Biomass Allocation of Xanthium strumarium L.: A key factor for invasive success at high elevation

Abstract

This study aims to investigate the importance of biomass allocation in the invasive success of Xanthium strumarium, an alien invasive species across an elevation gradient in Pakistan. This plant was selected as a model due to its lowland invasion capacity and going up the elevation gradient. Sites were sampled in three different elevation groups, ≤ 200m, ≤ 600m, and ≤ 1000m while ≥ 1400m above sea level, to analyze X. strumarium biomass allocation, related environmental variables, and community diversity. Root/Below ground, stems, leaves, fruits, total dry biomass and, its ratios were found to vary with elevation (P < 0.05). The total dry biomass and density of the species had a significant negative effect on community diversity, where the crown cover was the main contributing factor to total biomass accumulation. Environmental factors such as elevation, sand, clay, nitrogen, organic matter, phosphorus, and pH were most strongly correlated in CCA-ordination, which indicates that several topographic, edaphic, and soil variables influence the spatial pattern of biomass allocation in this invasive species. It was concluded that X. strumarium invasion continues at a higher elevations, adapting to new environmental conditions, particularly reproductive dry biomass.