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E. Sayad 2010. Nitrogen retranclocation in pure and mixed plantations of Populus deltoides and Alnus subcordata
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Figure 1: N retranslocation of each species in mixed plantations and between the two species in pure
plantations
4. Discussion
In line with our results, Parrotta (1999) showed that N retranslocation were not significantly
different among treatments for Eucalyptus. He implied that this result suggest that the
association with either Nitrogen fixing species is not (yet) having any positive influence on
nutrient availability of Eucalyptus. The same conclusion could be stated for the current results.
It means that the species have not any effect on nitrogen cycling of other one. In contrary to our
results about the two species Cuevas and Lugo (1998) found different nitrogen retrenslocation
between the species. In this case it could be concluded that the nitrogen requirements of these
two species at this age are similar, although Alnus had the lower retranclocation. Finally, it
should be implied that nutrient retranslocation was not differed as a result of mixing these
species at this age.
References
Binkley, D., Menyailo, O., 2005. Tree Species Effects on Soil: Implications for Global Change,
NATO Science Series. IV Earth and Environmental Sciences-Vol.55. 358 pp.
Cuevas, E., and Lugo, A.E., 1998. Dynamics of organic matter and nutrient return from litterfall
in stands of ten tropival tree plantation species. Forest Ecology and Management,
112:263-279.
Ghasemi, R., 2000. Study of phenology of different Populus in Karaj and Safrabasteh Gilan.
M.Sc. thesis of Tarbiat Modarres University. 171 p.
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.