Molybdenum in forests-A short review

This review deals with the importance of molybdenum (Mo) in nitrogen fixation in forests as well as the distribution of Mo in the various components of a forest ecosystems and its cycling. With regard to nitrogen (N) fixation in tropical forests, the limiting factor is the availability of phosphorus in soils. For the temperate and boreal forests, the Mo availability is more crucial. The canopies of the tropical forests retain Mo from precipitation, which is used for N fixation by the microorganisms living there. There is also retention of Mo in throughfall deposition by the canopy of temperate forests but so far, there has been no information as to the biological processes taking place there. The contribution of Mo in bulk and throughfall deposition in the Mo cycling is more important than once thought. There is great variability in Mo concentrations in tree leaves either conifers or broadleaves and even within the same species. In soils, the organic matter, clay and the oxides of Al, Fe and Mn play a predominant role in preventing Mo from leaching.