Peter Thomas

Peter Thomas
Keele University · School of Life Sciences

BSc MSc PhD

About

233
Publications
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18,370
Citations

Publications

Publications (233)
Article
Full-text available
Mortality of cacti after grassland fires is usually <25% within 2years. Little, however, is known about long-term mortality. This study followed the fate of 50 marked plants of each of four species of small cacti (Coryphantha vivipara, Echinocereus pectinatus, Echinomastus intertextus and Mammillaria heyderi) on burnt and unburnt desert-grassland i...
Article
Many succulents live in fire-prone habitats with fire frequencies ranging from 1-3 years (Canadian Prairies) to >250 years (Sonoran Desert). Mortality after a fire is often >50% but rarely total. A few plants are left unburm in réfugia but most cacti and leaf succulents persist by survival of the apical meristem, an adaptation to the normal climate...
Article
Full-text available
Cyrenaica is a distinguished region located in the south of the Mediterranean region. Eighty-nine plant taxa were collected and identified as having medicinal properties from four main valleys in Cyrenaica in 2001 and 2013. Collections included the same 47 families in both years, dominated by Lamiaceae (9%) followed by Apiacea (8%) and Asteraceae (...
Article
Full-text available
Genders of dioecious species often show secondary sexual dimorphisms (not directly related to the sex organs), which may be related to reproductive demand for resources during the year. Our working hypothesis stated that phenology influences yearly sex-specific pattern of foliar nitrogen concentration in dioecious species. The concentration of carb...
Article
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Reviewed: Mountain Ash: Fire, Logging and the Future of Victoria's Giant Forests By David Lindenmayer, David Blair, Lachlan McBurney, and Sam Banks. Clayton South, Australia: CSIRO Publishing, 2015. xii + 173 pp. AU$ 59.95, US$ 46.95. ISBN 978-1-486-30497-4.
Preprint
The star formation and metal enrichment histories of galaxies - at any epoch - constitute one of the key properties of galaxies, and their measurement is a core aim of observational extragalactic astronomy. The lack of deep rest-frame optical coverage at high-redshift has made robust constraints elusive, but this is now changing thanks to the \emph...
Preprint
Full-text available
With its exquisite sensitivity, wavelength coverage, and spatial and spectral resolution, the James Webb Space Telescope is poised to revolutionise our view of the distant, high-redshift ($z>5$) Universe. While Webb's spectroscopic observations will be transformative for the field, photometric observations play a key role in identifying distant obj...
Article
Full-text available
Lack of tree fecundity data across climatic gradients precludes the analysis of how seed supply contributes to global variation in forest regeneration and biotic interactions responsible for biodiversity. A global synthesis of raw seedproduction data shows a 250‐fold increase in seed abundance from cold‐dry to warm‐wet climates, driven primarily by...
Article
We present the intrinsic and observed sizes of galaxies at z ≥ 5 in the First Light And Reionisation Epoch Simulations (FLARES). We employ the large effective volume of FLARES to produce a sizeable sample of high redshift galaxies with intrinsic and observed luminosities and half light radii in a range of rest frame UV and visual photometric bands....
Article
Full-text available
The relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundat...
Preprint
Full-text available
The James Webb Space Telescope (JWST) is set to transform many areas of astronomy, one of the most exciting is the expansion of the redshift frontier to $z>10$. In its first year alone JWST should discover hundreds of galaxies, dwarfing the handful currently known. To prepare for these powerful observational constraints, we use the First Light And...
Preprint
Full-text available
We present the intrinsic and observed sizes of galaxies at $z\geq5$ in the First Light And Reionisation Epoch Simulations (FLARES). We employ the large effective volume of FLARES to produce a sizeable sample of high redshift galaxies with intrinsic and observed luminosities and half light radii in a range of rest frame UV and visual photometric ban...
Article
Full-text available
Using the First Light And Reionisation Epoch Simulations (Flares) we explore the dust driven properties of massive high-redshift galaxies at z ∈ [5, 10]. By post-processing the galaxy sample using the radiative transfer code skirt we obtain the full spectral energy distribution. We explore the resultant luminosity functions, IRX-β relations as well...
