Reindeer faeces and burning alleviates allelopathic effects of Empetrum humus on local plants

Abstract

Empetrum hermaphroditum is one of the dominant species in many reindeer summer grazing areas in Northern Norway, forming unproductive, late successional stable vegetation covers. As studies of amount, and effect of, plant secondary metabolites emerging from E. hermaphroditum indicates strong inhibitory effect on other organisms, it is considered an invasive and allelopathic species. To investigate the effect of two potential ecological disturbances that can cause switch in vegetation cover from unproductive Empetrum domination to a more productive herbaceous plant dominated ecosystem, we compared soil pH and growth of Avenella flexuosa and Solidago virgaurea in heat treated, reindeer faeces fertilized and untreated humus obtained from E. hermaphroditum dominated areas. Measures of total plant biomass differed significantly both between treatments and between species, with all treatments having significantly different effects. Largest level of plant dry weight and pH was measured in fertilized humus, medium level in burned humus and the lowest level where obtained in untreated humus. Results indicate that heat treatment and addition of fertilizer to Empetrum humus improved growing conditions, by elevating pH or nutrient levels and likely omitting allelopathic effects of E. hermaphroditum.