Deciduous tundra shrubs shift toward more acquisitive light absorption
strategy under climate change treatments
Abstract
The effects of climate change on plants are particularly pronounced in
the Arctic region. Warming relaxes the temperature and nutrients
boundaries that limit tundra plant growth. Increased resource
availability under future climate conditions may induce a shift from a
conservative economic strategy to an acquisitive one. Following the leaf
economics spectrum that hypothesizes a strategy gradient between
survival, plant size and costs for the photosynthetic leaf area, light
absorption of tundra plants may increase.
We investigated climate change effects on light absorptance and the
relationship between light absorptance (fraction of absorbed
photosynthetically active radiation, FAPAR) and structural and
nutritional leaf traits, performing a soil warming and surface soil
fertilization experiment on two deciduous tundra shrub species.
Our results show that fertilization and warming both increase light
absorptance in Arctic shrubs and that FAPAR is correlated with leaf
nutrients but not with structural leaf traits. This indicates an
economic strategy shift of shrubs from conservative to acquisitive
induced by warming and fertilization. We found species-specific
differences: FAPAR was influenced by warming alone in Betula nana but
not in Salix pulchra, and FAPAR was correlated with leaf phosphorus in
B. nana but not in S. pulchra. We attribute this to water limitation of
B. nana that generally grows in drier areas within the study site
compared to S. pulchra.
We conclude that FAPAR is a measure that opens up more possibilities to
estimate nutritional leaf traits and nutrient cycles, plant economic
strategies, and ecological feedbacks of the tundra ecosystem on broader
scales.