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Vertical Hydrologic Exchange And Ecological Stability Of Desert Stream Ecosystem

Vertical Hydrologic Exchange And Ecological Stability Of Desert Stream Ecosystem. Maurice Valett , Stuart Fisher, Nancy Grimm, and Philip Camill. Introduction. "Streams and rivers are open ecosystems that are heavily influenced by interaction with adjacent systems"

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Vertical Hydrologic Exchange And Ecological Stability Of Desert Stream Ecosystem

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  1. Vertical Hydrologic Exchange And Ecological Stability Of Desert Stream Ecosystem Maurice Valett, Stuart Fisher, Nancy Grimm, and Philip Camill

  2. Introduction • "Streams and rivers are open ecosystems that are heavily influenced by interaction with adjacent systems" • Material and Energy exchange • physical-chemical • Hyporheic Zone • Biota • distribution, diversity, abundance, compexity • Biogeochemical • saturated sediments • Nutrient transport • concentrations often high

  3. Introduction • Sonoran Desert Streams • Flash Floods • decimate biota • affect physical-chemical conditions • Spatial Intermittency • causes mortality • alters hyporheic conditions • Hydrologic Linkage • Resistance • Resilience

  4. Methods • Hypothesis: HyporheicZone (hydrologic linkage) would promote ecosystems resilience • Reach Morphometry and hydrology • Upwelling and Down welling • Nutrient Concentrations • NO3 -N • SRP • Chlorophyll & Phaeophytin and AFDM • Standing Crop • Post Flood Recovery

  5. Results: Physical Spatial Variation Exchange Upwelling Stationary Downwelling Figure 1

  6. Results: Physical Temporal Variation Exchange Upwelling Stationary Downwelling Figure 2

  7. Results: Nutrients Exchange effects on Surface Chemistry Table 1

  8. Results: Nutrients Exchange effects on Surface Chemistry Figure 3

  9. Results: Nutrients Exchange effects on Benthic Algal community Figure 4 Table 2 Upwelling Downwelling Upwelling Downwelling

  10. Results: Post Flood Recovery Exchange effects on Post Flood Recovery Upwelling Downwelling Figure 5

  11. Results: Post Flood Recovery Exchange effects on Post Flood Recovery Upwelling Upwelling Downwelling Downwelling Figure 5 Figure 6

  12. Results: Post Flood Recovery Exchange effects on Post Flood Recovery

  13. Discussion: Physical • Spatial: characterized by Vertical Hydraulic Gradient (VHG) • Summer Floods increased upwelling magnitudes within 2 days • Winter Floods decreased intensity of downwelling following a long post flood period • VHG increased after a lag (Post Flood)

  14. Discussion: Nutrients • NO3-N concentration strongly correlate with magnitude of upwelling • SRP dynamics controlled by physical-chemical processes • Upwelling supported larger algae communities but was related to time (days post flood)

  15. Conclusion • Link between hyporheic and benthic process • supply limiting nutrients • might be a source of algal drift and transport • Open nature of streams promotes • rapid recovery following disturbance • RESILIENCE RESISTANCE • physical • chemical • biological

  16. Arid fluvial (or riparian) ecosystems are subject to a pendulum of extreme conditions within a small-scale time and space continuum. • How does the hyporheic zone mitigate system stability in regards to resistance and resilience in response to a flash flood disturbance?

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