| 1. |
- Elmendorf, Sarah C., et al.
(författare)
-
Assessments of recent tundra change based on repeated vegetation surveys.
- 2010
-
Ingår i: Abstract GC53B-05 presented at 2010 Fall Meeting, AGU, San Francisco, Calif., 13-17 Dec..
-
Konferensbidrag (refereegranskat)abstract
- Results from experimental warming studies suggest tundra vegetation will respond rapidly and dramatically to climate warming, and indeed, NDVI data from remote sensing and repeat aerial photography suggest such changes may already be occurring. NDVI changes, however, may reflect responses to a variety of processes. Repeat measurements of permanently marked plots offer an invaluable opportunity to monitor detailed changes in vegetation composition and abundance. Here, we report results from a synthesis of repeat measurements of 195 permanent plots in Arctic and alpine tundra plant communities in North America (90 plots), Europe (82 plots), Asia (10 plots), Australia (12 plots), and Antarctica (1 plot) that were revisited at least twice between 1980 and 2010, with an average timespan of 13 years between first and last sampling periods. Annual air-temperature warming over the sampling period varied considerably among sites, ranging from slight cooling to increases of nearly 2°C per decade. In our preliminary analyses, we found significant tundra-wide increases in vegetation height as well as abundance of evergreen shrubs and graminoids, but declines in mosses. We anticipated that changes in vegetation height, abundance of deciduous shrubs, and percent of vegetated ground would be highest in areas where climate warming is occurring most rapidly, but found no support for these predictions in our observational dataset. It is possible that local vegetation dynamics in these areas are affected more by other longer-term non-equilibrium processes such as recovery from glaciation, or an alternative suite of local drivers, such as snow cover, precipitation, disturbance or herbivory.
|
|
| 2. |
- Elmendorf, Sarah C., et al.
(författare)
-
Plant communities in a warming tundra: a synthesis of experimental and monitoring plot data.
- 2011
-
Ingår i: 29th Oikos meeting, Tjärnö, Sweden, 7-9 February 2011.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Remote sensing data indicate that rapid and dramatic changes in tundra vegetation data may already be occurring over much of the Arctic. Repeat measurements of long-term warming experiments and permanently marked monitoring plots offer invaluable opportunities to hone predictions about future climate impacts and assess recent change. Here, we report results from two synthesis projects with sites spanning North America, Europe, Asia, Australia, and Antarctica. Data sets include 59 warming experiments up to 20 years in length, as well as observational data from 156 tundra vegetation monitoring studies, conducted in 43 sites, over a 5-25 year period. Experimental data confirmed that warming increases the height of vascular plant groups and the abundance of deciduous shrubs, but longer-term experiments suggest some vegetation responses may not be sustained. Monitoring plots showed some indications of tundra greening over time, but links between temporal vegetation change and the degree of ambient climate change at the study site were weak.
|
|
