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CLIMATE CHANGE AND MICHIGAN FORESTS

Get in

Touch with

Trees!

Lesson 1

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Why Are Forests Important?

Habitat

Economy

Recreation

Nutrient cycling

Air purification

Other______________

Prevent soil erosion

Water retention

Cooling

Carbon sink

Jobs & Careers

Other ______________

When students are done brainstorming their own list of reasons why forests are important, use this slide to go over their ideas. You can have students come up and check off which they agreed on, or add their own ideas to the list.

More information about each of these benefits forests provide humans and the environment:

Habitat: Trees and other plants provide habitat for mammals, birds, insects, bacteria, and fungi.
Economy: Forests provide the wood used for constructing buildings, crafting furniture, and making paper. Many forest plants are a source of compounds used in medicines and health products. For example, salicylic acid is a willow tree hormone that is used in aspirin.
Recreation: Recreational activities in forests include hiking, camping, snowmobiling, skiing/snowboarding, off-road vehicle riding, hunting, photography, and bird watching. Many people also explore forests simply to enjoy the beauty of the natural environment. Have you ever enjoyed looking at the fall colors of a forest?
Nutrient cycling: Nutrients are continuously cycled in forests. When plants and animals die, they decompose, and this releases nutrients into the soil. These nutrients can be absorbed by roots and used to help plants grow. Animals eat the plants and keep the nutrients in their bodies. When these plans and animals die, the nutrient cycle continues.
Air purification: During photosynthesis plants take in greenhouse gases including carbon dioxide (CO₂), sulfur oxides (SO_x), and ozone (O₃). Plants convert these gases into usable materials, and release oxygen (O₂) back into the atmosphere. In this way plants act as air filters by absorbing pollutants and releasing oxygen.
Prevent soil erosion: The roots of trees and other plants form an underground matrix that helps keep soil in place.
Water retention: Roots hold soil in place. This prevents rainwater from draining away quickly. Instead, rainwater is slowly filtered through the soil. Excess water drains into creeks, rivers, or underground aquifers.
Cooling: Trees provide shade from the sun, keeping the area cooler. They also help to absorb some heat from the atmosphere.
Carbon sink: As trees grow they use the carbon from carbon dioxide to make sugars and other compounds and to build new cells. Trees “lock up” some of that carbon as wood. This helps reduce the amount of carbon dioxide in the atmosphere. The carbon is released again when trees are burned or decompose.
Jobs & Careers: Can you think of any forest-related jobs or careers? Forests provide many jobs for people living in both urban and rural areas. These are all jobs that involve trees or forests: arborist, timber harvester, parks and recreation staff, forest manager, and forest ecology researcher. Throughout this unit we will explore forest-related careers.

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How do plants grow?

Let’s review what we know about plant growth. How do plants grow? Accept several student answers. What do plants need to grow? Plants capture light energy from the sun in their cells and use it to make sugar for food. This process is called photosynthesis. Photo means “light,” and synthesis means “putting together.” The sugar is sent to the rest of the plant and used to build more cells and make the plant larger. Photosynthesis also requires carbon dioxide from the air, and water and nutrients from the soil.

[Notes Page Q1 ANSWERS: light, carbon dioxide, water, nutrients]

Optional Review using Photosynthesis Infographic:

Pigments are colored chemical compounds found in plants that absorb light. Chlorophyll is a green pigment that makes plants green. It absorbs the light energy needed for photosynthesis.
Stomata are openings on the underside of leaves that open and close to let carbon dioxide (CO₂) into the leaf and oxygen (O₂) out of the leaf.
The equation for photosynthesis is: 6CO₂+ 6H₂O + Energy (sunlight) 🡪 C₆H₁₂O₆ + 6O₂
Three components are needed before photosynthesis can occur: carbon dioxide, light energy (sunlight), and water. These are all listed on the left side of the equation because they are the “inputs”. The “outputs” of photosynthesis are energy (in the form of carbohydrates) and oxygen. These are both shown on the right side of the equation.

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What factors affect plant growth?

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Temperature:

How does temperature affect plant growth?

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Temperature determines how fast photosynthesis occurs.

Temperature influences how much water is available for plants to use for photosynthesis.

Temperature determines when photosynthesis can occur and how fast photosynthesis occurs. This means means temperature determines how quickly or slowly plants grow. The times during the year when the best range of temperatures and conditions allow a plant to photosynthesize and grow is called the plant’s “growing season”.

