Carbon uptake and release by leaves of forest plants play a crucial role in determining global atmospheric chemistry, which in turn influences the temperature of the Earth’s surface. Given this, climate models continue to seek ways of improving how leaf carbon exchange is accounted for in vegetation-climate models. Central to this objective is determining whether plants adapted to thermally contrasting environments (e.g. tropical versus temperate ecosystems) exhibit inherent differences in a range of leaf traits (and relationships among those traits) central to carbon exchange.
Dr. Shuang Xiang from Prof. Shucun SUN’s group of Chengdu Institute of Biology, Chinese Academy of Sciences have collaborated with Prof. Owen Atkin from Australian National University addressed the following question: do cold-adapted evergreen temperate wet forest species exhibit inherent differences in leaf traits associated with carbon capture and release (e.g. photosynthesis, respiration, leaf area:mass relationships and leaf nitrogen concentration) than their warm-adapted tropical counterparts.
Researchers grew 12 temperate and 13 tropical Australian tree species in a common, temperature controlled environment, with all plants being provided with non-limiting nutrients and water, which aims to address this question. The prediction was that cold-adapted forest species would exhibit inherently higher rates of photosynthesis and respiration than their tropical counterparts.
They found that rates of photosynthesis and respiration were indeed higher in the temperate species (compared to their tropical counterparts), with higher rates of carbon exchange in the temperate species being linked to higher concentrations of nitrogen (i.e. one of the key nutrients required for proteins and thus metabolic capacity) and maximal rates of key, underlying photosynthetic processes associated with light capture and CO2 fixation. Thus, they suggest that adaptation to thermally contrasting environments is linked to inherent changes in the patterns of nitrogen investment and the capacity of key metabolic processes that control carbon exchange with the atmosphere.
More results entitled “Contrasting leaf trait scaling relationships in tropical and temperate wet forest species" was published in Functional Ecology in April of 2013.