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Understanding and quantification of phosphorus (P) fluxes are key requirements for predictions of future forest ecosystems changes as well as for transferring lessons learned from natural ecosystems to croplands and plantations. This review summarizes and evaluates the recent knowledge on mechanisms, magnitude, and relevance by which dissolved and colloidal inorganic and organic P forms can be translocated within or exported from forest ecosystems. Attention is paid to hydrological pathways of P losses at the soil profile and landscape scales, and the subsequent influence of P on aquatic ecosystems. New (unpublished) data from the German Priority Program 1685 ''Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources'' were added to provide up-to-date flux-based information. Nitrogen (N) additions increase the release of water-transportable P forms. Most P found in percolates and pore waters belongs to the so-called dissolved organic P (DOP) fractions, rich in orthophosphate-monoesters and also containing some orthophosphate-diesters. Total solution P concentrations range from ca. 1 to 400 μg P L -1 , with large variations among forest stands. Recent sophisticated analyses revealed that large portions of the DOP in forest stream water can comprise natural nanoparticles and fine colloids which under extreme conditions may account for 40-100% of the P losses. Their translocation within preferential flow passes may be rapid, mediated by storm events. The potential total P loss through leaching into subsoils and with streams was found to be less than 50 mg P m -2 a -1 , suggesting effects on ecosystems at centennial to millennium scale. All current data are based on selected snapshots only. Quantitative measurements of P fluxes in temperate forest systems are nearly absent in the literature, probably due to main research focus on the C and N cycles. Therefore, we lack complete ecosystem-based assessments of dissolved and colloidal P fluxes within and from temperate forest systems. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Forest phosphorus cycle during ecosystem developmentForests are complex biogeochemical systems in which nutrient cycles readily change and become re-adjusted upon interactions with biotic and abiotic controls over diurnal, annual, decadal, centennial, and longer timescales (Hedin et al., 2003). Phosphorus (P) is an essential element for all living organisms. Modern agriculture avoids P limitation of primary production by continuous application of fertilizers, while forest ecosystems have developed efficient strategies for adapting to low P supply (Elser et al., 2007;Ilg et al., 2009;Rennenberg and Schmidt, 2010;Hinsinger et al., 2011). Increasing production of forests biomass in response to high atmospheric nitrogen (N) input and climate c...

During the 20th century, afforestation resulted in plantations of Pine and Eucalypt becoming the main crops in north‐central Portugal with associated and well‐known soil water repellency (SWR). The aim of this study was to improve the insights in the temporal dynamics and abrupt transitions in water repellency of the topsoil and the mechanism that determine the behaviour of SWR. Topsoil water repellency was monitored in the Caramulo Mountains (north‐central Portugal) between July 2011 and June 2012. The intensity of SWR was measured in situ at soil depths of 0, 2.5 and 7.5 cm using the ‘molarity of an ethanol droplet’ test. Volumetric soil moisture content was monitored in situ using a Decagon ECH2O EC‐5 probe. SWR behaviour broadly followed five alternating dry and wet periods during the 12‐month period, with more pronounced differences in the Pine site than in the Eucalypt site. SWR under Eucalypt was substantially more temporally dynamic than under Pine, with double the number of moderate and large SWR changes at the 7.5 cm depth. Soil moisture content and antecedent rainfall were better correlated to SWR under Pine than under Eucalypt, although in both cases insufficient to predict the temporal variations. Copyright © 2013 John Wiley & Sons, Ltd.

Litter decomposition was studied for 2 years in a mixed forest serving as a water protection area (RhineNeckar conurbation, SW Germany). Two experiments differing in initial dry weight equivalent in litterbags were set up: one to compare decomposition of European beech leaves (Fagus sylvatica) with common oak leaves (Quercus robur), and the other comparing decomposition of Scots pine needles (Pinus sylvestris) with black cherry leaves (Prunus serotina Ehrh.), respectively. Mass losses were greater for oak litter than for beech (75.0 versus 34.6%), and for cherry litter than for pine (94.6 versus 68.3%). In both experiments, a strong initial loss of soluble compounds occurred. The changes in litter N and P concentrations and the decrease in C-to-N ratio coincided with changes in residual mass. However, neither tannin and phenolic concentrations nor NMR could explain the pronounced variation in mass loss after 2 years. Differences in litter palatability and toughness, nutrient contents and other organic compounds may be responsible for the considerable differences in residual mass between litter types. The fast decay of black cherry leaves appears to play a major role in the present humus dynamics at the studied site. Since black cherry has a high N demand, which is mainly met by root uptake from the forest floor, this species is crucial for internal N cycling at this conurbation forest site. These effects together may significantly contribute to prevent nitrate leaching from the forest ecosystem which is subject to a continuous N deposition on an elevated level.

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