Understanding Biomes and Terrestrial Ecosystems

• Biomes are basic units of the biosphere.
• A biome is a large geographical region with a particular climax community.
• Earth's biological communities are organized based on dominant vegetation, geographic location, climate, and other factors.
• Physical environment aspects include precipitation, temperature, and water depth.
• These aspects have a strong influence on species' traits living in that environment.
• The same biome can occur geographically in distinct areas with similar climates.

Terrestrial Biomes

• These are large-scale environments characterized by temperature ranges and precipitation amounts.
• Temperature and precipitation affect the types of vegetation and animal life that can exist in those areas.
• They are ecosystems on land that are usually identified by the growth form of vegetation, climate and location.
• Major terrestrial biomes: tundra, forest, grassland and desert.

Tundra Biome

• Tundra is the coldest of all the biomes.
• The word tundra comes from the Finnish word "Tunturi," meaning "treeless plain."
• Tundra is a region south of the Arctic that extends across North America, Europe, and Siberia.
• Areas that would be tundra in the Northern Hemisphere are oceans.
• There are arctic and alpine tundras.
• Arctic tundra is cold and desert-like, located in the northern hemisphere.
• Alpine tundra is found on mountains throughout the world at high altitude, where trees cannot grow.
• A tundra biome is characterized by permafrost, frost-molded landscapes, low temperatures, little precipitation, inadequate nutrients, high winds, and short growing seasons.
• Lichens, mosses, grasses, sedges, and low-growing shrubs are prominent.
• Animals include: reindeer, caribou, wolves, arctic hares, arctic foxes, and snowy owls.

Taiga (Boreal)

• Represents the largest terrestrial biome, occurring south across the tundra.
• Trees become more extensive and closer, giving way to evergreen forests.
• This evergreen forest belt is found in Eurasia and North America: two-thirds in Siberia, the rest in Scandinavia, Alaska, and Canada.
• It has frigid winters and cool summers with moderate to low precipitation.
• It has a growing season of about 120 days.
• Consists mostly of evergreen trees (conifers with needle-like leaves, such as pine, fir, and spruce).
• Varying animal species can be found in the summer, e.g. woodpeckers, hawks, moose, bear, weasel, lynx, fox, wolf, deer, hares, and chipmunks

Forest

• Characterized with trees and other woody vegetation.
• Can be classified by numerous characteristics, with seasonality being the widely used.
• Tropical rainforests have the most remarkable species diversity.
• Occur around the equator, where the climate is uniform throughout the year.
• Typically warm and moist.
• Different species of trees have large, broadleaves, thick vines and many epiphytes attached.
• The rainforest also inhabits a wide array of animal species such as snakes, lizards, frogs, lemurs, sloths, monkeys, and colorful birds.
• Varying rainfall amounts characterize temperate deciduous forests.
• Found in Europe and Eastern North America.
• It has moderate temperature and rain, long winters, and seasonal animals.
• Common trees: oak, maple, hickory, chestnut, shrubs, small trees, herbaceous plants, ferns, lichens, and mosses.
• Varying animals can be found e.g. wolves, gray foxes, bobcats, deer and squirrels

Grassland

• Grasslands are dominated by grasses rather than large shrubs or trees and occur in temperate and tropical climates.
• This biome has hot summers and cold winters, moderate to low precipitation, grasses and small shrubs, and large mammals or a variety of smaller ones.
• The world's grassland includes the Savanna of South Africa, Steppes of Russia, Pampas of South America, and Prairies of North America.

Desert

• Occurs in hot and dry climates.
• Soil is sandy and poor.
• Characterized by specialized vegetation, especially cacti with reptiles (snakes, lizards), insects, scorpions, and rodents.

Aquatic Biomes

• Classified into two categories: marine and freshwater biomes.

Marine

• Water depth distinguishes between marine biomes and whether there is a substrate on which organisms can attach.
• Ocean, coral reefs, and estuaries are the three types of the marine biome.

