Download Effects of moisture stress on Douglas

Effects of moisture stress on
Douglas-fir physiology and growth
Tom Hinckley, College of Forest Resources,
University of Washington, Seattle, WA
Preface Introduction Context Methods Impacts Water & Nitrogen
Content of January 29 meeting - 1
Sun:
Quantity,
vapor
pressure
gradient
Rain, cloud, &
fog: Quantity,
intensity, timing
Snow: quantity,
elevation, rainon-snow, etc.
Climate, climate change
Future
• Jeremy Littell
• Dave Spittlehouse
Past
• Renee Brooks
Preface Introduction Context Methods Impacts Water & Nitrogen
Content of January 29 meeting -2
Soil properties
Soil water content
Hydraulic Conductivity
Groundwater
Hydraulic redistribution
• Frederick Meinzer
Soil moisture
• Jeffrey McDonnell
Preface Introduction Context Methods Impacts Water & Nitrogen
Content of January 29 meeting -3
Climate: Weather
Site: Microclimate & topography
Physiology & Growth
• Tom Hinckley
Water Use Efficiency
• Andy Black
Preface Introduction Context Methods Impacts Water & Nitrogen
Outline
• 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?
Preface Introduction Context Methods Impacts Water & Nitrogen
Whole Plant Context
• 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
Preface Introduction Context Methods Impacts Water & Nitrogen
Simple Model of How Trees Might
Abovegrd stress:
Respond to Stress • light
• ozone
• herbivory
Carbon
Storage
Carbon
Production
Leaf Growth
Root Growth
• Does the model work?
Water &
Nutrient
Utilization
Water &
Nutrient
Uptake
Belowgrd stress:
• nutrients
• water
• oxygen
Preface Introduction Context Methods Impacts Water & Nitrogen
Responses To Belowground Stress
• Tree Scale
Reich et al. (1980. Forest Science 26: 590) Quercus spp.
Borchert (1975. Physiologia Plantarum 35: 152) Quercus spp.
Preface Introduction Context Methods Impacts Water & Nitrogen
Individual Tree Response Cont.
• Experiment with Douglas-fir and
nitrogen (Friend et al. 1990. Can. J. For.
Res.)
Nitrogen Stressed
Non-Stressed
Total o
+N
-N
Micro- +N
environm ent
-N
N Concen
Foliage
Foliage
0.4 l
No N
Roots
Stress (n)
r1 low
2.5 l
Macroenvironm
ent
r2 high
r1 low
0.4 l
Severe N
Roots
Stress (s)
r2 high
of Micro-
environm
Preface Introduction Context Methods Impacts Water & Nitrogen
Stand Response
Changes with
Fertilization
Aboveground
Belowground
Site II-
Site IV+
Net Primary Productivity
Aboveground
Belowground
Site II-
Site IV+
Net Primary Productivity
• Keyes and Grier (1981.CJFR): young and
high site 40-year-old Douglas-fir
Preface Introduction Context Methods Impacts Water & Nitrogen
Broader Geographic Comparison
Pseudotsuga
menziesii
Tsuga
heterophylla
Lee et al. (2007. Forest Ecology &
Management 242: 195)
Preface Introduction Context Methods Impacts Water & Nitrogen
Site Water Balance & Productivity
Soil depth & texture
Water holding capacity
Full April 1
Output: Pan AET
Input: PPT
Climate change
Pisi
Tshe
Psme Mixed
Juoc
• Grier and Running.
1977. Ecology
Preface Introduction Context Methods Impacts Water & Nitrogen
Take-home Messages
• 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
Preface Introduction Context Methods Impacts Water & Nitrogen
Methods
• Scholander-Hammel Pressure Bomb
(PMS)
• Leaf or stomatal conductance
• Sap velocity, sap flux
• Soil moisture
• Canopy microclimate (eddy flux)
• Remote sensing including air & groundbased LiDAR
• Air spade, ground penetrating radar
Preface Introduction Context Methods Impacts Water & Nitrogen
Physiological Processes Impacted
• Warmer,
Stomatal longer,
closure drier ‘summers’:
• Reductions in photosynthesis
•
Stomatal
closure
(decreases
in
• Reductions in growth
carbon
gain;
offset
partially
by
• Changes in carbon allocation
increases in CO2 [WUE]; vpg may
• Senescence & abscission of foliage
increases, however)
• Decreases in nutrient uptake
• Allocation to roots
• Cavitation of conducting elements
• Decreases in tree/stand leaf area
• Die-back, mortality
Preface Introduction Context Methods Impacts Water & Nitrogen
Water Used & Thresholds
•
•
•
•
•
•
•
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
Preface Introduction Context Methods Impacts Water & Nitrogen
Irrigation
• 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)
Preface Introduction Context Methods Impacts Water & Nitrogen
Leaf Area, Water & Fertilization
• Water use: IF (1.8 mm), F (1.2 mm)*, I
and C (0.7 mm).
• Growth efficiency (SMI/LAI): IF (2.9
Mg/ha•y•LAI), 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
Preface Introduction Context Methods Impacts Water & Nitrogen
Summary
• 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
Elongation Rate (mm/h)
Orphaned Slides (not used in formal
talk
• Experiment with corn and water (John
Boyer)
Leaf
4
Silk
2
Nodal roots
0
Stem
0
-1.2
-0.8
-0.4
Growing Region Water Potential (MPa)
Role of N mineralization on
fine root production
• Grier et al. (1981. CJFR): young vs. oldgrowth Pacific silver fir
High
Percentage of
Total NPP
allocated to fine
roots
Includes
high & low
site Psme,
young and
old Abam
and young
Tshe
Low
N Mineralization
Preface Introduction Context Methods Impacts Water & Nitrogen
What’s ‘new’ in Douglas-fir
water relations
• 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
Critical Role of Leaf Area in NPP
1995 Remeasure OG
(+ 16 years)
24
Net Primary Productivity
-1 -1
(Mg ha y )
• Data from
Abam (cited
in Hinckley et
al. 1999.
Phyton). First
measures 80
- 82; foliage
re-measured
1995)
Keyes (1982)
YL YH
31 (YH)
16
24 (YL)
•
200 (OG)
8
0 03
9
16
24
8
Foliar Biomass (Mg ha -1)