Photosynthesis is a chemical reaction. Generally, the cooler the temperature, the slower the rate of a chemical reaction. The warmer the temperature, the faster the rate of a chemical reaction. So, if it is cold plants will photosynthesize more slowly, and higher temperatures speed up photosynthesis. However, eventually it can become too hot for a plant to photosynthesize. This is because some of the chemicals used during photosynthesis (called enzymes) will break apart when it is too hot.

Photosynthesis also requires water. When the temperature is too high (too hot), water evaporates and becomes more scarce. This means that during periods of extremely high temperatures, plants must conserve water and photosynthesis cannot occur. During freezing temperatures, water is locked up in ice, snow, and the frozen ground where it is hard for the plant to get. Extreme hot or cold temperatures usually prevent photosynthesis.

[Notes Page Q2 ANSWERS: how much water, how fast photosynthesis occurs]

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Precipitation:

How does precipitation help plants grow and survive?

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Photosynthesis – Precipitation influences how much water plants can access and use for photosynthesis and growth.

Heat movement – Plants allow water vapor to exit openings in the leaves, taking heat with it.

Structure – Water held in plant cells gives plant leaves and stems shape and structure.

Precipitation

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Light:

How does light affect plant growth?

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The amount of light and the intensity of light plants receive determine how much energy is available for photosynthesis.

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Soil:

How does soil type affect plant growth?

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Soil type determines how much water and what types of minerals are available.

Soil type determines how much water and minerals are available to a plant. Minerals are naturally occurring inorganic substances that provide organisms with necessary building blocks to grow.

[Notes Page Q5 ANSWERS: how much water and what types of minerals]

Optional:

There are three main types of soils. Clay soils have very small particle sizes and do not drain water quickly. Silty soils have a mixture of clay and sand, and retain water and minerals for an intermediate amount of time before they drain away. Sandy soils have larger particle sizes and drain water more quickly. The length of time water is held in the soil also determines the amount of minerals which can dissolve in the water. Both water and the dissolved minerals are taken up by plant roots for cell maintenance and growth. Many areas contain a mixture of these three soil types.

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Temperature

Precipitation

Soil

Light

Are these factors the same in

every environment?

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Trees grow where they are adapted to live

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Smaller, waxy needles limit water loss and protect photosynthetic cells.

Keeping leaves year-round saves energy and allows photosynthesis to occur when conditions permit.

The cone shape of the tree helps conifers drop heavy snow.

Conifers are adapted to colder climates

Coniferous trees (conifers) are more adapted to northern Michigan which is cooler and has less light intensity than lower Michigan. These two factors shorten the growing season for plants in northern Michigan. Conifers have adapted to survive these conditions. Their leaves (needles) are small and waxy, which helps to prevent water loss and protects the cells where photosynthesis occurs. Since conifers never lose their leaves, they can photosynthesize whenever conditions allow it. Keeping their leaves year-long also saves conifer trees energy because they do not have to regrow all of their leaves each spring. Generally, conifers have an upside-down cone shape that prevents heavy snow from piling up and breaking off tree limbs.

[Notes Page Q7 ANSWERS: Cone-bearing, narrow, waxy leaves called needles; leaves do not shed with cold seasons]

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Broad, flat leaves capture more light.

The open shape of the branches exposes leaves to the maximum amount of light possible.

Shedding leaves prevents water loss and damage during winter.

Deciduous trees are adapted to more moderate climates

Deciduous trees are more adapted to southern Michigan which has warmer average temperatures and greater light intensity. Since water is limited in winter, these warmer temperatures make water available for a longer period of time to the plants. This water availability and light intensity lengthens the growing season for southern Michigan plants. Generally, deciduous trees have an open shape that helps expose their leaves to as much sunlight as possible. Deciduous trees also have broad leaves that can capture more sunlight. However, these leaves are too delicate to withstand winter. Dropping their leaves in the fall prevents the trees from losing water and prevents cell and leaf damage during freezing winter temperatures. By gathering so much energy with a long growing season, an open shape, and broad leaves, the deciduous tree can regrow leaves each spring.

[Notes Page Q8 ANSWERS: Broad, flat leaves; leaves change color in fall; tree loses its leaves in the fall]

[END OF NOTES PAGE QUESTIONS]

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Forests provide important services for humans and the environment.

Factors that affect plant growth include: temperature, precipitation, light, and soil type.

Plants are adapted to grow in a particular environment.

Wrap Up