Black alder
Alnus glutinosa
Family: Betulaceae
Fire effect on plant
Fire is likely to top-kill black alder, but belowground parts are likely to survive
Key traits
Black alder is a tree whose occurrence is closely linked to the availability and abundance of water, found primarily in low-lying damp and riparian places. It is fast-growing, with rapid increases in height in the first 10 years (Kajba and Gračan 2003), early reproductive maturity and seed set (as early as second growing season), and large quantities of seed are produced by year six (Funk 1990).
The response of black alder to fire is poorly described in the literature; however, it is a vigorous resprouter after felling. Resprouting from predominantly basal but also aerial parts after cutting has been described in the species, suggesting that it could resprout from the root crown after fire. The rapid vertical growth in the first decade, combined with its relatively thick bark (1-1.5 cm thick; Diamantopoulou et al 2018), suggests that this species may be able to resist the effects of surface fires, and resprout from aerial buds that are above the flaming zone. There is anecdotal evidence of black alder trees surviving a large forest fire in Poland, with survival linked to the dampness of its habitat (Orczewska et al 2015).
Black alder can regenerate after fire by recruiting from seed. In fact, alder establishment from seed requires high levels of light and moisture (Fitter and Peat 1994), usually achievable only on disturbed sites. After a forest fire in Poland, large black alder stands developed from the seed bank (Orczewska et al, 2015). The black alder seed bank has a high viability (germination can be as high as 80%; Kajba and Gračan, 2003), but that is short lived (few seeds survive beyond the first germination season; McVean, 1955). Seed is wind- and water-dispersed.
Plant response to fire
The moist environments that black alder lives in means that fire is relatively rare and likely provides protection against extremely high flaming temperatures (i.e., because the wet soil resists heating and combustion, thus protecting belowground parts). Fire preceded by drought conditions will likely be highly damaging. This shade-intolerant species appears to benefit from disturbance that maintains high light availability, like fire, in generating high seedling recruitment.
Timing of life history
Long-lived perennial. Time to maturity can be as little as 2 years. Flowering March to April.
Conservation status
None.
References
Adie, H. and Lawes, M.J. 2023, Solutions to fire and shade: resprouting, growing tall and the origin of Eurasian temperate broadleaved forest. Biology Reviews 98: 643-661. [Empirical evidence; Academic literature]
Diamantopoulou, M.J., Özçelik R, Hakkı Yavuz, H. 2018. Tree-bark volume prediction via machine learning: A case study based on black alder’s tree-bark production. Computers and Electronics in Agriculture 151, 431-440. [Empirical evidence; Academic literature]
Fitter, A. H. and Peat, H. J. 1994. The Ecological Flora Database. Journal of Ecology 82: 415–425. [Empirical evidence; Academic literature]
Funk, D.T. 1990. Alnus glutinosa (L.) Gaertn. European Alder. R.M. Burns, B.H. Honkala (Eds.), Silvics of North America: 2. Hardwoods. Agriculture Handbook 654, U.S. Department of Agriculture, Forest Service, Washington, DC (1990), pp. 105-115 [Empirical evidence; Grey literature]
Kajba, D, Gračan, J. 2003 EUFORGEN Technical Guidelines for Genetic Conservation and use for Black Alder (Alnus glutinosa). International Plant Genetic Resources Institute, Rome, Italy. [Empirical evidence; Grey literature]
McVean, D.N. 1955. Ecology of Alnus glutinosa (L.) Gaertn.: II. Seed distribution and germination. Journal of Ecology 43: 61-71 [Empirical evidence; Academic literature]
Orczewska, A., Prukop, M. and Strzelczyk, A. 2016. Recovery of the herbaceous layer in the young silver birch and black alder stands that developed spontaneously after a forest fire. Ecological Research 31: 125–133 [Empirical evidence; Academic literature]