Archaeophytes in Britain

The concept of 'archaeophytes' (alien taxa which became established in a study area before AD 1500) is widely used in floristic analyses in central and northern Europe, but few authors have applied it to the British flora. Six criteria for the recognition of archaeophytes are outlined, drawing upon evidence of fossil and recent history, current habitat and European and extra-European distribution. These are used to identify 157 probable archaeophytes in Britain. Only five of these are known from fossil records from the Neolithic; most are first recorded in archaeological contexts in the Late Bronze Age, Iron Age, Roman or Medieval periods. As a group, archaeophytes (unlike neophytes) have declined in Britain in the 20th century. Comparison of the accepted status of these species in the Czech Republic, Germany, Poland and Finland demonstrates that over 50% are treated as archaeophytes in central Europe, but in Finland many are absent or only present as casual introductions. Species regarded as archaeophytes in these countries but as natives in Britain are also reviewed. The indirect nature of the evidence used to identify archaeophytes means that it is usually impossible to be certain about the history of a species; in particular, archaeophytes which have successfully invaded semi-natural habitats are likely to be overlooked as natives. The suggestion that a species is an archaeophyte is best regarded as a hypothesis to be tested by further studies. There is considerable scope for archaeological investigations aimed at addressing these botanical problems

Survival and relative frequency of native woody species and their specialist Lepidoptera on Coll, Inner Hebrides, two millennia after deforestation

The Hebridean island of Coll has almost certainly been predominantly treeless for at least two millennia; it was certainly largely deforested when the first surviving written description of the island was made in the sixteenth century. A survey of the surviving native trees, shrubs and lianes carried out between 1997 and 2011 showed that only Salix aurita is present in any quantity, with all other species being reduced to small, relict stands or scattered individuals. Juniperus communis (at least 650 bushes), Populus tremula (450 trees) and Sorbus aucuparia (121 trees) are the commonest of these species and represent contrasting strategies, with P. tremula present as long-lived suckering clones and the others as freely seeding but probably short-lived individuals. Betula pubescens (42 trees), Hedera helix (50 plants), Corylus avellana (17 trees), Quercus spp. (11 trees) and Salix cinerea (4 stands) are the rarest surviving native species. Historical records indicate a decline since the 1930s of Betula pubescens, Corylus avellana and caninoid Rosa species. The commoner native species have the highest representation of the regional species of host-specific Lepidoptera, with Salix aurita supporting 42% of the regional species pool whereas Betula,\ud Corylus, Hedera and Quercus support ,10%. Woody species may become increasingly frequent in the future now that subsidised fencing allows areas to be grazed more selectively and broad-leaved trees are currently being established in plantations from which they may spread

Polarization spectroscopy of a closed atomic transition: applications to laser frequency locking

We study polarization spectroscopy of Rb vapour. A weak probe beam analyses the birefringence induced in a room temperature vapour by a strong counterpropagating circularly polarized pump beam. In contrast to most other work on polarization spectroscopy, we use a polarization beam splitting cube and two detectors (rather than a polarizer and one detector) to analyse the probe beam. The signal is in the form of a derivative of a Lorentzian. For theoretical analysis we study the closed atomic transition 5 2S1/2 (F = 3) --> 5 2P3/2 (F' = 4) in the D2 line of 85Rb. We study the time needed to redistribute population among the mF states, derive an expression for the expected lineshape and present experimental data in excellent agreement with theory. The polarization spectrum provides an ideal error signal for frequency stabilization of a laser. We describe the geometry and parameters for optimizing the error signal

A vascular plant red list for England

The results detailed in this vascular plant Red List present for the first time the current state of England's flora measured against standardised IUCN criteria. Almost one in five species has been assessed as threatened, with many more species assessed as "Near Threatened". The destruction and transformation of semi-natural habitats across the English landscape since the publication of the first Atlas of the British Flora (Perring & Walters 1962) is well known, and these changes are mirrored not only in the long list of taxa assessed as threatened in England but also in the decline in distribution by 20% or more of a suite of "Near Threatened" species, some of which were previously assumed to be widespread and with relatively stable distributions. The strategic approach advocated by Lawton et al. (2010) to restore, create and connect extant habitats at the landscape scale is essential if the declines identified in this and other Red Lists are to be arrested. Such an approach demands long-term commitment, considerable resources and a recognition of the benefits to be gained from a more diverse and adaptable environment

Staphylococcus aureus ‘Down Under’: contemporary epidemiology of S. aureus in Australia, New Zealand, and the South West Pacific

The clinical and molecular epidemiology of Staphylococcus aureus disease has changed considerably over the past two decades, particularly with the emergence and spread of community-associated methicillin-resistant S. aureus (CA-MRSA) clones. Indeed, some of the first global descriptions of CA-MRSA were from remote indigenous communities in Western Australia, and from Pacific Peoples in New Zealand. The epidemiology of S. aureus infections in the South West Pacific has several unique features, largely because of the relative geographical isolation and unique indigenous communities residing in this region. In particular, a number of distinct CA-MRSA clones circulate in Australia and New Zealand, such as sequence type (ST) 93 methicillin-resistant S. aureus (MRSA) (Queensland clone) and clonal complex 75 S. aureus (Staphylococcus argenteus) in Australia, and ST30 MRSA (Southwest Pacific clone) in New Zealand. In addition, there is a disproportionate burden of S. aureus disease in indigenous paediatric populations, particularly in remote Aboriginal communities in Australia, and in Pacific Peoples and Maori in New Zealand. In this review, we provide a contemporary overview of the clinical and molecular epidemiology of S. aureus disease in the South West Pacific region, with a particular focus on features distinct to this region