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UCSB EEMB 171 - Quiz 1 2016B Key (1)

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Your Name:EEMB/ES 171-Winter 2014 Quiz # 1 Read each question carefullyUse the back if you need to1. (6 points) What is soil texture? Texture is only the % mix of sand, silt and clay mineral particles. 2. (12 points). Why do ecosystem ecologists generally work with “functional groups” or “growthforms” of plants, rather than species? Because we are interested in biogeochemical processes and functions. Many species of plants are functionally equivalent—i.e. Mediterranean annual grasses all behave in very similar ways. Also, there are often too many species to consider individually—we need to condense down into a manageable number of groups. So full 12 point answer should hit both the idea of function and of numbers. Perfect answer that only considers one aspect is maximum 8 points. 3. (12 points). Briefly define the difference between Resistance and Resilience. Is the concept of resilience relevant in the face of ongoing increases in global temperature? Resistance is the ability of a system to resist change in the face of disturbance. Resilience is the ability of a system to recover to the initial state following a disturbance. Climate change is an ongoing and growing pressure—so a system can’t truly be “resilient” in the face of it because the disturbance is not going away. A system can be resistant and avoid changing substantially in the face of the constant stress of climate change. 6 points for adequately explaining the difference between resistance and resilience. 6 points for getting the connection to climate change.Your Name:4. (16 points). ClORPT is an important formula in ecosystem science. A. (10) What do the letters stand for? Very briefly, why are they each important?Cl Climate: Rainfall and Temp drive essentially all aspects of ecosystem function. O Organisms: those that have access to the site. Control the community composition.R Relief: the physical structure of the landscape that regulates energy input, erosion, etc.P Parent material: the geological substrate an ecosystem develops on. Controls the ultimate availability of mineral nutrients, the texture of the soils, hydrology, etc. T Time: Time controls how completely a system develops—soil weathering, plant succession, etc. 2 points for explaining each term. B. (6) If you were going to design a large-scale field experiment to analyze the influence of parent material on ecosystem structure and function, how would you use the ClORPT concept to guide developing that experiment? You would use ClORPT to help try to find sites where (to the extent possible) only P varied. So you’d look for a region in an area with a single climate zone, where the same plants have access to the site; you’d pick sites of similar slope and aspect, etc. E.g. find areas in the hills above Santa Barbara with different rock types. 5. (12 points) Many plants are highly tolerant of aboveground herbivory. They get between 50 and 90% of their leaves eaten and they grow back quickly. However, very few plants are tolerant of belowground herbivory. They get 20-25% of their root system eaten and they die. Why do youthink there is such a strong difference in responses to above and belowground herbivory?Leaves are the source of C and plants retain reserves in their stems. So if foliage gets eaten, they can continue to photosynthesize with the leaves that are left, and can use existing reserves to produce new ones. To do this though, they need nutrients and water, which an intact root system remains quite capable of supplying. But if the root system is disrupted, the demand for water remains high. Yet, the root system is now not able to provide enough and the plant becomes water stressed, that limits photosynthesis and the ability to supply C to produce new roots. The plant goes into a death spiral.Your Name:6. (14 points) Match up the specific ecological/hydrological terms with their closest analogies from economics and life:A) AET: Actual payment Monthly Income B) PET: Credit card bill Credit card billC) Rainfall: Monthly income An inheritance from a rich uncleD) Soil water storage: Savings account Actual payment to the credit card companyE) Groundwater Aquifer: Inheritance Size of your savings account Briefly explain each analogy.AET, PET, and Rainfall should be obvious. Soil water storage is renewable and can rise and fall with the seasons and shift in income and expense. That is equivalent to a bank account. A groundwater aquifer is deep storage of ancient water. It doesn’t easily recharge. Hence, it is equivalent to an inheritance. 1.5 points for getting each match correct. 6.5 points total for explaining the logic. 7. (14 points total? Or 8?). You are doing a water balance on an area. The following values are for the summer only. Briefly explain your answers.PET = 1200 mmRainfall = 1600 mmSoil water holding capacity = 300 mmSoil water at the beginning of summer = 100 mma) (8 points) What is AET for this summer? AET: Well. PET is less than rainfall. So AET = PET = 1200 mm. b) (6 points?) What is streamflow? Streamflow = Rainfall – AET – change in soil storage. There are 400 mm of excess rain after accounting for AET. Soil can hold an additional 200 mm of water. Ergo, 200 mm will run off. If you forget to account for changing soil storage the maximum possible score is 2.Your Name:8. (14 points) You are studying the productivity of a particular plant. You set up a factorial experiment with treatments of added nitrogen (N), phosphorus (P), and N+P plus a control. Then you measure growth. The data is in the table. Unfortunately, your research assistant lost one set of samples.Treatment Growth (g)Control 5+N 8+P Lost data+N +P 12A. (8 points) If Liebig’s Law were strictly true for this plant, what would you predict that growth in the +P treatment would be? Why?Liebig’s law says that ONLY one nutrient at a time may be limiting. Since adding N alone increased growth, that means that (if Liebig’s law is true) P alone can have no effect. Thus, the +P treatment would have to have growth exactly equal to the control: 5. B. (6 points) Your technician goes back to his lab notes, and says that he thinks the growth data for the P treatment was 10. How would that change your interpretation of the nutrient needs of this plant? What would that say about Liebig’s law?Since in fact, each N and P increased growth somewhat, then the plant was simultaneously co-limited by both N and P. This violates Liebig’s law and indicates


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