Glossary
Find definitions for the key scientific and technical terms that are used across our website and communication channels below.
General Key Terms
Abiotic (stress)
(Stress caused by) physical and environmental factors.
Adaptive variation
The genetic differences among populations of a tree species that influence how well individual trees can survive and thrive under different environmental conditions, especially in response to climatic factors and disease pressures.
Afforestation
The process of establishing a forest in an area where there was no previous tree cover/forest before (or not for a long time).
Atmospheric nitrogen deposition
The process by which reactive nitrogen compounds, emitted into the atmosphere from various sources (including aeroplanes, cars, and certain factories), are deposited onto the Earth’s surface. This deposition can occur through both wet (e.g., rain, snow) and dry (e.g., gaseous absorption, particle settling) processes.
Bioclimatic zones
Regions defined by climate and natural vegetation.
Biological control agent
A living organism, or natural substance derived from them, that is used to control pests and diseases.
Biosecurity threats
A range of risks associated with the introduction and spread of harmful organisms, including pests, pathogens, and invasive species, which can negatively impact human, animal, plant, and environmental health. These threats can arise from natural sources, accidental releases, or deliberate acts of bioterrorism.
Biotic (stress)
(Stress caused by) living organisms such as bacteria, viruses, fungi and insects.
Broadleaf/Broadleaved
A category of trees that have wide, flat leaves rather than needle-like leaves. A category of trees that have wide, flat leaves rather than needle-like leaves. These trees are usually deciduous and lose their leaves in winter.
Continuous Cover Forestry (CCF)
A woodland management approach that involves selectively thinning trees to create a diverse forest structure, whilst maintaining canopy cover.
Crown
A crown is the uppermost part of a tree, comprising all the branches, leaves, flowers, and fruits that extend from the trunk.
Cultivars
A specific variety of tree that has been selected and cultivated for particular desirable traits.
Diminished heritage
The loss or weakening of cultural, historical, and emotional connections that people have with specific tree species.
Ecosystem services
The benefits that human beings obtain from ecosystems, contributing to our well-being and a healthy planet. Examples include clean air, food, water, recreation, and raw materials (like wood).
Epidemic
The rapid spread of a disease or condition, exceeding what is normally expected.
Evapotranspiration
The process by which water is transferred from the land to the atmosphere, by water leaving the soil (evaporation) and water lost through plant leaves and stems (transpiration).
Evolutionary relatedness
The degree of genetic and evolutionary similarity between native and non-native tree and plant species.
Farmer champions
Members of the farming community that act as a type of knowledge intermediary.
Fungarium
A collection of dried fungal specimens, serving as a scientific and historical archive of fungi from around the world. For more information, see The Fungarium | Kew.
Heritable traits
Characteristics of the tree that can be passed to their offspring.
Host trees
A tree species that provides resources, such as nutrients, water, or physical support, to another organism, typically a pest or pathogen.
Inoculate
The intentional introduction of a pathogen or pest into a host tree under controlled conditions to study its effects.
Invasive species
A non-native organism that establishes, spreads, and causes harm to its new environment, threatening biodiversity, ecosystems, and the economy. These species, which can be plants, animals, bacteria, or other life forms, often out compete native species for resources and lack natural predators in their new habitat, leading to significant ecological and economic damage.
Knowledge intermediaries
People or organisations that help to connect experts or evidence with people who benefit from the information.
Knowledge interventions
Approaches to presenting, packaging and delivering information that are intended to improve engagement with it, and application of it, amongst target audiences.
Lethal control methods
Control methods which are designed to kill pests such as grey squirrels.
Microbiome
The microorganisms, including bacteria, fungi, and viruses, which live in a particular environment.
Mycelium materials
Biodegradable materials made from the root-like structure of fungi (called mycelium) combined with agricultural waste such as straw, husks, or sawdust.
Non-lethal control methods
Control methods which are designed to manage or deter pests such as grey squirrels, without causing death.
Pathogen (& Pathogenicity)
An organism or agent that can cause disease. Pathogens include viruses, bacteria, fungi, and protists. They can infect a wide range of hosts, including plants and animals. Pathogenicity is the ability of a pathogen cause disease.
Phenotype
Observable characteristics, such as height, biomass, leaf shape and so on.
Photosynthetic pathways
The routes by which organisms turn sunlight, water, and carbon dioxide into food and oxygen.
