Alnus glutinosa

Common Alder

Physical Traits & Growth

Typical max. heightiMaximum height in typical conditions, in metres. Full data also shows maximum achievable height in exceptional conditions.:
40m in ideal conditions, typically 20-25m 1
25m 5
25m, usually no more than 12m 6
31m 7

Max. canopy widthiLikely maximum horizontal width of the canopy, in metres:
Conical to ovoid, typically <10m spread 1
4-8m wide 2
Spreading, broad domed or conical crown 3

Size of shadowiSize of shadow based on a fully grown tree, categorised as low, medium or high: Moderate (159 sqm)

Canopy densityiShading intensity of the canopy when in full leaf. Categorised from open to dense.: Open 1

Leaf emergenceiTime of leaf emergence, categorised as very early, early, late, or evergreen: Early (Apr to Nov 1)

Growth rateiHow quickly the tree grows during establishment. Categorised as low, moderate or high, with very high used in exceptional cases.: Moderate to high 12

LongevityiExpected lifespan of the tree:
Typically 100 years 8, potentially 250+ years 2
Only 20-25 yrs lifespan on poor sites 6

Management & Systems

Typical systemsiCommon agroforestry or silvicultural systems where this species is used:
Lowland, semi-upland 2
Arable, pasture and veg systems 5

Approach to silvicultureiCoppicing and pollarding ability:
Coppices well 4 when young 13, or grown as open or forest tree 3
Can be pollarded 1

Establishment requirementsiCommon requirements to establish the tree:
Fast growing 1
Not seriously attacked by herbivores 36
Risk of poor growth in tubes 9

Management requirementsiCommon long-term management needs such as pruning. Categorised as low, moderate or high.: Minimal or no pruning 1

Pruning timeiOptimal season for pruning: Spring (late) to summer 1

Common Alder, Reading, UK / Tom Staton / https://creativecommons.org/licenses/by-sa/4.0/deed.en

Products & Economy

Food productsiCommon food products such as fruits and nuts: –

Wood productsiCommon wood products, including timber, turnery, and pulp:
Timber (generally low quality) 5
Max YC 12 4, ranging from 4 to 14 2

BiomassiCommon biomass products such as fuelwood: Biomass 3, charcoal 5

Speciality productsiOther speciality and niche products: –

Time until market (food)iNumber of years until the tree produces food products: –

Time until market (timber)iNumber of years until the tree produces wood products:
Maximum rotation 60-70 years 6
Reduced lifespan of 20-25 yrs lifespan on poor sites 6

Ecology & Utility

Nutrient and organic matter accumulationiRough estimate of soil-improving properties, with larger and deeper-rooting trees predicted to have higher value. Categorised as low, moderate or high.: Low – low canopy area

Nitrogen fixationiNitrogen-fixing properties, categorised as yes or no: Yes 11

High carbon sequestrationiAll trees sequester carbon, but faster-growing, larger trees generally have higher sequestration potential.:
Short-term (20 years): High
Medium-term (40 years): High
Long-term (60 years): High

Native status in the UKiCategorised as native, long-established, or recent introduction.: Native 1

High wildlife valueiMost trees are likely to be of some value to wildlife, but some trees are of generally higher value to various wildlife groups:
Moderate 5
Highest value for foliage invertebrates, fruits and seeds 5

Other environmental impactsiOther impacts such as water consumption and nutrient leaching:
High water consumption in wet conditions 2
Can increase nitrate leaching and acidification in areas already receiving moderate N deposition 3

Pollinators

Flowering period (pollinator benefit)iTypical flowering months: Feb-Mar 1

High pollen and nectar value for pollinatorsiValue of flowers to pollinators: Low 1

Susceptibility & Risks

Risk of toxicity to livestockiReported potential toxicity to livestock, categorised as yes or no. Toxicity is complex and often context-specific.: None known

Risks to farming operationsiOther risks such as suckering roots, very large tree size, secondary host for aphids, and flammability:
Produces many seeds that readily germinate on nearby moist ground 2
Can sometimes be invasive 4

Disease susceptibilityiSusceptibility of the tree (not tree products) to diseases, e.g. fungal and bacterial disease:
Moderate
Many pathogenic fungi, but rarely of importance 9
Susceptible to Phytophthora 35 and honey fungus 6

Invertebrate pest susceptibilityiSusceptibility of the tree (not tree products) to invertebrate pests, e.g. aphids and other insects:
Low
May be susceptible to alder sucker and leaf-mining sawflies 6
Many potential pests, but few are economically important 9

Vertebrate damage susceptibilityiSusceptibility of the tree (not tree products) to vertebrate pests, e.g. squirrels and deer:
Low to moderate
Low sensitivity to browsing 7 and low palatability 8, not seriously attacked by Rabbits 5
Commonly browsed by deer in summer 9