Robert W. ChristophersonCharlie Thomsen

Chapter 19Ecosystem Essentials

Vocalic Eruption in Iceland

Flight Cancellation

Earth’s Major Plates

Figure 11.17

Arrows represent 20 million years of movement.

The space on Earth where life exist forms a sphere which extends from ocean floor to ~8km altitude into the atmosphere.

Ecosystem: A self-sustaining association of living plants, animals and microbes and their nonliving physical environment. 1) Natural ecosystems are open systems with respect to energy and matter.

2) Ecosystem boundaries often function as transition zone, not sharp demarcations.

3) Natural ecosystems can varying significantly in size

Biosphere

Ecology is the study of the relationship between organisms (human beings, plants, animals, microbes) and their environment.

a) the living organisms have impacts on the environment.

lichens/mosses grow on rocks soils growth of trees add litter to soils more fertile soil wolfs eat deer reduce deer population less grazing b) through altering the environment, their impacts also have feedbacks

to themselves. lichens/mosses grow on rocks soils higher plants to grow lichens/mosses compete out Wolfs eat deer reduce deer population less food for wolf

Ecology

Deforestation: timber economic gains better life more people more space for agriculture more food more people loss of other lives loss of resources soil erosion land degradation less foodAgriculture more food more people expansion loss of other land (grass, forest, wetland …) fertilization/pesticide more food pollution diseaseUrban expansion better living more people expansion loss of other landsFossil fuel use better living more people global warming/pollution

Humans as Most the Active Agent

Like any system in general, it is made up of several components, each function independently yet in concert.

biotic

individuals population Communities producers (plants), consumers (animals), decomposers

Abiotic Ecosystem Components

soils, light, heat (temperature), water, air   As ecosystems are open systems, there are constant flow of

energy and matter through the system to keep the system alive.

Ecosystem Components

Biotic and Abiotic Components

Figure 19.2

26126roplastlight/Chlo

22 O6OHCO6H6CO

Small Leaves do the Big Job: Photosynthesis

CO2

H2O

Losing water is the price to pay for gaining CO2

Plants also keep cool with transpiration (1) cools leaves (2) brings nutrients to where they are needed

stoma

Underside

Stomatal Regulation

1. Stoma opens when light shine on the leaf, thus opens during the day to absorb CO2 and closes during night to prevent unnecessary water loss.

2. Stoma closes when there is limited water in the soil.3. Stoma closes when the air is too dry, i.e. high vapor pressure deficit. 4. Stoma closes to save water when CO2 concentration is high in the air.

Gross Primary Production and Respiration

GPP: Gross Primary Production, the amount of carbohydrate (C6H12O6) produced through photosynthesis is called GPP.

Plant Respiration: All living organism needs energy to stay alive. Plants do too. Plants use about 50% of GPP they produce to stay alive. The respiration is the opposite process of photosynthesis. We call this respiration as autotrophic respiration (Ra).

Energy OHCOOOHC 2226126

Autotrophic respiration is use for two purpose: (1) to keep living tissues alive, called maintenance respiration. (2) To realize growth, call growth respiration.Note: Energy is not heat energy as said in the textbook, but energy in the

form plant can use, ATP (Adenosine Triphosphate)

Net Primary Production

NPP: Net Primary Production is the balance of GPP after plant respiration (autotrophic respiration) is taken away.

NPP = GPP – Ra

NPP is the part of photosynthesis product that can be used for growth, including

LeavesBranchesStemsRoots

Part of NPP become food resources available for the consumers ( herbivores, carnivores, humans)

Biomass vs. Net Primary Production

BiomassThe dry weight of the living organisms. e.g. the total dry weight of leaves, branches, stems, and roots would be the biomass of a tree, not including the dead leaves or stems on the floor.

For plants, Biomass is the accumulated NPP that stays as part of the living organism. Due to litter fall and mortality, Biomass is less than the annual NPP added up. Biomass is a cumulative figure, NPP is an annual figure.

For forests, the biomass eventually levels off as the addition of growth from NPP breaks even with loss of biomass due to litter fall and mortality.

Net Primary Productivity

Figure 19.7

Satellite measure of chlorophyll concentration

Carbon Cycle and Balance

Figure 19.10

Input: 6.3 (fossil) + 1.6 (landuse)=7.9Output: 1.4 +1.7 =3.1Balance: 7.9-3.1 = 5.8Actual increase seen: 3.2Missing 2.2 C in the atmosphere: missing sink

Producers, Consumers, and Decomposers

Producers: Plants on land Phytoplankton in oceans

Consumers: Primary (herbivores), secondary (carnivores), tertiary (carnivores), omnivores

Decomposers: bacteria and fungi  

Energy/Matter Flow in Ecosystems

Energy, Nutrient, and

Food Pathways

Figure 19.13