Introduction to Dendrology

Introduction to Dendrology

• Dendrology is the study of woody plants, including trees, shrubs, and woody vines.
• A woody plant is any plant that has wood.
• Wood is primarily composed of cellulose and lignin molecules.
• Cellulose and lignin provide support and facilitate the movement of water, nutrients, and sugars throughout the plant.
• Woody plants typically have an above-ground stem covered by a layer of thickened bark and continue vegetative growth above ground from year to year.

Dendrology as a Sub-Discipline

• Dendrology is a sub-discipline of botany and forestry.
• It deals with systematics (including nomenclature), morphology, phenology, ecology, geographic range, and natural history.

Dendrologists

• Dendrologists study woody plant names, habits, ranges, habitats, and distinguishing characteristics.

Modern Dendrology Applications

• The USDA Forest Service uses dendrology for comprehensive management of sustainable and productive forests and related natural resources.
• Wildlife biologists use dendrology to learn how and which trees provide cover, nesting sites, and food for various wildlife.
• Natural history includes the knowledge of edible or poisonous plants and their practical uses by people.
• Global forestry requires knowledge of international trees in terms of their economic uses, conservation, and management.
• Wetland management relies on identifying tree species indicative of wetlands.

Importance of Woody Plants

• Woody plants provide food, shelter, shade, and fuel.
• They produce wood, oxygen, absorb carbon dioxide, and control erosion.

Course Objectives

• The course aims to teach plant identity, relationships, life history, habitats, distribution, uses, and other qualities.
• It intends to expand powers of observation, discrimination, conceptualization, and general curiosity.

Tree Definition

• A tree is a woody plant that reaches at least 13 feet in height at maturity.
• Trees generally have a single trunk at least 3 inches in diameter when measured at breast height (4 1/2 ft or 137 cm), which is unbranched for several feet above the ground, and have a definite crown.
• A crown includes all aboveground parts of the plant, including stems, leaves, and reproductive structures.

Mature Tree Sizes

• Measurements are taken at diameter at breast height (dbh).
• Breast height is standardized at 4 1/2 feet (137 cm).

Angel Oak

• The Angel Oak is a Live Oak (Quercus virginiana) native to the Lowcountry of Coastal Carolina.
• It is believed to be over 1500 years old.
• The Angel Oak is named after previous owners, Martha and Justin Angel.
• The Angel Oak has a wide spread canopy but is not very tall, standing at 65 feet.
• The Angel Oak has a circumference of 25.5 feet.
• The Angel Oak has a diameter of 160 feet.
• The leaves provide an area of shade measuring 17,000 square feet.
• The longest limb measures 89 feet.
• The largest limb circumference measures 11.25 feet.
• Some of limbs are so large and heavy that they rest on the ground, and can even drop underground for a few feet and then come back up.

Perspective

• The size, age, shape, dominance, beauty, and potential uses of trees evoke feelings of wonder and excitement.

Distinctions Among Trees, Shrubs, and Vines

• The difference between trees and shrubs is subjective.
• Poison-sumac is a shrub in the Great Lakes but can grow into a 25-foot tree in Georgia.
• Plant species may be shrubby near the edges of its range but still have large proportions elsewhere.
• Several woody plant species start as vines and then become shrubs as they mature.
• Some shrubs may exhibit vine-like characteristics at the ends of long branches.

Definitions of Shrubs and Vines

• Shrubs are smaller than trees.
• Shrubs usually have several erect, spreading, or prostrate stems and a general bushy appearance.
• Vines climb and can be woody or herbaceous.
• Herbaceous vines have little to no woody tissue and typically persist for a single growing season.
• Lianas are woody vines.
• Temperate regions contain liana species, including wild grape, moonseed, trumpet creeper, crossvine, greenbrier, poison-ivy, and Virginia creeper.

Habit

• Habit, in botany/zoology, refers to the general appearance of an organism.
• The three main plant habits for woody plants are tree, shrub, and liana.
• There are subgroups of habits within these three main types.

Habitat

• Habitat refers to the area or natural environment in which an organism or population normally lives.
• A habitat consists of physical factors, like soil, moisture, temperature, and light, coupled with biotic factors, like food availability and the presence of predators.
• A habitat is not always a geographic area; for parasites, it could be the host's body or even a cell within it.

Ecology

• Ecology is the branch of biology dealing with the relationships and interactions between organisms and their environment, including other organisms.