Epsilon Archive for Student Projects

Abstract

Roots, as a place for nutrient acquisition, are closely related to the growth of trees. In the root economics spectrum, fine roots have acquisitive traits or conservative traits, based on the trade-offs between enhancing growth rate by high nutrient uptake rate and metabolism, and enhancing defence and life span. Meanwhile, another gradient in the spectrum represents the nutrient source to the roots, either through a “do-it-yourself” strategy that increases the nutrient uptake by extending the soil exploration through longer roots, or through a “outsourcing” strategy that invests carbon to develop a mycorrhizal collaboration. For the purpose of linking the relationship between tree height growth, wood density, tree vitality (good or poor) and fine root traits, we collected and analysed 72 root samples (3 breeds × 3 blocks × 2 vitality classes × 4 replicates) from two Scots pine (Pinus sylvestris) breeds that were bred for height increment (HT1 & HT2) and one breed that were bred for purposes other than height (PL) from a 38-year-old stand. Through comparing root morphology traits including average diameter, specific root length, specific root area, root tissue density and root chemical traits including nitrogen content, carbon content, carbon-to-nitrogen ratio, we detected a trend of conservative strategy and observed lower wood density in the numerically highest breed, and discovered no significant differences in root traits between trees in good and poor vitality. We posit that, during the growth of trees, the roots traits might be considerably influenced by the environment, rather than a simple trade-off between acquisitive and conservative strategies. Unlike what is commonly believed, fast-growing trees don’t necessarily have acquisitive root strategies, instead they tend to adjust the root traits according to the available resources in the environment, which might improve the defence and survive of trees.