Intro to Ecology/ physical environment

what is ecology?

• scientific study of interactions between organisms and between organisms and their environment

• NOT environmental, conservation, resource management

example of hypothetico deductive method

observation: climate change is happening, marshes are getting saltier

question: how does saltwater intrusion affect bald cypress trees?

hypothesis: salinity negatively affects bald cypress

prediction: if you grow bald cypress seedlings in 0ppt and 20 ppt salinity, the high salinity group will have lower survival

if amphibian decline is occurring across the globe and the mountain yellow legged frog is endangered with lower population density with invasice trout full lakes and higher without invasive fish what is the:

ecological question?

hypothesis?

formulate prediction and describe how to test hypothesis

ecological question (broad): why are frog populations declining?

hypothesis: the invasive trout species (predators) are negatively impacting the frog population

prediction: if you were to remove the trout (predators) the frog populations would increase

• test by removing trout and count the frog populations before and after

what does physical environment include/ mean?

• is the ultimate determinant of where organisms can live, resources available, population growth rate

• includes:

  • climate (temperature, wind, precipitation, radiation)

  • chemical environment (salinity, pH, gases in atmospher/ water)

  • soil environment (nutrient cycling)

climate vs weather

weather: current temp, humidity, precip, wind, cloud cover

climate: longterm description of weather based on averages and variation meausured over decades

geographic distribution of organisms

• determined by clinate

• average conditions

• variability over time

  • climate extremes

  • timing and seasonality

• affects rate of weathering (nutrient) and distrubance (fire, hurricanes)

what drives climate?

• the sun is the ultimate sourve of energy that drives the global climate system

• if earths temperature is to remain the same, energy gains from solar radiation must be offset by energy losses

hadley cells

• tropical uplift

• rainy in the tropics and dry high pressure zones at 30 latitude (deserts)

polar cells

• cold dense air subsides at the poles and moves toward equator

• polar deserts

ferrell cells

• intermediate cell creating the temperate zones beteen 30 degree and 60 degree latitude

coriolis

• air circulation patterns combined with the rotation of the earth create east/ west prevailing wind patterns

  • ocean currents driven by surface drag of prevailing sinds

  • can affect air temperature and precipitation on land

regional climate influences: proximity to oceans

• maritime less variation vs continental climate

• water has higher heat capacity tan land, can absorb/ store more energy without changing temp

• source of moisture

regional climate influences: mountains

• rain shadow effect

• lapse rate: temperature decreases with elevation b/c there are fewer air molecules to absorb heat

vegetation

albed: the anout of solare radiation that a surface reflects light colors, more albedo, less heating of the land surface

texture: rough surfaces allow greater transfer of energy by wind (convection than smooth: more vertical heat transfer out of the system

evapotranspiration = evaporation and transpiration

• reduce air temperatures and moves moisture from soil to air

how does deforestation affect climate?

• evapotranspiration and latent heat loss decreases, so does precipiation

• albedo increase'

• sensible heat loss increases

net surface increase, precipitation decrease

what happens when earth’s surface is warmed?

• solar radiation heats earth’s surface which emits infrared radiation and wamrs the air above it

• warm is less dense than cool air, and it rises (uplift)

• atmospheric pressure decreases with altitude, so the rising air expands and cools, water vapor and forms clouds

what determines a location’s climate

• seasonal climate variation temperature, precipitation

seasonal climate variation: temperature

• tilt from the earths axis relative to its plane of revolution around sun

• temperature and polar regions pronounced changes in temperature due to variation in solar radiation, angle intensity due to amount of atmosphere, length of day

• NH: solar radiation peak june 21 and SH: december 21

seasonal climate variation: precipiation

• intertropical convergence zone (ITCZ): zones of maximum solar radiation and atmospheric uplift

  • 23.5N in june and 23.5S in december

• tropical regions experience a lot of variation precipitation but not in solar radiation

chemical environment

• salinity

• pH

• oxygen

salinity

• concentration of dissolved salts in water

• salts: positively and negatively charged ions that disassociate in water

  • affects ability of orgnaisms t take up water ad nutrients

• salinity of the oceans and water bodies varies

  • evaporation, precipitation, sea ice melting, input of salts

  • dead sea 337 ppt ocean water average 35 ppt

• salinization

salinization

soils in arid regions become saline when water is brought to the surface by roots or irrigation and high rates of evapotranspiration result in salt build-up

pH

• pH of water influences metabolic functions and chemistry/ availability of nutrients

• organisms have a limited range of tolerance

• more important in freshwater systems bc ocean salts buffer pH (bind H+)

• soil depends on parent material (granite = cidic, limestone = basic)

  • as soil develops pH decreases due to organic matter input and easy leaching of basic ions

oxygen

• most organsim require O2 for metabolism exceptions though

• oxygen concentrations in atmosphere 21%

• vares substantially in soils and aquatic environments

  • oxygen diffusion is lower than consumption by organisms

  • low oxygen n deep waters, ocean/ lake sediments, flooded soils

  • waves ad currents can mix oxygen