Physiological adaptations
An internal body process that helps an organism survive and reproduce in its environment.
Progeny
A descendent or offspring.
Provenance
The geographical origin of seeds or planting stock.
Regenerative materials
Materials designed to restore, renew, or improve natural systems rather than deplete them.
Seed zones
Geographically defined areas where tree populations have adapted to specific local environmental conditions, such as climate, soil, and elevation, and where seeds or saplings can be sourced for planting with a high likelihood of successful growth.
Seedlots
A specific batch or quantity of seeds, often from a particular source or seed zone.
Soil hydraulic lift
The process by which some deep-rooted plants take in water from lower soil layers and exude that water into upper, drier soil layers.
Species assemblage
The specific combinations of tree species found in a particular area, influenced by both environmental factors and interactions between species.
Structural diversification
The variation in the physical structure of forest stands, specifically, the diversity in tree sizes, shapes, ages, and spatial arrangements within a forest. This includes differences in canopy layers, the presence of understorey vegetation, and the mix of tree species types (e.g., broadleaf vs. conifer, evergreen vs. deciduous).
UK National Tree Seed Project
Kew launched the UK National Tree Seed Project (UKNTSP) in 2013. The project collected and stored seed from native trees and shrubs throughout the UK. Multiple collections were being made, right across the native range of each species, in order to develop genetically representative collections in the MSB. Over 10 million seeds have been successfully stored. For most of these collections each mother tree was georeferenced, and their seed stored separately. For more information, see UK National Tree Seed Project (Legacy) | Kew.
Vector
An organism that transmits a pathogen, disease, or parasite from one animal or plant to another.
Virulence
The degree or severity of a disease.
Genetics and Genomics
Epigenetic variation
Differences in gene function that arise from modifications to DNA, not changes in the DNA sequence itself.
Gene expression
The production of a protein from the DNA blueprint.
Gene flow strategies
Planned approaches for managing how genetic material (i.e. genes) moves between tree populations, especially through seed and pollen dispersal, to enhance the adaptability and resilience of forests under climate change.
Genetic bottleneck
A sharp reduction in genetic variation caused by a significant decrease in the number of reproducing individuals. In the context of afforestation, collecting seeds from a limited number of parental trees within a larger population can lead to genetic bottlenecks.
Genetic control
The extent to which specific traits are determined by the tree’s genetic makeup and can be inherited by its offspring.
Genetic diversity
Variation in genetic traits within a species or population.
Genetic homogenisation
Loss of genetic differences among populations, often reducing landscape-level complexity, which may result in reduced adaptability and resilience.
Genetic markers
Specific DNA sequences that vary between individuals and can be used to identify trees, assess genetic diversity, and track traits like growth or disease resistance.
Genome
The complete set of genetic material in an organism. It includes all of the organism’s DNA, which contains the instructions needed for growth, development, functioning, and reproduction.
Genome assemblies
The process and result of reconstructing the complete DNA sequence of a tree from fragmented sequencing data. These assemblies are essential for understanding the genetic makeup of different tree species and identifying traits like resistance to disease.
Genome-environment association (GEA)
The statistical relationship between genetic variations (genotypes) and environmental factors. It is a method used to study how organisms adapt to their local environments by identifying specific genes that are associated with particular environmental conditions.
Genome reference sequences
Comprehensive representations of the DNA sequence from a single tree. These sequences serve as a template or baseline for comparing the genomes of other individuals within the species.
Genome sequence
The complete DNA blueprint of individual trees, which is used to understand how genetic variation influences tree growth, resilience, and adaptation to environmental conditions, especially under climate change.
Genome (re)sequencing
The process of determining the complete DNA sequence of a tree’s genome. This includes identifying the order of all the nucleotides (A, T, C, and G) that make up its genetic material.
Genome variants
Genetic differences that are identified across the entire genome of an individual organism.
Genomic basis
The underlying genetic features, such as DNA sequences, genes, and structural variants, which contribute to resistance or susceptibility to disease.
Genomic control
The specific influence of DNA-level variation, such as genes, loci, and single nucleotide polymorphisms (SNPs), on adaptive traits in trees. It goes beyond general heritability to identify which parts of the genome are responsible for traits like disease resistance, stress tolerance, water use efficiency, and growth and stem form.
