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Aljaste, Arvo, 2011. Warming alters photosynthetic rates of sub-boreal peatland vegetation. Second cycle, A2E. Alnarp: SLU, Southern Swedish Forest Research Centre



Boreal peatlands are important in the global carbon cycle. Despite covering
only 3% of the global land area, peatlands store approximately one third of all soil
carbon. Temperature is one of the major drivers in peatland carbon cycling as it
affects both plant production and CO2 fluxes from soils. However, it is relatively
unknown how boreal peatland plant photosynthesis is affected by higher
temperatures. Therefore, we measured plant photosynthetic rates under two different
warming treatments in a poor fen in Northern Michigan. Eighteen plots were
established that were divided into three treatments: control, open-top chamber (OTC)
warming and infrared (IR) lamp warming. Previous work at this site has shown that
there was a significant increase in canopy and peat temperature with IR warming (5°C
and 1.4°C respectively), while the OTC’s had mixed overall warming. Plots were
divided equally into lawns and hummocks. We measured mid-day carbon dioxide
(CO2) uptake on sedges (Carex utriculata), shrubs (Chamaedaphne calyculata) and
Sphagnum mosses. Sphagnum moss net primary production (NPP) was also measured
with cranked wires and compared with CO2 uptake.
Our results indicate that there was no significant difference in sedge CO2
uptake, while shrub CO2 uptake significantly decreased with warming. A significant
increase occurred in Sphagnum moss gross ecosystem production (GEP), ecosystem
respiration (ER) and net ecosystem exchange (NEE). Contrary to the positive CO2
exchange of Sphagnum, overall NPP decreased significantly in hummocks with both
warming treatments. The results of the study indicate that temperature partly limits
the photosynthetic capacity of plants in sub-boreal peatlands, but not all species
respond similarly to higher temperatures.

Main title:Warming alters photosynthetic rates of sub-boreal peatland vegetation
Authors:Aljaste, Arvo
Supervisor:Chimner , Rodney A. and Magnusson, Tord
Examiner:Agestam , Eric
Series:Master thesis / SLU, Southern Swedish Forest Research Centre
Volume/Sequential designation:172
Year of Publication:2011
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:SM001 Euroforester - Master's Programme 120 HEC
Supervising department:(S) > Southern Swedish Forest Research Centre
Keywords:Peatlands, CO2 uptake, Climate change, microtopography
Permanent URL:
Subject. Use of subject categories until 2023-04-30.:Nature conservation and land resources
Non-renewable energy resources
Deposited On:23 Jun 2011 13:48
Metadata Last Modified:20 Apr 2012 14:20

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