dc.creatorPérez, Cecilia A.
dc.creatorCarmona, Martín R.
dc.creatorArmesto, Juan J.
dc.date.accessioned2010-06-30T14:48:08Z
dc.date.available2010-06-30T14:48:08Z
dc.date.created2010-06-30T14:48:08Z
dc.date.issued2010
dc.identifierAustral Ecology (2010) 35, 148–156
dc.identifierdoi:10.1111/j.1442-9993.2009.02020.x
dc.identifierhttps://repositorio.uchile.cl/handle/2250/120033
dc.description.abstractHeterotrophic nitrogen fixation is a key ecosystem process in unpolluted, temperate old-growth forests of southern South America as a source of new nitrogen to ecosystems. Decomposing leaf litter is an energy-rich substrate that favours the occurrence of this energy demanding process. Following the niche ‘complementarity hypothesis’, we expected that decomposing leaf litter of a single tree species would support lower rates of non-symbiotic N fixation than mixed species litter taken from the forest floor.To test this hypothesis we measured acetylene reduction activity in the decomposing monospecific litter of three evergreen tree species (litter C/N ratios, 50–79) in an old-growth rain forest of Chiloé Island, southern Chile. Results showed a significant effect of species and month (anova,Tukey’s test, P < 0.05) on decomposition and acetylene reduction rates (ARR), and a species effect on C/N ratios and initial % N of decomposing leaf litter.The lowest litter quality was that of Nothofagus nitida (C/N ratio = 78.7, lignin % = 59.27 4.09), which resulted in higher rates of acetylene reduction activity (mean = 34.09 SE = 10.34 nmol h-1 g-1) and a higher decomposition rate (k = 0.47) than Podocarpus nubigena (C/N = 54.4, lignin % = 40.31 6.86, Mean ARR = 4.11 0.71 nmol h-1 g-1, k = 0.29), and Drimys winteri (C/N = 50.6, lignin % = 45.49 6.28, ARR = 10.2 4.01 nmol h-1 g-1, k = 0.29), and mixed species litter (C/N = 60.7,ARR = 8.89 2.13 nmol h-1g-1).We interpret these results as follows: in N-poor litter and high lignin content of leaves (e.g. N. nitida) free-living N fixers would be at competitive advantage over non-fixers, thereby becoming more active. Lower ARR in mixed litter can be a consequence of a lower litter C/N ratio compared with single species litter.We also found a strong coupling between in situ acetylene reduction and net N mineralization in surface soils, suggesting that as soon N is fixed by diazotroph bacteria it may be immediately incorporated into mineral soil by N mineralizers, thus reducing N immobilization.
dc.languageen
dc.publisherEcological Society of Australia
dc.subjectacetylene reduction activity
dc.titleNon-symbiotic nitrogen fixation during leaf litter decomposition in an old-growth temperate rain forest of Chiloé Island, southern Chile: Effects of single versus mixed species litter
dc.typeArtículo de revista


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