No abstract

The distribution and cycling of lead (Pb) was examined in an urban forest of Aleppo pine stand in Athens. Concentrations of the soluble fraction of Pb in bulk and throughfall deposition were low, reflectingthe change in petrol form in recent years. However, Pb concentrations in forest floor remain high due to Pb accumulation in previous years. The soil A horizon showed unexpectedly high levels of Pb concentration resulted probably from Pb migration from organic horizons. Pb concentrations in pine needles, litterfall and wood were low, whereas tree bark acted as a sink for Pb and stored high amounts of the metal.

The nutrient cycling and foliar status for the elements Ca, Mg, K, N, P, S, Fe, Mn, Zn and Cu were investigated in an urban forest of Aleppo pine (Pinus halepensis) in 2004 in Athens, Greece in order to draw conclusions on the productivity status and health of the ecosystem. The fluxes of bulk and throughfall deposition were characterized by the high amounts of Ca, organic N and sulfate S. The magnitude of the sulfate S fluxes indicated a polluted atmosphere. The nutrient enrichment in throughfall was appreciable for ammonium N, P and Mn. The mineral soil formed the largest pool for all the elements followed by the forest floor, trunk wood and trunk bark. The understory vegetation consisting of annual plants proved important for storing N, P and K. Compared to current year needles of Aleppo pine in remote forests of Spain, the needles of the Aleppo pine trees in Athens had significantly higher concentrations of Ca, N, P and Cu and significantly lower concentrations of Mg and Zn. The soil had a high concentration of calcium carbonate and accordingly high pH values. When all inputs to the forest floor were taken into account, the mean residence time of nutrients in the forest floor followed the order Fe > Mn > Cu > Ca > Mg > P > Zn > N > K > S.

This paper presents an investigation of trend in historic hydrological time series of areal annual precipitation on and mean annual runoff from the basin of the Evinos River in western Greece. Using different tests for randomness, a statistically significant long lasting decreasing trend was found in the precipitation record, whereas an also significant fluctuating "local" trend was detected in the runoff record. Further, it is shown that the effects of precipitation change on mean annual runoff can be quantified through a magnification factor. Détection de tendances dans les séries hydrologiques du bassin versant de la rivière EvinosRésumé Ce travail présente une analyse des tendances de séries historiques annuelles de précipitations et de débits recueillies dans de bassin versant de la rivière Evinos, située en Grèce occidentale. Après avoir utilisé différentes méthodes statistiques permettant de dignostiquer si ces séries sont ou non de type purement aléatoire, une tendance significative à la décroissance, de longue durée, a été mise en évidence dans le cas des précipitations, alors que des tendances fluctuantes, de courtes durées, ont été détectées dans le cas des débits. Il a été de plus montré que les effets sur le débit annuel des modifications concernant les précipitations pouvaient être quantifiés grâce à un facteur d'amplification.

The nitrogen cycle in a mature, mountainous European beech (Fagus sylvatica) forest in Greece was examined for two hydrological years, 2001–2002 and 2002–2003. Bulk deposition was 1383 mm in 2001–2002 and 2392 mm in 2002–2003. Winter temperatures were mild in the first year and low in the second year. Despite these climatological differences, the inorganic N inputs to the forest floor, by means of throughfall and stemflow, were quite similar for the two years, i.e. 12.4 and 14.6 kg ha yr. Litterfall production was significantly (p < 0.05) higher in the second year but the N amounts in litterfall did not differ. The ratio of N/P in foliar tissue did not change significantly in 2003 compared with ratio values in the last years. The N amounts used for the annual stem and branch increments are rather high preventing, in this way, some nitrogen from being recycled in the near future. The total soil N content to a depth of 80 cm amounted to more than 5000 kg ha, and the C/N ratio in the Oh horizon was approximately 15 but the beech forest did not appear susceptible to N leaching. The concentrations of ammonium and nitrate N in stream water did not reach high values reported in the literature, and did not differ significantly in the two hydrological years. The fluxes of inorganic N in throughfall plus stemflow were higher than those in stream water indicating N retention in soil. Another reason for N retention in the ecosystem is probably the large difference between N requirements and uptake indicating N deficiency. Despite the maturity of the beech trees, the low C/N ratio in the Oh horizon and the relatively high N content in soil, the forest can be considered to be neither saturated nor having reached a N saturation transition stage.–1–1–1