Global Change Research from the Ground Up

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Mean global temperature anomalies: last 1000 yrs

indirect measuresdirect

measures

projections

IPCC (2001)

Projected changes in average annual water runoff by 2050, relative to average runoff for 1961-1990

IPCC (2001)

IPCC (2001)

Millennium Ecosystem Assessment (2005)

Atmosphericnitrogen deposition

global environmental change

elevated CO2 warming precipitation nitrogen

Percentage change in average annual total Australian wheat yield for CO2 (levels of 700 ppm)

IPCC (2001)

rainfall change

global environmental change

elevated CO2 warming precipitation nitrogen

global environmental change

elevated CO2 warming precipitation nitrogen

additive effects?

Jasper Ridge Global Change Experiment(1998-present)

Jasper Ridge, California Toronto, Ontario

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Jasper Ridge, California Toronto, Ontario

Native perennial grasses (Danthonia californica and Nassella pulchra)

Non-native annual grasses (Avena barbata, A. fatua, Bromus hordeaceus and Lolium multiflorum)

Non-native forbs (Geranium dissectum, Erodium botrys and Crepis vesicaria)

Native annual forbs (Hemizonia congesta and Epilobium brachycarpum)

Annual grassland

The annual grassland as a model system

1. Small individuals = community level treatmentsin a small area

2. Annual lifecycle = treatments over multiple generations

3. Established plant and soil microbial communities

20 cm

Year 1 Year 2 Year 3 Year 4

Jasper Ridge Global Change Experiment(1998-present)

CO2 - free air emitters: ~ 680 ppm

open top chamber for CO2 delivery

Jasper Ridge Global Change Experiment(1998-present)

NO3- - application: 7 g N m-2 y-1

Jasper Ridge Global Change Experiment(1998-present)

heat - infrared lamps: 1-2 °C

Jasper Ridge Global Change Experiment(1998-present)

H2O - irrigation: ambient + 50%

NO3- H2Oheatcontrol

heatNO3

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heatH2O

NO3-

H2O

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ambient CO2

NO3- H2Oheatcontrol heat

NO3-

heatH2O

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(Shaw et al. 2002)

NO3- H2Oheatcontrol

heatNO3

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680 ppm CO2

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NO3-

heatH2O

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heatH2O

(Shaw et al. 2002)

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(Shaw et al. 2002)

Dukes et al. (2005)

Dukes et al. (2005)

Fire!July 2003

Net primary production

NO3- added

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Annual grasses

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Herbivore effects

Slug feeding preferences and abundance in plots explain over 50% of variation in productivity

Lessons learned from the JRGCE:

1. Global change will result in changes in ecosystemproductivity and plant species composition

2. Unforeseen interactions of climate change withnitrogen pollution and elevated CO2

Wildcards: influence of disturbance and herbivores

Davis (1981)

Invasive species

My current research:Winter warming and N deposition

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Agricultural field near London, ON

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air soil surface

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continuous snow cover

Agricultural field near London, ON

Effects of freezing on soil

soil aggregatedisruption

microbial lysis

plant litter breakdown

root lysis

leaching losses of C, N and P

CO2, N2O

Effects of freeze-thaw

soil aggregatedisruption

microbial lysis

plant litter breakdown

root lysis

Long-term warming and N deposition experiment

Long-term warming and N deposition experiment

Objective:

To explore the interactive effects of climate warming and increased atmospheric N deposition on a temperate ecosystem

- specific emphasis on winter warming

Grasses:Poa pratensis (Kentucky blue grass) – perennial Bromus inermis (smooth brome) – perennial

Forbs:Solidago altissima (tall goldenrod) – perennial Cirsium arvense (Canada thistle) – perennial

Medicago lupulina (black medick) – annual/perennial, legumeMelilotus alba (white sweet-clover) – annual/perennial, legumeLotus corniculatus (bird’s foot trefoil) – perennial, legume

110 V AC soilsurface

150 Wceramic infraredheater

reflector

weatherprooflightbulb socket

metal pipe

Heating bracket (heats 3 plots)

Side view:

height-adjustablebracket

1 m

Block design

1 plot

= dummy heater

= IR heater(n=10)

1 m

1 plot

= dummy heater

= IR heater

heated-all year

heated-late-fall

to spring

1 m

1 plot

= dummy heater

= IR heater

heated-all year

heated-late-fall

to springN

N

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Soil monitoring

- soil temperature- 2 and 5 cm depth- hourly

- volumetric water content- 0-15 and 0-30 cm depth- hourly

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winter warmedwarmed

- PTFE/quartz lysimeters- no retention/contamination- durable- 50 cm depth

Soil water collection

Terry BellSoil microbial enzyme activities

and microbial community structure

Jennifer HutchisonPrimary production and

plant species composition

Paul Mensink and Eric MoiseInvasive wood snails

Michelle TurnerNitrogen leaching losses

and net mineralization

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Cirsium

Lotus

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April 3 June 11

Net Ecosystem Exchange