DOI: 10.5061/dryad.vd129
title: Data from: Above and belowground responses of four tundra plant functional types to deep soil heating and surface soil fertilization

description: 1.Climate warming is faster in the Arctic than the global average.
 Nutrient availability in the tundra soil is expected to increase by
 climate warming through 1) accelerated nutrient mobilization in the
 surface soil layers, and 2) increased thawing depths during the growing
 season which increases accessibility of nutrients in the deeper soil
 layers. Both processes may initiate shifts in tundra vegetation
 composition. It is important to understand the effects of these two
 processes on tundra plant functional types. 2.We manipulated soil thawing
 depth and nutrient availability at a Northeast-Siberian tundra site to
 investigate their effects on above and belowground responses of four plant
 functional types (grasses, sedges, deciduous shrubs and evergreen shrubs).
 Seasonal thawing was accelerated with heating cables at ~15 cm depth
 without warming the surface soil, whereas nutrient availability was
 increased in the surface soil by adding slow-release NPK fertilizer at ~5
 cm depth. A combination of these two treatments was also included. This is
 the first field experiment specifically investigating the effects of
 accelerated thawing in tundra ecosystems. 3.Deep soil heating increased
 the aboveground biomass of sedges, the deepest-rooted plant functional
 type in our study, but did not affect biomass of the other plant
 functional types. In contrast, fertilization increased aboveground biomass
 of the two dwarf shrub functional types, which both had very shallow root
 systems. Grasses showed the strongest response to fertilization, both
 above and belowground. Grasses were deep-rooted, and they showed the
 highest plasticity in terms of vertical root distribution, as grass root
 distribution shifted to deep and surface soil in response to deep soil
 heating and surface soil fertilization, respectively. 4.Synthesis - Our
 results indicate that increased thawing depth can only benefit deep-rooted
 sedges, while the shallow-rooted dwarf shrubs as well as flexible-rooted
 grasses take advantage of increased nutrient availability in the upper
 soil layers. Our results suggest that grasses have the highest root
 plasticity, which enables them to be more competitive in rapidly changing
 environments. We conclude that root vertical distribution strategies are
 important for vegetation responses to climate-induced increases in soil
 nutrient availability in Arctic tundra, and that future shifts in
 vegetation composition will depend on the balance between changes in
 thawing depth and nutrient availability in the surface soil.
description: 2015.05.18_weighing
 results abovegroundaboveground biomass of
 each plant functional type in each treatment2015.04.15_weighing
 results belowgroundbelowground biomass of
 each plant functional type in each treatmentplant
 abundanceplant abundance of each
 plant functional type in each treatment measured by point quadrat in 2010
 and 2013abioticsabiotic factors in each treatment in 2014, including active layer thickness, summer temperature (June-August), annual temperature at different depths, concentrations of NH4, NO3, PO4 and K measured by resin bags.temperature completemonthly average temperature of each treatment from Aug 2011 to Jul 2014 measured at 0cm, 5cm, 15cm, 25cm