Long-term development of nursing mixtures of Sitka spruce and larch species in an experiment in northern Scotland

William L. Mason


Aim of the study: An experiment was established in 1966 to compare the growth and development of 50: 50 mixtures of Sitka spruce (Picea sitchensis) with either Japanese larch (Larix kaempferi) or tamarack (L. laricina) with that found in pure plots of Sitka spruce. The site was one of moderate nitrogen availability where the presence of heather (Calluna vulgaris) could be expected to limit the growth ofSitka spruce.

Area of the study: North-east Scotland.

Material and methods: There were different patterns of spruce growth in the pure plots and in the mixtures, with faster spruce growth in mixture in the years approaching and immediately following canopy closure (i.e. ages 15-25). Foliage analysis suggested that this was linked with improved nitrogen status of spruce trees in the mixed compared to the pure plots.

Main results: At years 20 and 25 there were significant differences in height, diameter, and basal area between treatments, with the largest basal area being found in the Japanese larch/Sitka spruce mixtures, indicative of overyielding in the mixed plots. However, when the experiment was clearfelled at 41 years of age, all treatments had self-thinned to produce spruce dominated stands of similar height with only an occasional larch tree surviving in plots that were originally 50:50 mixtures.

Research highlights: There were no differences between treatments in basal area, harvested volume or sawlog outturn after 41 years. These results can be interpreted as showing facilitation between the larch and the spruce during the establishment phase followed by competition for light once canopy closure had occurred.

Keywords: Mixed stand dynamics; facilitation; nitrogen status; product outturn.

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Anonymous, 2010. A Guide for Increasing Tree Species Diversity in Wales. Forestry Commission Wales, Aberystwyth, UK. pp. 41.

Brooker RW, Maestre FT, Callaway RM, Lortie CL, Cavieres LA, Kunstler G et al., 2008. Facilitation in plant communities: the past, the present, and the future. J Ecol 96: 18-34.

Cameron AD, Watson BA, 1999. Effect of nursing mixtures on stem form, crown size, branching habit and wood properties of Sitka spruce (Picea sitchensis (Bong.) Carr.). Forest Ecol Manag 122: 113-124. http://dx.doi.org/10.1016/S0378-1127(99)00036-5

Carey ML, McCarthy RG, Miller HG, 1988. More on nursing mixtures. Irish Forestry 45: 7-20.

Carlyle JC, Malcolm DC, 1986. Nitrogen availability beneath pure spruce and mixed larch and spruce stands growing on a deep peat. I. Net N mineralization measured by field and laboratory incubations. Plant Soil 93: 95-113. http://dx.doi.org/10.1007/BF02377149

Dimbelby GW, 1962. The development of Heathlands and their Soils. Oxford Forestry Memoirs 23, Oxford University Press.

Edwards PN, Christie JM, 1981. Yield models for forest management. Forestry Commission Booklet 48, HMSO, London, UK.

Felton A, Lindbladh M, Brunet J, Fritz O, 2010. Replacing coniferous monocultures with mixed-species production stands: an assessment of the potential benefits for forest biodiversity in northern Europe. Forest Ecol Manag 260: 939-947. http://dx.doi.org/10.1016/j.foreco.2010.06.011

Forestry Commission, 2003. National Inventory of Woodland and Trees: Great Britain, 68 pp. http://www.forestry.gov.uk/pdf/nigreatbritain.pdf/$FILE/nigreatbritain.pdf . Accessed on March 15, 2014.

Forrester DI, 2014. The spatial and temporal dynamics of species interactions in mixed species forests: from pattern to process. Forest Ecol Manag, 312: 282–292. http://dx.doi.org/10.1016/j.foreco.2013.10.003

Forrester DI, Vanclay JK, Forrester RI, 2011. The balance between facilitation and competition in mixtures of Eucalyptus and Acacia changes as stands develop. Oecologia 166: 265-272. http://dx.doi.org/10.1007/s00442-011-1937-9

Gabriel K, Blair I, Mason WL, 2005. Growing broadleaved trees on the North York Moors: results after nearly 50 years. Q J Forest 99: 21-30.

Gamfeldt L, Snall T, Bagchi R, Jonsson M, Gustaffson L, Kjellander P et al., 2013. Higher levels of multiple ecosystem services are found in forests with more tree species. Nature Communications. 4: 1340. http://dx.doi.org/10.1038/ncomms2328

Garforth MF, 1979. Mixtures of Sitka spruce and lodgepole pine in South Scotland: History and future management. Scottish Forestry 33: 15-28.

Grant A, Worrell R, Wilson S McG, Ray D, Mason WL, 2012. Achieving diversity in Scotland's forest landscapes. Forestry Commission Scotland Practice Guide, Forestry Commission, Edinburgh, UK. 30 pp.

Kelty MJ, 2006. The role of species mixtures in plantation forestry. Forest Ecol Manag 233: 195-204. http://dx.doi.org/10.1016/j.foreco.2006.05.011

Kennedy F, 2002. The Identification of Soils for Forest Manage¬ment. Forestry Commission Field Guide. Forestry Commission, Edinburgh, UK. pp. 56.

Kerr G, Nixon CJ, Matthews RW, 1992. Silviculture and yield of mixed-species stands: the UK experience. In: The Ecology of mixed-species stands of trees (Cannell MGR, Malcolm DC, Robertson PA, eds). Blackwell, Oxford, pp. 35-52.

