Mixed Deciduous Woodland Research Articles

Pleistocene Bats (Late Irvingtonian and Late Rancholabrean) from Nuckolls and Sherman Counties, Nebraska

We documented rare finds of fossil bats from two localities representing the Pleistocene epoch in southern and central Nebraska, Albert Ahrens locality (No-104, late Irvingtonian age, Middle Pleistocene), Nuckolls County, and Litchfield (Sm-102, late Rancholabrean age, latest Pleistocene), Sherman County. The Albert Ahrens local fauna with strong boreal influence yielded two bats, Lasiurus cf. borealis and Cf. Myotis sp. The Litchfield local fauna, also with a strong boreal influence, yielded two bats, Eptesicus fuscus and Cf. Myotis, among a diverse Pleistocene fauna of small vertebrates and pollen record indicating a boreal mixed conifer and deciduous woodland that contrasts with mixed grass prairies of the area in historic times prior to anthropogenic conversion. Vertebrate fauna from the Litchfield site can be assigned to the Rancholabrean land mammal age based on the presence of Bison, on faunal correlation, and on several extralimital taxa of small mammals. The fossil bat taxa are widespread in North America and still extant in Nebraska today; their glacial stage occurrences in a nonkarstic (caveless) region is consistent with previous interpretations of the Albert Ahrens and Litchfield local faunas as indicating cool equable climates and wooded parkland environments. These are the first bats to be reported from each of the respective paleofaunas.

Mid-late Holocene vegetation history of the Argive Plain (Peloponnese, Greece) as inferred from a pollen record from ancient Lake Lerna.

This study provides a high-resolution reconstruction of the vegetation of the Argive Plain (Peloponnese, Greece) covering 5000 years from the Early Bronze Age onwards. The well dated pollen record from ancient Lake Lerna has been interpreted in the light of archaeological and historical sources, climatic data from the same core and other regional proxies. Our results demonstrate a significant degree of human impact on the environments of the Argive Plain throughout the study period. During the Early Bronze Age evidence of a thermophilous vegetation is seen in the pollen record, representing the mixed deciduous oak woodland of the Peloponnesian uplands. The plain was mainly used for the cultivation of cereals, whereas local fen conditions prevailed at the coring site. Towards the end of this period an increasing water table is recorded and the fen turns into a lake, despite more arid conditions. In the Late Bronze Age, the presence of important palatial centres modified the landscape resulting in decrease of mixed deciduous oak woodland and increase in open land, partly used for grazing. Possibly, the human management produced a permanent hydrological change at Lake Lerna. From the Archaic period onwards the increasing human pressure in association with local drier conditions caused landscape instability, as attested by a dramatic alluvial event recorded in the Pinus curve at the end of the Hellenistic Age. Wet conditions coincided with Roman times and favoured a forest regeneration pattern in the area, at the same time as we see the most intensive olive cultivation in the pollen record. The establishment of an economic landscape primarily based on pastures is recorded in the Byzantine period and continues until modern times. Overgrazing and fires in combination with arid conditions likely caused degradation of the vegetation into garrigue, as seen in the area of the Argive Plain today.

A multi-proxy Holocene palaeoenvironmental record of climate change and prehistoric human activity from Lough Cullin, southeast Ireland

A multiproxy (pollen, microcharcoal, loss-on-ignition, magnetic susceptibility and geochemistry) sequence from Lough Cullin, southeast Ireland, supported by a high-resolution radiocarbon chronology, modelled using Bayesian approaches, provides a record of environmental change for much of the Holocene. Following the establishment of mixed deciduous woodland, climatic deterioration was likely responsible for pronounced vegetation change and erosion, 7615–6500 cal. BC to 6245–5575 cal. BC, evidence for the ‘8.2 Kyr’ BP climate event. The so-called ‘elm decline’ is dated to 4220–3980 cal. BC and whilst there are possible indications of an anthropogenic cause, clear evidence of woodland clearance with cereal pollen is recorded at 3900–3700 cal. BC, 3790–3580 cal. BC and 3760–3650 cal. BC, during a period of clearance and farming of 320–450 years duration. A reduction in farming/settlement and woodland regeneration during the Middle Neolithic parallels the archaeological record, with low levels of activity during the Late Neolithic/Chalcolithic after 2960–2525 cal. BC, prior to increases during the Bronze Age then woodland clearance and agriculture between 1500–1410 and 1275–1000 cal. BC, corresponding with the archaeological evidence. A subsequent ‘step-wise’ reduction in human activity follows, from the latter date to 815–685 cal. BC, and a brief but pronounced cessation at 690–535 cal. BC. Renewed woodland clearance and agriculture commenced until 415–250 cal. BC. From the latter date until cal. AD 390–540, the Late Iron Age/Early Medieval period, a phase of woodland recovery is attested, followed by renewed landscape disturbance and arable agriculture in particular, continuing to the close of the record at cal. AD 780–1035.

