DOI: 10.5061/dryad.8w9ghx3t6
title: Climate warming could free cold-adapted trees from C-conservative allocation strategy of storage over growth

description: Carbon allocation has been fundamental for long-lived trees to survive
 cold stress at their upper elevation range limit. Although carbon
 allocation between NSC (non-structural carbohydrate) storage and
 structural growth is well-documented, it still remains unclear how ongoing
 climate warming influences these processes, particularly whether these two
 processes will shift in parallel or respond divergently to warming. Using
 a combination of an in situ downward-transplant warming experiment and an
 ex situ chamber warming treatment, we investigated how subalpine fir trees
 at their upper elevation limit coordinated carbon allocation priority
 among different sinks (e.g., NSC storage and structural growth) at
 whole-tree level in response to elevated temperature. We found that
 transplanted individuals from the upper elevation limit to lower
 elevations generally induced an increase in specific leaf area, but there
 was no detected evidence of warming effect on leaf-level saturated
 photosynthetic rates. Additionally, our results challenged the expectation
 that climate warming will accelerate structural carbon accumulation while
 maintaining NSC constant. Instead, individuals favored allocating
 available carbon to NSC storage over structural growth after one year of
 warming, despite the amplification in total biomass encouraged by both in
 situ and ex situ experimental warming. Unexpectedly, continued warming
 drove a regime shift in carbon allocation priority, which was manifested
 in the increase of NSC storage in synchrony to structural growth
 enhancement. These findings imply that climate warming would release trees
 at their cold edge from C-conservative allocation strategy of storage over
 structural growth. Thus, understanding the strategical regulation of the
 carbon allocation priority and the distinctive function of carbon sink
 components is of great implication for predicting tree fate in the future
 climate warming.
description: # Data on: Climate warming could free cold-adapted trees from
 C-conservative allocation strategy of storage over growth
 [https://doi.org/10.5061/dryad.8w9ghx3t6](https://doi.org/10.5061/dryad.8w9ghx3t6) This dataset is the data used in the paper on global change biology entitled "Climate warming could free cold-adapted trees from the C-conservative allocation strategy of storage over growth". We used a combination of an *in situ* downward-transplant warming experiment and an *ex situ* chamber warming treatment to assess the impact of global warming on whole-tree C allocation of firs grown at their cold edge ## Description of the data and file structure **The Dataset-1 file includes the data considering the effects of downward-transplant warming on functional traits, growth, and NSC storage.** 1. Asat: saturated photosynthesis (µmol CO<sub>2</sub> m<sup>-2</sup> s<sup>-1</sup>); 2. sla: specific leaf area, total one-sided fresh leaf area divided by dry weight (cm<sup>2</sup> g<sup>-1</sup>); 3. twig\_density: density of the twig as the ratio of dry mass to the volume of that mass (g cm<sup>-3</sup>); 4. root\_density: density of the root as the ratio of dry mass to the volume of that mass (g cm<sup>-3</sup>); 5. height\_increment: the difference between tree height at the beginning and the end of the growing season (cm); 6. RBAI:  relative stem basal area increment (cm<sup>2</sup> cm<sup>-2</sup> yr<sup>-1</sup>); 7. shoot\_increment: shoot length increment (mm); 8. RGR:  dividing the whole-tree biomass at the end of the growing season by that at the beginning of the growing season (g g<sup>-1 </sup>yr<sup>-1</sup>); 9. NSC: the biomass-weighted mean concentration of whole-tree NSC, including soluble sugars and starch (mg/g) ***Definition of column names*** * Elevation (m): in order to simulate warmer climates, saplings from the upper elevation site (3150 m) were transplanted to the middle (2950 m) and the low elevation sites (2760 m); * Total\_biomass: whole-tree dry matter weight (g); * Twig\_biomass: twig (shoot) dry matter weight (g); * root\_biomass: root dry matter weight (g); * initial\_height: initial tree height (cm); * initial\_shoot: initial shoot length (mm); * May\_biomass: total biomass of samples sampled in May (g); * Sep\_biomass: total biomass of samples sampled in September (g) * Code: the identity of the individuals; * Chamber: the identity of the growth chamber **The Dataset-2 file includes data considering the effects of chamber warming treatment on growth and NSC storage.** 1. height\_increment: The difference between the current measurement and the last time the tree height was measured (cm); 2. shoot\_increment: The difference between the current measurement and the last time the shoot length was measured (mm); 3. RBAI:  relative basal area increment (cm<sup>2</sup> cm<sup>-2</sup>) 4. biomass: the biomass of the sample at each samplings (g); 5. NSC: the biomass-weighted mean concentration of whole-tree NSC, including soluble sugars and starch (mg/g) ***Definition of column names*** * date: sampling dates; * treatment: chamber warming treatment (i.e., "cur" refers to the current ambient air temperature scenario, "50-y" and "100-y" refer to the temperature scenarios after 50 and 100 years of warming, respectively); * Code: the identity of the individuals; * Chamber: the identity of the growth chamber