Countdown to 5/23/11

1.1.4 Describe how the first and second Laws of thermodynamics are relevant to environmental systems. Energy exists in a variety of forms Can only change forms – not created or destroyed. 1 st law = conservation of energy -> enters system in form of sunlight – converted to biomass by photosynthesis – passed along food chains as biomass – consumed & ultimately leaves ecosystem as heat.  The total amount of energy in a system doesn’t change, but the amount of available energy does.  Energy is less usable at end of system than at beginning.  2 nd law states that energy goes from a concentrated form into a dispersed form.  Availability of energy to do work diminishes  System becomes disordered  Energy moves in one direction.

Environmental systems 1 st and 2 nd laws of thermodynamics still apply

1.1.5 Explain the nature of equilibria Open systems tend to have a state of balance among the components of a system. Allows systems to return to an original state following disturbance. Steady-state equilibrium Typical of most open systems in nature. Fluctuation in system and deviation results in a return towards it Static equilibrium No inputs or outputs of matter or energy and no change in system over time (flat line). Stable and unstable equilibrium If return to original equilibrium after disturbance = stable If forms new equilibrium = unstable

Equilibrium examples Steady-state, static, stable, and unstable equilibrium

1.1.6 Define and explain the principles of Positive and negative feedback. + Feedback happens when a change in the state of a system leads to additional and increased change. - Feedback works by reducing the effect of one of the system’s components. Act as stabilizing forces within systems -> steady-state equilibrium.

Positive and negative feedback loops + amplifies or increases change - tends to neutralize or counteract deviation

1.1.9 Construct and analyse quantitative Models involving flows and storages in a system. A model is a simplified description designed to show the structure or workings of an object, system, or concept. Can be used to show quantitative flows and storages in a system.

Evaluate the strengths and Limitations of models. Have advantages and disadvantages. Adv – predict and simplify complex systems, adjustable without waiting for outcomes, results can be shown to other scientists and public  Dis – may not be accurate, they rely on the expertise of the people making them, may be interpreted differently by different people, only as good as the data going in, different models may show different effects using the same data.

2.1.4 Explain the principles of pyramids Of numbers, pyramids of biomass, and pyramids of productivity, and construct such pyramids from given data. Graphical models of quantitative differences that exist between trophic levels of a single ecosystem Pyramid of numbers – populations at different trophic levels…not always pyramid shaped. Pyramid of biomass – shows masses at different trophic levels…can be pyramid shaped. Represent momentary stock Pyramid of productivity – similar to biomass pyramid but also includes the rate of restock.

Pyramids Biomass and productivity

2.3.3 Describe and evaluate methods for Estimating the biomass of trophic levels in a community. Usually use dry weight Samples massed and multiplied by population estimate for area

2.3.5 Apply Simpson’s diversity index and Outline its significance. Diversity is considered as a function of two components: the number of different species and the relative numbers of individuals of each species. D=diversity index N=total number of organisms of all species found n=number of individuals of a particular species. Sigma = sum of See sample problem pg. 35

2.5.6 Define the terms and calculate the Values of both gross primary productivity (GPP) and net primary productivity (NPP) from given data. GPP is the gain by producers in energy or biomass per unit area per unit time. Difficult to calculate NPP is the gain in energy or biomass per unit area per unit time remaining after allowing for respiratory losses. Look at practice problem pg. 54

2.5.7 Define the terms and calculate the The values of both gross secondary productivity (GSP) and net secondary productivity (NSP) from given data. Animals do not use all the biomass they consume. Some is excreted GSP in animals is the amount of energy or biomass assimilated minus the energy or biomass of the faeces. Some of the energy assimilated by animals is used in respiration, to support life processes, and the remainder is available to form new biomass (NSP). This is the new biomass that is then available to the next trophic level. Practice probs. Pg. 54

2.6.3 Describe the role of density- dependent and density-independent Factors, and internal and external factors, in the regulation of populations. Density dependent factors are related to population density. Competition for space, resources, disease, parasitism, and predation are all examples. Tend to be biotic Density independent factors are unrelated to population density Tend to be abiotic Density independent factors are unrelated to population density cont. Extreme weather events, long term climate change Internal factors include density- dependent fertility or size of breeding territory, and External factors include predation or disease.

DI or DD?

2.6.7 Describe factors affecting the nature Of climax communities. Climatic and edaphic (characteristics of the soil)factors, and human activities determine the nature of a climax community.