Grouping nitrogen fixing trees into discrete functional groups based on litter decomposition rate does not make sense

Functional grouping of nitrogen fixing trees into discrete groups is a good approach to understanding their influence on ecosystem functioning in their new environment. Most of previous studies have reported faster leaf litter decomposition rates of nitrogen fixing than non-nitrogen fixing species. Meta-analysis using published data is the best way for functionally grouping of nitrogen fixing trees from non-nitrogen fixing trees based on litter decomposition rate. Meta-analysis was used for analyzing litter decomposition rate from published data. The data extracted from 5 papers and 16 species that used laboratory method and 27 papers and 41 species that used litterbag method. Leaf litter decay constant (k year-1 ) of the nitrogen fixing trees was not different from non-nitrogen fixing trees. Initial leaf litter quality (N or C/N, lignin/N, Tannin and Phenolics) of nitrogen fixing trees in all studies was higher than non-nitrogen fixing trees. Totally, it could be highlighted that leaf litter decomposition is species dependent and functional grouping of the tree species based on nitrogen fixing ability is not reasonable, although it is apparent that the litter quality of the two groups is different.