Abstract
The Arctic is viewed as most sensitive to climate warming and subject to a general greening. Yet, summer weather conditions, which differ greatly among years, are believed to have little direct effect on arctic plant productivity. The dominant view is that between-year variation in aboveground plant biomass is small and poorly related to weather conditions in the same year in the Arctic. Here, we test this view based on a 12-year investigation of peak plant biomass among habitats, plant functional types, and species in high-arctic Svalbard.
Our study revealed twofold variation (range 23–46 g/m2) in plant biomass between years, this being strongly related to summer temperature (r = 0.92). Importantly, we found strong plant biomass–summer temperature relationships across habitats, plant functional types, and species, and little evidence for a lagged effect of previous year's biomass. Responses were of similar orders of magnitude, indicating that summer weather conditions were the key driver of plant productivity at all three levels of investigation.
We propose three key factors behind such tight relationships between summer temperature and plant biomass in the same year. First, our methodological approach, a combination of nondestructive shoot density estimates in small, permanent plots and destructive shoot mass estimates outside these plots, allowed us to overcome the otherwise overwhelming small-scale spatial heterogeneity in aboveground plant biomass typical for high-arctic tundra vegetation. Second, the high-latitude location (78° N) makes the vegetation most susceptible to temperature differences due to their influence on process rates. Third, Svalbard's oceanic nature dictates prevalent cloud cover, making summer temperature a good proxy for light availability and thus an index of photosynthetic activity required for plants to produce biomass.
The present study challenges the prevailing notion that relationships between summer weather and vascular plant performance in the Arctic are weak and highly variable among plant species. This has important implications for our understanding of how and at which temporal scales future climate change will shape arctic plant productivity and, in turn, the dynamics of other ecosystem components in the low-productivity, bottom-up regulated ecosystems of the High Arctic.
Our study revealed twofold variation (range 23–46 g/m2) in plant biomass between years, this being strongly related to summer temperature (r = 0.92). Importantly, we found strong plant biomass–summer temperature relationships across habitats, plant functional types, and species, and little evidence for a lagged effect of previous year's biomass. Responses were of similar orders of magnitude, indicating that summer weather conditions were the key driver of plant productivity at all three levels of investigation.
We propose three key factors behind such tight relationships between summer temperature and plant biomass in the same year. First, our methodological approach, a combination of nondestructive shoot density estimates in small, permanent plots and destructive shoot mass estimates outside these plots, allowed us to overcome the otherwise overwhelming small-scale spatial heterogeneity in aboveground plant biomass typical for high-arctic tundra vegetation. Second, the high-latitude location (78° N) makes the vegetation most susceptible to temperature differences due to their influence on process rates. Third, Svalbard's oceanic nature dictates prevalent cloud cover, making summer temperature a good proxy for light availability and thus an index of photosynthetic activity required for plants to produce biomass.
The present study challenges the prevailing notion that relationships between summer weather and vascular plant performance in the Arctic are weak and highly variable among plant species. This has important implications for our understanding of how and at which temporal scales future climate change will shape arctic plant productivity and, in turn, the dynamics of other ecosystem components in the low-productivity, bottom-up regulated ecosystems of the High Arctic.
| Original language | English |
|---|---|
| Pages (from-to) | 3414-3427 |
| Number of pages | 14 |
| Journal | Ecology |
| Volume | 95 |
| Issue number | 12 |
| Early online date | 1 Dec 2014 |
| DOIs | |
| Publication status | Published - Dec 2014 |
Bibliographical note
We are grateful to Telenor for the use of their cabin Telely and UNIS for invaluable logistical support. We are indebted to notably Steve Albon for catalyzing the plant ecological work and Justin Irvine for organizing the formative early field campaigns. Suzan van Lieshout and Nanette Madan were instrumental in the setting up of plots and painstaking measuring of plant biomass during the first year of this investigation. Sandra van der Graaf and Eve Harvey ascertained continuation in 1999 and Anke Fischer helped with the plant biomass measurements in 2006. Brage B. Hansen, Helen Anderson, and two anonymous referees provided valuable comments to an earlier draft; Helen also kindly made the maps in Fig. 1. The work would not have taken place without financial support from the Research Council of Norway, Natural Environment Research Council, and the Centre for Ecology and Hydrology.Keywords
- climate change
- high-arctic Spitsbergen
- July temperature
- long-term study
- permanent plots
- plant community biomass
- plant functional type
- Svalbard
- tundra ecosystem
- vegetation
