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Bud break, leaf expansion Why Monitor Leaf Phenology?

9:15 - 10:00 AM Approaches for determining growing season length Bud break, leaf expansion, litterfall. Estimation through heat-sum. Quantitative monitoring through sap flux.

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Bud break, leaf expansion Why Monitor Leaf Phenology?

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  1. 9:15 - 10:00 AMApproaches for determining growing season length Bud break, leaf expansion, litterfall.Estimation through heat-sum.Quantitative monitoring through sap flux.

  2. 1) Bud break, leaf expansion (leaf phenology) affect the cycling of water and carbon in the environment.2) In addition, leafing out is among the most sensitive biological responses to climate change. Therefore, leaf phenology records can help us understand plant responses to climate change. For example, across the world, many spring events are occurring earlier—and fall events are happening later—than they did in the past. Bud break, leaf expansionWhy Monitor Leaf Phenology?

  3. Bud break, leaf expansionWhy Monitor Leaf Phenology? Despite their importance, broadly distributed phenological data are relatively rare. With sufficient observations, we can document patterns of phenology for critical plant species across the state, and then use this information to build models to help us understand and adapt to changing landscapes and climates.

  4. Bud break, leaf expansion, litterfall.Main objectives for this coming year: Is the timing of spring tree phenology (green tip of leaf emerging from buds)and leaf out (full leaf development) different between West and East North Carolina?If so, what simple factors affect such differences?

  5. 1st assignment: Litterfall collection (useful for deciduous forests with adequate spatial and temporal sampling schemes)

  6. 2nd assignment: Estimation of bud break and full leaf development through heat-sum • What is the influence of temperature on bud break and full leaf expansion? • Definition: sum of number degrees of average temperature >5°C (41°F) for each day • Example: Grapes begin to grow when the temperature reaches above 10°C (41°F). To reach maturity, a total amount of heat above this temperature is required. Successful growth in Southern France for grapes is about 800°.

  7. 3rd assignment: Sap flow as a proxy for bud break?

  8. 3rd assignment: Sap flow as a proxy for bud break?

  9. 3rd assignment: Sap flow as a proxy for bud break?

  10. Notion of vapor pressure deficit • Vapor Pressure Deficit, or VPD, is the difference (deficit) between the amount of moisture in the air and how much moisture the air can hold when it is saturated (Wikipedia). • = driving force for transpiration

  11. Normalizing sapflow by VPD

  12. End leaf expansion? 100% 50% Bud break? 15% Sapflow corrected for VPD  conductance

  13. September October November December Litterfall and sapflow Cumulative litter

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