Fix the mistake: Diversity and Distribution of Vegetation

Vegetation, Physiognomy, and Life Forms

The group of plants growing in a particular place is called vegetation. Vegetation displays a characteristic appearance (physiognomy) depending on climate and topography.

Basic Knowledge

Vegetation refers to all the plants growing in a region, while its characteristics in terms of appearance are called physiognomy. The dominant species, which has the greatest number of individuals and characterizes the vegetation, determines its physiognomy. For example, in Japan's warm-temperate zone, evergreen broad-leaved trees such as sudajii and arakashi are dominant, and the vegetation is called a laurel forest.
A classification of plant forms and lifestyles is called life forms. The classification by Raunkiaer (Raunkiaer) is famous. Based on the position of dormant buds, plants are classified into ①phanerophytes (buds 30cm or more above the ground), ②chamaephytes, ③hemicryptophytes, ④cryptophytes (such as bulbs), ⑤therophytes (overwintering as seeds), and ⑥hydrophytes. The dominant life form differs according to climate zone: phanerophytes prevail in the tropics, while hemicryptophytes prevail in polar regions.
Vegetation is broadly classified into forests (tall trees), grasslands (herbaceous plants), and deserts (sparse vegetation).

Key Terms
Vegetation (all plants growing in a region)
Physiognomy (the outward appearance of vegetation: forest, grassland, or desert)
Dominant species (the species with the greatest population or occupied area that determines physiognomy)
Life forms (classification based on plant form and growth style)
Raunkiaer's life forms (classification based on the position of dormant buds)
Stratification (the vertical structure of a forest, including the canopy, subcanopy, shrub, herb, and ground layers)

Further Exploration

Forests have a vertical stratified structure, divided from top to bottom into the canopy layer (20m or higher), subcanopy layer, shrub layer, herb layer, and ground layer. Each layer has a different light environment, and the amount of light reaching the lower layers decreases sharply. Shade plants, which can grow even in weak light, dominate the lower layers, while sun plants, which require strong light, dominate the upper layers. This creates resource partitioning for light.
The ground layer contains forest-floor plants and the litter layer, where organic matter decomposes and nutrients cycle. A forest is not merely a collection of trees but a sophisticated three-dimensional structure in which light, water, and nutrients are shared. Even under the same climate, when forest structure becomes stable, its physiognomy eventually becomes stable as well (this will be studied later in succession).

Key Points
  • Vegetation = all plants in a region; physiognomy = its outward appearance
  • Dominant species determine physiognomy
  • The three major physiognomic types are forest, grassland, and desert
  • Raunkiaer's life forms are classified by the position of dormant buds
  • Forest stratification ranges from the canopy layer to the ground layer
  • Sun plants occupy upper layers and shade plants occupy lower layers
  • Forest-floor plants and the litter layer support nutrient cycling

Points to Note

① Distinguish vegetation (a group of plants) from physiognomy (outward characteristics). ② A dominant species is not simply a numerous species; it characterizes the vegetation. ③ Raunkiaer's classification is based on the position of dormant buds, not their shape or size. ④ Forest stratification consists of the canopy, subcanopy, shrub, herb, and ground layers. Do not confuse the order.

Practice

  1. What is the outward characteristic of vegetation called?
  2. What part of a plant did Raunkiaer use as the basis for classifying life forms?
  3. What is the uppermost layer of a forest's stratified structure called?

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