Macdonald E, Mochan S, Connolly T, 2009. Validation of a stem straightness scoring system for Sitka spruce (Picea sitchensis (Bong.) Carr.). Forestry 82: 419-429. http://dx.doi.org/10.1093/forestry/cpp011

Macdonald JAB, 1936. The effect of introducing pine species among checked Sitka spruce on a dry, Calluna-clad slope. Transactions of the Royal Scottish Arboricultural Society 50: 83-86.

Macdonald JAB, Macdonald A, 1952. The effect of interplanting with pine on the emergence of Sitka spruce from check on heather land. Scottish Forestry 6: 77-79.

McIntosh R, 1983. Nitrogen deficiency in established phase Sitka spruce in upland Britain. Scottish Forestry 35: 185-193.

Mason WL, 2007. Changes in the management of British forests between 1945 and 2000 and possible future trends. Ibis 149: 41–52. http://dx.doi.org/10.1111/j.1474-919X.2007.00696.x

Mason WL, Connolly T, 2014. Mixtures with spruce species can be more productive than monocultures: evidence from the Gisburn experiment in Britain. Forestry; 87(2): 209-217. http://dx.doi.org/10.1093/forestry/cpt042

Mason WL, Perks MP, 2011. Sitka spruce (Picea sitchensis) forests in Atlantic Europe: changes in forest management and possible consequences for carbon sequestration. Scand J Forest Res, supplement 11: 72-81. http://dx.doi.org/10.1080/02827581.2011.564383

Mason WL, Quine CP, 1995. Silvicultural possibilities for increasing structural diversity in British spruce forests: the case of Kielder forest. Forest Ecol Manag 79: 13-28. http://dx.doi.org/10.1016/0378-1127(95)03618-0

Mason WL, Edwards C, Hale SE, 2004. Survival and early seedling growth of conifers with different shade tolerance in a Sitka spruce spacing trial and relationship to understorey light climate. Silva Fenn 38: 357-370. http://dx.doi.org/10.14214/sf.404

Miller HG, 1981. Forest fertilisation: some guiding concepts. Forestry 54: 157-167. http://dx.doi.org/10.1093/forestry/54.2.157

Morgan JL, Campbell JM, Malcolm DC, 1992. Nitrogen relations of mixed-species stands on oligotrophic soils. In: The Ecology of mixed-species stands of trees (Cannell MGR, Malcolm DC, Robertson PA, eds.). Blackwell, Oxford, pp 65-85.

O'Carroll N, 1978. The nursing of Sitka spruce I. Japanese larch. Irish Forestry 35: 60-65.

Paquette A, Messier C, 2011. The effect of biodiversity on tree productivity: from temperate to boreal forests. Global Ecol Biogeogr 20: 170-180. http://dx.doi.org/10.1111/j.1466-8238.2010.00592.x

Pretzsch H, 2009. Forest dynamics, growth and yield. Springer-Verlag, Berlin, Germany. pp. 664.

Pyatt DG, Ray D, Fletcher J, 2001. An Ecological Site Classification for Forestry in Great Britain. Forestry Commission Bulletin 124. Forestry Commission, Edinburgh, UK. pp 74.

Quine CP, 2000. Estimates of mean wind climate and probability of strong winds for wind risk assessment. Forestry 73: 247–258. http://dx.doi.org/10.1093/forestry/73.3.247

Read DJ, Freer-Smith PH, Morison JIL, Hanley N, West CC, Snowdon P, eds., 2009. Combating Climate Change – A Role for UK Forests. An Assessment of the Potential of the UK's Trees and Woodlands to Mitigate and Adapt to Climate Change. Edinburgh (UK), The Stationery Office.

Robinson RK, 1972. The production by roots of Calluna vulgaris of a factor inhibitory to the growth of some mycorrhizal fungi. J Ecol 60: 219-224. http://dx.doi.org/10.2307/2258051

Ryan EA, Alexander IJ, 1992. Mycorrhizal aspects of improved growth of spruce when grown in mixed stands on heathland soils. In: Mycorrhizas in Ecosystems (Read DJ, Lewis DH, Fitter AH, Alexander IJ, eds). CAB International, Wallingford, Oxford, UK. pp. 237-245.

Smith SA, McKay HM, 2002. Nutrition of Sitka Spruce on Upland Restock Sites. Forestry Commission Information Note 47. Forestry Commission, Edinburgh, UK.

Taylor CMA, 1991. Forest fertilisation in Great Britain. Forestry Commission Bulletin 95, HMSO, London, UK.

Taylor CMA, Tabbush PM, 1990. Nitrogen deficiency in Sitka spruce plantations. Forestry Commission Bulletin 89, HMSO, London, UK.

UKFS, 2011. The UK Forestry Standard, 116 pp. http://www.forestry.gov.uk/pdf/FCFC001.pdf/$FILE/FCFC001.pdf . Accessed on March 15, 2014.

Watson BA, Cameron AD, 1995. Some effects of nursing species on stem form, branching habit and compression wood content of Sitka spruce. Scottish Forestry 49: 146-154.

Weatherell J, 1957. The use of nurse species in the afforestation of upland heaths. Q J Forest 51: 298-304.

Zehetmayr JWL, 1960. Afforestation of upland heaths. Forestry Commission Bulletin, 32. HMSO, London, UK.

Zhang Y, Chen HYH, Reich PB, 2012. Forest productivity increases with evenness, species richness and trait variation: a global meta-analysis. J Ecol. 100(3): 742-749. http://dx.doi.org/10.1111/j.1365-2745.2011.01944.x

DOI: 10.5424/fs/2014233-06084

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