EEB142 Study Questions Answers

EEB142 Study Questions Answers - EEB142 Final Exam Study...

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EEB142 Final Exam Study Questions 1 1. What adaptations allow Spartina alteriflora to persist in low marsh areas? What positive interactions with invertebrate animals also aid in the survival of S. alterniflora? Arenchyma tissues brings oxygen to roots, which allows survival in low zone. Mussels through facultative mutualism, cordgrass provide attachment sites and enhance food supply for mussels; mussel filter feeding deposits nutrient-rich feces on roots and byssal threat attachment limits erosion. Fiddler Crabs also through facultative mutualism, fiddler crab oxygenate the soils through burrowing and deposit feeding (less decay) and removes dead plant material; cordgrass roots stabilize soil for burrows, loose enough to burrow, but dense enough to be stable. 2. Through what mechanism do S. patens and Juncus outcompete S. alterniflora? Through what mechanism does Juncus outcompete S. patens? S. patens and Juncus are root mats, which grow slower, but in long-run outcompete below-ground runners, which grow fast. Juncus outcompetes S. patens because it grows earlier in spring (pre-emptive competition). 3. Salicornia and Distichlis are found in areas with S. patens and Juncus. What mechanisms allow for this pattern? Salicornia disperses many seeds, seeds germinate in very saline conditions, colonizes early then displaced. Distichlis send runners into patches, runners send water, lowers salinity in patch through shading preventing evaporation, facilitates later growth of Juncus and S. patens. 4. How do Snow Geese positively affect arctic salt marshes when their population levels are low? When Snow Geese populations are high? Light-grazing: Snow geese stimulate productivity in thin plant population by feeding on grasses and “grub” by digging at shoots and roots; goose fecal matter fertilizes marsh. Overgrazing: Loss of marsh plant populations lead to hypersaline conditions, anoxic soils and plants can not reestablish population. 5. How do crabs and mussels indirectly benefit Spartina alterniflora in the lower areas of salt marshes? Fiddler Crabs also through facultative mutualism, fiddler crab oxygenate the soils through burrowing and deposit feeding (less decay) and removes dead plant material; cordgrass roots stabilize soil for burrows, loose enough to burrow, but dense enough to be stable. Mussels through facultative mutualism, cordgrass provide attachment sites and enhance food supply for mussels; mussel filter feeding deposits nutrient-rich feces on roots and byssal threat attachment limits erosion. 6. Explain three ways that humans are affecting the hydrological cycle. What is the overall impact in terms of freshwater availability for human use? Increasing runoff to sea: (1) impervious surfaces (asphalt) – water does not soak into ground and water
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This note was uploaded on 12/06/2011 for the course EEB 142 taught by Professor Halpin during the Fall '11 term at UCLA.

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EEB142 Study Questions Answers - EEB142 Final Exam Study...

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