Introduction

Adaptive capacity: species ability to accommodate or cope with environmental changes.

Climate-based vulnerability assessment: assessment that characterizes species’ exposure, sensitivity and intrinsic adaptive capacity to climate change. A key tool in climate change adaptation planning.

Climate stressor: changes in climate that surpass the past environmental conditions and can affect forest health and/or increase tree mortality. This can include changes to growing conditions (e.g. temperature or precipitation) or climate-related disturbances (e.g. fire or drought).

Exposure: magnitude of environmental change an individual will experience. Environmental change includes changes in temperature and precipitation across space and time or changes in disturbance regimes like fire or drought.

Impact: Combined effect of exposure and sensitivity of a climate stressor on a species or system.

Sensitivity: the degree to which a species is likely to be affected by or respond to environmental change.

Species’ vulnerability to climate change: The level to which a species is exposed to an environmental change, how it could be affected (i.e. sensitivity), and how it could cope with or accommodate (i.e., adaptive capacity) this change.

Sensitivity

Geographic range: spatial area where a given species is found. This area is defined by environmental tolerances) and biotic factors such as its ability to disperse, presence of disease or competition with other species.

Leaf traits: Morphological or physiological attributes of a leaf that are useful to infer plant function, such as rates of growth and nutrient acquisition. For example, one commonly used leaf trait is Specific leaf area, which is the area of a leaf measured when it is still fresh divided by its oven dried mass.

Meristematic tissue: living tissues capable of division and growth in plants. These tissues can be found at many locations on a plant, including stems, roots and buds. Depending on the species, some of these tissues can produce clones through vegetative reproduction.

Plant morphology: Form or structural development of a plant.

Plant phenology: timing of recurrent or periodic biological events and how they are linked to seasonal cues (e.g., changes in light or temperature) or interannual variation in these environmental cues (climate variation). Examples of phenological events can be flowering, bud burst, seed production or leaf senescence.

Plant physiology: Chemical and physical processes associated with plant functioning and growth.

Resprouting: the ability of species to activate dormant buds and reproduce vegetatively in response to disturbance. Can be an important process by which species re-establish populations after disturbance.

Seed bank: Natural storage of seeds. Can be in the soil or in specialized structures (e.g. cones). The duration of seed viability in seed banks varies greatly between species (from days to decades).

Stomatal sensitivity: ability of a species to open or close its stomata in response to changes in light and humidity

Plant trait: morphological, physiological, and/or phenological attributes that determine a plant response to a stressor

Tree crown: the upper part of a tree that extend from the main stem. Includes branches, leaves, and reproductive structures

Vegetative reproduction: reproduction by asexual means, i.e., a plant’s ability to produce a new genetically identical individual (a clone) from specialized reproductive tissues (e.g. rhizomes, stolons, bulbs) or plant fragments.

Xylem cavitation/embolization: phenomenon by which hydraulic tension (or pressure) in the xylem exceeds atmospheric pressure during a drought event, causing an air bubble to form (i.e., an embolism) in the xylem. Cavitation reduces water conductivity in the stem, or the ability to transport water.

Xylem resistance to cavitation: Xylem hydraulic pressure at which a certain percentage of xylem conductivity (i.e. transport of water and sap) is lost. The most commonly used index of resistance to cavitation is Ψ50, or the hydraulic pressure at which 50% of xylem conductivity is lost.

Adaptive capacity

Adaptive capacity: species ability to accommodate or cope with environmental changes.

Allele: one of several alternative forms of a gene occupying the same specific location (locus) on a particular chromosome.

Expected heterozygosity (He): expected genetic diversity (i.e. heterozygosity) at a given locus within a population assuming Hardy-Weinberg equilibrium (i.e., in absence of other evolutionary forces; therefore, genetic variation in a population remains constant from generation to generation).

Gene: sequence of nucleotides that comprises DNA. Basic functional unit that is transferred from parent to offspring.

Genetic diversity: degree of genetic variability present within and among individuals of a population or a species.

Genotype: combination of alleles specific to a locus or to multiple loci in an individual. In a broad sense, it refers to the genetic makeup of an organism.

Heterozygous: indicates the presence of at least two different alleles at a locus (i.e. specific location of a gene on a chromosome) in an individual.

Heterozygosity: refers to the proportion of individuals that are heterozygous at a given locus (i.e. specific location of a gene on a chromosome).

Interspecific hybridization: process by which two parents from different species cross and exchange genetic material, and produce progeny.

Introgression: long-term process by which genetic material (e.g. genes) moves from one species (donor) into the gene pool of another (recipient) by repeated backcrossing. Hybridization is the first step in this process.

Locus: specific location of a gene on a chromosome.

Phenotype: observable characteristics of an individual resulting from its genetic makeup (genotype), its environment and the interaction between the two. Tree morphology and/or physiology are examples of observable characteristics of an individual’s phenotype.

Phenotypic plasticity: ability of an individual to express different phenotypes under different environmental conditions.

Population genetic differentiation: proportion of the genetic diversity found in a given subpopulation relative to the total genetic variation across all populations.