The Archaeology of Abbey Wood, Strata Florida, Ceredigion, Wales

ABSTRACT Abbey Wood today is a beautiful, if ill-kept, mixed deciduous woodland a few hundred metres to the south of the former Cistercian monastery of Strata Florida in the Upper Teifi Valley in central Ceredigion, Wales. It consists of a number of different elements of land use and ecology, largely self-regenerated wood and scrub, some older tree specimens and patches of open rough pasture. There are ecological traces of historic management such as pollards and coppice boles, as well as extensive areas of archaeological earthworks on the woodland floor. These appear to demonstrate that the wood, as its name suggests, was originally planted onto open agricultural land perhaps as early as the twelfth century at the time of the Abbey’s foundation. The present extent is approximately 80 hectares (c.200 acres), but early estate maps show that 250 years ago it was larger and much more coherent as a managed wood. Some conifers were planted by the Forestry Commission in the mid-twentieth century. This article will argue that the historic wood was the main source of timber for the Abbey and that this re-founded institution, as part of its re-shaping of a pre-existing traditional landscape sacrificed good arable land for the purpose.

Quantitative dynamics of the early Pliocene climate and vegetation in the Lena River Delta (northern Yakutia, Eastern Siberia)

Early Pliocene climate and vegetation evolution in the Lena River Delta (northern Yakutia, Eastern Siberia) are quantitatively studied for the first time in de­ tail, based on a palaeobotanical record. Palaeobotanical data for this time-interval were obtained on 28 palynofloras from the Sardakhskaya Formation in the coastal cliffs of the Sardakh-Sisse Island (Lena River Delta). In this first integrative study we apply the Coexistence Approach (CA) for quantification of palaeoclimate, the Plant Functional Types (PFT) approach and Integrated Plant Record (IPR) vegetation analysis for quantification of palaeovegetation. Our investigation documents the persistence of temperate climate with two warmer and colder phases. Moreover, our reconstructions show significantly higher mean values of all temperature parameters in comparison to previous estimations. Overall hu­ mid climate conditions (up to 1500 mm) prevailed throughout the early Pliocene correspond to an oceanic climate. Our reconstruction indicates relatively strong temperature and precipitation seasonality. Our data for vegetation show more open vegetation in comparison to previous studies reconstructing mixed conifer- deciduous forests for the early Pliocene of Northeast of Russia. Based on PFT, the early Pliocene vegetation of northern Yakutia in Lena River Delta mainly was presented by more or less open mixed deciduous woodlands of warmer or colder temperate type. The results obtained from the PFT approach generally are in ac­ cordance with our data obtained from IPR approach. However, based on IPR, periodically forests and grasslands were obtained in addition to open woodlands.

The Effect of Willow Short Rotation Coppice Cultivation on the Biodiversity Quality of Ground-Layer Invertebrates

The biodiversity quality of ground-layer invertebrates within the cropped area of a plantation of the biomass crop willow short-rotation coppice (SRC) grown within a floodplain was compared to the biodiversity quality of the neighbouring plots of floodplain grassland and a mixed deciduous woodland plantation. Pitfall traps were used to collect ground beetles (Carabidae) and arachnids (Araneae and Opiliones) in the plots over a period of two years. A range of biodiversity indices was used to assess the biodiversity quality of each of the three plots, and the willow SRC was compared to each of the controls using Mann-Whitney tests. The willow SRC transitioned from almost bare ground to young woodland during the two years of the study, which affected comparisons with alternative land uses as the habitat during the second year was very different from the habitat at the start of the study. Compared to plantation woodland, in the first year, the effect was mostly positive, but this declined in the second year. Compared to grassland there was a largely negative effect in both years. However, when in combination with other habitats, willow SRC cultivation on floodplain land may have an overall positive effect on invertebrate biodiversity quality.

