Arctic Ecology Laboratory

Long-Term Response of Plants at Barrow and Atqasuk to ITEX Warming Experiments

Robert D. Hollister, Patrick J. Webber , Steven P. Rewa, and Craig E. Tweedie

Objectives: Describe and interpret patterns of plant species response to temperature.

The approach of the research is to use variation in temperature related to 3 causes:

1. manipulative experiments (ITEX OTCs);
   
2. natural interannual variability; and
   
3. natural temperature gradients (Barrow/Atqasuk) to understand plant-temperature relations.

The research consists of four study sites (Figure A). Within each site measures of plant response are collected (Figure B). All species within a site are monitored (Figure C). This work is in association with the International Tundra Experiment (ITEX) (Figure D). The project has 5 interacting tasks described below.

Prominent results and statements are bolded.

We would like to thank the National Science Foundation for supporting this research, the Computational Ecology and Visualization Laboratory for use of its printing facilities, and the many individuals that helped with this research.

Figure A - The four MSU ITEX study sites. The sites span a natural temperature gradient (Barrow to Atqasuk) and a moisture gradient (Dry Heath to Wet Meadow vegetation types). At each site there are 24 OTC and 24 control plots.	Figure D - A circumpolar map showing the ITEX field sites and a photograph of an ITEX open-"top" chamber (OTC). ITEX is a collaborative network of individual investigators studying plant-temperature relations of tundra vegetation. The standard ITEX experiment uses OTCs to simulate regional climate warming.
Plant Measures Phenology (first greening, bud, flower, seed, dispersal, & browning): 2-3 times a week;done on all marked individuals & the first occurrence per species in each plot Growth Progression (leaf & inflorescence length): 1-2 times a week; done on a select group of marked species & the tallest inflorescence in the plot Inflorescence Counts (pre, during, & post anthesis & eaten): 1-2 times a week; the total number of individuals at each stage was counted for a select group of the species Total Season Measures (leaf & inflorescence length & number, number of ramets per unit area): done once on all marked individuals & the three largest flowering individuals of each species in each plot Community Composition (point frame method): 2 times throughout the experiment, once on the summer after the site was established and again in year 2000, for all plots at all sites
Figure B - The plant measures collected at all MSU operated ITEX sites.
Atqasuk Barrow Dry Heath Antennaria friesiana Arctagrostis latifolia Artemisia borealis Carex bigelowii Cassiope tetragona Diapensia lapponica Hierochloe alpina Ledum palustre Luzula arctica Luzula confusa Minuartia obtusiloba Pedicularis lapponica Polygonum bistorta Salix phlebophylla Trisetum spicatum Vaccinium vitis-idaea Wet Meadow Betula nana Calamagrostis sp. Carex aquatilis Carex rariflora Carex rotundata Dupontia fisheri/psilosantha Eriophorum angustifolium Eriophorum russeolum Juncus biglumis Luzula wahlenbergii Pedicularis sudetica Polygonum viviparum Salix polaris Salix pulchra Saxifraga foliolosa Dry Heath Alopecurus alpinus Arctagrostis latifolia Carex aquatilis/stans Cassiope tetragona Draba lactea Draba micropetala Festuca brachyphylla Juncus biglumis Luzula arctica Luzula confusa Oxyria digyna Papaver hultenii Papaver lapponicum Pedicularis kanei Poa arctica Poa malacantha Potentilla hyparctica Ranunculus nivalis Ranunculus pygmaeus Salix rotundifolia Saxifraga caespitosa Saxifraga cernua Saxifraga flagellaris Saxifraga foliolosa Saxifraga nivalis Saxifraga punctata Senecio atropurpureus Stellaria laeta Vaccinium vitis-idaea Wet Meadow Alopecurus alpinus Arc"top"hila fulva Calamagrostis holmii Cardamine pratensis Carex aquatilis/stans Carex subspathacea Cerastium beeringianum Chrysosplenium tetrandrum Cochlearia officinalis Draba lactea Draba micropetala Dupontia fisheri Eriophorum angustifolium/triste Eriophorum russeolum Eriophorum scheuchzeri Hierochloe pauciflora Juncus biglumis Luzula arctica Luzula confusa Melandrium apetalum Pedicularis kanei Petasites frigidus Poa arctica Ranunculus nivalis Ranunculus pygmaeus Salix pulchra Salix rotundifolia Saxifraga caespitosa Saxifraga cernua Saxifraga foliolosa Saxifraga hieracifolia Saxifraga hirculus Stellaria humifusa Stellaria laeta
Figure C - The list of species occurring in the MSU ITEX sites. Bold species are abundant enough for adequate statistical representation.

Continue browsing this poster:

1. Beginning
2. Objective
3. Task 1
4. Task 2
5. Task 3
6. Task 4
7. Task 5

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