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Height-diameter models for mixed-species forests consisting of spruce, fir, and beech

100%

Petras R., Bosela M., Mecko J., Oszlanyi J., Popa I.

Folia Forestalia Polonica. Series A . Forestry

2014

tom 56

nr 2

Height-diameter models define the general relationship between the tree height and diameter at each growth stage of the forest stand. This paper presents generalized height-diameter models for mixed-species forest stands consisting of Norway spruce (Picea abies Karst.), Silver fir (Abies alba L.), and European beech (Fagus sylvatica L.) from Slovakia. The models were derived using two growth functions from the exponential family: the two-parameter Michailoff and three-parameter Korf functions. Generalized height-diameter functions must normally be constrained to pass through the mean stand diameter and height, and then the final growth model has only one or two parameters to be estimated. These “free” parameters are then expressed over the quadratic mean diameter, height and stand age and the final mathematical form of the model is obtained. The study material included 50 long-term experimental plots located in the Western Carpathians. The plots were established 40–50 years ago and have been repeatedly measured at 5 to 10-year intervals. The dataset includes 7,950 height measurements of spruce, 21,661 of fir and 5,794 of beech. As many as 9 regression models were derived for each species. Although the “goodness of fit” of all models showed that they were generally well suited for the data, the best results were obtained for silver fir. The coefficient of determination ranged from 0.946 to 0.948, RMSE (m) was in the interval 1.94–1.97 and the bias (m) was –0.031 to 0.063. Although slightly imprecise parameter estimation was established for spruce, the estimations of the regression parameters obtained for beech were quite less precise. The coefficient of determination for beech was 0.854–0.860, RMSE (m) 2.67–2.72, and the bias (m) ranged from –0.144 to –0.056. The majority of models using Korf’s formula produced slightly better estimations than Michailoff’s, and it proved immaterial which estimated parameter was fixed and which parameters were free.

Cyclic changes in tree species composition of mixed-species forest in Western Carpathians: role of disturbance and tree regeneration

80%

Saniga M., Balanda M., Kucbel S., Jaloviar P.

Polish Journal of Ecology

2011

tom 59

nr 4

The paper presents results acquired by an analysis of stand structure, regeneration processes and disturbance regime of a mixed natural forest located in the Carpathians (Central Slovakia). The data were collected on two permanent research plots located on different geological bedrocks (andesite and migmatites). Significant differences in the composition of the upper tree layer were observed among two types of geological bedrock. On the plot I (andesite), European ash (Fraxinus excelsior L.) occurred as a dominant component. An opposite situation was observed on the plot II (migmatites). The coexistence of beech (Fagus sylvatica L., spruce (Picea abies L. Karst.) and ash was recorded in the upper layer. The middle and lower layers were almost identical on both types of bedrock. The dominance of beech with the admixture of other tree species was observed. Regarding the structure of the present forest stand in relation to the structure of the gapmakers and natural regeneration, we observed a partial cyclical alternation of the tree species composition of this natural forest within the time span of several developmental cycles. The analysis of natural regeneration implied a crucial role of ungulates for the growth enforcement of ash individuals in the next generation of natural forest. Under the current condition, a negative trend in tree species diversity of the future generation of natural forest towards the dominance of beech was found.

Ograniczanie wyników

1 Folia Forestalia Polonica. Series A . Forestry

1 Polish Journal of Ecology

1 Balanda M.

1 Bosela M.

1 Jaloviar P.

1 Kucbel S.

1 Mecko J.

1 Oszlanyi J.

1 Petras R.

1 Popa I.

1 Saniga M.

1 2014

1 2011

Wyniki wyszukiwania

Height-diameter models for mixed-species forests consisting of spruce, fir, and beech

Cyclic changes in tree species composition of mixed-species forest in Western Carpathians: role of disturbance and tree regeneration