A 40,000 year record of vegetation, environment and climate change from Chongqing, Central China

Congping is a wetland at about 2100 m asl in Chongqing Province. It is surrounded by a shrubby grassland which grades into a mixed conifer and deciduous woodland. A record based on pollen, microcharcoal and geochemistry has been used to reconstruct an environmental history covering the last approximately 40 kyr BP. The site was wooded throughout the entire record and there were two relatively warm periods; during Marine Isotope 3 (MIS 3) and for the Holocene from about 9 kyr BP. From 27 to 18 kyr BP a gradual cooling occurred and the coldest part of the record was between 22 and 18 kyr BP when a mixed conifer cool temperate deciduous forest occurred, The warmest part of the record lasted from about 9 to 1.5 kyr BP when mixed evergreen and deciduous forest occurred. The broad pattern of changes is in accord with pollen records from Dajiuhu in Hubei, and demonstrates that this was a regional signal. A moist central China at Last Glacial Maximum (LGM) shows that the East Asian Summer Monsoon was delivering enough moisture on the mainland to sustain forest cover, even at 2120 m asl. The large-scale changes are interpreted as relating to changes in Earth's orbital parameters and sea-level changes in the South China Sea which had an impact on moisture delivery into central China. It is surmised that the westerlies which created dry climates in northeastern China trapped the summer Monsoon influence enough to keep central China moist. The Younger Dryas (YD) is present in the weathering parameters as evident in several changes in elemental abundance delivered to the sediments. The Congping record shows no clear evidence of human impact on its vegetation, and there were no local fires to have caused any vegetation changes. In the last 1.5 kyr BP a slight cooling caused a rise in conifers, a decline in broad-leaved tree taxa and increased weathering rates.

Biological Flora of the British Isles:Poa nemoralis

AbstractThis account presents information on all aspects of the biology ofPoa nemoralisL. (Wood Meadow‐grass) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of theBiological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history, and conservation.The grassPoa nemoralisis widespread and frequent to locally common across the British Isles, except for western and central Ireland, and northern Scotland. In both its native Eurasian range and introduced ranges in, for example, the Americas, its main habitat comprises temperate (mixed) deciduous woodland. The species finds important secondary habitats in hedgerows, as well as in non‐woodland vegetation such as on cliffs, screes and walls or sporadically in grassland and heathland. Although not always taxonomically or morphologically distinct units, the species is suspected to comprise many cytological races and hybrid polyploid populations with variable morphology. Morphological variation amongP. nemoralispopulations may also be a sign of local environmental adaptation or a result of introgressive hybridization with other, morphologically variable members ofPoasectionStenopoasuch asP. glauca,P. compressaorP. pratensis.Poa nemoralisis a small‐statured, loosely caespitose grass, with populations ranging from a few individual tufts to those visually defining the aspect of the herbaceous understorey. The species tolerates moderate to deep shade on the forest floor, yet it tends to forage for available light, occurring more and growing taller in canopy gaps, forest edges and hedgerows. The amount of light is central to its survival and reproductive ecology, being important for flower induction, seed production and seed germination. The species produces large quantities of small, light seeds which facilitate spatial and temporal dispersal.The species occupies a wide range of soil pH (3–7) and nutrient conditions (C/N ratio ranges between 10 and 25), though it clearly prefers moderately acid and somewhat drier soils with limited litter thickness, avoiding soils with mor humus types.Poa nemoralisdisplays distinct small‐scale acidifuge responses, being absent in areas of low soil pH (<3).Poa nemoralisis a moderately strong indicator of ancient woodland: it can quickly colonize recently established wooded areas adjacent to ancient woodland when it is not hindered by dispersal limitation and elevated nutrient levels. Nonetheless, dispersal limitation impedes rapid colonization of isolated, recently established woodlands, in spite of ample records of zoochorous seed dispersal. While currently frequent to locally common, the species is at risk if ancient woodlands continue to decline in its native Eurasian range. Across N.W. Europe, it is already in moderate decline in temperate deciduous ancient woodlands because of acidification, eutrophication and darkening of the forest understorey. In its introduced ranges, it is considered invasive.