Article
Full-text available
Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a dataset that collates reproductive time-series d...
Article
Full-text available
Scots pine is one of the most widely occurring pines, but future projections suggest a large reduction in its range, mostly at the southern European limits. A significant part of its range is located in the Caucasus, a global hot-spot of diversity. Pine forests are an important reservoir of biodiversity and endemism in this region. We explored demo...
Article
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High-resolution cosmological hydrodynamic simulations are currently limited to relatively small volumes due to their computational expense. However, much larger volumes are required to probe rare, overdense environments, and measure clustering statistics of the large scale structure. Typically, zoom simulations of individual regions are used to stu...
Preprint
Full-text available
Using the First Light And Reionisation Epoch Simulations (\textsc{Flares}) we explore the dust driven properties of massive high-redshift galaxies at $z\in[5,10]$. By post-processing the galaxy sample using the radiative transfer code \textsc{skirt} we obtain the full spectral energy distribution. We explore the resultant luminosity functions, IRX-...
Article
Full-text available
Female individuals of dioecious plants invest their resources more in storage and defence, and the males have higher nitrogen content invested in the production of pollen grains. An unresolved problem is whether this strategy occurs only in sexually mature plants or can also occur in juvenile plants. To answer this, Taxus baccata (L.) needles from...
Preprint
Full-text available
High-resolution cosmological hydrodynamic simulations are currently limited to relatively small volumes due to their computational expense. However, much larger volumes are required to probe rare, overdense environments, and measure clustering statistics of the large scale structure. Typically, zoom simulations of individual regions are used to stu...
Article
Full-text available
Causes of secondary sexual dimorphism (SSD) in dioecious plants are very poorly understood, especially in woody plants. SSD is shown mainly in mature plants, but little is known about whether secondary sexual dimorphism can occur in juveniles. It is also assumed that stress conditions intensify differences between the sexes due to the uneven reprod...
Article
We present a modified version of the L-Galaxies 2020 semi-analytic model of galaxy evolution, which includes significantly increased direct metal enrichment of the circumgalactic medium (CGM) by supernovae (SNe). These more metal-rich outflows do not require increased mass-loading factors, in contrast to some other galaxy evolution models. This mod...
Article
Full-text available
Climate change is altering patterns of seed production worldwide with consequences for population recruitment and migration potential. For the many species that regenerate through synchronized, quasiperiodic reproductive events termed masting, these changes include decreases in the synchrony and interannual variation in seed production. This break‐...
Article
Full-text available
This account presents information on all aspects of the biology of Crataegus laevigata (Poir.) DC (Midland hawthorn) (C. oxyacanthoides Thuill.) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habi...
Article
In this work we introduce a physically motivated method of performing disc/spheroid decomposition of simulated galaxies, which we apply to the Eagle sample. We make use of the HEALPix package to create Mollweide projections of the angular momentum map of each galaxy’s stellar particles. A number of features arise on the angular momentum space which...
Article
Full-text available
We present the photometric properties of galaxies in the First Light and Reionisation Epoch Simulations (Flares). The simulations trace the evolution of galaxies in a range of overdensities through the Epoch of Reionistion (EoR). With a novel weighting scheme we combine these overdensities, extending significantly the dynamic range of observed comp...
Preprint
We present a modified version of the L-GALAXIES 2020 semi-analytic model of galaxy evolution, which includes significantly increased direct metal enrichment of the circumgalactic medium (CGM) by supernovae (SNe). These more metal-rich outflows do not require increased mass-loading factors, in contrast to some other galaxy evolution models. This mod...
Article
Full-text available
We introduce the First Light And Reionisation Epoch Simulations (Flares), a suite of zoom simulations using the Eagle model. We resimulate a range of overdensities during the Epoch of Reionisation (EoR) in order to build composite distribution functions, as well as explore the environmental dependence of galaxy formation and evolution during this c...
