Common juniper
Juniperus communis
Family: Cupressaceae
Fire effect on plant
Common juniper will be killed by all except fires of very low severity.
Key traits
Common juniper is an evergreen gymnosperm shrub or small tree that resproust poorly after low-severity fires (although even these may cause mortality; Clifton et al. 1997). It is unclear from the literature if resprouting is from basal or epicormic buds, although the thin bark of this species (<6 mm at maturity) makes basal resprouting only likely. It is highly sensitive to moderate- to high-severity fires, which cause mass mortality in this species (Quevedo et al. 2007). For example, fire in a Pinus sylvestris woodland with an understorey of juniper in Poland killed 70% of junipers, with that percentage rising to 100% where there was a dense grass layer, with no signs of re-sprouting (Faliński 1998). Similarly, intense moorland fires in the UK kill or seriously damage common juniper, with flaming temperatures of 800°C killing all individuals, while 600°C permitted some survival but led to poor vegetative regeneration (Mallik and Gimingham 1985).
Common Juniper does not have an effective soil seed bank, so regeneration after fire is from seeds from surviving individuals (García et al. 1999; Lloret and Vilà 2003).
Plant response to fire
The main subspecies of juniper in the UK (J. communis subsp. communis and J. communis subsp. nana) are sensitive to fire. However, subspecies nana, a small procumbent shrub of well-drained bogs, upland heaths, and montane scrub in northern England and Scotland, seems especially intolerant of burning (Poore and McVean 1957; McVean 1961). The disappearance of this subspecies in heath has been ascribed in some instances to a single fire (Thomas et al. 2007). The natural distribution of junipers in Britain has undoubtedly been reduced by burning in the past, and the occurrence of high-severity fires linked with climate change further threaten this species. However, low-severity fire has been found to be a useful tool in rejuvenating declining juniper stands by encouraging natural regeneration (Kerr 1968; Miles and Kinnaird 1979).
Timing of life history
Perennial species. Seeds produced from 10 years. Flowering May to June.
Conservation status
BAP - Juniperus communis, Juniperus communis subsp. hemisphaerica.
References
Clifton, S.J., Ward, L.K. and Ranner, D.S. 1997. The status of juniper Juniperus communis L. in north-east England. Biological Conservation 79; 67–77. [Empirical evidence; Academic literature]
Faliński, J.B. 1998. Dioecious woody pioneer species (Juniperus communis, Populus tremula, Salix sp. div.) in the secondary succession and regeneration. Phytocoensis 10: (N.S.), Supplementum Cartographiae Geobotanicae 8, Warszawa–Białowieza. [Empirical evidence; Academic literature]
García, D., Zamora, R., Hódar, J.A. and Gómez, J.M. 1999. Age structure of Juniperus communis L. in the Iberian Peninsula: conservation of remnant populations in Mediterranean mountains. Biological Conservation 87: 215–220. [Empirical evidence; Academic literature]
Kerr, A.J. 1968. Tynron Juniper Wood National Nature Reserve: Management and Research 1957–68. Nature Conservancy Council, unpublished report. [Empirical evidence; Grey literature]
Lloret, F., Vilà, M. 2003. Diversity patterns of plant functional types in relation to fire regime and previous land use in Mediterranean woodlands. Journal of Vegetation Science 14: 387-398. [Empirical evidence; Academic literature]
Mallik, A.U. and Gimingham, C.H. 1985 Ecological effects of heather burning. II. Effects on seed germination and vegetative regeneration. Journal of Ecology 73: 633–644. [Empirical evidence; Academic literature]
McVean, D.N. 1961. Post-glacial history of juniper in Scotland. Proceedings of the Linnean Society of London 172: 53–55. [Empirical evidence; Academic literature]
Miles, J. and Kinnaird, J.W. 1979. The establishment and regeneration of birch, juniper and Scots pine in the Scottish Highlands. Scottish Forestry 33: 102–119. [Empirical evidence; Academic literature]
Poore, M.E.D. and McVean, D.N. 1957. A new approach to Scottish mountain vegetation. Journal of Ecology 45: 401–439.
Quevedo, L., Rodrigo, A., Espelta, J. M. 2007. Post-fire resprouting ability of 15 non-dominant shrub and tree species in Mediterranean areas of NE Spain. Annals of Forest Science 64: 883-890.
Thomas, P.A., El-Barghathi, M. and Polwart, A. 2007. Biological Flora of the British Isles: Juniperus communis L.. Journal of Ecology 95: 1404-1440. https://doi.org/10.1111/j.1365-2745.2007.01308.x