Implications of fragile landscapes for endemic pollinators in an eastern afro-montane biodiversity hotspot of Kenya

This study was carried out to determine how disturbances could shape the natural occurrence of African meliponine bee species in different ecological habitats of Taita hills of Kenya and how this could lead to changes in their diversity. Habitats sampled were indigenous forests, exotic forests, mixed highland forests, Acacia dominated bush lands, mixed deciduous woodlands and grasslands which were further categorized as either fragmented or un-fragmented habitats based on levels of disturbance. The study sites were chosen based on various features such as, forest fragment size, level of forest fragment isolation, forest fragment age, and level of degradation. In all study locations, meliponine bee species were sampled using the conventional complementary method, belt transect (direct observation of nesting colonies synonymous to a visual census) from the months of March to September 2014 (combining both the long rainy season and dry season). Nesting colonies of the 4 meliponine bee species, namely, Hypotrigona gribodoi, Meliponula ferruginea (black), Hypotrigona ruspolii and Plebeina hildebrandti, were surveyed following a successive gradient. In each study site (25 ha), 20 linear transects of 250 m × 20 m each were established using a global positioning system (GPS) receiver to mark coordinates with relation to habitat type. Data such as nesting site/substrate, GPS coordinates of nest, and names of nesting trees were recorded. A total of four species depicted by the Renyi diversity profile was recorded in five out of the six main habitat types surveyed and a further extrapolation with Shannon index (EH) also predicted the highest species richness of 4.24 in a deciduous habitat type with more trees and vegetation and the lowest species of 1.01 in isolated forest patches habitat type. These meliponine bee species (Hypotrigona gribodoi, Hypotrigona ruspolii, Meliponula ferruginea (black) and Plebeina hildebrandti) were observed to be unevenly distributed across all six sampled habitats, further indicating that mixed deciduous habitat proved to be more diverse than Acacia dominated bush lands, grasslands and exotic forest strips which have all undergone varying levels of fragmentation. This has revealed that unprecedented conversions of natural habitats leading to fragmentations of such habitats is a key driving factor causing increased habitat isolation and vulnerability in this afro-montane region which may potentially distort local assemblages of native pollinators such as meliponine bee species.
 Keywords: Meliponine bees, habitat fragmentation, diversity, Eastern Afro Montane

Modelling the effect of the 2018 summer heatwave and drought on isoprene emissions in a UK woodland.

Projected future climatic extremes such as heatwaves and droughts are expected to have major impacts on emissions and concentrations of biogenic volatile organic compounds (bVOCs) with potential implications for air quality, climate and human health. While the effects of changing temperature and photosynthetically active radiation (PAR) on the synthesis and emission of isoprene, the most abundant of these bVOCs, are well known, the role of other environmental factors such as soil moisture stress are not fully understood and are therefore poorly represented in land surface models. As part of the Wytham Isoprene iDirac Oak Tree Measurements campaign, continuous measurements of isoprene mixing ratio were made throughout the summer of 2018 in Wytham Woods, a mixed deciduous woodland in southern England. During this time, the United Kingdom experienced a prolonged heatwave and drought, and isoprene mixing ratios were observed to increase by more than 400% at Wytham Woods under these conditions. We applied the state-of-the-art FORest Canopy-Atmosphere Transfer canopy exchange model to investigate the processes leading to these elevated concentrations. We found that although current isoprene emissions algorithms reproduced observed mixing ratios in the canopy before and after the heatwave, the model underestimated observations by ~40% during the heatwave-drought period implying that models may substantially underestimate the release of isoprene to the atmosphere in future cases of mild or moderate drought. Stress-induced emissions of isoprene based on leaf temperature and soil water content (SWC) were incorporated into current emissions algorithms leading to significant improvements in model output. A combination of SWC, leaf temperature and rewetting emission bursts provided the best model-measurement fit with a 50% improvement compared to the baseline model. Our results highlight the need for more long-term ecosystem-scale observations to enable improved model representation of atmosphere-biosphere interactions in a changing global climate.

