Epsilon Archive for Student Projects

Abstract

Understanding the influence of temperature on the exchange of nutrients between plants and
mycorrhizal fungi is important. Fine roots are the major belowground sink for plant photosynthates
and these are the place where plant – mycorrhizal symbiosis occurs. In this study, I investigated
whether warming influences the exchange of leaf and root carbon (C) and nitrogen (N) in the
ericaceous dwarf shrub Empetrum hermaphroditum. I performed a greenhouse experiment
consisting of 56 microcosms where I labelled 48 microcosms (8 controls) with 13CO2 gas and 15Nglycine,
and then quantified 15N and 13C in leaves, fine roots and soil under two different
temperatures. I found that temperature significantly increased the average excess amount of 15N
atom percent in leaves with higher values for elevated temperature than for ambient temperature,
while values in roots and soils were not significantly different. On the other side, the average value
for 13C atom percent excess in leaves was significantly higher in warm temperature while the
difference between ambient and elevated temperature was marginally significant in the fine roots.
Soil atom percent excess of 13C was not significantly different between ambient and elevated
temperature. The ratio of foliar 15N to fine root 13C i.e., the amount of 15N uptake by the leaves per
unit of 13C provided to the fine roots was also higher in warm temperature (40.29 ± 7.22) than
ambient temperature (23.63 ± 5.68). My results suggest that future global warming may influence
the ericaceous dwarf shrub E. hermaphroditum to fix more photosynthetic C in its foliar tissues
with greater amount of belowground C allocation and N uptake. This may influence its competitive
interactions with species in boreal forest ecosystem.