Genomic (data) analysis
Analysis of the genetic information obtained from the DNA of tree populations.
Genomic diversity
The variation found across the entire genome of individual trees within a species or population.
Genomic offset estimates
A predictive measure of how well a tree’s genetic makeup (its genotype) matches the environmental conditions it is likely to face in the future, especially under climate change.
Genomic structural variation
Where entire regions of DNA are inverted, duplicated, deleted or moved elsewhere in the genome in some individuals.
Genomic variation
The differences in DNA sequences among individual trees, which can influence their susceptibility or resistance to disease.
Genomics
The study of an organism’s complete set of DNA, including all of its genes, and how that DNA interacts within the organism and with its environment.
Genotype
The set of genes that influence how a tree grows and interacts with its environment.
Mapping
In the context of tree genome research, mapping means aligning short DNA sequences (called reads) from individual ash trees to a known, high-quality reference genome. Essentially a complete and well-assembled version of the ash tree’s DNA.
Nucleotide bases
The fundamental building blocks of DNA: adenine (A), cytosine (C), guanine (G), and thymine (T). Changes at single bases can identify individual differences.
Pangenome
The complete set of genes found across all individuals of a species.
Protein-coding gene
A section of DNA that is the blueprint for a protein. Proteins are large molecules that carry out lots of different functions in an organism, especially in the cells.
Read
In the context of tree genome research, a read is a short fragment of DNA sequence that has been decoded by a sequencing machine.
Scaffold
In the context of tree genome research, a scaffold is a stretch of DNA sequence that may contain gaps, but the order and orientation of the pieces are known.
Single nucleotide polymorphism (SNP)
A variation at a single position in a DNA sequence among individuals.
Tree genotypes
The set of genes that influence how a tree grows and interacts with its environment.
Pests, Pathogens, Diseases, and Impacts
Acute oak decline (AOD)
Acute oak decline is an emerging disease of oak trees (trees in the Quercus genus) which was first observed in the UK late in the 20th century. It can kill oak trees within four to six years of the onset of symptoms.
The disease is found mostly on mature oak trees, but younger trees can also be affected. It is caused by multiple agents, especially bacteria, and thousands of trees are affected. For infection to occur, it is likely the trees need to be weakened (predisposed) by certain factors, especially environmental factors. For more information, see Acute oak decline – Forest Research.
Agrilus convexicollis beetle
A non-regulated invasive bark boring beetle believed to be a secondary colonist of diseased ash trees. It is related to the emerald ash borer (Agrilus planipennis) but is thought to be much less destructive to living trees.
Ash dieback (Hymenoscyphus fraxineus)
Ash dieback is a highly destructive disease of ash trees (Fraxinus species), especially the United Kingdom’s native ash species, common ash (Fraxinus excelsior). It is caused by a fungus named Hymenoscyphus fraxineus (H. fraxineus), which is of eastern Asian origin. For more information, see Ash dieback (Hymenoscyphus fraxineus) – Forest Research.
Bark stripping
A destructive behaviour carried out by grey squirrels (Sciurus carolinensis) where they remove tree bark in order to access the sweet, sap-filled phloem tissue beneath. Bark removal can severely impact tree health, lead to tree death and significantly reduce the economic value of timber.
Cerambycidae monochamus beetles
A genus of longhorn beetles within the family Cerambycidae, known for their role as vectors of the pinewood nematode (Bursaphelenchus xylophilus), the causal agent of Pine Wilt Disease (PWD).
Cryphonectria hypovirus 1 (CHV1)
A virus that infects the fungus Cryphonectria parasitica, which causes sweet chestnut blight. CHV1 is known for inducing hypovirulence, meaning it reduces the fungus’s ability to cause severe disease.
Dothistroma needle blight (Dothistroma septosporum)
Dothistroma needle blight (DNB) is an economically important disease of conifer trees (trees with cones and needles), and particularly pines (trees in the Pinus genus). It is caused by the fungus Dothistroma septosporum. It causes premature needle defoliation, resulting in loss of timber yield and, in severe cases, tree death. For more information, see Dothistroma needle blight (Dothistroma septosporum) – Forest Research.
