Author(s):
Madeira, M. 
; Abreu, F.G. ; Pereira, E.
Date: 2009
Persistent ID: http://hdl.handle.net/10400.5/2175
Origin: Repositório da UTL
Subject(s): fraxinus angustifolia; ash-tree; gross rainfall; throughfall; soil nutrients; freixo; gotejo; precipitação bruta
Description
The effect of the ash-tree (Fraxinus angustifolia
Vahl) crown on characteristics of
throughfall and stemflow solutions was assessed
in wet pastures located in north eastern
Portugal. The amounts de gross rainfall,
throughfall and stemflow were measured
continuously and samples were periodically
collected to determine pH, dissolved organic
C (DOC) and N (DON), and nutrients.
The annual fluxes of DOC, DON, Cl, K, Na,
Ca, Mg and P in gross rainfall were, respectively,
3.93, 0.92, 0.20, 0.06, 1.81, 2.40,
1.11, 1.16, 0.29 and 0.06 g m-2, while those
regarding throughfall were 4.42, 0.20, 1.82,
1.82, 0.31, 0.54, 0.62 and 0.20 g m-2; the flux
of N-NH4
+ was nil and that of N-NO-
3 was
negative (-0.03 g m-2). The fluxes in relation
with stemflow were small if expressed on a
tree crown projection area basis, but can be
much greater if the actual area affected is
considered. The amounts and distribution of
nutrients turned to the soil by throughfall and
stemflow may lead to soil chemical characteristics
differentiation beneath tree crowns-------------------Avaliou-se a concentração e os fluxos
de nutrientes no gotejo e no escorrimento
do tronco de freixo (Fraxinus angustifolia
Vahl), num lameiro do Nordeste de Portugal.
A precipitação bruta, a precipitação sob
coberto (throughfall) e o escorrimento do
tronco (stemflow) foram objecto de monitorização
e amostras foram colhidas periodicamente
para determinação do pH, dos teores
de carbono (COD) e azoto (NOD) orgânicos
dissolvidos e de nutrientes. Os fluxos anuais
de COD, NOD, Cl, K, Na, Ca, Mg e P na
precipitação bruta foram, respectivamente,
3.93, 0.92, 0.20, 0.06, 1.81, 2.40, 1.11, 1.16,
0.29 e 0.06 g m-2, enquanto no gotejo foram
de 4,42, 0,20, 1,82, 1,82, 0,31, 0,54, 0,62,
0.20 g m-2; o fluxo de N-NH4
+ foi nulo e o de
N-NO-
3 foi negativo (-0,03 g m-2). A expressão
dos fluxos devido ao escorrimento do
tronco variará com a área influenciada por
esta solução. A restituição de nutrientes ao
solo pelo gotejo e pelo escorrimento do tronco
poderá contribuir para diferenciar as características
do solo sob a copa das árvores.
