Ecosystem-Climate Interactions

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1 Ecosystem-Climate Interactions Dennis Baldocchi UC Berkeley 2/1/2013

2 Topics Climate and Vegetation Correspondence Holdredge Classification Plant Functional Types Plant-Climate Interactions Canopy Microclimate

3 Plants are associated with Climate Theophratus Linneaus Von Humboldt Plant communities were integrative with numerous emergent properties Arthur Tansley & Frederick Clements Ecosystems are a random assemblages of adapted species Henry Gleason 3

4 Biogeography: How Does Climate affect the Global Distribution, Structure and Function of Vegetation? The roles of rainfall, evaporation, potential evaporation and minimum and maximum temperature

5 Vegetation and Climate: Holdredge Classification Scheme

6 Pros and Cons of Holdredge Classification Pro: Simple Driven with Easy to measure Climate Variables Con: Annual Mean Climate Variables can be poor surrogates for functional biophysical variables, like sunlight, evaporation and soil moisture e.g. annual rainfall does not equal available water in soil; e.g. annual mean temperature does not reflect growing season temperature or length of growing season

7 Relation with plant functional types and water balance in North America Potential Evaporation minus ppt adapted from Stephenson, 1990

8 IPCC dataset

9 IPCC dataset

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11 Virtual Field Trip

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13 Tropical Evergreen Broadleaved Rainforests Latitude: 14 +/- 9 degrees Rain > 1500 mm ET: ~ mm Potential ET: < 2000 mm/yr T min > 15 C LAI ~5.2 +/- 1.2 m 2 m -2 Ht: ~28 +/- 9 m Tree Density: 385 +/- 221 stem/ha Biomass: / gc m -2 Stand Age: > 100 years Year-Round Growing Season

14 Temperate Deciduous Broadleaved Forests Latitude: 44 +/- 9 degrees Rain: mm ET: 300 to 600 mm Potential ET: < 1000 mm/yr T min > -5 to -20 C LAI: 6.1 +/- 3.5 m 2 m -2 Ht: 19 +/- 7 m Above Ground Biomass: 10,882 +/ gc m -2 Stem density: 1723 stem/ha Stand Age: 75 +/- 50 Spring-Summer Growing Season, days

15 Boreal Conifer Evergreen Forest Latitude: 58 +/- 7 degrees Rain: ~ mm ET: ~ mm Potential ET: < 500 mm/y T min < -40 C LAI: ~4.1 +/- 3.0 Ht: 14 +/- 7m Biomass: 5761 gc m -2 Tree Density: / stem/ha Stand Age: 72 +/- 52 years Summer Growing Season, ~ 100 days

16 Temperate Conifer Forests Year Round Growing Season in Snow- Free Zones Rain Xeric: mm Mesic: mm ET: mm Potential ET: ~ 1000 mm/yr T min : > -20 C (Xeric) >-5 C (Mesic) Leaf area Index < 3 (Xeric) 6-10 (Mesic) Biomass 200 g m -2 (xeric) 500 g m -2 (mesic) Ht: 15 to 40 m (Xeric) 40 to 100 m (Mesic)

17 Mediterranean Woodlands: Deciduous and Evergreen Broadleaved Rain: ~ mm/year ET: < 500 mm/yr Potential ET mm/yr T min : -1 to 15 C LAI: ~1-3 Height: ~5 to 15 m Hydrological Growing Season, Autumn-Winter- Spring; System Shuts down in Summer

18 Tropical/semi-Tropical Savanna: Drought Deciduous and Evergreen Broadleaved Woodland with C 4 Grass Understory Hydrological Growing Season, wet summer Rain: mm/year ET: < 1000 mm Potential ET ~ 4000 mm T min : > 0 C LAI: ~2-3 Height Deciduous: ~10 to 30 m; Evergreen: to 70 m

19 Luyssaert et al GCB Synopsis

20 Grasslands

21 Perennial Grasses, Summer Growing Season Annual Grasses, Winter- Spring Growing Season Rain: mm/year ET: < 400 mm Potential ET: < 1000 mm/y T min : -1 to 15 C LAI: ~1-3 Biomass: 3 g m -2 Height Perennial, < 1 m Annual, < 1 m Grasslands

22 Exceptions: Grasslands with High Rainfall (1-3 m) Llanos, Venezuela Seasonal Flooded Tropical Grassland, with sparse Trees Grassland or Savanna? (Blydenstein, 1969, Ecology) Highly leached, inundated, hardpan soils limit tree growth Man and fires push back tree growth and sustain grasses Abandoned pasture reverts to brush

23 Wetlands

24 Wetlands: Fens, bogs, Marsh Short Summer Growing season in Boreal Zone, Yearround in Tropics T ave : -1 to 15 C LAI: ~1-3 NPP: up to 1000 gc m -2 y -1 Biomass: g m -2 Height boreal, < 1 m Temperate/tropical, 3 m

25 Climate-Plant Interactions How does Climate Constrain Vegetation Structure and Function? Why do certain plants have big leaves and others have small ones? What biophysical factors limits plant height, density and vigor? How does Climate affect Biodiversity?