Dutch elm disease (DED)
Dutch elm disease is a highly destructive disease of several species of elm (trees in the Ulmus genus). It is caused by two related fungi, Ophiostoma novo-ulmi and Ophiostoma ulmi, although almost all cases are now caused by O. novo-ulmi. The fungus is spread from tree to tree by elm bark beetles. It has killed tens of millions of elm trees in the United Kingdom since O. novo-ulmi was accidentally introduced, probably during the 1960s. For more information, see Dutch elm disease (Ophiostoma novo-ulmi) – Forest Research.
Emerald ash borer (Agrilus planipennis)
Emerald ash borer (EAB) is an exotic beetle pest of ash trees (Fraxinus species). It is a member of the beetle family Buprestidae, and causes significant damage to the trees, including dieback and death. There have been no reported discoveries of the pest in the United Kingdom (UK), but agencies remain vigilant for an accidental introduction. For more information, see Emerald ash borer beetle (Agrilus planipennis) – Forest Research.
Grey squirrels (Sciurus carolinensis)
A non-native, invasive species originally from eastern North America. They were introduced to Great Britain in the 19th century and have since spread widely, now numbering over 2.7 million individuals across the UK. For more information on the management of grey squirrels, see Management of grey squirrels – Forest Research.
Internal wood failure
Stem cracking.
Larger eight-toothed European spruce bark beetle (Ips typographus)
The larger eight-toothed European spruce bark beetle is a destructive pest of spruce trees (trees in the Picea genus) as well as some tree species in other conifer genera. For more information, see Larger eight-toothed European spruce bark beetle (Ips typographus) – Forest Research.
Larval galleries
Tunnels chewed through the wood by the beetle larvae.
Larval galls
Abnormal plant growths, often called swellings or deformities, which develop as a result of insect larvae feeding on plant tissue.
Lesions
A localised area of damaged or abnormal tissue, often appearing as a sunken, discoloured, or dark area on the bark, branches, or leaves. These lesions can be caused by various factors like fungal infections, bacterial diseases, or even physical wounds.
Oak mildew
Powdery mildew of oak is caused by the fungus Erysiphe alphitoides and it is a common pathogen of oak throughout Europe. Erysiphe attacks young leaves and soft shoots, covering them with a felty-white mycelium, causing them to shrivel and blacken. For more information, see Oak mildew – Forest Research
Oak shake
A condition affecting oak trees that causes stem cracking, which significantly reduces the value and long-term usability of harvested timber. Whilst several biological factors and environmental triggers are known to contribute to shake, the exact causes remain unclear.
Ophiostoma novo-ulmi
The fungus that causes Dutch elm disease (DED). It invades and blocks the water-conducting systems of trees. This results in the wilting and death of the tree. For more information, see Dutch elm disease: Symptoms and Diagnosis – Forest Research.
Phytophthora
Phytophthora species are highly aggressive tree pathogens causing root rots and foliar and fruit diseases. Aerial Phytophthoras are rain dispersed and can cause foliar and shoot blight and stem and branch cankers. Root rotting species tend to be transmitted in soil and river water and on animal and human vectors and cause feeder root rot and stem collar necrosis. Several Phytophthora species are considered to be involved in the oak decline (for both Quercus robur and Q. petraea) that is reported as widespread across Europe. A number of studies have shown that decline is accelerated or exacerbated when Phytophthoras are present. For more information, see Phytophthoras – Forest Research.
Phytophthora pluvialis
Phytophthora pluvialis is a fungus-like pathogen known to affect a variety of trees including western hemlock, tanoak, pine (Pinus radiata, Pinus patula and Pinus strobus) and Douglas fir. It was originally reported in Oregon, USA in 2013 on tanoak and Douglas fir and was subsequently identified as the pathogen responsible for ‘red needle cast’ of radiata pine in New Zealand. Phytophthora pluvialis was discovered in a woodland in Cornwall in September 2021, where it was found to be affecting mature western hemlock and Douglas fir trees. For more information, see Phytophthora pluvialis – Forest Research.
Pine beauty moth (Panolis flammea)
A native UK insect species known for its potential to cause significant damage to certain non-native pine tree species. For more information, see Pine Beauty | Butterfly Conservation.
Pine wilt disease (PWD)
A lethal wilting disease affecting conifer trees, caused by the pinewood nematode (PWN), (Bursaphelenchus xylophilus). It is considered one of the most serious global threats to conifer forestry. The nematode spreads between trees via Monochamus beetles (family Cerambycidae), which carry the nematode on their bodies. The PWN enters trees through beetle feeding wounds and egg notches, proliferates inside the tree, and then transfers to developing beetles within the wood. When these beetles emerge and move to new trees to feed and mate, they further spread the nematode, perpetuating the disease cycle. For more information, see Pine wood nematode (Bursaphelenchus xylophilus) – Forest Research.
