Aging increases arbuscular mycorrhizal fungal diversity in iron ore mine sites

Abstract

Arbuscular mycorrhizal (AM) fungal colonization, spore density, and AM fungal richness were assessed with mine age. Iron ore mines with ages ranging from 10 to 50 years located in the state of Goa constituted the study sites. Most of the selected plant species assessed from recently mined areas also had higher colonization levels. However, AM fungal spore density increased with the increase in the age of mines. Spores of a total of 39 AM fungal species were isolated and characterized from various mine sites. Among the AM fungal species Acaulospora spinosa was most dominant (30-90 percent) followed by Glomus macrocarpum (20-80 percent), Acaulospora scrobiculata (60 percent), Racocetra gregaria (20-60 percent), Cetraspora pellucida (30-50 percent), and Gigaspora margarita (10-40 percent). Shannon's diversity index was highest at the oldest mine site and least at the recently mined site. In contrast, Simpson's dominance index was highest in the recently mined area and least at the oldest site. Diversity indices were more significant in the well-established mine than in the recently degraded mine. The study indicates that the severity of disturbance, the harshness of the site, low inoculum levels, edaphic characteristics, and time are known to influence the rate of AM fungi. Thus, revegetation of any disturbed site can occur over time with high species richness and diversity of AM fungi. They are essential in establishing a healthy plant community and facilitating plant succession.