ITEX syntheses: Attribution of ecological change to warming across the biome

Sandra Angers-Blondin

Isla H. Myers-Smith, Anne Bjorkman, Sarah Elmendorf, Team Shrub, ITEX Network, ShrubHub Network and many more University of Edinburgh A warming …

Anne Bjorkman A warming Arctic…

Gergana Daskalova The Arctic is warming

Temperature Change (ºC/year)

Mean Annual Temperature Change 1978 to 2013 A Greening of the Arctic…

Jeff Kerby The Arctic is greening

Increasing NDVI

Decreasing NDVI

GIMMS 3g Satellite Data 1982 to 2015 IPCC Reports – detection and attribution

IPCC WG2 Chapter 4, Summary report 2014 Why tundra matters – feedbacks

Vegetation Change

Albedo Nutrient (Reflectance) Cycling

Permafrost Carbon Thaw Storage Climate Change

Myers-Smith et al. ERL 2011, Crowther et al. Nature 2016, Gestel et al. Nature 2018

The Network approach Shrub Hub

International Tundra Experiment High Latitude Drone Ecology Network

Tundra Tundra Tea Trait Bag Team Experiment Our research questions…

1. How is tundra vegetation changing?

2. Is climate warming causing vegetation change? Variables of interest:

Phenology Change Shrubification Compositional Change Trait Change Phenology

Anne Bjorkman Qikiqtaruk – High NDVI Herschel Island Low NDVI Plants are greening up earlier in the spring

18 June 2016 Plant senescence – yellowing of first leaf

Growing season 26 June 2016 length

Leaf emergence – bud burst

15 August 2016

Myers-Smith et al. in prep. Plants are greening up earlier in the spring

Later 18 June 2016 Plant senescence – yellowing of first leaf

Growing season ~5 days 26 June 2016 length earlier per decade Leaf emergence – bud burst

Earlier 15 August 2016

Myers-Smith et al. in prep. Plants are greening up earlier in the spring

Tundra: Change in first leaf date – 1950s to 2010s

~5 days earlier per decade

Lilac Honeysuckle

Earlier Later Schwartz et al. 2016 Phenology ~ temperature

Summer Temperature (°C) High Arctic Low Arctic Prévey et al. GCB 2017 Phenology over time

ITEX phenology sites: 150 150 40 40

60 60

30 30 100 100

40 40 20 20

Count of sites Count of sites 50 50 20 20 10 10 Count of site − species combinations Count of site − species combinations Count of site − species combinations Count of site − species combinations 0 0 0 0 0 0 −0.050−0.050−0.025−0.025 0.0000.000 0.0250.025 0.0500.050 −2 −2 0 0 2 2 −6 −6 −3 −3 0 0 3 3 6 6 ChangeChange in summer in summer temperature temperature (°C/year) (°C/year) ChangeChange in leaf in −leafout− outdate date (days/year) (days/year) ChangeChange in flowering in flowering date date (days/year) (days/year)

Bjorkman et al. in prep. Phenology ~ snow melt + temperature +

!

Assmann et al. in prep. Detection Attribution +/− ✓ Shrubification

Andy Cunliffe It was warmer and shrubbier in the past!

Willow pollen:

Klemm et al. Paleo 2013 Shrubification

1987 2009

Qiqiktaruk – Herschel Island, Canadian Arctic Shrubification

1987 2013

Qiqiktaruk – Herschel Island, Canadian Arctic Shrubification

1987 2014

Qiqiktaruk – Herschel Island, Canadian Arctic Shrubification

1987 2015

Qiqiktaruk – Herschel Island, Canadian Arctic Shrubification

1987 2016

Qiqiktaruk – Herschel Island, Canadian Arctic Shrubification

1987 2017

Qiqiktaruk – Herschel Island, Canadian Arctic Shrubification

Phenology

Historical Ecology

Dendroecology

Ecological Monitoring

Experiments

Myers-Smith et al. ERL 2011, Myers-Smith et al. 2017 Shrubs increase ~ warming

Tall shrubs of increasing abundance Probability

Summer temperature change (ºC)

Elmendorf et al. NCC 2012, PNAS 2016 Shrub height ~ experimental warming (standardized) Increase in height height in Increase

Canopy Shrubs Forbs Grams

Effects of warming on vegetation height

Elmendorf et al. Ecol. Lett. 2012 Shrub growth ~ temperature

Low sensitivity (∆AIC < 5)

High sensitivity ((∆AIC = 40)

× Not sensitive to climate

Myers-Smith et al. NCC 2015, Myers-Smith et al. J. Ecol. 2017 Detection Attribution +/− ✓ + ✓ Plant composition Plant cover ~ time

Myers-Smith et al. in review Plant cover ~ time

Myers-Smith et al. in review Plant cover ~ time

Myers-Smith et al. in review Plant cover ~ time

ITEX plant cover sites:

Elmendorf et al. NCC 2012, PNAS 2016 Plant community change favours warm-loving species More warm loving

Elmendorf et al. NCC 2012, PNAS 2016 Detection Attribution +/− ✓ + ✓ +/− ✓ Traits

Sandra Angers-Blondin The traits of species, VegetationTrait not their identity, affect change ecosystem function Leaf traits link to decomposition and carbon cycling

Specific Leaf Leaf Area (SLA) Nitrogen (N)

Rates of photosynthesis & decomposition

warming Carbon uptake, storage, and release

CO2 Trait change ~ warming

expected observed

Observed: Plant height (cm) Plant height changes in line with predictions expected But other traits like SLA lag observed

Specific Leaf Area (mm/mg) Summer Time Temperature (ºC) Bjorkman, et al. in revision How will plants respond to future change?

Warming Tundra Trait Common garden experiments Team experiments

Estimates of traits in non- + + = analog warmer climates

Detection Attribution +/− ✓ + ✓ +/− ✓

+ (height) ✓(height) /✗(other) Our research questions…

1. How is tundra vegetation changing?

2. Is climate warming causing vegetation change? Other drivers of change Nitrogen Herbivory fertilization

Fire CO2 Fertilization Below-ground matters: up to 80% of tundra biomass

Simplicity: attribution of vegetation change to climate

∆ Phenology

Climate Warming ∆ Composition

∆ Trait Complexity: direct versus indirect mechanisms

Sea Ice Melt ∆ Phenology

Climate Warming ∆ Composition Carbon Storage Herbivores

Permafrost Thaw ∆ Trait In summary…

1. How are tundra ecosystems changing? • Changing phenology (some of the time) • Shrubification and increased plant cover and height

2. Is climate warming causing vegetation change? • Plant phenology and growth is climate sensitive • Plant communities are responding to warming Sandra Angers-Blondin Where we quantify shrub change? Climate Warming Sea Ice Melt Permafrost Thaw

Global Change Drivers

Compositional Change Phenology Change Trait Change

Tundra Ecosystem Reponses

Surface Reflectance Trophic Impacts Carbon Storage

Ecosystem- level Impacts Jeff Kerby Thank you! For more information… https://teamshrub.com/

[email protected]

@TeamShrub #TeamShrub Less vegetation More vegetation Less carbon in biomass and More carbon in biomass and more carbon in soils? less carbon in soils?

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