Pine wood nematode (Bursaphelenchus xylophilus)
A microscopic roundworm, scientifically named Bursaphelenchus xylophilus, that causes Pine Wilt Disease (PWD). It is a pathogenic organism that infects conifer trees, particularly pines, by entering through wounds created by Monochamus beetles during feeding or egg-laying. Once inside the tree, the nematode multiplies rapidly, disrupting water transport and leading to tree wilting and death. PWN also uses beetles as vectors, hitching rides on their bodies to spread from one tree to another, continuing the disease cycle. For more information, see Pine wood nematode (Bursaphelenchus xylophilus) – Forest Research.
Slime flux
A bacterial infection that causes white foam to seep from crevices in the bark.
Sweet chestnut blight (Cryphonectria parasitica)
Sweet chestnut blight is a destructive disease of sweet chestnut trees (trees in the Castanea genus) caused by the ascomycete fungus Cryphonectria parasitica. It was formerly known as Endothia parasitica. It can also affect a few other plant species. For more information, see Sweet chestnut blight (Cryphonectria parasitica) – Forest Research.
Volatile Organic Cuticular Compounds (VOCCs)
Chemical cues given off by the UK beetle species (potential carriers/vectors).
Xylella fastidiosa
Xylella is a plant disease which can affect several species of broadleaved trees widely grown in the UK, such as oak, elm and plane, as well as a wide range of other commercially grown plants. It is caused by a bacterium called Xylella fastidiosa (X. fastidiosa), which has four known sub-species. It is a quarantine organism, which means suspected sightings must be notified immediately to the plant health authorities. For more information, see Xylella (Xylella fastidiosa) – Forest Research.
Yew gall midge (Taxomyia taxi)
An insect whose larvae cause galls (abnormal growths) on yew trees. These galls typically develop from buds and are frequently observed in areas where ancient yew trees are experiencing decline.
Plant, Tree, and Fungi Species and Related Terms
Ash (Fraxinus excelsior)
A native broadleaved tree with excellent timber properties that is an important host for many species of flora and fauna and consequently of high ecological value.
Ash is under severe threat from ash dieback disease (Hymenoscyphus fraxineus), and its abundance in the British landscape is likely to decrease. The ability to plant ash is now severely restricted due to concerns over tree health. Ash is categorised as a principal tree species. For more information, see Ash (AH) – Forest Research.
Birch (Betula)
Birch trees are a genus (Betula) of deciduous hardwood trees known for their distinctive white or silvery bark and graceful form. They are characterised by their thin leaves, often triangular in shape, and are typically found in temperate and boreal regions of the Northern Hemisphere. Birch trees are also known for their use in various applications, including as a source of firewood, in furniture making, and in traditional medicine. The two most common native Birch species in the UK are silver birch (Betula pendula) and downy birch (Betula pubescens). For more information, see Birch Trees – Forest Research.
Castanea genus
A group of deciduous trees in the Fagaceae family, which includes species commonly known as chestnuts. These trees are the natural hosts of the fungal pathogen Cryphonectria parasitica, which causes sweet chestnut blight.
Conifer (Pinophyta)
Conifers, or softwood trees, are cone-bearing and usually evergreen trees. They are a distinct group of trees that are economically significant due to their ability to grow quickly even on poor soils and in harsh climates. These trees yield timber that is highly suitable for industrial use, which has led to their widespread planting and management across many countries. Examples of conifer trees found in the UK include Scots pine, Douglas fir, and Norway spruce.
Defoliated
The removal of a plant/tree’s leaves, either naturally due environmental factors like disease or grazing, or through human intervention.
Douglas fir (Pseudotsuga menziesii)
Douglas-fir is one of the most economically important conifers in the Pacific northwest. Despite its common name Douglas-fir was discovered by Archibald Menzies in 1793 and introduced to Britain by David Douglas in 1872. Initially planted as estate specimens it is now mainly planted for commercial forestry. Some of the heritage specimens are now the tallest trees in Britain with examples reaching over 66 m in height. Douglas-fir is categorised as a principal tree species. For more information, see Douglas fir (DF) – Forest Research.
