tree diary applied to schools becomes a multi-year citizen science project with excellent educational outcomes. Possible structure: each class chooses 3-5 trees in the school garden. Every month, the class takes a 20-30 minute outing to observe and document the project trees. At the end of the school year, the diary contains 10 months of observations with photographs, measurements, and children's notes. The diary stays at school and is picked up by the next year's class — which already has a year of data. After 5-10 years, the diary is a real phenological document with scientific value. Some Italian schools that started these projects in the 1990s now have diaries documenting 30 years of their garden trees' history — including the earlier arrival of spring flowering, the gradual shift in autumn colors, diseases and recoveries.

The tree diary for seniors: connection, memory, and wellbeing

For seniors — especially those with limited mobility or in care facilities — a tree diary of a garden or park visible from the window is a project of connection with the natural cycle with powerful effects on psychological wellbeing. It doesn't require going outside. It only requires looking out the window every day, taking a photo with your phone, writing a few lines. The continuity of observation — seeing the same leaves grow, change color, and fall — is a form of connection with time and nature that counters the sense of isolation and stagnation many seniors experience. In some Italian care homes, the tree diary has been introduced as a therapeutic activity with documented positive results on residents' mood and cognitive activity.

How to build a tree diary: materials and getting started

• Essential materials: a sturdy notebook (preferably with a hard cover and opaque paper that doesn't absorb moisture), a black pencil or pen (holds up better over time), clear tape or glue to attach leaves, a small 5x magnifying glass (for details), your phone for photographs. Total cost: 10-15 euros.
• Choose your tree: the most important criterion is accessibility. Your diary tree must be one you can visit every month without extraordinary effort. The tree in your yard, the building's garden, the park you walk through every day. It doesn't need to be rare or monumental — it needs to be reachable and accessible in every season.
• The first page of your diary: dedicate your first visit to filling out the tree presentation sheet. Full tree photograph, bark photograph, single leaf photograph on white background, trunk circumference measurement, species (identified with PlantNet if needed), GPS location, date, weather of the day. This sheet is your zero point — the reference from which your entire diary develops.
• Build a monthly routine: every first of the month (or every full moon Sunday, or any other periodic date that makes sense for you) make your monthly visit to your tree. Take the photograph from the same position, write 5-10 lines about what you saw, attach a leaf if available. Nothing more is needed. Continuity matters more than quantity of details.
• Add stories of encounters: whenever something interesting happens on or under the tree (a nest found, a woodpecker spotted, a fungus growing on the root, a frost night that changed the leaves) write it in your diary with the date. These special events, recorded over time, become the narrative thread of your diary — the living story of a relationship with a specific living being.

The tree diary has no deadline. It doesn't end with the end of the school year, it doesn't stop when children grow up, it doesn't close when the owner moves house. It only stops when you decide to stop — and often you don't stop, because after six months of continuous observation your relationship with that tree has become something real that you don't want to abandon. It's perhaps the simplest and most lasting naturalistic project that exists. And in the end, after years, what you have in your hands is not just a notebook: it's the story of a friendship with a tree.