To answer your question about why it is wrong to say that micro economics studies the tree and macro economics studies the forest -
The difference between microeconomics and macroeconomics can be explained by using the example of a tree and a forest.
Microeconomics is the like the study of an individual tree, standing in a thick forest of thousands of individual trees of different species. A microeconomist might study the systems that make an individual tree function efficiently, providing it with the sustanence it needs to thrive in the forest.
A macroeconomist, however, will take a broader look at the forest as a whole, and observe how the thousands of trees work together in conjunction with the sun, the soil, the oxygen, nitrogen, and water in the environment that make the entire forest function efficiently as one giant organism.
In other words
Microeconomics concerns itself not with the health of the economy as a whole, rather with the individual markets, firms, and consumers within the economy, and the challenges of efficiency and resource allocation faced by those markets.
Macroeconomics, on the other hand, studies the health of the economy as a whole. Macro deals with aggregates, or “collections of specific economic units treated as if they were one.
Therefore while studying macroeconomics you will begin to see the forest through the trees
What you really need to understand is that an example of the tree and forest is used to explain the difference between microeconomics and macroeconomics, (like a metaphor that is a figure of speech in which an implicit comparison is mad between two unlike things that actually have something in common)
In reality, Botany is the study of all types of plants and Dendrology is the study of trees. It studies only wooded plants. Dendrology may be considered a subcategory of botany that specializes in wooded plants.
A forest, also referred to as a wood or the woods, is an area with a high density of trees.
forestry teach you about both forest and trees.
According to Prof Lionel Robbins “Economics is a science which studies human behaviour as a relationship between ends and scarce means which have alternative uses.”