Downy birch (Betula pubescens)
Downy birch is one of two native birches in Britain and was historically an important source of wood for fuel, charcoal and small wood products, particularly wooden bobbins. It was not seen as a timber tree and the increased use of plastics saw it fall out of general use. There is increasing interest in the potential for birch as a productive forest species. Downy birch is a native tree and is categorised as a Principal tree species. For more information, see Downy birch (DBI) – Forest Research.
Elm (Ulmus)
A historically significant and culturally iconic tree species in the British landscape, which has suffered major decline due to disease, particularly Dutch elm disease caused by the fungus Ophiostoma novo-ulmi.
Field elm (Ulmus minor)
One of the two native elm species in Britain (the other being wych elm, Ulmus glabra). A species of elm tree which was once widespread across the UK landscape. It is one of the native European elm species that has been heavily affected by Dutch elm disease (DED).
Foliage
The leafy parts of a tree or plant
Forest stand
A section of a forest where the trees and other plants are similar in species, age, and structure, and where the soil and land shape (topography) are also alike. See also Mixed species stand.
Fraxinus (genus)
A group of tree species commonly known as ash trees, which includes over 40 species distributed across Europe, Asia, and North America.
Gymnosperm
A group of seed-producing plants that includes conifers like Sitka spruce. Gymnosperms are characterised by:
- Producing seeds without a protective fruit (unlike angiosperms, which have seeds enclosed in fruits).
- Typically having needle-like or scale-like leaves.
- Often being evergreen and forming large forests, especially in temperate and boreal regions.
Mixed species stand
A forest stand that contains two or more different tree species growing together in the same area under similar environmental conditions.
Monoculture
Forests made up trees of the same age and from a single species.
Mycorrhizal associations
Symbiotic relationships between fungi and plant roots.
Mycorrhizal fungi
Soil-based fungi which interact with tree roots and support trees in accessing soil nutrients.
Needle morphology
The physical characteristics and structural traits of tree needles, such as their length, width, shape, and surface features, which may influence the tree’s resilience to environmental stressors and diseases.
Norway spruce (Picea abies)
Norway spruce is a European native and was present in Britain pre-glacial. As an early reintroduction (before 1550) it was widely planted and is an important forest tree but fell out of favour when the more productive Sitka spruce (Picea sitchensis) became available. More recently the arrival in Britain of the European spruce bark beetle (Ips typographus) poses a distinct threat to both species. Norway spruce is categorised as a principal tree species. For more information, see Norway spruce (NS) – Forest Research.
Oak (Quercus)
Oak trees are a group of trees and shrubs belonging to the genus Quercus within the beech family. They are known for their distinctive lobed leaves, hard wood, and characteristic acorns. There are around 500 different species of oak, found in the Northern Hemisphere, and they can be either deciduous or evergreen. There are two native oak species in the UK: pedunculate oak (Quercus robur) and sessile oak (Quercus petraea), and three non-native species: turkey oak (Quercus cerris), holm oak (Quercus ilex), cork oak (Quercus suber). For more information, see Oak Trees – Forest Research.
Pine (Pinus)
A group of coniferous tree species, some of which are non-native to the UK, which are being considered for planting to diversify and strengthen UK treescapes. These trees are part of the broader effort to increase forest resilience against future threats such as pests, diseases, and climate stress. For more information, see Pine trees – Forest Research.
Prunus
A genus of flowering plants in the Rosaceae family that includes economically and ecologically important species such as almond (Prunus dulcis), and wild cherry (Prunus avium). These species are native or naturalised in the UK and are being studied for their susceptibility to Xylella fastidiosa.
Scots pine (Pinus sylvestris)
Scots pine is one of three native conifers but is the only one of commercial importance. It is tolerant of dry conditions which makes this an increasingly valuable species for sites in eastern Britain where drought risk is likely to increase under climate change. Scots pine is categorised as a principal tree species. For more information, see Scots pine (SP) – Forest Research.
Silver birch (Betula pendula)
Silver birch is one of two native birches in Britain and was historically an important source of wood for fuel, charcoal and small wood products, particularly wooden bobbins. It was not recognised as a timber tree and the increased use of plastics saw it fall out of general use. There is increasing interest in the potential for birch as a productive forest species. Silver birch is a native species and is categorised as a principal tree species. For more information, see Silver birch (SBI) – Forest Research.