26 Plant-Habitat Interactions and Constraints Plants that grow rapidly under conditions with sufficient soil moisture are unable to survive under dry conditions. Tolerance to low light and soil moisture is interdependent and inversely correlated. Plants that can photosynthesize at high rates and grow rapidly under high light are unable to survive at low light (they are shade intolerant) Shade tolerant plants have low growth rates and photosynthetic potentials, even under high light conditions. Smith and Huston, 1989 ESPM 129 Biometeorology 26

27 General Constraints of Climate and Environment on Plants Sunlight Available sunlight drives photosynthesis. ~1.4 g dry matter is produced for 1MJ of intercepted sunlight (2.5% efficiency). Heats Surface and Evaporates Water Water Hydrates cells Causes turgor for growth and cell expansion Transfers nutrients Water vapor is lost as stomates open to acquire CO 2 Temperature Regulates rates of biochemical and enzymatic reactions Determines if water is gas, liquid or solid

28 Photosynthesis Scales with Water Use: Wet EcoSystems Transpire a lot and can Achieve High Photosynthesis Dry EcoSystems cannot afford to Transpire a lot, so they have limited photosynthesis Rosenzweig, 1968 AmNat

29 Dominant Environmental Controls on Net Primary Productivity Churkina and Running, 1998, Ecosystems

30 Species Diversity has Links with Climate, too Kleidon and Mooney, 2000 GCB

31 BioClimatology: How does Vegetation, Disturbance or Land Use Change affect Climate? Roles of albedo, surface roughness, surface conductance, leaf area & physiological capacity Role of Forests in Climate Mitigation

32 Biophysics: Energy Exchange Net Radiation Budget Energy Partitioning Solar Radiation Terrestrial Radiation Sensible heat Latent heat Soil Heat Conduction

33 Energy Balance Partitioning: Crops vs Forests PBL: 1500 m PBL: 1000 m = 0.15 R g R n = 0.85 R g = 0.25 R g LE = 0.6 R n R n = 0.65 R g H = 0.3 R n H = 0.05 R n LE n = 0.8 R n G = 0.02 R n S = 0.15 R n S = 0.08 R n

34 Clearing for agriculture in W. Australia altered climate 30% less ppt over farmlands 10% more ppt over heathlands Chapin Lecture Notes Photo: S. Chambers

35 Vegetation effects on climate: Role of Tropical Deforestation Shukla et al. 1990

36 Plant-Atmosphere Interactions Change Net Radiation Albedo vegetation color, height and density Surface Temperature and Longwave emission Surface Resistance to Moisture Loss Snow Melt and Albedo Feedback Change Surface Resistance Evaporation Sensible Heat exchange Photosynthesis and Carbon Capture Cloud Formation and Precipitation Feedbacks Change Structure Wind and Turbulence Light Capture

37 Climate Services by Vegetation Rain and Clouds Runoff to Streams and Lakes Warming or Cooling the Surface Carbon and Pollution Sink Bonan, 2008, Science Red Arrow: Warming Blue Arrow: Cooling

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39 How Forests affect the Chemical Composition of the Atmosphere OH h C 5 H 8 RO 2 NO 2 ROOH O 3 NO f(par, T L ) NO + O 3 = NO 2 NO 2 + h = NO + O

40 Microclimate Sunlight Temperature Wind and turbulence Humidity Trace gases, CO 2, O 3, VOCs Aerosols Sources of Variation Spatial Vertical,horizontal Temporal Hour, day, season

41 Sunlight in Forests Radiation and Forests direct sunlight Diffuse Sunlight

42 Vertical Structure of Wind: Impact of Canopy Roughness Wind and Turbulence

43 Temperature and Plants Day Temperature Night

44 Summary Plant Structure and Function are linked to available sunlight, temperature and rainfall Plant Functional Types are a useful concept for explaining how plants respond to Climate Links between PFT and Climate can explain Geographic Distribution of Plants Plants affect the Local Microclimate, and Vice Versa

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46 Vegetation-Atmospheric Chemistry-Climate Interactions Aerosols which scatter/reflect sunlight, cool, enhance photosynthesis by better light capture; VOC emission =f(temperature) VOCs contribute to photochemical ozone production, in presence of NOx, and aerosol production VOCs transmit biological signal and are defense compounds against insects and pathogens Laothawornkitkul et al New Phytologist Tansley review.pdf

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