Preprint
In this work we introduce a physically motivated method of performing disc/spheroid decomposition of simulated galaxies, which we apply to the Eagle sample. We make use of the HEALPix package to create Mollweide projections of the angular momentum map of each galaxy's stellar particles. A number of features arise on the angular momentum space which...
Preprint
Full-text available
We present the photometric properties of galaxies in the First Light and Reionisation Epoch Simulations (FLARES). The simulations trace the evolution of galaxies in a range of overdensities through the Epoch of Reionistion (EoR). With a novel weighting scheme we combine these overdensities, extending significantly the dynamic range of observed comp...
Article
Climate change is altering patterns of seed production worldwide [1–4], but the potential for evolutionary responses to these changes is poorly understood. Masting (synchronous, annually variable seed production by plant populations) is selectively beneficial through economies of scale that decrease the cost of reproduction per surviving offspring...
Article
When following the growth of structure in the Universe, we propose replacing merger trees with merger graphs, in which haloes can both merge and split into separate pieces. We show that this leads to smoother mass growth and eliminates catastrophic failures in which massive haloes have no progenitors or descendants. For those who prefer to stick wi...
Article
Full-text available
Nebular emission lines associated with galactic H ii regions carry information about both physical properties of the ionized gas and the source of ionizing photons as well as providing the opportunity of measuring accurate redshifts and thus distances once a cosmological model is assumed. While nebular-line emission has been extensively studied at...
Article
Full-text available
Highly variable and synchronised production of seeds by plant populations, known as masting, is implicated in many important ecological processes, but how it arises remains poorly understood. The lack of experimental studies prevents underlying mechanisms from being explicitly tested, and thereby precludes meaningful predictions on the consequences...
Article
Full-text available
Many plants benefit from synchronous year-to-year variation in seed production, called masting. Masting benefits plants because it increases the efficiency of pollination and satiates predators, which reduces seed loss. Here, using a 39-year-long dataset, we show that climate warming over recent decades has increased seed production of European bee...
Article
We have updated the Munich galaxy formation model, L-galaxies, to follow the radial distributions of stars and atomic and molecular gas in galaxy discs. We include an H2-based star-formation law, as well as a detailed chemical-enrichment model with explicit mass-dependent delay times for SN-II, SN-Ia, and AGB stars. Information about the star forma...
Article
Full-text available
Horse-chestnut (Aesculus hippocastanum L.) is an endemic and relict species from the Mediterranean biodiversity hotspot and a popular ornamental tree. Knowledge about the evolutionary history of this species remains scarce. Here, we ask what historical and ecological factors shaped the pattern of genetic diversity and differentiation of this specie...
Article
We implement a detailed dust model into the L-Galaxies semi-analytical model which includes: injection of dust by type II and type Ia supernovae (SNe) and AGB stars; grain growth in molecular clouds; and destruction due to supernova-induced shocks, star formation, and reheating. Our grain growth model follows the dust content in molecular clouds an...
Article
In this work we update the L-Galaxies semi-analytic model (SAM) to better follow the physical processes responsible for the growth of bulges via disc instabilities (leading to pseudo-bulges) and mergers (leading to classical bulges). We address the former by considering the contribution of both stellar and gaseous discs in the stability of the gala...
Article
Full-text available
Age estimation (Tabbush and White 1996) of woodland yews at Kingley Vale, West Sussex, UK have yielded very high ages, which have been frequently cited. However, measurement of annual ring width at Kingley Vale, and repeat measurement of yews from various sites suggests substantially higher growth rates and so lower ages than estimating age from on...
Preprint
We implement a detailed dust model into the L-Galaxies semi-analytical model which includes: injection of dust by type II and type Ia supernovae (SNe) and AGB stars; grain growth in molecular clouds; and destruction due to supernova-induced shocks, star formation, and reheating. Our grain growth model follows the dust content in molecular clouds an...
Article
This account presents information on all aspects of the biology of Aesculus hippocastanum L. (horse-chestnut) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biot...
