High-Arctic phenology shifts: climate change consequences for reproductive success and community composition

Zoe Panchen W. Garfield Weston Postdoctoral Fellow in Northern Research Phenology shifts due to climate change

Phenology Willow (Day of Year green-up (DOY))

Arnica Year Temperature (°C)

Tundra green-up, flowering and fruiting Cotton-grass fruit generally getting earlier as climate warms Phenology responses differ Flowering Time Fruiting Time

Mountain avens flowering Mountain avens fruiting 3.6 days/decade earlier 5.8 days/decade earlier (-2.3 days/°C) (-3.4 days/°C)

Purple saxifrage flowering no significant change

(-1.8 days/°C)

5yr rolling average rolling 5yr

Peak fruiting DOY fruiting Peak 5yr rolling average rolling 5yr Peak flowering DOY flowering Peak Purple saxifrage fruiting no significant change (0 days/°C)

• Differences among • Differences among phenological events of same species

Panchen & Gorelick (2015) Arctic plant reproductive success

With warmer Arctic temperatures … • greater germination • more viable seed

Silene acaulis Moss campion Müller et al. (2011) Plant community composition changes

With warmer Arctic temperatures … • change in Arctic plant community composition • Arctic -ification

1966: Siberian tundra 2009: Siberian tundra Phenology – reproductive success - plant community structure What is the relationship between • Flowering times and reproductive success? • Phenology-reproductive success and species composition and abundance changes? Expect shift towards greater proportion of species that benefit most from climate change.

Salix Dryas Poa Papaver Oxyria Pedicularis arctica integrifolia glauca radicatum digyna hirsuta

Arctic Mountain Glaucous Arctic Mountain Hairy Willow Avens Bluegrass Poppy Sorrel Lousewort Alexandra Fiord

Alexandra Fiord, Ellesmere Island (79°N)

Open top chambers (OTC), Alexandra Fiord Phenology, reproductive success & plant community composition

Warmed vs control plots Seed germination Point frame counts

Phenology Reproductive Community success structure • flowering times • seed quantity • composition • green-up times • seed weight • abundance • fruiting times • seed viability Seed quantity

Mountain Avens Mountain Sorrel Hairy Lousewort Arctic Willow Arctic Poppy (Dryas) (Oxyria) (Pedicularis) (Salix) (Papaver)

Seed count per plant

• Dryas: More seeds in warmed versus control plots • Oxyria and Pedicularis: No difference in warmed versus control plots • Salix and Papaver: Fewer seeds in warmed versus control plots Seed weight

Mtn Avens Mtn Sorrel Lousewort Willow Poppy (Dryas) (Oxyria) (Pedicularis) (Salix) (Papaver)

Mean seed weight (mg)

Plants in warmed plots produce heavier seeds Except Poppy Seed viability Arctic Willow (Salix) Mountain Avens (Dryas)

% germination

R2=0.51, N=108, P<.0001 R2=0.73, N=166, P<.0001

Mountain Sorrel (Oxyria) Arctic Poppy (Papaver)

% germination

R2=0.04, N=70, P=.0774 R2=0.24, N=19, P=.0317

Mean seed weight (mg) Mean seed weight (mg) Heavier seeds = greater germination Phenology - reproductive success

Hairy lousewort Mountain sorrel Mean seed weight Mean seed weight (mg) (Pedicularis hirsuta) () Mean seed weight (mg)

Peak flower day of year Mature fruit day of year

Earlier flowering/fruiting Heavier seeds Reproductive successSalix – species composition 80 warmed 70 Salix arctica % 60 Arctic willow germi- 50 nation 40 is 30 control “taking over” 20 10 Arctic Willow 0

Papaver 80 70 Papaver % radicatum germi- 60 Arctic poppy 50 nation control is 40 30 “now seen less 20 often in 10 warmed Arctic Poppy 0 warmed plots”

Germination day Reproductive success – species composition % germi- nation MountainDryas Avens (Dryas) MountainOxyria Sorrel (Dryas) 80 80 control 70 70 60 60 warmed 50 50 40 40 30 warmed 30 20 20 10 control 10 0 0

Germination day Germination day

Poa Pedicularis glauca Only seeds from hirsuta Only 1/3650 seeds warmed plots germinated! germinated • tetrazolium test +ve • germination conditions Glaucous Hairy not met Bluegrass Lousewort Seedling vigor Seedling weight (mg) WillowSalix (Salix) PoppyPapaver (Papaver) 0.9 0.18 0.8 0.16 0.7 0.14 0.6 0.12 0.5 0.10 0.4 0.08 0.3 0.06 0.2 0.04 0.1 0.02 0 0.00 GD03 GD05 GD08 GD10 GD12 GD15 GD17 GD19 GD12 GD15 GD17 GD19 GD22 GD24 GD26 Mountain OxyriaSorrel (Oxyria) MountainDryas Avens (Dryas) 2.5 1.6 1.4 2.0 1.2

1.5 1.0 0.8 1.0 0.6 0.4 0.5 0.2 0.0 0.0 GD03 GD05 GD08 GD10 GD12 GD15 GD17 GD19 GD22 GD24 GD26 GD03 GD05 GD08 GD10 GD12 GD15 GD17 GD19 GD22 GD24 GD26 Germination day Germination day Salix warmed plots seedlings more vigorous Earlier germinating Salix seeds are more vigorous In warmed plots…

Salix Papaver ↓ # seeds ↓ # seeds ↑ seed weight ↓ seed weight ↑ germination ↓ germination Arctic Arctic ↓ seedling vigor Willow ↑ seedling vigor Poppy

Oxyria ~= # seeds Dryas ↑ # seeds ↑ seed weight ↑ seed weight ↓ germination ↑ germination Mountain ↑ seedling vigor Mountain ?↑seedling vigor Sorrel Avens % germination over the years

Arctic Willow (Salix) Mountain Avens (Dryas)

Mean % germination

R2=0.39, N=280, P<0.0001 R2=0.30, N=323, P<0.0001

Mountain Sorrel (Oxyria) Arctic Poppy (Papaver)

Mean % germination

R2=0.51, N=113, P=0.0126 R2=0.45, N=105, P=0.8481 Preliminary analysis suggests … • Warmer temperatures appear to increase some reproductive success measures • Link between phenology, reproductive success and plant community composition/species abundance but ... further analysis required

Salix Dryas Poa Papaver Oxyria Pedicularis arctica integrifolia glauca radicatum digyna hirsuta

Arctic Mountain Glaucous Arctic Mountain Hairy Willow Avens Bluegrass Poppy Sorrel Lousewort Acknowledgements

Greg Henry Esther Frei Elise Gallois Cassandra Elphinstone Sofie Agger Andrew Butt Hailey May Natalie Maslowski Isabel Hagen Alexandra Fiord, Ellesmere Is, Nunavut