Long-term experimental warming effects on tundra plant sexual reproduction in the high Arctic

Predictions that climate warming will enhance plant sexual reproduction in the High Arctic were examined using a field experiment at a polar oasis and a polar semi-desert site in the eastern Canadian High Arctic. Small open top chambers (OTCs), which simulated climate warming, were established in plant communities along a soil moisture gradient in 1992. Over two growing seasons, fresh and over-wintered seeds across a range of species were collected from aerial seed banks exposed to experimental warming and ambient conditions. Seeds were weighed and germinated to measure changes in reproductive effort and success in response to experimental warming. OTCs increased within-plot growing season air temperatures by 1 - 2°C, which is within range of general circulation model (GCM) predictions for climate warming in the Arctic. Reproductive effort and success of fresh seeds were enhanced by warming in most species, depending on initial site conditions. Enhanced reproductive effort and success may be attributed to warming conditions, which advanced dates of snowmelt and extended the growing season. Similar effects on over-wintered seeds were likely, but seed dispersal prior to over-wintered seed harvests confounded these results. Inter-annual variability in reproductive success appeared to be diminished by experimental warming. Further testing will verify if this result is an indicator of long-term (> 10 y) warming effects. Results of this study confirm predictions that long-term warming will enhance sexual reproduction in high arctic plants. These changes will have implications for plant demographics at the community-level and the rate and extent of bare-ground colonization, particularly if rates of seedling establishment also increase.Arts, Faculty ofGeography, Department ofGraduat

Flower and seed biomass, and germination rate of arctic tundra plants in response to long term experimental warming

We provide new information on changes in tundra plant sexual reproduction in response to long-term (12 years) experimental warming in the High Arctic. Open-top chambers (OTCs) were used to increase growing season temperatures by 1-2 °C across a range of vascular plant communities. The warming enhanced reproductive effort and success in most species; shrubs and graminoids appeared to be more responsive than forbs. We found that the measured effects of warming on sexual reproduction were more consistently positive and to a greater degree in polar oasis compared with polar semidesert vascular plant communities. Our findings support predictions that long-term warming in the High Arctic will likely enhance sexual reproduction in tundra plants, which could lead to an increase in plant cover. Greater abundance of vegetation has implications for primary consumers - via increased forage availability, and the global carbon budget - as a function of changes in permafrost and vegetation acting as a carbon sink. Enhanced sexual reproduction in Arctic vascular plants may lead to increased genetic variability of offspring, and consequently improved chances of survival in a changing environment. Our findings also indicate that with future warming, polar oases may play an important role as a seed source to the surrounding polar desert landscape

Tundra Trait Team : A database of plant traits spanning the tundra biome

Motivation The Tundra Trait Team (TTT) database includes field-based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade-offs, trait-environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained Spatial location and grain The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (> 1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub-Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain Major taxa and level of measurement All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release.Peer reviewe

Tundra Trait Team:a database of plant traits spanning the tundra biome

Abstract Motivation: The Tundra Trait Team (TTT) database includes field‐based measurements of key traits related to plant form and function at multiple sites across the tundra biome. This dataset can be used to address theoretical questions about plant strategy and trade‐offs, trait–environment relationships and environmental filtering, and trait variation across spatial scales, to validate satellite data, and to inform Earth system model parameters. Main types of variable contained: The database contains 91,970 measurements of 18 plant traits. The most frequently measured traits (> 1,000 observations each) include plant height, leaf area, specific leaf area, leaf fresh and dry mass, leaf dry matter content, leaf nitrogen, carbon and phosphorus content, leaf C:N and N:P, seed mass, and stem specific density. Spatial location and grain: Measurements were collected in tundra habitats in both the Northern and Southern Hemispheres, including Arctic sites in Alaska, Canada, Greenland, Fennoscandia and Siberia, alpine sites in the European Alps, Colorado Rockies, Caucasus, Ural Mountains, Pyrenees, Australian Alps, and Central Otago Mountains (New Zealand), and sub‐Antarctic Marion Island. More than 99% of observations are georeferenced. Time period and grain: All data were collected between 1964 and 2018. A small number of sites have repeated trait measurements at two or more time periods. Major taxa and level of measurement: Trait measurements were made on 978 terrestrial vascular plant species growing in tundra habitats. Most observations are on individuals (86%), while the remainder represent plot or site means or maximums per species. Software format: csv file and GitHub repository with data cleaning scripts in R; contribution to TRY plant trait database (www.try-db.org) to be included in the next version release