Poster
Full-text available
Potted T. baccata female and male individuals were grown with or without fertilization. During the three-year experiment, pulse-modulated chlorophyll a fluorescencence and antioxidative enzymes were monitored. Effects of the sexe and fertilization treatment on key photochemical parameters and antioxidative enzymes were investigated.
Preprint
In this work we update the L-Galaxies semi-analytic model (SAM) to better follow the physical processes responsible for the growth of bulges via disk instabilities (leading to pseudo-bulges) and mergers (leading to classical bulges), showing the impact of these processes on the fractional breakdown of our galaxies into different morphological types...
Article
Full-text available
We present a comparison of the observed evolving galaxy stellar mass functions with the predictions of eight semi-analytic models and one halo occupation distribution model. While most models are able to fit the data at low redshift, some of them struggle to simultaneously fit observations at high redshift. We separate the galaxies into ‘passive’ a...
Preprint
Full-text available
We present a comparison of the observed evolving galaxy stellar mass functions with the predictions of eight semi-analytic models and one halo occupation distribution model. While most models are able to fit the data at low redshift, some of them struggle to simultaneously fit observations at high redshift. We separate the galaxies into 'passive' a...
Article
Full-text available
This account presents information on all aspects of the biology of Ulmus glabra Hudson (wych elm) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors,...
Article
Full-text available
In dioecious woody plants, females often make a greater reproductive effort than male individuals at the cost of lower growth rate. We hypothesized that a greater reproductive effort of female compared with male Taxus baccata individuals would be associated with lower female photochemical capacity and higher activity of antioxidant enzymes. Differe...
Article
Full-text available
The aim of this study was to update figures for the presence of dioecy among the gymnosperms and investigate its correlation with climate, growth form, pollination and seed dispersal syndromes, and risk of extinction. Dioecy was found in almost 65% of contemporary gymnosperm species, a higher percentage than previous estimates. It dominates in 8 of...
Article
Full-text available
We present a comparison of nine galaxy formation models, eight semi-analytical and one halo occupation distribution model, run on the same underlying cold dark matter simulation (cosmological box of co-moving width 125$h^{-1}$ Mpc, with a dark-matter particle mass of $1.24\times 10^9 h^{-1}$ Msun) and the same merger trees. While their free paramet...
Chapter
The tree produces carbohydrates but tree physiologists often talk about the amount of carbon fixed by photosynthesis. The amount of carbon fixed by a tree, minus its running costs (i.e. respiration), gives the net gain in carbon compounds. The movement of carbohydrates (carbon) occurs from sources (suppliers) to sinks (users) associated with growth...
Chapter
Roots, the 'hidden branches' of a tree, are vital for the development and persistence of trees. Roots are vital conduits for water, nutrients, carbohydrates and hormones travelling basipetally, acropetally and from one portion of the root system to another. All below-ground organs originate from the root apical meristem (RAM) which is first develop...
Chapter
Nutrition is fundamental to tree performance in natural environments and managed landscapes. The central aim of tree nutrition management should be to maintain the nutrient supply within an 'adequate' range without allowing nutrients to become either deficient or toxic. Before exploring potential management strategies to enhance the nutrition of tr...
Chapter
By understanding the traits and strategies that help trees cope with their natural environment, it is possible to apply this knowledge to the management of trees in the landscapes. Acknowledging the ecological heritage of the tree improves tree selection and the chances of successful tree establishment, which are critical if the provision of ecosys...
Chapter
A large number of living things, including algae, lichens and plants, live on the outside of trees. They are classed as epiphytes because they take nothing from the tree and are just using the tree as a handy place on which to grow; as such, they are different from parasites which take things from the tree. Until recently, pest and disease manageme...
Chapter
Leaves, and the conglomeration of leaves that make up the tree crown, have the fundamental task of intercepting light. Angiosperm trees normally produce broad leaf blades (lamina) for the interception of light. Compared with angiosperm leaves, those of gymnosperms tend to be much smaller in size and most feel more robust than angiosperm leaves. Nee...
