SN2 Biology Lecture 6: Intro to Ecology: Climate & Biomes PDF

SN2 Biology Lecture 6 Intro to Ecology Climate & Biomes chapter 52  Discovering Ecology Ecology is the scientific study of the interactions between organisms and the environment that determine the distribution and abundance of organisms. Interactions between organism...

SN2 Biology Lecture 6 Intro to Ecology Climate & Biomes chapter 52  Discovering Ecology Ecology is the scientific study of the interactions between organisms and the environment that determine the distribution and abundance of organisms. Interactions between organisms and the environment limit the distribution of species The structure and distribution of terrestrial biomes are controlled mainly by climate Terrestrial biomes A large land area with characteristic groups of organisms adapted to their physical environment. The reason we get all this variation is because of differences in local climates  Key points 1. Climate varies systematically on the planet 2. Solar radiation ultimately drives variation in climate 3. Climatic variation ultimately shapes broad- scale vegetation Understanding climate helps us account for the distribution of organisms because Earths biomes are an outcome of climatic forces.  Climate The long-term prevailing weather conditions in an area constitute its climate Four major abiotic components of climate are: o Temperature; o precipitation; o sunlight; o Wind Global climate patterns are determined largely by: o solar energy and o Earth’s movement in space  Climate is affected by Latitudinal Variation in Sunlight Intensity The angle at which sunlight hits Earth affects its intensity (amount of heat and light per unit of surface area) Intensity of sunlight is strongest in the tropics where sunlight strikes Earth most directly Equator: 1. More photons per unit area 2. Less atmosphere to pass through The poles receive about ½ as many photons as the equator per year  Latitudinal variations in climate High: Polar climates. One Season: COLD HIGH Middle: Temperate Climates MIDDLE 4 Seasons: Winter, Summer, Spring, Fall LOW Low: Tropical Climates 2 Seasons: Rainy, Dry MIDDLE HIGH The warming effect of the sun causes temperature variations, which drive evaporation and circulation of air and water This causes latitudinal variations in climate  Climate affected by Temporal variation in the distribution of solar radiation = seasonal variation Seasonality at high latitudes is caused by the tilt of Earth’s axis of rotation and its annual passage around sun  Climate is affected by Atmospheric circulation Beyond distance from the sun, other main sources for smaller-scale variation in temperature include: 1) Temporal variation – day/night and seasonal 2) Large scale movement of air & the mechanisms that create their differences across the Earth*. *To understand this, think about this:  Climate is affected by Atmospheric circulation Sunlight (solar radiation) In each hemisphere there are three “air” cells - next slide… Rising air expands cools releasing rain Warm moist air rises Tropical Desert Desert rainforest Equator  Global Air Circulation creates precipitation! 3 2 1 1 2 3 Each hemisphere is split into three convection cells Wet 60 N Dry / Wet at Dry 30 N equator 30 S  Implications of global patterns of air circulation & moisture These broad-scale patterns are a function of the interaction between the sun, air circulation, and moisture. Wet at equator Wet Wet 60 N 60 S Dry / Dry / 30 N 30 S So far pretty good match predicting where habitats such as tropical rainforest & deserts exists… 30°N 30°S  Other factors affecting climate OCEAN CURRENTS The UK & Europe are on the same line of latitude as Canada. o Do they experience the same climate? o North Atlantic Drift (red arrow) = warm current that flows up from the equator keeps Europe warmer than it should be at that latitude Oceans, their currents, and large lakes moderate climate of nearby terrestrial environments * Thurso Scotland & Juneau Alaska ~same latitude, but Thurso much milder than Juneau (*) * Pacific Coast cold Arctic water – Oregon & N. California are cool (blue arrow ; cool beaches) But East. N. America, current brings warm water from Caribbean = Warm beaches (red arrows)  How to Read a Climograph A climograph / climate graph, is a time-based graph that presents a location's average temperature and precipitation. Look at the title to see what location’s climate is being described by the graph. Line Graph = avg temperature Average for each precipitation month by month. Months of the year.  