A tree increases its mass and does not violate the law of conservation of matter because the tree converts the energy from the sun into energy for growth through the process of photosynthesis. It also leaches nutrients from the soil for growth through its roots for growth.

The energy from the sun and the nutrients in the soil are transferred to the mass of the tree, and no energy or matter are lost.

matter is neither created nor destroyed.

In 1842, Julius Robert Mayer discovered the Law of Conservation of Energy. In its most compact form, it it now called the First Law of Thermodynamics:

energy is neither created nor destroyed.

In 1907 (I think), Albert Einstein announced his discovery of the equation E = mc2 and, as a consequence, the two laws above were merged into the Law of Conservation of Mass-Energy:

the total amount of mass and energy in the universe is constant.

Generally, textbooks would add that mass and energy can interconvert.

In the case of the tree, no new matter is created, water and carbon dioxide and radiant energy from the sun are turned into tree matter through photosynthesis–process through which light energy, water, and carbon dioxide are converted into oxygen and organic materials that can be used in the plant.

It is an interesting way of looking at things.

I hope this helps.

The way a tree grows is by obtaining energy in terms of heat and through photosynthesis.

The energy it obtains is then transformed into matter.

The matter has not been created or destroyed, and thus adheres to the law of conservation of matter.

e=mc^2 is one of the most famous equations which theorizes that matter is just another form of energy.