Carbon and nutrient inputs by litterfall into three chestnut high forest stands in North Portugal
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abstract
The litterfall in three high forest chestnut stands, located in different soil types, in Bornes, Marão and Padrela, north of Portugal, with 45, 63 and 65 years old, respectively, was collected during two years in December by a quadrate method with 0.5*0.5m. To the sampling of the presented study there were collected four kinds of samples – (1) leaf litter constituted by vegetal materials resulting from the litterfall of the year; (2) leaf litter constituted by a mixture of vegetal materials in different decomposition stages; (3) soil from 0-5 cm depth and (4) soil from 5-10 cm depth. The litter of the year was separated into the fractions leaves, branches, fruits and fruit cases. The fractions were dried at 70ºC, weighted and the concentrations of N, P, K, Ca, Mg, S, B e C were measured. The total amount of litter in the three chestnut stands was 8.3, 7.7 and 12.4 Mg ha-1, respectively. Leaves are the main constituents of the total litter with 54, 62 and 50 %, respectively. The proportion of the other litter fractions varies between 10 and 19 % for the hedgehogs, 20 and 32 % for the branches and 4 and 10 % for the fruits. Regarding the concentration of the nutrients in the litter fractions, in general, leaves are rich in N>Ca>Mg>K>P>S; fruits are rich in N>K>Mg>Ca>P>S. In branches, the N and Ca concentration dominate by far and the fruit cases are rich in N and K. The return of nutrients by litterfall is relevant: it varies between 57 and 141.6 kg ha-1 year-1 for N, 5 and 10 kg ha-1 year-1 for P, 13 and 45 kg ha-1 year-1 for K, 28 and 65 kg ha-1 year-1 for Ca, 18 and 34 kg ha-1 year-1 for Mg, 2 and 8 kg ha-1 year-1 for S, 87 and 117 g ha-1 year-1 for B. The carbon in the litterfall varies between 4 and 6.3 Mg ha-1 year-1. It was verified that the biomass nutrients concentrations is strongly dependent of the soil like suggest some authors.