Chapter
Providing temperatures are suitable for growth, water is the factor that most constrains the development and growth of all plants, including trees. Water held with the cells maintains the stiffness of the cell (cell turgor) and provides the substrate for biological activity, including key processes such as photosynthesis. It provides the solvent in...
Chapter
One of the most remarkable things about trees is that the tree habit has evolved independently over a large number of plant families, making it one of the best examples of convergent evolution in nature. While primary growth is vital to all plants, it is secondary growth that allows trees to accumulate a rigid structure capable of supporting an exp...
Chapter
All angiosperm trees are capable of producing flowers. Gymnosperms do not have flowers: they have male and female cones. In both cases, the flowers and strobili are capable of producing seeds that are necessary for creating the next generation. Tree flowers come in many different shapes and sizes. The most basic division in flower type is based on...
Article
This account presents information on all aspects of the biology of Sorbus torminalis (L.) Crantz (Wild Service-tree) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses...
Article
We introduce the Cluster-EAGLE (C-EAGLE) simulation project, a set of cosmological hydrodynamical zoom simulations of the formation of $30$ galaxy clusters in the mass range $10^{14}<M_{200}/\mathrm{M}_{\odot}<10^{15.4}$ that incorporates the Hydrangea sample of Bah\'e et al. (2017). The simulations adopt the state-of-the-art EAGLE galaxy formation...
Article
We introduce the Hydrangea simulations, a suite of 24 cosmological hydrodynamic zoom-in simulations of massive galaxy clusters (M_200c = 10^14-10^15 M_Sun) with baryon particle masses of ~10^6 M_Sun. Designed to study the impact of the cluster environment on galaxy formation, they are a key part of the `Cluster-EAGLE' project (Barnes et al. 2017)....
Article
Full-text available
Interannual variation in radial growth is influenced by a range of physiological processes, including variation in annual reproductive effort, although the importance of reproductive allocation has rarely been quantified. In this study, we use long stand-level records of annual seed production, radial growth (tree ring width) and meteorological con...
Article
Interannual variation in radial growth is influenced by a range of physiological processes, including variation in annual reproductive effort, although the importance of reproductive allocation has rarely been quantified. In this study, we use long stand-level records of annual seed production, radial growth (tree ring width) and meteorological con...
Article
Full-text available
Tree masting is one of the most intensively studied ecological processes. It affects nutrient fluxes of trees, regeneration dynamics in forests, animal population densities, and ultimately influences ecosystem services. Despite a large volume of research focused on masting, its evolutionary ecology, spatial and temporal variability and environmenta...
Article
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 m...
Article
We study the quenching of star formation as a function of redshift, environment and stellar mass in the galaxy formation simulations of Henriques et al. (2015), which implement an updated version of the Munich semi-analytic model (L-GALAXIES) on the two Millennium Simulations after scaling to a Planck cosmology. In this model massive galaxies are q...
Article
Using the L-Galaxies semi-analytic model we simultaneously fit the HI mass function, stellar mass function and galaxy colours. We find good fits to all three observations at z = 0 and to the stellar mass function and galaxy colours at z = 2. Using Markov Chain Monte Carlo (MCMC) techniques we adjust the L-Galaxies parameters to best fit the constra...
Article
Merger trees are routinely used to follow the growth and merging history of dark matter haloes and subhaloes in simulations of cosmic structure formation. Srisawat et al. (2013) compared a wide range of merger-tree-building codes. Here we test the influence of output strategies and mass resolution on tree-building. We find that, somewhat surprising...
Article
We present an analysis of the iron abundance in the hot gas surrounding galaxy groups and clusters. To do this, we first compile and homogenise a large dataset of 79 low-redshift (|z| = 0.03) systems (159 individual measurements) from the literature. Our analysis accounts for differences in aperture size, solar abundance, and cosmology, and scales...
Article
Full-text available
This account presents information on all aspects of the biology of Fraxinus excelsior L. (Ash) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, res...