Rm. Palma et al., Seasonal changes of bioelements in the litter and their potential return to green leaves in four species of the Argentine subtropical forest, ANN BOTANY, 85(2), 2000, pp. 181-186
The aim of this work was to analyse the nutrient concentrations of N, P, Ca
, Mg, K and Na in mature leaves, branches and fruits and to investigate rel
ationships between the contents of these bioelements in senescent and fresh
leaves in four forest species: Gleditsia amorphoides (Espina Corona), Pata
gonula americana (Guayaibi), Chlorophora tinctoria (Mora) and Astronium bal
ansae (Urunday). The study site was located in the Colonia Benitez Estricta
Nature Research (Chaco, Argentina). In this subtropical forest, total litt
er was collected monthly and was sorted into three groups: (1) leaves; (2)
branches and fruit; (3) unidentified. Total dry matter was recorded and ana
lysed for N, P, Ca, Mg, K and Na. Espina Corona had the highest leaf concen
trations of N, while Mora had the highest concentrations of Ca and Mg. The
highest leaf concentrations of P were found in Espina Corona, Mora and Urun
day. No significant differences in K were found among the different species
. Na concentrations were higher in Espina Corona and Guayaibi than Mora and
Urunday. A marked seasonal variability was observed in the concentrations
of N, P and K, with no important differences for Ca and Mg, except in Espin
a Corona. These variations in nutrient concentrations were greater in leave
s than in branches and fruits. N and P were translocated to other tree orga
ns and Ca, Mg and Na were accumulated in mature leaves. The bioelement K is
the only one that undergoes leaching and mobilization in all species. Reso
rbed N and P can be used for the production of new leaf organs in the follo
wing annual cycle. This resorption supports a portion of the production of
new foliage, diminishing the demand from soil. (C) 2000 Annals of Botany Co
mpany.