Affiliation:
1. Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden, Chinese Academy of Sciences Wuhan China
2. Key Laboratory of Reservoir Aquatic Environment Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences Chongqing China
3. University of Chinese Academy of Sciences Beijing China
4. College of Science Tibet University Lhasa China
Abstract
AbstractCarbon allocation has been fundamental for long‐lived trees to survive cold stress at their upper elevation range limit. Although carbon allocation between non‐structural carbohydrate (NSC) 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 1 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.
Funder
National Natural Science Foundation of China
Subject
General Environmental Science,Ecology,Environmental Chemistry,Global and Planetary Change