Holocene vegetation dynamics in the Campine coversand area (Liereman, N Belgium) in relation to its human occupation

Palaeoecological studies in coversand areas are sparse as organic remains generally do not preserve well in sandy deposits. An AMS-dated Holocene peat sequence in a palaeochannel in a natural depression (the Liereman), flanked by coversand ridges proved to be an exceptional and valuable archive of long-term vegetation dynamics in the Campine (N Belgium). Analyses of microfossils, such as pollen, spores and non-pollen palynomorphs, as well as macrofossils of plants and other organisms have given insight in the vegetation dynamics over the past 11,500 years. Grasslands developed during the Rammelbeek phase of the Preboreal at the expense of the birch woodlands that characterized the Friesland phase of the Preboreal. During the Preboreal the depression was ecologically diverse with abundant resources for human subsistence, such as permanent fresh water, game and edible plants. However, to date no contemporaneous archaeological sites are known in the area. In the woodlands on the coversand ridges pines became the dominant regional vegetation towards the Boreal. The resulting lowering of ground water levels led to a decrease of the water availability and associated resources for hunter-gatherer societies. Yet, (early) Mesolithic hunter-gatherers settled in the area, however only temporarily. During the Atlantic coniferous forests were succeeded by mixed deciduous woodlands, while the freshwater availability decreased further. This possibly explains the near absence of middle and late Mesolithic sites in the Liereman area. From the Subboreal onward deciduous woodlands opened, probably as a result of human activity. Finally, through deforestation the area in and around the Liereman depression was partly cleared for agricultural purposes during the Subatlantic.

Forest clearance and land use by early farmers in Europe: Insights from north Greek oral history

European prehistorians have long debated whether Neolithic farmers, especially in temperate central and northern Europe, exploited cleared woodland for short-term ‘slash-and-burn’ crop husbandry or for cultivation of ‘permanent’ gardens/fields. Because empirical evidence was scarce and rather indirect, circumstantial arguments based on the relative costs and benefits of the two rival regimes have hitherto dominated this debate, but more direct archaeobotanical proxies for Neolithic crop husbandry (based on weed ecology and crop isotopes) now favour the predominance of intensively cultivated permanent plots. At the same time, it is argued from ongoing experimental cultivation at Forchtenberg in southern Germany that short-term slash-and-burn husbandry offers much better returns on both land and labour, at least on poor soils marginal for Neolithic cereals. This paper presents oral historical evidence for mid-twentieth century clearance and subsequent long-term cultivation of mixed deciduous woodland in the Pieria region of northern Greece. These data extend the sparse European ethnographic and historical record of manual clearance for crop husbandry to deciduous woodland of the northern Mediterranean, while also providing comparative material against which to evaluate experimental results. Pierian farmers achieved good cereal yields for many years on cleared woodland, with very limited use of fire, demonstrating the viability of a permanent-cultivation regime for early farmers in the north Mediterranean, but suitable land was scarce in Pieria and informants had no experience of the alternative slash-and-burn regime. Conversely, the Forchtenberg experiments have effectively tested only the slash-and-burn regime under soil pH conditions hostile to successful long-term cultivation. Evaluation of these experiments in the light of the Pierian data suggests that long-term cultivation of cleared woodland would have offered Neolithic famers better returns than slash and burn under good or neutral soil conditions. Comparison of the likely returns of the two rival regimes thus offers no grounds for questioning archaeobotanical indications of Neolithic permanent cultivation. The Pierian and Forchtenberg data agree, however, in suggesting that the time elapsed between clearance and reliable grain harvests, under either regime, may have been long enough to pose a significant challenge to the survival of pioneer Neolithic farmers, especially if these were colonists settling beyond ‘commuting’ distance from their previous homes.

