### aggregation | vegetation | forest:

Tropical forest
* Many tropical forests are wetlands.
* Most tropical forests have several distinct layers.
* absorb much of carbon dioxide that is released in the atmosphere.
* are a key part of the world's environmental fabric
  - about to extinct
* are also subject to fires started by humans for agricultural clearing
  - very important economically for plant-improvement breeding
  - among the most threatened habitats
  - by no means the only sites with endangered biodiversity
  - characterized by the greatest diversity of species
  - cluttered with species
  - diverse and include hardwood trees like teak and mahogany
* are found near the Earth's equator
  - generally rainforests
  - great storehouses of natural life
  - home to more than half of earth's plant and animal species
  - the home to a huge number of animal species
  - under considerably high human threat
  - vertically more complex
* contain the finest hardwood timber in the world.
* cover a land area that is almost exactly the size of South America
  - half of the island
  - the coastal plains and the northern lowlands are semi-arid with savannah
* enrich our lives.
* harbor a far greater number and variety of species than do temperate forests.
* have a thin layer of soil that is kept in place by dense forest.
* have the highest bird species diversity and the tundra and open ocean the lowest
  - diversity of any biome
* provide global services as reserves of biodiversity and as carbon sinks.
* stabilize the world's climate.
* store much more carbon than eucalyptus.
* survives by rapid utilization of decomposing leaf litter.
* tend to be difficult to photograph
  - recover faster than their temperate counterparts

### aggregation | vegetation | forest:

Urban forest
* are small pockets of green in a gray landscape
  - the most visible element of the urban ecosystem
* build communities.
* can act as important stepping stones connecting ecosystems and benefitting wildlife
  - contribute to the economic vitality and the quality of life in cities
* contribute to clean air, cooling buildings, aesthetics, and recreation in parks.
* help reduce stormwater runoff, energy use and air pollution.
* is classified as wooded land surrounded by development
  - simply a forest that's maintained in an urban area
* lead to better air quality, cleaner waterways and more wildlife.
* provide habitat for wildlife.

Young forest
* capture more carbon from the atmosphere than old forests.
* have a well-defined shrub layer and understory.

### aggregation | vegetation:

Ground cover
* are essentially any plant used in a mass grouping to cover or hold the soil.
* are located in backpacks
  - forests
  - low-growing plants which can be used to cover an area in the landscape
  - slow in covering bare ground
* can include plants that are annuals, perennials, and shrubs.
* collect fallen leaves which become incorporated into the soil as organic matter.
* created by trees and associated debris protects soil from rill and sheet erosion.
* helps hold soil in place and dissipates some of the energy of rainfall.
* is cleared by overgrazing, scrub removed by burning, trees by felling
  - dense with a wide range of species
  - determined by counting the number of points that intersect residue
  - one ecologically significant function of the true mosses
* protects the soil from wind and water erosion, and from drying and crusting.
* provides wildlife habitat, reduces soil erosion and improves water quality.

Groundcover
* Some groundcovers are edible, such as strawberries or low-growing herbs
  - require less sunlight and less moisture and nutrients than grass
* also use less water and fertilizer.
* catch and slow rainfall and allow moisture to evaporate from leaf surfaces.
* come in a variety of textures and leaf shapes.
* help to suppress the growth of weeds.
* is vegetation.