Crops and fodder: evidence for storage and processing activities in a functional area at the Roman settlement of Monte Mozinho (northern Portugal)

Archaeobotanical material was recovered in two contiguous compartments of a compound in Monte Mozinho (Penafiel, northern Portugal). These areas comprise storage facilities from three different typologies—dolium, pits and above-ground quadrangular structures in the corner of the compartments. Few carpological materials were found inside the storage structures and all these are cereals which were most likely stored as clean grain. Recovered grains are probably remnants of the last stored crops prior to abandonment of the area. A radiocarbon date obtained on grains of rye positions this event at a time within the 3rd century and the beginning of the 4th century a.d. Outside the structures from compartment 2, abundant crop processing by-products, mostly weeds and chaff, were recovered. Since traditional agricultural communities tend not to waste such organic material, it is likely that it was kept in the area to be used as fodder. Data is ambiguous regarding the possible existence of fodder crops mixed with these by-products. Overall, there is a predominance of millets (Panicum miliaceum and Setaria italica) and rye (Secale cereale), but naked wheat (Triticum aestivum) is also a relevant crop. The presence of oat (Avena) is significant but it is difficult to interpret due to its exclusive presence alongside weeds and chaff. Grape pips (Vitis vinifera) were also found, but these are rare. The Late Roman carpological material from Monte Mozinho is of great relevance on a regional level. It documents and dates the presence of rye and testifies to a multifunctional system in which plant husbandry and animal breeding were intertwined.     

Vegetation of the Lago de Sanabria area (NW Iberia) since the end of the Pleistocene: a palaeoecological reconstruction on the basis of two new pollen sequences

Various pollen sequences from lacustrine deposits close to Lago de Sanabria (NW Iberia) have for several decades been a key source of information for palaeoenvironmental reconstructions of SW Europe, though their interpretation has been the subject of some controversy. Here we present two new pollen sequences obtained from this area, and a new palaeoenvironmental reconstruction of the region. The available pollen data reach back to before 18,000 b.p., a period of very harsh climate with seasonal (non continuous) sedimentation and a landscape characterised by herbaceous formations dominated by Gramineae and Artemisia, and scrub formations dominated by Ericaceae and Cistaceae. Subsequently sedimentation became continuous, and various regional forest expansions are apparent. At a local level, the first forest expansion began about 12,000 b.p., when Betula pollen reached 70% followed by peaks in Pinus sylvestris-type (>80%) and Quercus robur-type (40%). The Younger Dryas saw a retreat of woodland formations in the area around the lake, with broadleaved deciduous woodland (largely oak) retreating at mid and low altitudes, but with pine woodland persisting in more sheltered sites. The climatic improvement in the Early Holocene favoured re-expansion of woodland, dominated by Pinus sylvestris-type at higher and Quercus robur and Q. pyrenaica at lower altitudes, until anthropogenic deforestation commenced around 4,000 b.p. The disappearance of natural pine woodlands in this region is probably largely attributable to human interference.     

Differences in the vegetation of the North Iberian Peninsula during the last 16,000 years

The dynamics of vegetation in the North Iberian Peninsula have been historically established from peaty and lacustrine records obtained in strongly continental mountainous areas. Pollen records located in areas with a more oceanic climate, have allowed a more precise evaluation of the changes and differences in the vegetation development of the various biogeographical areas in the North Iberian Peninsula, during the Late-glacial and Holocene. It was found that: (1) The vegetation of the Cantabrian–Atlantic province in northern Iberian Peninsula responded to climatic changes during the last 16000 years. (2) Tree vegetation declined during the Oldest Dryas, with steppe vegetation in the interior and cryophilous vegetation along the coast. (3) During the time of the Lateglacial Interestadial, lowlands, arboreal vegetation was dominant in the landscape (Pinus, Betula, Quercus, Corylus). (4) During the Younger Dryas the differences between coast and interior are less obvious. (5) During the Holocene oceanic decidious forests of Quercus robur, Corylus avellana, Tilia sp. and Fagus sylvatica were present along the coast. At low altitudes, in the interior, forests of Quercus robur / pyrenaica, enclaves of pine woods and Mediterranean types of forest (Quercus ilex, Olea europea) were present. At higher altitudes Pinus (P. sylvestris and P. uncinata) or mixed forests of Pinus and Betula were dominant.     

