Des Callaghan

Des Callaghan
Bryophyte Surveys Ltd

PhD

About

65
Publications
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393
Citations

Publications

Publications (65)
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Introduction Codonoblepharon forsteri (Dicks.) Goffinet is a rare epiphytic moss characteristically associated with water-filled holes in trees. We reviewed its range and population and assessed effects of climate change. Methods An inventory of sites from where Codonoblepharon forsteri has been recorded was compiled. Extent of occurrence (EOO) an...
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Introduction This study was carried out to investigate the population status and ecology of the moss Codonoblepharon forsteri (Dicks.) Goffinet (syn. Zygodon forsteri (Dicks.) Mitt.) at Burnham Beeches, UK. Methods Population size and abundance were evaluated as the count of host trees and occupied 10 cm grid cells, respectively. All trees known t...
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The occurrence of Riccia warnstorfii in the British Isles are discussed.
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Introduction The moss Philonotis marchica (Hedw.) Brid. is rare in Europe and threatened with extinction. In this study, its status and ecology in Britain were investigated. Methods Surveys were carried out at all sites from which Philonotis marchica has been reported in Britain since 1859, together with further locations nearby. Geographical coor...
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Introduction The moss Micromitrium tenerum is rare in Europe and threatened with extinction. The aim of this study was to investigate its population status and ecology in England. Methods Surveys were undertaken at most of the sites from where Micromitrium tenerum has been reported in England. Geographical coordinates of colonies were recorded wit...
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Introduction Ditrichum cornubicum is one of the world's rarest bryophytes and is undergoing a long-term decline as its habitat is gradually lost to vegetation succession in derelict mining areas. This study investigates short-term changes in abundance of the species at two sites in Cornwall (UK), including within trial management plots where turf-s...
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Introduction. This study investigated the ecology of Petalophyllum ralfsii in an oceanic dune system, including relationships with grazing livestock, hydrology and habitat restoration. Methods. The study site was two large slacks at Newborough Warren, NW Wales, UK. In areas of one slack, there are 6-yr-old ‘restoration scrapes’, where vegetation wa...
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Introduction. Although Madagascar is known for its unique fauna and vascular flora, the country’s bryophyte flora in contrast is understudied and under collected. Arising from a bryophyte collecting expedition undertaken in May–June 2016, this paper describes a new species of simple thalloid liverwort, Fossombronia isaloensis, from Madagascar. Meth...
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Introduction. This study investigated the ecology of two boreal-montane bryophytes, the saxicolous moss Bartramia halleriana and the epixylic liverwort Crossocalyx hellerianus, at the edge of their ranges, in oceanic deciduous woodland in Wales. Methods. The study site comprises two adjoining woodlands, Allt Penyrhiw-iar (canopy trees ca. 100 yr ol...
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Introduction. This study investigated the ecology of Pallavicinia lyellii in a mire habitat dominated by Molinia caerulea, including potential abundance, frequency of sexes and sporophytes, and characteristics of the light climate beneath the herbaceous canopy. Methods. Within the study site (Cors Fochno, Wales, UK), P. lyellii was surveyed in Marc...
Preprint
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Introduction This study investigates the ecology of two boreal-montane bryophytes, the saxicolous moss Bartramia halleriana and the epixylic liverwort Crossocalyx hellerianus , at the edge of their ranges, in oceanic deciduous woodland. Methods The study site comprises two adjoining woodlands, Allt Penyrhiw-iar (canopy trees ca. 100 yr old) and Al...
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Introduction. Dumortiera hirsuta is rare in Europe, occurring in the UK at the northern edge of its world range. This study investigated its status and ecology in England. Methods. A detailed search was made for D. hirsuta at all sites where it has been reported in England since 1841. Number of occupied 1 m grid cells was recorded and interpreted a...
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Introduction. Physcomitrium eurystomum is rare in Europe and threatened with extinction. This study investigates its status and ecology in Britain. Methods. A detailed search was made for P. eurystomum at all sites where it has been reported in Britain, plus four other locations nearby. Geographic coordinates of colonies were recorded with GPS unit...
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Introduction. Bryophyte diaspore banks are virtually ubiquitous in soil environments but remain poorly known and rarely given attention during conservation planning. This study investigates the frequency and composition of bryophyte diaspore banks of coastal dune slacks and considers conservation implications. Methods. A total of 327 soil samples w...
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Introduction. Leptoscyphus cuneifolius has a very limited distribution in Europe and is threatened with extinction in several regions. This study investigates its ecology at Coed y Rhygen, the most important site in Wales. Methods. GPS-based surveys documented the distribution of L. cuneifolius within the study site. Hillshade analysis was used to...
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Introduction. Dicranum undulatum has been lost from many sites due to destruction of peatlands. This study investigates its status and ecology at the last surviving location in southern Britain. Methods. The study site, Fenn’s, Whixall, Bettisfield, Wem and Cadney Mosses, is one of the largest lowland raised bogs in Britain. Distribution and abunda...
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Introduction. Pallavicinia lyellii is recognised as being of principal importance for conservation in England and is threatened with extinction in Europe. The aims of this study were to investigate the current status, conservation and ecology of the species in S Hampshire, a key region for the plant. Methods. All recent and historic locations for P...
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Introduction. Weissia × mittenii (Bruch & Schimp.) Mitt. emend. A.J.E.Sm. (Weissia multicapsularis × W. rostellata) has only been reported from five localities globally, all in south-east England, and was last found in 1920. The purpose of this paper is to typify the name W. × mittenii, provide a description of this hybrid taxon and clarify its dia...
