Effects of moisture stress on Douglas-fir physiology and growth

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Effects of moisture stress on Douglas-fir
physiology and growth

• Tom Hinckley, College of Forest Resources,
  University of Washington, Seattle, WA

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Content of January 29 meeting - 1
Preface Introduction Context Methods
Impacts Water Nitrogen
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Content of January 29 meeting -2
Preface Introduction Context Methods
Impacts Water Nitrogen
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Content of January 29 meeting -3
Preface Introduction Context Methods
Impacts Water Nitrogen
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Outline
Preface Introduction Context Methods
Impacts Water Nitrogen

• Context
• Major physiological processes affected by
  moisture stress
• Methods for assessing tree moisture stress
• Water-use requirements
• Soil water tensions and plant water potential
  thresholds that result in growth reductions to
  growth cessation
• Does fertilization improve water-use efficiency?

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Whole Plant Context
Preface Introduction Context Methods
Impacts Water Nitrogen

• An integrated system
• Water loss at foliage level
• Water transport
• Water uptake
• Important to note that nitrogen stress has been
  regarded as the main control of growth
  productivity in Douglas-fir in PNW

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Simple Model of How Trees Might Respond to Stress
Preface Introduction Context Methods
Impacts Water Nitrogen

• Does the model work?

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Responses To Belowground Stress
Preface Introduction Context Methods
Impacts Water Nitrogen

• Tree Scale

Reich et al. (1980. Forest Science 26 590)
Quercus spp. Borchert (1975. Physiologia
Plantarum 35 152) Quercus spp.
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Individual Tree Response Cont.
Preface Introduction Context Methods
Impacts Water Nitrogen

• Experiment with Douglas-fir and nitrogen (Friend
  et al. 1990. Can. J. For. Res.)

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Stand Response
Preface Introduction Context Methods
Impacts Water Nitrogen

• Keyes and Grier (1981.CJFR) young and high site
  40-year-old Douglas-fir

Aboveground
Aboveground
Net Primary Productivity
Net Primary Productivity
Belowground
Belowground
Changes with Fertilization
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Broader Geographic Comparison
Preface Introduction Context Methods
Impacts Water Nitrogen
Pseudotsuga menziesii
Tsuga heterophylla
Lee et al. (2007. Forest Ecology Management
242 195)
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Site Water Balance Productivity
Preface Introduction Context Methods
Impacts Water Nitrogen
Soil depth texture Water holding capacity Full
April 1 Output Pan AET Input PPT Climate change
Pisi
Tshe
Mixed
Psme
Juoc

• Grier and Running. 1977. Ecology

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Take-home Messages
Preface Introduction Context Methods
Impacts Water Nitrogen

• Water and nutrients intertwined in PNW
• Young soils
• Climatic regime
• Water long enough, would change site class
• Leaf area (tree/stand) sets the productivity
  potential (species, site, length of time when
  temperature/light and water also)
• Climate change
• Length of growing season
• Shifts in distribution of snow pack, cloud and fog

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Methods
Preface Introduction Context Methods
Impacts Water Nitrogen

• Scholander-Hammel Pressure Bomb (PMS)
• Leaf or stomatal conductance
• Sap velocity, sap flux
• Soil moisture
• Canopy microclimate (eddy flux)
• Remote sensing including air ground-based LiDAR
• Air spade, ground penetrating radar

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Physiological Processes Impacted
Preface Introduction Context Methods
Impacts Water Nitrogen

• Stomatal closure
• Reductions in photosynthesis
• Reductions in growth
• Changes in carbon allocation
• Senescence abscission of foliage
• Decreases in nutrient uptake
• Cavitation of conducting elements
• Die-back, mortality

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Water Used Thresholds
Preface Introduction Context Methods
Impacts Water Nitrogen

• Water used 0 - 500 l (kg) per day
• Water used 0 - 5 mm per day
• Winter desiccation
• Wilting
• Length of growing season.
• Site
• Height

Soil water holding capacity is often associated
with nutrition
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Irrigation
Preface Introduction Context Methods
Impacts Water Nitrogen

• Dale Cole It makes no sense to irrigate (PNW)
• Re-examine that statement
• Lessons from the SE
• Series of studies conducted by T. Albaugh, L.
  Allen, T. Dean, P. Dougherty, B. Ewers, E.
  Jokela, K. Johnsen, L. Kress, T. Martin, R. Oren,
  L. Samuelson, R. Teskey
• Loblolly pine (FL, GA, LA, NC, OK)

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Leaf Area, Water Fertilization
Preface Introduction Context Methods
Impacts Water Nitrogen

• Water use IF (1.8 mm), F (1.2 mm), I and C (0.7
  mm).
• Growth efficiency (SMI/LAI) IF (2.9
  Mg/hayLAI), F (2.7), I (2.4), C (1.9)
• Soil water availability poor predictor of
  productivity.
• Soil nutrient availability much better
• Understory control (nutritional)
• Genetics/disease control
• Genetic potential in its native range
• Fertilization provides greatest gain

Improved depth of rooting
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Summary
Preface Introduction Context Methods
Impacts Water Nitrogen

• Site nutrient availability is critical
• Water (or competition for) is critical early for
  root establishment.
• Water likely to become more critical in the
  future
• Unknowns

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Orphaned Slides (not used in formal talk

• Experiment with corn and water (John Boyer)

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Role of N mineralization on fine root production

• Grier et al. (1981. CJFR) young vs. old-growth
  Pacific silver fir

High
Includes high low site Psme, young and old Abam
and young Tshe
Percentage of Total NPP allocated to fine roots
Low
N Mineralization
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Whats new in Douglas-fir water relations
Preface Introduction Context Methods
Impacts Water Nitrogen

• Role of height (Bond, Meinzer, Ryan)
• Role of storage (Bond, Cermak, Meinzer)
• Role of hydraulic redistribution (Brooks,
  Meinzer)
• Role of night-time transpiration (Ferrell)
• Role of roots - microorganisms - guild

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Critical Role of Leaf Area in NPP

• Data from Abam (cited in Hinckley et al. 1999.
  Phyton). First measures 80 - 82 foliage
  re-measured 1995)