How Different Aspen Trees Grow and How Their Leaves Breathe

Greg Howard
23rd May, 2024

Image Source: Natural Science News, 2024

Key Findings

The study in Estonia evaluated the growth and physiological traits of 22 hybrid aspen genotypes to identify the best performers for afforestation
Genotypes from southern latitudes (Sweden, Latvia, Germany) showed almost three times higher growth compared to northern genotypes (Finland)
Southern genotypes had lower water use efficiency but higher growth potential, making them more suitable for biomass production in Estonia's climate

Afforestation, the process of planting trees on non-forest land, has emerged as a vital strategy for climate mitigation and biodiversity enhancement in the European Union. Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) is a promising candidate for such initiatives, given its potential for producing woody biomass. However, identifying the best-performing genotypes for biomass production and understanding their physiological adaptations remain key challenges. A recent study by the Estonian University of Life Sciences aims to address these gaps by evaluating the growth and physiological traits of 22 hybrid aspen genotypes^[1]. The study focused on determining the growth performance and leaf physiological characteristics, such as stomatal conductance, net photosynthesis, and intrinsic water-use efficiency, of these genotypes. The researchers also examined how these traits varied according to the geographical origin of the European (P. tremula) and North American (P. tremuloides) parent species when transferred to hemiboreal Estonia (58° N). The genotypes were assessed over a period from young (3-year-old) to mid-rotation age (13-year-old) in a completely randomized progeny trial. The gas exchange parameters were measured during the summer of 2021, which was notably warmer (+4 °C) and drier (17% precipitation from normal) compared to the long-term average. These conditions provided a robust test of the genotypes' physiological adaptability to stress. The study found significant differences in growth and physiological traits among the genotypes. These differences were influenced by the geographical origin of the parent species, indicating that both genetic and environmental factors play crucial roles in determining the suitability of hybrid aspen for afforestation projects. This finding is consistent with earlier research on other Populus species. For instance, a study on short-rotation coppice (SRC) poplar plantations in Belgium highlighted the importance of considering intergenotypic differences in water use strategies to enhance biomass yield^[2]. Moreover, the study's focus on gas exchange parameters ties in with previous research on carbon isotope ratios in Populus deltoides×nigra hybrids, which showed that discrimination between carbon isotopes (δ(13) C) can serve as an effective proxy for transpiration efficiency and whole-plant water use efficiency^[3]^[4]. These earlier findings underscore the importance of integrating physiological traits with genetic and environmental data to optimize biomass production and water use efficiency in hybrid aspen. By comparing genotypes from different geographical origins, the researchers could identify which genotypes were more adaptable to the specific climatic conditions of hemiboreal Estonia. This information is crucial for selecting the most suitable genotypes for large-scale afforestation projects aimed at maximizing biomass production while ensuring resilience to climate variability. In summary, the study by the Estonian University of Life Sciences provides valuable insights into the growth performance and physiological adaptability of hybrid aspen genotypes. It builds on earlier research by highlighting the importance of considering both genetic variability and environmental conditions in afforestation efforts. These findings will help inform future strategies for selecting the best-performing genotypes for climate mitigation and biodiversity enhancement projects across Europe.

Genetics Biochem Plant Science

References

Main Study

1) Growth ranking of hybrid aspen genotypes and its linkage to leaf gas exchange

Published 22nd May, 2024

https://doi.org/10.1186/s12870-024-05104-6

Related Studies

2) Water use of a multigenotype poplar short-rotation coppice from tree to stand scale.

https://doi.org/10.1111/gcbb.12345

3) Environmental and physiological determinants of carbon isotope discrimination in terrestrial plants.

https://doi.org/10.1111/nph.12423

4) Genotype differences in 13C discrimination between atmosphere and leaf matter match differences in transpiration efficiency at leaf and whole-plant levels in hybrid Populus deltoides x nigra.

https://doi.org/10.1111/j.1365-3040.2012.02556.x