Fish, feather, fur and forest: Exploitation of wild animals in medieval Novgorod and its territory

The city of Novgorod the Great in north-west Russia has been subjected to extensive excavation of its superbly preserved medieval anaerobic deposits for many decades. Situated on the River Volkhov near Lake Ilmen and surrounded by mixed boreal and deciduous woodland and seasonally flooded meadowlands, Novgorod was well-placed for the exploitation of local wild fauna and flora. It was also the focus for international trade in furs obtained from a much broader catchment area. Although its inhabitants relied heavily on domestic animals and crops for their food, evidence for the acquisition of wild resources is also provided by animal bones, plant macrofossils, birch-bark documents and other archaeological finds. Pollen analysis has also provided information about landscape history of its hinterland. Even from a limited programme of sieved sampling, it is clear that a very large number of fish bones were present in the deposits. The main taxa are cyprinids, pike and zander, whereas birch-bark documents, largely concerned with tribute, mention salmonids and sturgeon, rare amongst the excavated remains. The wild bird assemblage is dominated by various species of ducks. Other waterfowl were utilised as well as large game birds such as capercaillie. Birds of prey are also present and other remains such as jackdaws reveal the local bird life in town. Wild mammals contributed little to the Novgorodian diet: bones of hare, beaver and elk being the most frequently found. Very few bones of fur-bearing mammals were recovered. The few remains include bear claws and bones of squirrel, marten, otter, and fox, in addition to beaver. Their paucity can be explained by the fact that most would have arrived from the hunting grounds to the north as prepared pelts without bones. Evidence for the hunting for these species is provided on sites deep within the forest zone such as Minino. Most of the wild animals eaten in Novgorod itself were obtained from the land and waters of its near hinterland. The paper discusses the character of the local forest based on pollen and other evidence. Models are being developed to provide a more detailed understanding of the changes in the composition of the forest during the medieval period and the consequences this had for wildlife. The paper demonstrates the benefits of developing a multi-disciplinary approach comparing urban assemblages with contemporary sites in its hinterland and further afield, to understand more fully how wild species were exploited in complex societies.

Wild boar impact on forest regeneration in the northern Apennines (Italy)

The foraging activities of wild boar (Sus scrofa L.) have been suggested to impact biodiversity and ecological processes in a wide array of ecosystems. Data indicate that wild boar affects forest vegetation by feeding on above- and belowground plant parts, as well as by soil disturbance causing plant mortality and influencing seedling recruitment. In this paper, we investigated wild boar impacts on forest regeneration within three different types of mixed deciduous woodlands, respectively dominated by chestnut (Castanea sativa), Turkey oak (Quercus cerris) and beech (Fagus sylvatica) occurring in the northern Apennines (Italy), a mountain area where wild boar numbers have increased rapidly in recent decades. The goal of our study was to present a robust procedure targeted towards estimating wild boar impact on fruitspredation and seedling survival of tree species. We evaluated the impact comparing wild boar excluding plots with completely access free ones. Differently from the majority of other experiments, we used replicated exclosure plots (by means of an electro-welded iron grid) excluding wild boars without excluding all other large ungulates such as deer and native small vertebrates. This method, tested with camera trapping surveys, was effective in reducing time spent by wild boar on experimental plots in comparison with other animals. Nevertheless, the number of fruit was similar in the exclosure plots and completely access free plots. Our study demonstrated, however, that wild boar feeds preferentially with the bigger fruits that are visually more attractive and have higher energetic potentialities too. The proportion of seedlings survived at the end of the period studied was significantly higher in wild boar excluding plots compared to those completely access free. Moreover, the dominant species were not equally influenced by the exclosure method, with chestnut and beech more markedly affected with respect to Turkey oak. Finally, the seedling survival of subordinate tree species, compared to the one of dominant plants, was reduced by the activity of wild boars in all the woodlands studied. This impact could lead to reduced tree species richness of the woodlands under study with negative effects on the biodiversity of plants and animals within these ecosystems.

