Associations Between Physical Functional Traits and Leaf Litter Decomposition Rates of 16 Plant Species Native to British Columbia.

Rates of certain soil processes, such as decomposition and nutrient cycling, are influenced by leaf litter traits. While associations between chemical traits, such as nitrogen content, and decomposition rate have been historically emphasized, relationships between decomposition rate and physical traits, such as leaf toughness, remain less well understood. The purpose of this study was to explore relationships between physical traits of leaf litter and green leaves of 16 plant species native to British Columbia and to investigate their potential for predicting short-term decomposition rate. Mass loss was measured from litterbag samples placed in a temperate rainforest at the University of British Columbia in Vancouver in December 2014, subsets of which were collected after 1.5, 3, 6, and 9 months. Decomposition rate was expressed as proportion of mass loss during Phase I (0 to 1.5 months) and Phase II (1.5 to 9 months) of the current study. Preliminary results suggest that green foliar traits and litter traits tend to co-vary in ways predicted by the leaf economics spectrum, which is thought to broadly reflect trade-offs in resource allocation and conservation between species. A strong linear relationship between leaching loss after 24 hours and Phase I mass loss suggests that early mass loss is dominated by leaching (R² = 0.51, p <0.01). Additionally, physical functional traits such as leaching loss and leaf toughness were more important in CART analyses predicting Phase I mass loss than were chemical traits, but chemical traits, such as % nitrogen and C:N, were more important than physical traits for predicting Phase II mass loss. These results highlight the utility of physical traits to predict early mass loss rates and suggest that mass loss in early stages of decomposition is largely due to leaching. This study will continue for three years.