Snags, stumps, and logs provide habitat

Three birds perched on a snag. A ball moss
(Tillandsia recurvata) also lives on this snag.

Dead standing trees are snags. If a snag is located so that it will not hurt people or damage property, leave it standing for its wildlife value. Snags are highly productive sources of habitat that work well in both natural areas and designed landscapes.

Tree basics

The vast majority of organisms on our planet depend upon the life-giving process of photosynthesis. Plants and other organisms with chlorophyll combine carbon dioxide from the air and water with energy from the sun to form sugars and oxygen gas. The plant can then combine the sugars to form starches, fats, enzymes, or whatever the plant needs. 

Photosynthesis: 6CO2 + 6H2O >> C6H12O6 + 6O2

Then most living organisms (plants, animals, fungi, bacteria) take in oxygen and digest the sugars in one form or another to gain energy for life through respiration, a process the equal and opposite of photosynthesis. 

Respiration: C6H12O6 + 6O2  >> 6CO2 + 6H2O 

Since trees normally live for many years, they sequester carbon in their wood and root tissues as long as they live, while the flowers, fruits and leaves store carbon only temporarily until they are eaten or decompose. Much of this decomposing plant matter ends up in the soil. But when a tree dies, the wood begins to break down as bacteria, fungi, insects, and other organisms begin to absorb the wood tissue so they can gain energy for life. As the wood deteriorates, then birds and other larger animals can consume the decomposers and so the carbon-based sugars stored in the wood moves up the food chain. The organisms store the sugars created during photosynthesis, but as they respire and when they die, the carbon is released into the atmosphere.

One note here on carbon sequestration: The soil sequesters 3 to 4 times as much carbon as all the terrestrial plants, including rain forests. Peat is especially important since it can sequester carbon for thousands of years. This is important because the more carbon sequestered means less carbon dioxide, our most abundant greenhouse gas, in the atmosphere and that is good for our only planet. (Read my article on peat moss.)

The value of trees

 An appreciation of trees

Trees in our yards and in our communities add to the global
population, which is crucial for slowing down climate change.

Here are just some of the many ways that trees are important not only in our urban and suburban neighborhoods, but also for the whole planet:

- Trees actually cool the air through transpiration. A mature deciduous tree like an oak will transpire more than 400 liters of water on a hot summer's day. In the process of liquid water evaporating (going from liquid to gas) the air is cooled. At 68˚F each gram of water that evaporates, cools the air by 585 calories. Transpiration: Forests' most important service

- Trees sequester carbon, by absorbing carbon dioxide (CO2) a long-lasting greenhouse gas, through the process of photosynthesis where they remove carbon dioxide from the air to make sugars, which are then stored in the various plant tissues. A typical hardwood tree can absorb as much as 48 pounds of carbon per year. This means it will sequester approximately 1 ton of carbon by the time it reaches 40 years old. Carbon sequestration

- Trees produce oxygen through photosynthesis, but trees and all the other organisms in the forest absorb most of that oxygen to live. Also read Transpiration: Forests' most important service where I talk about three cycles in the forest: Carbon, Oxygen, and Water.

- Trees remove carbon monoxide (CO) and other air pollutants from the air. They are absorbed primarily through stomata (pores) on the leaves where they diffuse into intercellular spaces and may be absorbed by water films to form acids or react with inner-leaf surfaces. Trees can remove significant amounts of air pollution in cities, where it is often concentrated. More information on this from the EPA.

Peat moss is never sustainable

There are many reasons why peat moss is never recommended for gardening.

Soil sequesters carbon

Sequester this carbon! Don't throw it away.

Sequester this carbon! Don't throw it away.

Carbon sequestration is tremendously important because keeping the CO2 levels low in the atmosphere will help keep the earth cooler. It’s the most abundant greenhouse gas.

As I found in doing the research for the Soil section in "Climate-Wise Landscaping," soil sequesters four times more carbon globally than all the terrestrial plants added together, including rainforests. It varies by region and soil type with the peat bogs doing much of the heavy lifting.

Transpiration: Forests' most important service

Through transpiration trees extract huge amounts of water from the soil
and spew it into the atmosphere.

Three Major Cycles in Forests

For a better understanding of the overall value of trees, we'll look at the three major cycles in forests. There are many other processes that also take place, but these three will provide a big-picture look at what's going on in forests, which can then be downsized to fit into our local activities in our yards and in our communities.
1) The Water Cycle:  Water moves through trees, evaporates into the air, forms clouds, rains or snows, both locally and globally. Water from the precipitation is soaked up by trees.
2) The Carbon Cycle:  Carbon absorbed during photosynthesis and is released during respiration, fire & decomposition.
3) The Oxygen Cycle:  O2 is produced through photosynthesis and absorbed through respiration.