Holocene mountain forest changes in central Mediterranean: Soil charcoal data from the Sila Massif (Calabria, southern Italy)

Soil charcoal analysis was performed on soil profiles excavated in the area of Cecita Lake on the Sila Massif (Calabria, southern Italy). Charcoals identification, combined with a good number of radiocarbon dating and the pedological analysis of the soils, allowed drawing a detailed history of the Holocene vegetation changes in the area. Five periods characterised by high concentration of radiocarbon dates – mirroring increased fire activity – are documented at ca. 10400-9000 BP, 8200-7200 BP, 5100-3700 BP, 3300-2400 BP and 600 BP to the present. Furthermore, a severe environmental change took place between the Middle Bronze Age and the Final Bronze Age/Iron Age (ca. 3600 to 3000 BP), when the mixed deciduous oak-silver fir woodland, which dominated the landscape until the Early Bronze Age, declined and was substituted by a Calabrian pine forest or by an open landscape. Available climate, pollen and historical/archaeological data are taken into account to investigate the possible causes of the detected environmental change and of the periods of increased fire activity. If climate seems to play a role in the fire regime during the first part of the Holocene, human action seems to be the triggering factor in the environmental change and the fire regime during the Late Holocene.

Animating tree colonization and growth

In the early twentieth century the woodland at Heald Brow, north-west England, was largely a tree-less pasture, but changing land management practices lead to natural tree colonization and the development of a mixed deciduous woodland with ash (Fraxinus excelsior), oak (Quercus robur), yew (Taxus baccata) and small-leaved Lime (Tilia cordata) the main components. The research focused on T. cordata due to its rarity and conservation value, and aimed to investigate the timing of its appearance, rates of reproduction by layering and the effects of competition on its longer-term survival. A small, 0.32ha area of woodland was mapped using standard field-based survey methods and increment cores were taken to provide minimum age estimates for living stems of all species present. The spatial and temporal data generated led to the development of a new micro-GIS animation method, using ArcGIS software, that visually highlighted secondary woodland establishment and development, and gave novel insights into the competitive interactions that governed the development. Results showed T. cordata colonization in the 1940s and layering developing in the 1960s. The later appearance and rapid establishment of T. baccata with its light-excluding canopy produced high competition scores and undoubtedly restricted further development of the main T. cordata canopy aided by F. excelsior at the periphery. This animation method and associated GIS analyses have potential application in both dendrochronological, wider ecological research and in conservation management.

Human Visual Search Performance for Camouflaged Targets

There is a paucity of published systematic research investigating object detection within the military context. Here, we establish baseline human detection performance for five standard military issued camouflage patterns. Stimuli were drawn from a database of 1242 calibrated images of a mixed deciduous woodland environment in Bristol, UK. Images within this database were taken during daylight hours, in summer and contained a PASGT helmet, systematically positioned within each scene. Subjects (20) discriminated between the two image types in a temporal 2AFC task (500ms presentation for each interval), with the detection scenario being the percentage of instances participants correctly detected the target. Cueing (cued/not-cued to target location), colour (colour/greyscale) and distance from the observer (3.5/5/7.5m) were manipulated, as was helmet camouflage pattern. A Generalized Linear Mixed Model revealed significant interactions between all variables on participant performance, with greater accuracy when stimuli were in colour, and the target location was cued. There was also a clear ranking of patterns in terms of effectiveness of camouflage. We also compare the results with a computational model based on low-level vision, and eye tracking data, with encouraging results. Our methodology provides a controlled means of assessing any camouflage in any environment, and the potential to implement a machine vision solution to assessment. In this instance, we show differences in the effectiveness of existing solutions to the problem of camouflage, concealment and deception (CCD) on the battlefield. Funded by QinetiQ as part of Materials and Structures Low Observable Materials Research Programme. Meeting abstract presented at VSS 2015. Language: en

Characteristic pollen source area and vertical pollen dispersal and deposition in a mixed coniferous and deciduous broad-leaved woodland in the Changbai mountains, northeast China