Oceans

• Large bodies of water (more than 70%) that dominate Earth's surface.
• Largest of all the ecosystems.
• Organisms include benthos, planktons, and nektons.
• Benthos lives on the ocean floor like clams, starfish, and snails.
• Plankton are small organisms floating near the surface and carried by current like protozoa, algae, and tiny crustaceans.
• Nekton are free-swimming organisms like fishes, squid, turtles, and whales.
• Zones of oceans: intertidal, pelagic, abyssal, and benthic; have a great diversity of species.
• The intertidal zone is where the ocean meets the land and where the high and low tides occur.
• Neritic zone extends to depths of about 200 m at the edge of the continental shelf, where photosynthesis occurs.
• Characterized with well-oxygenated water, contains silt, low in pressure, and has a stable temperature.
• Phytoplankton and floating Sargassum (marine seaweed), zooplankton, protists, small fishes, and shrimp are found in the neritic zone.
• The neritic zone is the food chain base for most of the world's fisheries.
• The pelagic zone is the open ocean, within this realm is thermal stratification.
• The photic zone of the sea is approximately 200 m, where light can penetrate.
• Below 200 m, is the aphotic zone, where light cannot penetrate.
• The flora in this zone includes surface seaweeds, and the Fauna consist of many fish and some mammals species.
• Beneath the pelagic is the benthic, deep-water region, which is beyond the continental shelf and consists of sand, silt, and dead organisms.
• As depth increases towards the abyssal zone, temperature decreases and light cannot penetrate further.
• High level of nutrients wherein diverse fungi, sponges, sea anemones, marine worms, sea stars, fishes, and bacteria exist.
• The abyssal zone is the deepest part of sea, characterized by a very low temperature, very high pressure, oxygen content, and a low nutrient content..
• Mid-ocean ridges, often with hydrothermal vents, are found in the abyssal zones and the ocean floors.
• Chemosynthetic bacteria used the hydrogen sulfide and emitted minerals from the vents, thus the food web start as invertebrates and fishes eat them.

Coral Reefs

• One of the most diverse ecosystems globally.
• Widely distributed in warm shallow waters, tropical seas, and others in the cold, dark depths of the ocean.
• Corals are the dominant organisms.
• Consists of both algae (zooxanthellae) and animal polyps responsible for building.
• Coral reefs can be found as barriers along continents, fringing islands, and atolls and considered as the rainforest of the sea.
• The "Coral Triangle" is the most extensive coral reef ecosystem, found as part of different countries like the Philippines, Indonesia, Malaysia, Papua New Guinea, the Solomon Islands, and Timor-Leste.

Estuaries

• Areas where freshwater merges with the ocean.
• Different salt concentrations create a fascinating, diverse, and unique ecosystem.
• Forms protected areas for many young offspring of crustaceans, mollusks and fish to begin their lives.
• Salinity influences organisms to adapt to this type of ecosystem.

Freshwater

• Includes standing water (lakes and ponds), flowing water (rivers and streams), and wetlands.
• Has a low salt concentration.
• Distinguished by characteristics such as water depth.

Ponds and Lakes

• Vary in size from a few square meters to thousands of square kilometers.
• Ponds last a couple of months, while lakes may exist for hundreds of years or more.
• Divided into three different "zones," usually determined by depth and distance from the shoreline.
• The littoral zone, the topmost zone near the shore of a lake or pond is usually is the warmest zone.
• It is shallow and absorbs more of the Sun's heat.
• It sustains a relatively diverse community of algae species, rooted and floating aquatic plants, snails, clams, insects, crustaceans, fishes, and amphibians.
• Vegetation and animals are the base food for other organisms, such as turtles, snakes, and ducks.
• The limnetic zone is near-surface open water, well-lighted, and is dominated by planktons.
• The profundal zone is the cold, deep-water part of the lake/pond; it is where plankton falls into when they die.

Streams and Rivers

• Streams and rivers are bodies of continuously flowing water that carry large amounts of water from the source (headwater).
• The source water is characterized as cold, low in nutrients, and transparent.
• Water flows from the source, causing the width of the channel gradually to widen and the current to slow, and travels through the opening.
• The water becomes warmer and murky from all the sediments that upstream has picked as it is near the mouth (opening).

Wetlands

• Wetlands are areas in which the soil is either permanently or periodically saturated with water.
• It is composed of shallow bodies of water like marshes, swamps, and bogs.
• Vegetation consists of plants rooted in the soil but has portions of leaves, stems, and flowers extending above the water's surface.