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Introduction. The present study investigates the taxonomy of European members of Weissia Hedw. subgenus Astomum Hampe., a group considered taxonomically difficult and including species of high conservation concern. Methods. A broad set of samples were subject to DNA sequencing and morphological analysis, plus a review of type material was undertake...
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Introduction: The best sites for oceanic bryophytes are typically in ravines that offer good potential for hydroelectric power (HEP) development. This preliminary study is the first to investigate population change in oceanic bryophytes of conservation concern at a site subject to HEP development. Methods: Populations of five hyperoceanic liverwort...
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This is the first detailed ecological investigation of the rare moss Bryum marratii Wilson. Results show occupancy of a niche at the two study sites that is unusual amongst bryophytes, within the upper edge of saltmarsh. All colonies (n=120), which comprise the largest populations in Wales, occur in an elevation zone of just 57 cm and are subject t...
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Cornish Path-moss is one of the world’s rarest bryophytes, presently known from just three sites, former copper mines in the UK and Ireland. Covering the two UK sites, for the first time this study provides a set of location coordinates (x-, y- and z-axis) that is comprehensive, accurate and precise, in addition to investigating aspects of its ecol...
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We provide observations confirming that viable fragments of bryophytes are dispersed by migratory birds after surviving transit through the alimentary canal. A specimen of Didymodon insulanus was cultured from a large fragment extracted from faeces of Mallard Anas platyrhynchos at Lake Windermere in Cumbria, England. Similar fragments were recorded...
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Knowledge of the species present within a site is often used to inform decisions that have significant implications for biodiversity conservation. This study surveyed eight woodland sites in north-west England for bryophytes. Searches for species within each site continued until all areas had been approached to within a minimum of 50 m and at least...
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This study provides an assessment of Cormorant occupancy and impact at stillwater game fisheries in England and Wales, during 1988/89 to 1992/93. A total of 167 waterbodies operated as ‘put-and-take’ trout fisheries was included within a questionnaire survey, and this provided the bulk of the data used in the analyses. The results show that Cormora...
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Sites that are particularly rich in rare species are of significant conservation value and there is consequently a need to ensure that they are highlighted by methods which aim to select sites for potential safeguarding. This study measures the value for rare bryophytes of 434 sites, located in South Lancashire, north-west England (UK). Using clust...
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Area of occupancy (AOO) is used commonly as a measure of species range size and the IUCN Red List Criteria provide thresholds of AOO for determining the extinction risk of species. Tortula freibergii is a rare moss globally and is considered to be a priority for conservation in the UK. This study provides the results of a comprehensive survey of th...
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In order to help understand rarity in bryophytes, the present study investigates attributes of 430 taxa (ranging from very rare to very common) within a region of north-west England (UK). Results show that rarity is largely congruent between the scale of the study area and the British Isles, even though the area of the former is only 0.7% of the la...
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Knowledge of the distribution of species is fundamental to their conservation. Hence, it is important to understand the completeness of distribution inventories and the location of the main gaps. In an attempt to do this within an area of north-west England, this study builds a model which predicts bryophyte species-richness in 1220 tetrads (2 × 2...
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Correlations between environmental variables and species distributions can make an important contribution to the formulation of hypotheses of cause-and-effect relationships. At a resolution of 2×2 km, presence/absence data for bryophytes have been collected recently for an area of 4553 km2 in north-west England. The aim of the present paper is to m...
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The National Vegetation Classification (NVC) is a phytosociological treatment of the British vascular and non-vascular vegetation that has been adopted widely. Since its publication between 1991 and 2000 there have been no studies which have attempted to identify clusters of bryophyte species within a site and assess their distribution in relation...
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The status and distribution of Common Scoters Melanitta nigra nigra in Britain and Ireland were determined from a survey in April–June 1995. Three visits were made to all known, and a sample of potential, breeding sites. A total of 439 birds was located, from which the British and Irish population was estimated at 195 pairs (100 in Ireland, 95 in B...
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In total, seven separate Torrent Duck taxa have been described, although a tentative classification followed in this paper includes only a single species Merganetta armata and three subspecies (M. a. armata, M. a. leucogenis and M. a. colombiana.) Distribution limits of these taxa are inadequately known, although preliminary delimitations are provi...
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An international initiative to stop and reverse the population and range expansion of the naturalised North American Ruddy Duck in the Western Palearctic, in order to safeguard populations of the globally threatened White-headed Duck from hybridisation, began in earnest in 1993. As part of this initiative, a census of North American Ruddy Duck in c...
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Seven geographically distinct populations of LYlhrum hyssopifolia L. (Lythraceae) currently exist in the British Isles, with the total population in mainland Britain recently numbering in the region of 600,000-700,000 individuals. Over 90% of this total occurs around a single lake in Gloucestershire. This site has only recently been colonized , and...

Questions

Question (1)
Question
I have a PhotosynQ MultispeQ v2.0. Leaf-clips are not commercially available for this device and so it is necessary to make them yourself. Can anyone please share images of leaf-clips they have made themselves for dark-adaptation of leaves prior to fluorescence measurements? Many thanks in advance for any help.

Projects

Project (1)
Project
This umbrella project comprises a series of smaller projects, each with a focus on better understanding the population status and ecology of notable bryophyte species in Britain, especially those threatened with extinction.