Pollen influx (number of pollen grains cm−2 year−1) can objectively reflect the dispersal and deposition features of pollen within a certain time and space, and is often used as a basis for the quantitative reconstruction of palaeovegetation; however, little is known about the features and mechanisms of vertical dispersal of pollen. Here we present the results from a 5 year (2006–2010) monitoring program using pollen traps placed at different heights from ground level up to 60 m and surface soil samples in a mixed coniferous and deciduous broad-leaved woodland in the Changbai mountains, northeastern China. The pollen percentages and pollen influx from the traps have very similar characteristics to the highest values for Betula, Fraxinus, Quercus and Pinus, among the tree taxa and Artemisia, Chenopodiaceae and Asteraceae among the herb taxa. Pollen influx values vary significantly with height and show major differences between three distinct layers, above-canopy (≥32 m), within the trunk layer (8 ≤ 32 m) and on the ground (0 m). These differences in pollen influx are explained by differences in (i) the air flows in each of these layers and (ii) the fall speed of pollen of the various taxa. We found that the pollen recorded on the ground surface is a good representation of the major part of the pollen transported in the trunk space of the woodland. Comparison of the pollen influx values with the theoretical, calculated “characteristic pollen source area” (CPSA) of 12 selected taxa indicates that the pollen deposited on the ground surface of the woodland is a fair representation with 85–90 % of the total pollen deposited at a wind speed of 2.4 m s−1 coming from within ca. 1–5 km for Pinus and Quercus, ca. 5–10 km for Ulmus, Tilia, Oleaceae and Betula, ca. 20–40 km for Fraxinus, Poaceae, Chenopodiaceae, Populus and Salix, and ca. 30–60 km for Artemisia; it is also a good representation with 90–98 % of the total pollen deposited coming from within 60 km at a wind speed of 2.4 m s−1, or 100 km at a wind speed: 6 m s−1, for the 12 selected taxa used in the CPSA calculation. Furthermore, comparison with the vegetation map of the area around the sampling site shows that the pollen deposited on the ground represents all plant communities which grow in the study area within 70 km radius of the sampling site. In this study, the pollen percentages obtained from the soil surface samples are significantly biased towards pollen taxa with good preservation due to thick and robust pollen walls. Therefore, if mosses are available instead, soil samples should be avoided for pollen studies, in particular for the study of pollen-vegetation relationships, the estimation of pollen productivities and quantitative reconstruction of past vegetation. The results also indicate that the existing model of pollen dispersal and deposition, Prentice’s model, provides a fair description of the actual pollen dispersal and deposition in this kind of woodland, which suggests that the application of the landscape reconstruction algorithm would be relevant for reconstruction of this type of woodland in the past.

Host-seeking mosquito distribution in habitat mosaics of southern Great Plains cross-timbers.

Landscape fragmentation often increases contact between humans, wildlife, and potential disease vectors. We examined how adult host-seeking mosquitoes respond to small-scale habitat differences within southern Great Plains cross-timber habitat mosaics in northern Oklahoma consisting of eastern red cedar (Juniperus virginianus L.) woodlands, mixed-deciduous woodlands, and adjacent grasslands. Mosquitoes responded most markedly to an overall grassland-woodland habitat gradient, with species separating by habitat based largely on tree density. Differences in abundance of host-seeking females occurred at fine spatial scales, sometimes varying dramatically over distances as little as 200 m when tree density changed abruptly. Tree type was not as important as tree density, although the West Nile virus vector Culex tarsalis Coquillett showed a greater affinity for areas containing eastern red cedar than for deciduous woodlands. The invasive Aedes albopictus Skuse showed equal affinity for both tree types. Conversion of grassland habitats in the Great Plains to more vegetated environments associated with humans (towns and homesteads) and the invasion of grasslands by eastern red cedar may change the species composition of mosquito, bird, and mammal assemblages and potentially alter arbovirus exposure for humans.

Wadeana dendrographa . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Wadeana dendrographa , a lichen-forming species occurring on rough nutrient-rich bark in wood-pasture and parkland, and lowland mixed deciduous woodlands. Some information on its dispersal and transmission and conservation status is given, along with details of its geographical distribution (North America (USA), Europe (France, Ireland, Portugal, Spain, UK)).