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The presence of the Early Bronze Age Avellino (AV) tephra in the Holocene lacustrine deposits of the Agro Pontino and Fondi basin provides a unique opportunity to reconstruct the Holocene depositional environment at the time of AV-tephra deposition. Marine terraces of the last Pleistocene transgression have been consolidated by soil formation and incised during the last glacial. This created a gully landscape in the Fondi basin and in the southeastern Agro Pontino. The inland central part of the Agro Pontino was drained by one major gully. At the final part of subsequent Holocene sea level rise, beach ridges closed the southeastern marine lagoons, creating a lacustrine and marshy environment. Shortly after, the Avellino eruption deposited its sandy tephra in these freshwater environments. By comparing altitudes of the AV-tephra in different environments two major implications emerge. First, at those locations where the AV-tephra is underlain by thick Holocene peaty and clayey deposits, significant subsidence occurred, while this has been limited at locations where the Pleistocene marine terrace occurs close to the surface. This subsidence is independently checked by comparing a modern LiDAR DEM and a detailed DEM from 1928. Second, the altitude of the AV-tephra reflects sea level in the coastal positions around −1.5 to −2 m a.s.l., while the only gully draining the lacustrine and marshy inland Agro Pontino was blocked around 0.5 m a.s.l. by the expanding sediment wedge of the Amaseno River, the major draining axis of the Agro Pontino. The AV-tephra layer will continue to play an important role in regional geological, palaeoenvironmental and geo-archaeological research.

Land subsidence has played and is still playing a significant role in coastal wetlands worldwide and in palaeogeographical reconstructions of such wetlands. The varying thickness of compaction-prone sediments over a stable subsurface is a key factor in determining its magnitude and in locating the most affected areas. In the coastal low-lying Agro Pontino (Lazio, Italy), subsidence of the past 90 years has been mapped using historical elevation data. Due to the fortunate preservation of distal Avellino tephra (AV-tephra, ca. 1900 cal. BCE) within its marshy strata, discovered a decade ago, detailed palaeogeographical reconstruction of the landscape in preparation for an assessment of its land use suitability in the Early Bronze Age (EBA) was possible. Current altitude variations of water-lain tephra in lake areas assumed to be connected necessitated a closer look at its original deposition altitude and the role of post-depositional subsidence. Recent subsidence patterns proved very useful for distinguishing stable from subsidence-prone areas. Two different EBA palaeo lake environments are distinguished: an inland and a near-coastal lake. The AV-tephra altitude variation within these lakes partly marks differential post-depositional subsidence within these lakes. Calculation of initial ripening of tephra-bearing lake deposits on top of shallowly buried Pleistocene ridges allowed for an estimation of original tephra deposition altitudes and associated lake levels. For the inland lake, a wide lake edge zone between 0.5 and 2 m above current sea level (m asl) was reconstructed, where EBA habitation or land use was possible. At the near-coastal lake, a water level of −1.5 to −1.3 m asl at the time of AV-tephra deposition was constrained. Because tephra deposition occurred here just after marine influence ceased, this altitude range is proposed to be a Relative Sea Level (RSL) index point at the time of AV-tephra deposition. The altitude range is in agreement with RSL models for tectonically stable areas in this region. The importance of subsidence in palaeogeographical, water level and RSL reconstructions in the region is stressed.

In the past decade (2000-2010), research within the scope of the 'Hidden Landscapes' project by RUG archaeologists provided important information on the Holocene history of the Agro Pontino graben. This information complemented earlier studies by Dutch Universities (UvA, RUG and UL). The graben was found to hold important tephrochronological, palaeoecological and archaeological archives, which deserve to be studied in more detail. This is demonstrated by the recent robust dating of the Avellino pumice layer at 3945 +/- 10 cal BP obtained from this archive (Sevink et al., 2011) and by the complex denudation record resulting from early land use in its hinterland. An overview is given of the recent knowledge on the Bronze Age to recent landscape that existed in the graben and of the major Early Bronze Age sites, of which most were associated with a large lake. Doubts have grown about the reliability of the existing chronological framework derived from earlier pollen cores by conventional radiocarbon dating. These doubts are discussed in the context of results from recent research, with emphasis on the 'hard water effect' that has been largely neglected in the earlier studies. The main current research topics are indicated. (C) 2013 Elsevier Ltd and INQUA. All rights reserved.