Other factors affecting climate Continentality: Effect of a location on a continent Why is there so little difference between summer and winter along the coast of California? o It takes the ocean a long time to heat & cool! o Wind blowing off of water moderates coastal areas. What is the difference between summer & winter in Saskatoon? BIG difference in seasons in Saskatoon …why? Land heats & cools quickly!! o Close to large body of water = smaller difference in temperature o Farther away from water = greater difference in temperature  Continentality: How Does It Affect Climate? Remember: continentality is the effect of location on a continent on the climate of a place. Inland locations typically have larger temperature ranges and (possibly) * * drier conditions than maritime locations. Compare these two locations. Which one is further inland? How can you tell?  Other factors affecting climate Mountains The higher you go, the colder it gets. As you go up in elevation, the air gets thinner and does not trap heat. Rising air releases moisture on the windward side of a peak and creates a “rain shadow” as it absorbs moisture on the leeward side Mountains affect the amount of sunlight reaching an area Every 1,000m increase in elevation produces a temperature drop of approximately 6°C  Elevation & vegetation Distribution of plants = ecology Remember: elevation affects climate, and climate affects the type of vegetation. In this photo, you can see the tree line-the highest point on a mountain that trees can survive.  Factors affecting Climate Sun: zones of latitude; temporal We’re here variation (seasons) Air Circulation: air circulation cells & moisture Ocean currents Continentality: location on continent Mountains / Elevation  Structure & distribution of terrestrial biomes tied to climate Biomes are major life zones characterized by vegetation type (terrestrial biomes) or physical environment (aquatic biomes) Biomes contain groups of organisms adapted to their environment. Climate is very important in determining why terrestrial biomes found in certain areas Rainfall and temperature are the two most important drivers  / Boreal Forest Quebec Biomes: Other: o Tundra – CA / QC o Tropical forest o Boreal Forest -- CA / QC o Desert o Temperate forest – CA / QC Climate vs. Terrestrial Biomes in North America Biomes are affected by average temperature and precipitation, and the pattern of temperature and precipitation through the year Terrestrial biomes are often named for major physical or climatic factors and for vegetation Terrestrial biomes usually grade into each other, without sharp boundaries  Terrestrial Biomes: Vegetation layers & plant types The forest floor is the bottom part of the forest. It is made of soil, dead plants, dead animals, and many small living plants The understory is the mid layer of a forest. Plants in the understory consist of seedlings and saplings of canopy trees, shrubs, grasses & forbs. Plants that grow in the understory must be shade tolerant because this layer receives much less intense light than the top layer of the forest The forest canopy refers to the upper layer or habitat zone, formed by mature tree crowns  Bijagua, Tropical wet forest, Costa Rica Tropical Rainforest Equatorial & subequatorial regions. 200 – 400 cm of rainfall a year (lots) Temp. high year-round! 25-29C average temp Vertically layered trees Plants evolved to grow quickly and high, not limited by water (competition for light!) Very high diversity of plants, animals, fungi (lots of sun & moisture year-round = lots of plants = lots of primary producers to support other life) Bijagua, Costa Rica in January Gunacaste, Costa Rica in January Wet Dry  Tropical Dry forests W E o Tradewinds cross the Caribbean, they warm and absorb moisture from the ocean. o But Costa Rica has a mountain range in centre, so as air rises it releases most of this precipitation on the eastern side of the central mountains. o Costa Rica’s mountain range force the air upwards causing the air to rise, expand, which creates cooling clouds Dry and rainfall. side o So, the West side is dry (for part of the year) and east side is wet. recall factors affecting climate Mountains Air rises and cools, releasing most of its moisture as precipitation On the leeward slope, the dry air descends and warms, and there is little precipitation. leeward slope / side Windward side Tropical DRY Tropical WET DRY WET  Desert o Distribution occur in bands around 30N & S o Precipitation LOW: