Chapter 52: An Introduction to Ecology and the Biosphere

Chapter 52: An Introduction to Ecology and the Biosphere (Book notes) 52.1 Earth’s climate varies by latitude and season and is changing rapidly. Climate: The long-term prevailing weather conditions in each area 4 factors affect climate:     Temperature Precipitation Sunlight Wind Global climate patterns are determined by the amount of sunlight and the Earth’s movement in space Latitudinal variation of sunlight intensity happens because of both the Earth’s shape and tilt on its axis. This causes the tropics to be hit directly and as you go further away from the tropics the more diagonal the angle. Global air circulation and precipitation patterns: The sunlight that hits the equator causes the global pattern of circulation and precipitation. The water evaporated at the equator rises and then cools and lets off the water as rain which flows away from the equator till about 30 o N and S. This dry air then picks up moisture and flow back to the equator and flows to the poles creates a cold and rainless environment. Other things that affect climates Seasonality: Because the Earth is revolving around the sun, it varies the amount of sunlight that reaches the hemispheres and affects things such as day length and temperature which can lead to a change in the environment and help animals and plants. Bodies of water: Ocean currents influence climates along coasts by heating or cooling overlaying air masses that pass across the land which can also bring rain and can moderate climates of nearby land. This only really works on the coast itself and fades as you go further inland. Occurs often in the Mediterranean. Mountains: These can also regulate air flow over land. When warm air approaches a mountain, it rises and cools causing rain on one side of the mountain and then a desert or other different climate on the other side. This is called a rain shadow. They also affect sunlight and the temperature on both sides. All three of these factors lead to species changing on either side of it. Organisms also affect Climate Forests absorb more sunlight, but this heating is going to be offset by transpiration which allows a cooling effect and increased precipitation. Deforestation causes these environments to become hotter and dryer. Microclimates: very localized, fine patterns in climates conditions such as under a shady tree, under a rock, a burrow Abiotic: nonliving factors that interfere with the distribution and abundance of organisms. Ex: sunlight, nutrients, fire, etc. Biotic (Not the ones from Mass Effect. Lol) : Living factors that interfere with the abundance of organisms Climate Change: The directional shift in the global climate that lasts 3 decades or more In response to climate change there are shifts in wind patterns and precipitation. This can either expand or constrict the dispersion range of a species and some species are not moving fast enough to keep up with the changes leading to decreasing populations 52.2 The Distribution of terrestrial biomes is controlled by climate and disturbances Biomes: Major life zones characterized by major vegetation in terrestrial biomes and physical environments in aquatic biomes. Climograph: A plot of the annual mean temperature and precipitation in a particular region Climograph are usually based on the annual averages but what is also super important is the pattern in climate variation such as the seasonality of rainfall or temperature fluctuations throughout the year. Ecotones: Places where two or more biomes overlap and can be narrow or wide. These are where biomes grade into one another. Many biomes containing trees have vertical layering of the vegetation which leads to things like different habitats for plants and animals Disturbances are a common feature of terrestrial biomes which keep the environment in constant flux and not a stagnant equilibrium. Some biomes even depend on them for survival. Disturbances: Events that change a community by either removing organisms from the biome or affecting resource availability. Events can include things like fires, storms, and human activity. These are several different terrestrial biomes with summarized characteristics:      Tropical Forest: The equator or sub-equator, in rain forest, there is constant rain, in a dry tropical forest it rains for 6 months and has a dry spell. High temperatures year-round with lots of vertical layering. There is high animal diversity, and a lot are living in other types of land. Desert: Usually around 30o or the interior of continents, low and variable rain with it varying by season and even day, usually filled with C4 and CAM plants, Water conserving animals, irrigation has brought many benefits though it has reduced diversity slightly. Savanna: occurs around the equator or sub equator, seasonal rainfall with a dry season, warm but has more seasonal variation, lots of grass with a few trees, large herbivores, insects, and carnivores, burnings have helped it survive but overharvesting and cattle has led to decline. Chaparral: Coasts at midlatitude, highly seasonal rain in the wet winters and dry summers, cool 3 seasons with hot summers, shrubs are small and fire-resistant , urbanization and fires reduce things Temperate Grasslands: Think the great plains, wet summer and dry winter, winters are cold and summers are hot, grasses with large grazers, most have become farm land    North Coniferous Forest: Right below the Arctic tundra, has rain but also has periodic drought, winters are cold and summers hot with many trees, many birds, not heavily bugs, logging is a particular interest here. Temperate Broadleaf Forest: Mid-latitude northern hemisphere, precipitation in all seasons, winters are cold, summers are hot and humid, deciduous trees are the primary plants, hibernating mammals, and birds migrate, most settled biome Tundra: Expansive areas over the Arctic and Antarctic, not very much rain, cold year-round, very low to ground plants, migrant game, mostly used for oil and minerals 52.3 Aquatic Biomes are diverse and dynamic systems that cover most of the Earth. Aquatic Biomes are characterized by both their physical environment and chemical environment. Many aquatic biomes have layers that go both vertically and horizontally. Photic Zone: The zone where enough light breaks through for photosynthesis. Aphotic Zone: The zone where there is little light that penetrates, and photosynthesis cannot occur. Pelagic Zone: It consists of the photic zone and aphotic zone in the open ocean. Deep in the pelagic zone is the abyssal zone which is 2000- 6000 m deep. At the bottom of these zones there is the benthic zone with sand and organic matter. Communities in this zone are called benthos and they feed on dead organic matter called detritus that comes from the upper water. Thermoclines: A narrow layer of abrupt temperature change that separates the warmer upper water from the lower cold water. Turnover: The mixing of waters because of changing water temperature profiles in a lake that allows oxygen-rich water to go to the bottom of the lake and the nutrient- rich water to rise. There are several different types of aquatic biomes with summarized characteristics:      Lakes: Oligotrophic lakes: Nutrient-poor and oxygen rich lake that is low in decomposition, Eutrophic lakes: Lakes that are nutrient rich but usually oxygen poor in deep parts or if there is ice, high in decomposition, Rooted and floating plants live in the littoral zone close to shore and limnetic zone away from shore is where phytoplankton and cyanobacteria live Wetlands: A habitat created by being inundated with water that supports plants that are adapted to water saturated soil, low in dissolved oxygen, high capacity to filter water, there are basin wetlands, riverine, and fringe wetlands Rivers and Streams: Speed and volume of moving water, salt and nutrients increase from head water to mouth, head water is usually rich in oxygen Estuary: The transition area between rivers and the sea, flows in the channels with their tides with varying salinity. Intertidal Zone: Periodically submerged or exposed to air based on the tides, upper zone experiences air and solubility changes and leads to strata, nutrients and oxygen are high and always refreshed with the tides.    Ocean Pelagic Zone: Open ocean constantly mixed and because of generally clearer water the photic zone extends to deeper, high in oxygen and low in nutrients Coral Reefs: Formed from Calcium Carbonate skeleton of corals and sensitive to temperatures, needs high amounts of oxygen, has lots of diversity Marine Benthic Zone: Seafloor of the coastal neritic zone, no sunlight, cold, high pressure , oxygen is sufficient 52.4 Interactions between organisms and the environment limit species distribution Dispersal: The movement of organisms or gametes away from the area of origin or centers of high population concentration. Range Expansion: An organism that reaches and lives in an area in which they did not exist previously, and this can lead to adaptive radiation. For an organism’s range to be considered expanded, the transplant needs to not only survive, but also successfully reproduce. There are biotic factors that can limit the range of organisms:    Predation Herbivores Parasites or Diseases There are also abiotic factors that can limit the range of organisms:  Environmental Temperature: Temperature affects biological processes and organisms need to prepare the biome’s temperatures.      Water and Oxygen: Animals rely on liquid water and need to be prepared to have ways to both find and conserve water and Oxygen is needed especially in aquatic environments where concentrations can be low. Salinity: Salinity affects osmotic balance and without a way to regulate that organisms would not survive Sunlight: While it can provide an input of energy into the ecosystem, there can be fierce competition if there is too little or heat, massive water loss, and possible DNA damage if there is too much PH: This affects the solubility of both nutrients and toxins and can limit through extremely basic or acidic conditions Soil and rocks: This can alter how plants grow in the environment and in aquatic biomes can affect the water’s chemistry. Organisms can be affected by their environments, but through their interactions organisms can also alter their ecosystems and adjust through evolution.