DOI: 10.5593/SGEM2014/B32/S14.066


Spalvis, K., Daugaviete, M., Platace , R., Daugavietis, U.
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-14-8 / ISSN 1314-2704, June 19-25, 2014, Book 3, Vol. 2, 493-500 pp

In the northern hemisphere Norway spruce (Picea abies Karst.) as one of the most productive and fast-growing conifer species has long been cultivated over vast areas. According to the literature data the spruce plantations in Europe take up some 6 to 7 million hectares. In the territory of present-day Latvia pure stands of spruce were established in woodlands already in the 19th century. Starting with the 1980s, spruce plantations for short rotation cultivation (till the age of 40 years) were on a larger scale established also in abandoned agricultural lands. Between 2000 and 2012, the area under similar plantations has reached 28,700ha. At first commercial thinnings at the age of 15 years the number of trees in the plantations is normally reduced to 1,500 stems•ha-1. In such a situation the major challenge is how to utilize the biomass thinned out. In the given study we have investigated the structure and amount of woody biomass that may be recovered in thinning 15-year pure stands of spruce. According to the field data, the weight of above-ground biomass of one tree in 15-year pure stands of spruce is on average 142.9kg (100%), of which stemwood makes 65.7 kg (46.0%) and tree foliage 76.9kg (53.9%), respectively. The biomass of green branches comprises the fraction of needles (38.1 kg or 49.5%) and young shoots (7.2kg or 9.4 %), which in biomass studies is known as tree foliage. In 21 to 25-year pure stands of spruce the above-ground biomass of one tree weighs on average 372kg (100%), of which stemwood is 244.5 kg (65.7%) and tree foliage 117kg (31.5%), respectively In similar spruce plantations the number of trees removed in the first commercial thinnings is 1,210 trees ha-1 with the yield of pulpwood 27.1m3ha-1, or stem biomass 21.5t ha-1, and tree foliage 17.8t ha-1. When thinning 21to 25-year plantations, on average 877 trees ha-1 are thinned out, with the yield of pulpwood 109m3ha-1, or stem biomass 86.3t ha-1, and tree foliage 21.6t ha-1. The profit calculations, when utilizing also tree foliage, show that in thinning 15 to16-year spruce plantations the gross profit is 1.8 times higher, compared to the case when only pulpwood is utilized. For 21 to 25- year plantations this increase in gross profit is 1.2 times higher compared to utilizing pulpwood alone.

Keywords: Norway spruce (Picea abies (L.) Karst.), plantation cultivation of spruce, above-ground biomass, stemwood, tree foliage, economic gain.

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