Climatic and human effects on the post-glacial dynamics of <Emphasis Type="Italic">Fagus</Emphasis> <Emphasis Type="Italic">sylvatica</Emphasis> L. in NW Iberia

Our aim is to determine the population dynamics of Fagus sylvatica L. during the last 4,000 cal. BP in NW Iberia and the causes of its spatial and temporal patterns, previous palaeoecological studies having shown that between the Upper Pleistocene and the recent Holocene Fagus survived in this region. A number of pollen sites have allowed a reconstruction of the regional dynamics of Fagus from the Last Glaciation to the present. Specifically, two high-resolution pollen sequences located in both extremes of the Cantabrian region were analysed to discuss the beech forest dynamics during the last four millennia. Beech pollen percentages increased progressively to dominant species levels in eastern Cantabria, but only brief, minor increases are recorded in the west, where they never exceeded 2%. The expansion in the east shows three well-defined stages: an initial increase that lasted up to about 2,500 cal. BP, coinciding with a general increase in total tree pollen throughout the Cantabrian Mountains; a stage lasting between 2,500 and 1,500 cal. BP, in which Fagus pollen levels fluctuated while total tree pollen percentages began to decline and Ericaceae to increase; and a final further increase peaking around 1,250 cal. BP. The first stage (ca. 4,000–2,500 cal. BP) probably formed part of the final ascent of the tree line at the end of the mid-Holocene as the consequence of climatic improvement. Its maintenance during the second stage, while other tree species began to recede under unstable environmental conditions, is attributable to displacement of other genera such as Corylus and Quercus. Its final peak may have been facilitated by human disturbance of woodland, Fagus being a competitive species readily able to take advantage of such disturbances. That no such process occurred in the western Cantabrian area may be due to both the direct biological influence of harsher climatic conditions, and the lack of interest by human populations in settling highlands, which is attributable both to this climatic factor and to the fact that, compared with the east, this area has a greater extent of lowland and wide flat valleys where settlements were concentrated.     

The last hornbeam forests in SW Europe: new evidence on the demise of <Emphasis Type="Italic">Carpinus betulus</Emphasis> in NW Iberia

Carpinus betulus L. is a mesic, usually considered late-successional tree widely distributed in Europe, but almost absent from Iberia, where it is generally assumed that disappeared during the coldest stages of the Würm. High-resolution pollen analyses were carried out in ¹⁴C dated sediments from a drowned estuary (ria) and a small mountain lake. Carpinus pollen identification was confirmed by comparative light and scanning electron microscopy. Hornbeam dynamics are interpreted using palaeoclimatic reconstructions based on independent proxies (diatoms, chironomids and dinocysts). Our results support that hornbeam declined between ca. 60,000 and ca. 9,000 cal yr bp, when multiproxy evidence suggests a major regional relative sea-level rise. Moreover, chironomid-inferred July temperatures show an increase of more than 6 °C between 15,600 and 10,500 cal yr bp, while freshwater aquatics and diatoms indicate a general tendency towards increasing precipitation and a more oceanic climate. Carpinus survived during the Würm in a variety of habitats in coastal valleys in NW Iberia which had adequate climatic and edaphic conditions. Such habitats might be comparable to the oak-ash, ravine, and hardwood floodplain forests currently existing in other regions of Europe. Large areas of these coastal ecosystems disappeared at the onset of the Holocene, when the sea-level rose. Later hornbeam was apparently unable to compete and expand further inland. Therefore, the sea-level rise combined with the climatically-induced Holocene tree succession and the increasing human impact during the Mid and Late Holocene led to hornbeam progressively becoming a marginal tree in the area.     

Some considerations about the postglacial history and recent distribution ofFagus sylvatica in the NW Iberian Peninsula

This paper presents a re-assessment of the evidence of beech (Fagus sylvatica) presence on the NW Iberian Peninsula in the different stages of the Late Quaternary. For this purpose, numerous pollen diagrams were re-examined and the present-day distribution of the species was documented. Beech pollen has been recorded in different periods, before the Würm Pleni-Glacial, during the Late Glacial and the Holocene, leading to the hypothesis that there existed local refugia forFagus sylvatica in the NW Iberian Peninsula, comparable to those in more eastern areas of southern Europe, the existence of which has been recognized.     