The pa´ramo soils of the mountainous upper Andean region (N3300 m a. s. l.) of the Rio Paute basin in central Ecuador are characterized by a thick, dark, highly organic epipedon and are classified as Andosols and Histosols. Their high water retention and buffering capacity play a key role in the hydrology of the region, which is subject to land use changes and increased cultivation. In the west (Western Cordillera), the soils are largely formed in the late Miocene and Pliocene volcanoclastic Tarqui formation, while in the east (Central Cordillera) they are formed in an older, mostly intermediate low-grade metamorphic rocks. Ten soil profiles were sampled and studied, using extraction techniques (oxalate and pyrophosphate) and XRD-techniques. Major differences in composition of the clay fractions were found that allow for distinction of three main groups of pa´ramo soils. A first group consists of soils influenced by recent volcanic ashes and dominated by organometallic complexes and with minor but distinct amounts of degraded mica, most probably formed by weathering of primary mica, present in these ashes. The second group comprises soils formed in volcanoclastic material of various Tertiary and earlier formations, containing residual primary and secondary crystalline clay-size minerals, as well as organometallic complexes whose genesis can be linked to the abundant presence of easily weatherable materials in these formations. A third group consists of soils in relicts of Tertiary, highly weathered regolith, formed under humid tropical conditions before the Andean uplift and occurring in the Central Cordillera. These soils contain kaolinite and gibbsite and develop into Histosols in the absence of significant organometallic complexation. volumen 127; número 1-2

High altitude tropical regions have been heavily deforested and offer large areas for carbon offsets by secondary forest regeneration. However, a general assumption exists that productivity, and thus, carbon sequestration of high altitude forests is low, but the scarcity of data from high altitude tropical forests does not allow for a sound confirmation of this assumption. To determine the carbon sequestration potential of natural forest regeneration and reforestation efforts at high altitudes, aboveground biomass was quantified of several successional stages of two monospecific secondary forests in the high Ecuadorian Andes. The studied forests were, at 3200 m, an Alnus acuminata forest with 8-, 20-, 30- and 45-year-old stands and, at 3600 m, a Polylepis incana forest with 6-, 15- and 30-year-old stands and old growth forest without known age. Both trees are pioneer species. Additionally, a soil survey was conducted and leaf N/P ratios and N and P retranslocation rates were determined. Total aboveground biomass (TAGB) estimates of the oldest stages of the two forests were 241 Mg ha−1 for the Alnus and 366 Mg ha−1 for the Polylepis forest. Productivity, expressed as annual aboveground biomass accumulation (ABA) was in both forests highest in the establishment phase (14.2 and 15.0 Mg ha−1 per year at 8 and 6 years, respectively) due to high sapling numbers, and then slowed down significantly (5.9 and 6.9 Mg ha−1 per year, respectively at age 30). TAGB and ABA figures of the investigated forests are comparable to those of lowland tropical forests and do not indicate a significant decrease of these parameters at higher altitudes in the tropics. Analysis of site conditions, ecological requirements and ecophysiological properties of the tree species indicated that in both cases an optimal combination of these factors strongly favoured forest growth. It is not possible to verify whether our forests are representative for other high altitude tropical forests or if they should be treated as exceptional cases. The results do show, however, that high carbon offsets at high altitudes are possible.

In the Gavarras (NE Spain), a large number of plots on respective schists, leucogranite and granodiorite was studied for their soils and vegetation. Results were used to check conclusions from earlier studies of Mediterranean forest soils (mostly shallow Regosols and Cambisols) on such acidic to intermediate rocks. They confirmed that the humus form depends on catenary position and lithology, and that aggregate stability and infiltration characteristics of the upper mineral soil horizon relate to humus form type. Aggregate stability of the topsoil was found to be relatively high in mor and mull type humus forms, but differences with moder type humus forms were not statistically significant. Differences in aggregate stability are attributed to the presence of stable humus-clay-iron complexes in mulls and to high fungal activity and organic matter content of mors. Low infiltration rates were only encountered in topsoils with mor type humus form, in line with results from the earlier studies. In deeper soil horizons with low organic matter content, aggregate stability will be largely related to soil reaction and base saturation. On leucogranite and granodiorite, these were found to vary strongly, most probably largely due to local differences in fast acid neutralizing capacity (ANC f ). These local differences are primarily attributed to differences in the mineralogical composition and texture of the soil material, connected with differences in lithology and/or brought about by erosion, colluviation and soil formation. Consonant with earlier studies, it is concluded that the susceptibility of these forest soils to erosion largely depends on properties of the upper mineral soil horizon, which are controlled by or related with humus form development. General trends in the latter are clear and can be used to predict this susceptibility. In the case of land degradation, which implies a more severe erosion, deeper soil horizons are also involved. Spatial variability in properties of these horizons, relevant for degradation, is considerable and not clearly related to humus form development. Accordingly, the abovementioned trends in humus form development cannot be used to predict the susceptibility to land degradation.