Sitka spruce (Picea sitchensis)
Sitka spruce is the largest of the spruce Genus (Picea) with some trees growing to a height of 80 m and a dbh of 500 cm. It is Britain’s most widely planted productive conifer growing in the milder wetter conditions of the west and north. Sitka spruce is categorised as a principal tree species. For more information, see Sitka spruce (SS) – Forest Research.
Stem form
The way that the trunk of a tree grows – this includes characteristics such as the straightness, taper, branching pattern, and overall shape of the tree stem.
Sycamore (Acer pseudoplatanus)
The sycamore is a large fast-growing deciduous tree to 30 m+ height with a broad native range. An early introduction to Britain with discussion ongoing as to when – mid 1500 s or possibly earlier – it is now widely naturalised in northern Europe and Britain. Sycamore is categorised as a principal tree species. For more information, see Sycamore (SY) – Forest Research.
Wych elm (Ulmus glabra)
One of the two native elm species in Britain (the other being field elm, Ulmus minor). It is indigenous to the UK and has historically been a common part of the British landscape, especially in upland and northern areas. Like other European elms, wych elm is highly vulnerable to the fungal pathogen Ophiostoma novo-ulmi, which causes Dutch elm disease that has devastated elm populations since the 1970s.
Yew (Taxus baccata)
One of the oldest living trees in northern Europe, yew is one of the three conifers native to Britain alongside Scots pine and juniper. Unlike other conifers, yew trees grow succulent (but poisonous) red fruits instead of cones. For more information, see Yew | Tree species | Forestry England.
Scientific Disciplines, Tools, and Methods
Acoustic velocity testing
Measures how fast sound waves travel through the wood, providing insights into wood stiffness and potential defects.
Arboriculture and Arboriculturist (Arborist)
Arboriculture is the scientific study and practical cultivation of individual trees, shrubs, vines, and other perennial woody plants for their care, management, and benefit to society. An Arboriculturist (or Arborist) is a professional in the practice of Arboriculture.
Arbotom
A non-destructive tool that uses sonic waves to create an image of a tree’s internal structure, which can reveal decay, and other defects.
Bioinformatics
An interdisciplinary field that uses computer science, statistics, and biology to analyse and interpret biological data.
Biosecurity modelling
The use of data-driven analytical frameworks and predictive tools to assess and anticipate risks posed by pests, diseases, and environmental stressors to tree species.
Cuticular extractions
The process of removing the cuticle, or outer layer, of a plant or insect, or the extraction of cuticular waxes from these cuticles.
Dendrochronology
Dendrochronology, also known as tree ring analysis, is the scientific method of dating based on the analysis of patterns of tree rings. These rings, formed annually, reflect variations in climate and environmental conditions during the tree’s lifespan, providing a record of past events and allowing for the precise dating of wood samples.
Detached needle bio-assay
A technique where a needle, or a part of it, is used to assess biological activity or response in a controlled environment, often involving a detached tissue sample or organism.
Ecological modelling
The construction and analysis of mathematical models of ecological processes, including both purely biological and combined biophysical models. Models can be analytic or simulation-based and are used to understand complex ecological processes and predict how real ecosystems might change.
Evolutionary modelling
The process of using mathematical and computational models to simulate and study how biological traits, genes, or species change over time through evolution.
Forest Sector Model (FSM)
A tool used in forestry economics and policy analysis to represent the complex interactions within the forestry sector, combing biophysical and economic elements. These partial-equilibrium models are used to understand and forecast how changes in one part of the sector (e.g., timber supply) might affect other parts (e.g., timber prices or forest management practices). They are crucial for informing policy decisions related to forest management, timber markets, and the broader bioeconomy.
Genome-wide association studies (GWAS)
A research method used to identify specific regions of a genome, called loci, which are statistically associated with traits such as resistance to disease.
Glasshouse setting
A controlled environment used for growing and studying plants under regulated conditions.
Hyperspectral reflectance
The measurement of how a material reflects light across many different wavelengths, helping to identify its composition or condition.
Internet of Things (IoT)
The network of physical devices that collect and exchange data with each other and with other systems via the internet. These connected “things” are equipped with sensors, software, and other technologies that allow them to sense their environment, process information, and communicate without human intervention, enabling automation, real-time monitoring, and improved efficiency in various aspects of life and business.
