Title

Warming alters photosynthetic rates of sub-boreal peatland vegetation

Author

Arvo Aljaste, Michigan Technological University

Date of Award

2011

Document Type

Master's Thesis

Degree Name

Master of Science in Forest Ecology and Management (MS)

College, School or Department Name

School of Forest Resources and Environmental Science

Advisor

Rodney A Chimner

Co-Advisor

Eric Agestam

Abstract

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.

Recommended Citation

Aljaste, Arvo, "Warming alters photosynthetic rates of sub-boreal peatland vegetation", Master's Thesis, Michigan Technological University, 2011.

https://doi.org/10.37099/mtu.dc.etds/151