Pedogenesis on acid, low-grade metamorphic rocks under well-developed forests was studied in the meso-mediterranean climatic zone. To that purpose three representative soil profiles on phyllite and sandstone under sclerophyllous oak, pine and heathland were selected. The major soil forming processes consisted of transformation of part of the K-mica (muscovite) to (hydroxy-interlayered) vermiculite and smectite, impoverishment both in major elements (A1, K, Mg and Fe) and fine particles, and redistribution of sesquioxides as organic complexes. These processes indicate clay hydrolysis under acid conditions and subsequent removal of solutes by lateral subsurface flow. The resulting impoverishment of the soil profiles could be mainly attributed to hydrolysis under acid conditions brought about by slow decomposition of organic matter. The proposed mode of pedogenesis deviates strongly from the current concept of fersiallitisation, and is probably restricted to acid parent materials in mediterranean climates where lateral removal of soluble weathering products is ensured throughout the largest part of the year.

An investigation is being made into the relationship between forest fire and hillslope hydrology in the Selva region of Catalonia over a three year period at sites with a known fire history. The major sites are on granite, granodiorite or on sediments derived from these rocks at locations between Santa Christina d'Aro and Santa Coloma de Farnes. It appears that there is a general relationship between the type of organic profile found in a forest and the impact of fire in terms of loss of organic matter, soil erosion hillslope hydrology and on the regeneration of the forest. This paper summarises the results of about 150 rainfall simulation experiments and presents an overview of work carried out so far. A major conclusion is that runoff processes are discontinuous and spatially structured due mainly to the effects of water repellency. As a result of surface properties (macropores, hydrophobic behaviour and swelling), four types of infiltration curve can be recognised. At many locations infiltration increases with time during the early part of an experiment, reaches a maximum value after about 30 minutes therupon subsequently decreasing. This type of relationship can not be modelled with standard infiltration equations. Illustrations are given of sections through both burnt and unburnt soils to show how the hydrophobic effect influences water penetration. It can be seen that infiltration patterns are similar for both burnt and unburnt soils and that micropores filled with organic matter are very important in conducting water through a water repellent surface layer. The hydrophobic layer traps water in the BC horizon and prevents evaporation and loss by upwards capillary movement. Although the hydrophobic effects mean that small areas sometimes have a high runoff coefficient, on larger areas there are many macropores and shrubs, beneath which the soil is permeable, and these trap runoff generated on the water repellent areas. The main effect of fire is to illiminate the storage of water in the organic horizons (several cm). At first infiltration rates remain high but later these decrease as there is a reduction in porosity. The sites having a moder type profile have better water retention properties, more organic matter that survives the fire and a faster rate of vegetation recovery. Sites with a mor type profile can be degraded and erode if they are subject to disturbance. The study provides another example of how, on seemingly uniform slopes, hydrological processes are structured by interactions with vegetation. The patterns produced by these interactions survive the effects of fire.

During a detailed soil survey in the Ter valley (province of Gerona, NE-Spain), loamy sediments were observed, which because of their geomorphological position and sediment characteristics were interpreted as loessial deposits. Previous studies suggested that loess deposition was of very minor importance in this part of the Mediterranean, which seemed to be in conflict with the results of the survey. To establish the nature and stratigraphy of these deposits considerable attention was paid to their distribution, pedology and stratigraphy, as well as to the fluvial deposits in the Ter valley. Results from the field survey strongly indicate that the loamy sediments are of aeolian provenance, but have been more or less reworked after their deposition. A fluvial origin can be excluded, as such would be in conflict with their distribution and composition, as well as with their soil development relative to that in the fluvial terraces. They can be divided into two units. The Younger Unit, marked by an at most moderate soil formation and weathering, has two intercalated palaeosols. The Older Unit is characterized by the presence of a deep rubified soil and a strongly developed calcic/petrocalcic horizon. Micromorphological studies on a number of representative sections confirmed that the deposits largely consist of more or less reworked material of aeolian origin. The texture of this material ranges from silt to fine sand, indicating a provenance from a nearby source area. Sedimentary structures allowing for a more precise indentification of the colluvial processes were not observed. Within the Younger Unit three members could be distinguished, separated by palaeosols. The lower palaeosol is characterized by brunification, bioturbation, and yellow argillaceous cutans, and regularly shows hydromorphic features. The upper palaeosol is also characterized by brunification and bioturbation, but has yellowish brown to orange argillaceous cutans and some matric cutans, and only locally shows hydromorphic features. In both palaeosols secondary carbonate redistribution is observed, dating from after the truncation and subsequent burial of the soil. The soil developed in the top of the deposits has a crystic matrix and is marked by a strong redistribution of carbonates (calcitans, neocalcitans, and nodules). Bioturbation in this soil is prominent. The truncated soil in the Older Unit shows iron segregation, giving rise to a red-brown argillicol plasma and a weak rubification of the matrix. In addition, common biological features and red-brown illuviation ferri-argillans are observed. Correlation of the various units and palaeosols with those described in the literature leads to the following tentative stratigraphy: deposition of the Older Unit during the Rissian, followed by soil formation during the Eemian. Deposition of the lower member of the Younger Unit during the Early Wurm, followed by soil formation in Early to Middle Wurm. Subsequently, deposition of the middle member before and soil formation during the Denekamp interstadial. The upper member probably dates from the Late-Wurm.