Leaf analysis
A scientific method used to detect early signs of stress in trees, whether caused by environmental factors like drought or biological threats such as pathogens.
LiDAR
Light Detection and Ranging (LiDAR) is a remote sensing method that uses laser light to measure distances and create detailed 3D representations of surfaces.
Liquid Chromatography-Mass Spectrometry (LC-MS)
An analytical technique used to identify and measure chemicals in a sample. LC-MS combines two methods:Â Liquid Chromatography (LC) separates the components of a mixture. Mass Spectrometry (MS) identifies and quantifies those components based on their mass.
Loci
Specific, identifiable positions or regions on a tree’s DNA where genetic variants occur. These loci are important because they can be associated with traits such as resistance or susceptibility to disease.
Long-read sequencing data
DNA that is sequenced in sections that average thousands of base pairs in length, rather than the more commonly used short-read.
Molecular-informed breeding
The use of DNA-based technologies to enhance traditional tree breeding programs, accelerating the development of trees with desired traits like disease resistance and climate resilience.
Multispectral imaging
Captures images at a few specific wavelengths across the electromagnetic spectrum (like red, green, blue, and infrared), allowing us to see details that aren’t visible in regular photos. It helps identify materials, detect changes, or analyse objects based on how they reflect light in different bands.
Nucleic acid extraction
A fundamental process in molecular biology and genetics that enables the isolation and purification of DNA or RNA from various biological samples.
Phylogenetic
The evolutionary relationships between different tree species.
Phylogenomic
The science of using whole-genome data to understand how species are related and how they evolved.
Plant physiology
The study of the functions of a plant, encompassing its internal processes, how it interacts with its environment, and its life cycle.
Proxies
Variables that provide an indirect measure of a target trait, but which are much easier to measure.
Reference assembly/genome
Carefully constructed representations of the complete DNA sequence of a single tree. These assemblies serve as a genetic blueprint for the species and are used as a standard for comparing the genomes of other individuals.
Remote sensing
The scanning of the earth by satellite or high-flying aircraft in order to obtain information about it.
Resistance microdrilling
A minimally invasive testing technique that measures wood resistance using a fine drill needle.
Ribonucleic acid (RNA)
The molecules that carry genetic instructions from DNA and help regulate how cells function, especially how they respond to stress or infection.
Short-read sequencing data
A DNA sequencing method where the DNA is broken into small fragments, and each fragment is sequenced individually.
Silviculture
Silviculture is the science and practice of cultivating and managing forest stands to ensure their long-term health, productivity, and resilience for various societal needs. It involves activities such as site preparation, regeneration, thinning, pruning, harvesting, and pest management to influence the forest’s structure and function, integrating ecological principles and management objectives to produce sustainable forest ecosystems.
Sonic tomography
A non-destructive testing technique that assesses the internal condition of trees by analysing how sound waves travel through the wood.
Spectral signatures
The unique patterns of electromagnetic radiation (light) that an object or material reflects or emits across different wavelengths.
Speed breeding
A technique used to make trees flower earlier by manipulating environmental conditions specifically, by providing longer daylight hours, elevated carbon dioxide levels, and short artificial winters. This method does not involve genetic modification.
Stem psychrometer
A scientific instrument used to measure water in plant tissues, particularly in tree stems and sometimes leaves. It helps researchers and foresters understand how much water a plant is retaining or losing, which is crucial for studying drought stress, irrigation needs, and overall plant health.
Time-calibrated phylogenetic tree
A type of evolutionary tree (diagram) that not only shows the relationships between species but also incorporates estimates of divergence times, i.e., when different species or lineages split from a common ancestor.
Transcriptomics
The study of RNA transcripts produced by tree cells in response to infection by a bacterium.
Tree ring analysis/data
The study of annual growth rings in trees to understand their historical growth patterns, environmental conditions, and responses to stressors.
Ultrasonic Anemometer
A wind sensor that uses ultrasonic sound waves to precisely measure wind speed and direction.
Science & Research
Our science programme will support the UK governments' forest and tree strategies and the successful delivery of tree planting programmes. Research outcomes will also directly contribute to the improved resilience of the UK’s forests, woodlands and trees and help promote enhanced capacity and capability in forest and tree health research.
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