Vegetation in the mountains of northwest Iberia during the last glacial-interglacial transition

A new core taken from a site in the Sierra de Courel range of mountains in the northwest Iberian peninsula, Spain, enables a palaeoenvironmental reconstruction to be made of the biological events resulting from climatic changes and human activities during the last 17,000 years in the area. The sequence begins with a phase characterised by the dominance of Gramineae (Poaceae) and Pinus. A markedly arid period with prevalence of Artemisia pollen occurred between 17,5000 and 15,500 uncal. B.P. Subsequently, a succession of woodlands with Betula, Pinus and other mesophilous and thermophilous trees was recognised during the period 15,500-13,500 uncal. B.P. Between 13,500 and 10,300 uncal. B.P. herbaceous vegetation formations indicating moister conditions dominated the pollen record, although a maximum of Gramineae has been dated during the period 11,300-10,300 uncal. B.P. Comparison with other pollen data from neighbouring mountains allows an interpretation of the vegetation changes during the glacial/interglacial transition in the mountains of northwest Iberia. The Holocene pollen record from the site does not differ markedly from other records in the area, tree expansion occurring before 10,000 uncal. B.P. and high values of deciduous Quercus mixed with other trees and shrubs persisting until 3500 uncal. B.P., when increased human activities are shown by a fall of the tree pollen percentages. Received July 7, 1999 / Accepted May 22, 2000     

Late Würm and early Holocene in the mountains of northwest Iberia: biostratigraphy,chronology and tree colonization

Northwest Iberia (Spain and Portugal) is a large and complex territory which is currently considered a contact border between two different biogeographical regions, the Eurosiberian and the Mediterranean. Such complexity is clearly influenced by several main factors, namely the winding mountain ranges of this region and their position on the peninsula, which result in several markedly different environments coexisting within distances of only a few kilometres apart, such as extremely oceanic or continental climates and high mountain areas or inland basins. This intricacy might also be reflected in the postglacial palaeoecological reconstructions which have been made for different mountain areas of northwest Iberia. Several isolated pollen diagrams from key sites in the area which have been published during the last decades have been questioned, because they show tendencies or chronologies apparently incompatible with global dynamics affecting the North Atlantic. In this paper we explore the possible integration of the biostratigraphies and chronologies of several selected pollen sites in this region. Northwest Iberia as a whole has been firstly divided into several more homogeneous biogeographical units, and high quality pollen sequences from each unit were selected to obtain reconstructions of local dynamics at each site and also approximations of the regional tendencies in each unit. Subsequently, the correlation between the different regional tendencies and their coherence in relation to the global climatic models performed for the North Atlantic is discussed.     

Upland vegetation in the north-west Iberian peninsula after the last glaciation: Forest history and deforestation dynamics

This paper presents the results of pollen analyses from organic sediments of seven cores (299 spectra) in a mountainous area of the north-west Iberian peninsula. The pollen diagrams, supported by seven¹⁴C dates, are used to construct a regional pollen sequence covering the main stages of vegetation dynamics, from the last phases of the Late-glacial until the present. During the Late-glacial Interstadial an important development of cryophilous forests (Betula andPinus) was recorded, although various mesophilous and thermophilous tree elements were also present. The Younger Dryas, palynologically clearly defined, is characterized by an important reduction in tree pollen percentages and the expansion of steppe formations (Poaceae andArtemisia). At the beginning of the Holocene, there was an expansion ofQuercus and a spread of other trees, which combined to give a vegetation cover of varied composition but dominated by mixed deciduous forests. Such forest formations prevailed in these mountains until 3000 years ago, when successive deforestation phases are recorded at various times as a result of increased farming activity. The results are compared with data from other mountainous areas in the northern Iberian peninsula and southern France.     

Assessment of anthropogenic pressures on South European Atlantic bogs (NW Spain) based on hydrochemical data

Cyanobacterial exudates are known to allelopathically inhibit submerged macrophytes, but the influence of the cyanobacteria growth phase on this effect is yet unknown. We compared the effect of exudates of the exponential growth phase of Microcystis aeruginosa Kütz. Elenk with exudates during the decline phase on seedlings of the macrophyte species Potamogeton crispus L. Biomass, chlorophyll content, the ratio of variable–maximum fluorescence (F _v/F _m), and light response capacity of P. crispus seedings were significantly inhibited when affected by M. aeruginosa exudates of the exponential growth phase but promoted by exudates of the decline phase. Tiller numbers of P. crispus increased by 350% under the influence of exponential phase exudates, but decreased by 60% when decline phase exudates were applied. Both exudates increased the malondialdehyde contents and decreased the activity of superoxide dismutase and peroxidase in P. crispus seedlings. We conclude that the exponential growth phase of cyanobacteria rather than the decline phase is important for disrupting photosynthesis and for inducing oxidative stress in submerged macrophytes. Planting P. crispus should thus not be applied in summer but during the cyanobacteria decline phase.