The clay soils on limestone in South Limburg range in age from Holocene (“young” soils; profiles 2 and 3) to probably Late Tertiary (profile 1) and show correspondingly great differences in their characteristics. 1. (A) The “young” soils are of two kinds. Inceptisols have been formed, with insignificant illuviation and bioturbation where no loess is present. If covered by loess, strong bioturbation and concurrent illuviation of clay and silt has occurred, resulting in the formation of Alfisols. Decalcification and desilication are the prominent weathering processes. Kaolinite and possibly smectite have been formed in the solum. 2. (B) The “old” soils are polygenetic and can be classified as Alfisols. Three phases (intervals) of soil formation — predominantly clay illuviation — can be distinguished. Abundant phytoliths, altered to quartz, point to a great age for the oldest pedogenic phase. Decalcification and desilication are the prominent weathering processes. Kaolinite has been formed and probably preferentially eluviated from the upper to the lower part of the solum.

Detailed soil mapping in the Ransdalerveld area pointed to the occurrence of clay soils of different ages, characteristics and genesis. Three representative soil profiles were therefore selected and studied in detail. In this first of three articles, some observations and conclusions on the distribution, age and characteristics of these soils are presented. The “old” soils, developed on the plateaus in predominantly limestone-weathering residues, are classified as Lithic Hapludalfs, whereas the “young” soils on the valley slopes are classified as Rendollic Eutrochrepts if they lack a loess cover and as Typic Hapludalfs if they have a loess cover. Weathering and soil formation are discussed in the second and third parts.

The alteration of the limestone into parent material is described and discussed in this second part. The chemical and mineralogical (X-ray and microscope) analyses of the solid materials and the chemical analyses of the interstitial waters permit the following conclusions about the parent materials. 1. (A) Of the “young” soils: decalcification and desilication have occurred; low-ordered tridymite has been formed by replacement of the carbonates which, together with plagioclases and magnesite (Mg-calcite), have subsequently been transformed into smectite and kaolinite. 2. (B) Of the “old” soils: decalcification and desilication have occurred; hematite has been transformed into goethite and amorphous iron hydroxide; transformation of muscovite into illite and neoformation of kaolinite have occurred. The parent material of “old” soils represents a more advanced weathering stage than that of the “young” soils.

Study of a series of plots on acid to intermediate rocks under well preserved mediterranean type forests in NE Spain showed that soils have well developed mor or moder type humus forms. Mor type humus forms were observed in soils with a shallow lithic contact or an abrupt textural change, and consist of an ectorganic layer (L, Fq, H) abruptly overlying a generally water repellent Ae or E horizon. Moder type humus forms, with a gradual transition between the ectorganic layer (L, Fa and the Ah horizon, were found in soils with more favourable rooting and soil moisture conditions, indicating that these conditions have a strong control over humus form development. Quantities of organic matter (ectorganic layer + Ah/Ae) ranged from about 5 kg/m2 in mor to about 10 kg/m2 in moder humus forms, the difference being due to the presence of a well developed Ah horizon in the latter. Rainfall simulator experiments showed that slopes with mor type humus forms are likely to produce hillslope runoff during summer rain storms in spite of the relatively high storage capacity of the ectorganic layer. This is due to the hydrophobicity of the mineral top soil (if dry), which hampers infiltration. Furthermore, during the wet season the soils commonly have a perched water table, inducing saturated overlandflow. Slopes with moder type humus forms, on the contrary, are very unlikely to produce any hillslope runoff, because of the high storage and infiltration capacity of the soils. On slopes with mor type humus forms, traditional management (cutting of the undertsory) leads to erosion of the ectorganic layer and thus to a reduction of its storage capacity. Forest fires have similar effects, since they lead to the (partial) destruction of the ectorganic layer and destroy the existing vegetation. As evidenced by the rainfall simulation experiments, in both cases hillslope runoff will strongly increase, inducing erosion of the mineral soil, in particular after fire. On slopes with moder type profiles the effects of fire and traditional management will be far more limited, because of the high storage and infiltration capacity of these soils, and hillslope runoff is not likely to increase, if occurring at all.

The loess cover in the region of Middachten near Arnhem is of the Last Glacial Age. An investigation of four profile-pits showed that, during the deposition of the loess, tundra soils with a thin Bt-horizon were formed. Solifluction and fresh deposits on these soils resulted in the formation of a series of loess layers, each showing more or less strongly developed flowstructures as well as remnants of Bt-horizons disturbed by the subsequent flowage-phenomena. Several of these profiles show fragipan-characteristics. The authors suggest a close relation between the formation of the fragipans and the occurrence of periglacial tundra climates.