Abstract Detail

Paleobotany

Gałka, Mariusz [1], Andrei-Cosmin, Diaconu [2], Angelica, Feurdean [3], Hedenas, Lars [4], Klaus-Holger, Knorr [5], Edyta, Łokas [6], Milena, Obremska [7], Normunds, Stivrins [8], Adnan, Akbar [9], Graeme, Swindles [10].

Is it something new or a repetition from the past? Long-term insight into the development of plant populations in Arctic Alaska.

Rising temperatures drive shifts in vegetation communities in the arctic zone. However, most of the results on the response of plant communities (species, biomass, phenology) to recent warming come from observational and experimental studies, with comparatively limited data concerning centennial to millennial temporal scales. Moreover, rising temperatures and fire have driven partial or complete thawing of permafrost peat as well as deepening of the active layer during recent decades in many arctic regions of the Northern Alaska region. Therefore, detailed long-term palaeoecological studies of degrading permafrost peatlands are important for understanding the relationships between climate, fire, vegetation, and hydrology and the response of high-latitude vegetation especially mosses populations to climate warming. Peatland ecosystems in the Arctic are important archives for palaeoenvironmental reconstruction owing to their sensitivity to climatic and hydrological change. Analysis of peat archives makes possible the reconstruction of plant population changes over the last centuries and millennia, and it also enables a determination of factors that impacted their development. Our study represents the multiproxy, late Holocene (the past 3000 years) data from northern Alaska. We applied high-resolution palaeoecological analysis: plant macrofossils, pollen, micro and microcharcoal, testate amoebae, and elemental analysis and stoichiometry, supported by radiocarbon and lead dating on eight peat cores taken in various types of peatlands (rich fens, poor fens, string fens) along N-S gradient from the northern slope of Brooks Mts. range to Prudhoe Bay. The objectives are to: i) reconstruct local, especially mosses population and regional vegetation changes during the late Holocene; ii) evaluate the influence of changes in climate and autogenous succession in the development of arctic plant communities. We address the following hypotheses: i) Sphagnum moss and shrubs (e.g. Betula nana) populations spread into Arctic areas following past warm climatic periods when their current northern distribution has expanded; ii) minerotrophic brown moss populations were dominant in the past, in wetlands ecosystems; iii) similar to the present plant populations characterised the past warm periods, and might be a pattern subjected to cyclic changes; iv) the responses of the herbaceous and moss populations vary between types of peatlands; v) some moss communities were more resilient to past and recent climate change due to their wider ecological tolerance to water table depth and pH. We observed that the strongest changes in plant populations are visible over the last decades. Generally, there was an increased abundance of macrofossils and pollen of shrubs eg. Ericaceae, Betula nana, Salix sp. and trees e.g., Picea in peat cores linked to warming stages of climate and this pattern was repeatedly observed. We also noticed an expansion of Sphagnum species, usually growing in dry habitat and brown mosses (Tomentypnum nitens, Aulacomnium turgidum, Loeskypnum badium) over last decades. Plant populations composed of Carex ssp. and brown mosses (Scorpidium scorpioides and Drepanocladus trifarius) showed resilience to climate changes over the last 2,000 years. Lastly, autogenous plant succession at peatland that developed towards ombrotrophic status was also an important factor for plant populations changes.

1 - University of Lodz, Biogeography, Paleoecology and Nature Protection, Banacha 1/3, Lodz, 90-237, Poland
2 - Babes- Bolyai University, Department of Geology, Cluj-Napoca, Romania
3 - Goethe University, Institute of Physical Geography, Frankfurt am Main, Germany
4 - Swedish Museum Of Natural History, Department Of Botany, Stockholm, SE-10405, Sweden
5 - University of Münster, Institute of Landscape Ecology, Muenster, Germany
6 - The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academ, Department of Mass Spectrometry, Cracow, Poland
7 - Institute of Geological Sciences, Polish Academy of Sciences, Warsaw, Poland
8 - University of Latvia, Department of Geography, Riga, Latvia
9 - University of Lodz, Biogeography, Paleoecology and Nature Protection, Lodz, Poland
10 - Queen's University Belfast, School of Natural and Built Environment, Belfast, Northern Ireland

Keywords:
peatland development
plant succession
mosses
climate change
shrub expansion.

Presentation Type: Oral Paper
Number: PB2003
Abstract ID:230
Candidate for Awards:Isabel Cookson Award