F 311 1st EditionExam # 2 Study Guide Week 6 Ecosystems and Soils Soils: What is it made of? - Forest ecosystems can only be sustained if soils are sustained.- Minerals: size, coarse fragment, sand, silt, clay make up 45% - Organic Materials: 5% of soil, half of chemical reactions occur here- Pores: air, water. 50% pores Mineral Particle Size and organic matter: - Clay: very small <2 micrometers (10^-6) - Silt: Medium between 2 micrometers and 50 micrometers- Sand: Large between 50 micrometers and 2 millimeters - Clays have the most surface area and sand has the least, therefor clay holds on to water more strongly and holds more water. - Coarse texted soils have higher flow rates of water - Soil particles bound together to form aggregates - Macropores= space between aggregates - Warmer soils have more organic matter because there is more decomposition and production in the soil Soil element nutrients for plants and effect of nutrients on growth:- Trees need more than a dozen elements, C, O and H are the three biggest, these elements come from the atmosphere and water.- N, P, Ca, K and Mg are important as well. N and P limit forest growth, Ca, K and Mg sometimes limit growth - More nutrients commonly means more growth - N= needed for proteins, enzymes, DNA- P=needed for ATP, lipids, DNA- K= needed for activating enzymes, salt levels - Ca= needed for cell walls- Mg= needed for chlorophyll, enzymes - Micronutrients= Iron, manganese, Zinc, Boron These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Fertilizing soils increases production of forests it produces more leaves and more growth per leaf, can be twice as profitable when comparing cost of fertilizer and production - Some plants have evolved to fix nitrogen with N-fixing bacteria that breaks the N2 bond in the atmosphere, many legumes do this, adding N fixing plants can increase the productivity of surrounding plantsCompaction:- Fertile soils have pore spaces for air and water, roots also need pore spaces to be able to push through soils- The more compaction in a soil the less pore space, this makes it harder for roots to penetrate thesoil- Bulk Density= Dry mass of the soil per unit of soil volume in kg/L - Coarse Fractions=Stones and rocks Soil development over time: - Soils develop on original parent material- Soil change over time does not necessarily affected growth or production - Soils change dramatically in a season and through generations Week 7 Productivity and Growth Decline NPP, GPP and tree carbon balance limitations:- NPP= GPP-respiration - GPP=Photosynthesis of the whole ecosystem - R=metabolic costs for growth and metabolism - NEP= NPP-what dies and decomposes - Tree carbon balance = GPP, Foliage NPP 4-13% , Wood NPP 9-47%, Foliage Rs 10-31% , Wood Rs 4-25% , TBCA (root production+resperiation+exudates+mycorrhizae) 26-62%Production ecology equation:- Production can be measured as mass or by the energy content of the mass, biologic materials have similar energy contents - Production= resource supply x proportion of supply captured x efficiency of using captured resource - Wood production= production – respiration and allocation to other tissuesDiameter and biomass growth of individual trees:- Trees slow down in diameter growth while accelerating in stem mass growth. This is because mass goes up faster in relation to diameter as diameter increases - Greatest total wood production always comes at highest density, but high total volume for densestands comes at a cost - The average tree per acre goes down as tree size increases Tree and forest lifespan: - Forests all show a decline in wood production with age, usually after leaf area peaks on trees- Forest age may alter water use and runoff - The basis of econ decisions in forestry is the length of the rotation - Wood growth often peaks at canopy closure and declines from there Hypotheses for stand growth decline with age/size:- Key problem in forest biology is figuring out where does CO2 go once it reaches the forest? - Working with fast growth forests, comparing physiology of young and old trees are ways of studying the C02 question - Fast growing tropical plantations are great for experiments because they are easy to manipulate - Hypothesis 1: Wood growth declines because of increased respiration (disproved)- Hypothesis 2: Reduced nutrient supply with stand development reduces wood growth (disproved)- Hypothesis 3: Increased allocation to non-woody components reduces wood growth (disproved)- Hypothesis 4: increased dominance causes a decline in wood growth because subordinate trees are less efficient at using resources meaning less photosynthesis or more allocation away from wood (disproved)- Hypothesis 5: Decreased GPP causes a decline in wood growth because nutrient supply drops or hydraulic limitation or genetic change or growth limitation (supported)- A decline in canopy photosynthesis not respiration or nutrition caused a growth decline in Eucs- Estimating GPP is hard to do, measure all components and estimate GPP by sum - Ultimate reason for decline in photosynthesis and efficiency remains a mystery Self-thinning:- Self thinning is the non-rapid amount of mortality in a forest - The ability of one tree to dominate another by using up the sites resources depends on the difference in sizes of trees - The size relationship often looks like a slanting line on a graph where you can easily get the slopeWeek 8 SuccessionCAI and MAI:- CAI= current annual increment, volume growth rate for current year or between measurement periods (vol-vol1/age-age1)- MAI= mean annual increment, average volume growth rate over entire life of stand, (vol/age) Succession definition and arguments against it:- Succession= physical environment modified by the community, orderly process of community development that is directional and predictable, culminates in a stabilized ecosystems (climax system) where maximum biomass and symbiotic function between organisms are maintained per unit of available energy flow, vegetation alters site and prepares for its next arrivals (Clements/relay florists), species colonize suitable sites in a scramble and far dispersers or fast growers dominate at first (Gleason/initial florists), disturbance changes communities and can restart the clock of succession or shift a system into different states- Arguments against succession: 1. Succession is not a