Transformation of solar radiation in Norway spruce standsinto produced biomass – the effect of stand density

https://doi.org/10.17221/46/2010-JFSCitation:Marková I., Pokorný R., Marek M.V. (2011): Transformation of solar radiation in Norway spruce standsinto produced biomass – the effect of stand density. J. For. Sci., 57: 233-241.
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The present paper is focused on an assessment of the effects of stand density and leaf area development on radiation use efficiency in the mountain cultivated Norway spruce stand. The young even-aged (17-years-old in 1998) plantation of Norway spruce was divided into two experimental plots differing in their stand density in 1995. During the late spring of 2001 next cultivating high-type of thinning of 15% intensity in a reduction of stocking density was performed. The PAR regime of investigated stands was continually measured since 1992. Total aboveground biomass (TBa) and TBa increment (ΔTBa) were obtained on the basis of stand inventory. The dynamic of LAI development showed a tendency to be saturated, i.e. the LAI value close to 11 seems to be maximal for the local conditions of the investigated mountain cultivated Norway spruce stand in the Beskids Mts. Remarkable stimuli (up to 17%) of LAI formation were started in 2002, i.e. as an immediate response to realized thinning. Thus, the positive effect of thinning on LAI increase was confirmed. The data set of absorbed PAR and produced TBa in the period 1998–2003 was processed by the linear regression of Monteith's model, which provided the values of the coefficient of solar energy conversion efficiency into biomass formation (ε). The differences in ε values between the dense and sparse plot after realized thinning amounted to 18%.
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