Quantifying the interrelationship between tree stand growth rate and water table level in drained peatland sites within Central Finland

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Date: July 2008
From: Canadian Journal of Forest Research(Vol. 38, Issue 7)
Publisher: NRC Research Press
Document Type: Report
Length: 6,285 words
Lexile Measure: 1510L

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Abstract: The quantitative relationship between stand growth rate and water table level in peatland forest sites has not been fully ascertained in the literature. In this study, we investigated this relationship by means of a bivariate regression model. Tree and stand attributes, including volume and past 5-year volume growth as well as median water table depth (WTM) during the 1984 growing season, were observed in 69 Scots pine (Pinus sylvestris L.) sample stands with three subplots established in each stand. All stands were located in deep-peated, moderately rich to poor organic soil sites in Central Finland (61[degrees]45'-62[degrees]26'N, 22[degrees]40'-28[degrees]29'E) that had been ditched for forestry about 25 years earlier (1959-1961). Prediction models for the fixed mean functions for 5-year volume growth and WTM as well as estimates for variances and the correlation of random effects at plot and subplot levels were estimated simultaneously using bivariate regression methods. The correlation of model residuals at the plot level was highly significant. The model was applied to simulate stand volume development for a period of 20 years. Simulations illustrated the dynamic interaction of stand volume, volume growth, and soil water levels: deep initial WTM resulted in stand growth and volume-development increases and subsequently further deepened the WTM in the stand. The model can be applied to southern boreal drained Scots pine peatlands to estimate the WTM in different stand volume conditions and to assess the effect of stand management on WTM.

Resume : La relation quantitative entre le taux de croissance d'un peuplement et le niveau de la nappe phreatique dans les tourbieres boisees n'a pas ete clairement etablie dans la litterature. Dans cette etude, avons etudie cette relation a l'aide d'un modele de regression bivariee. Les caracteristiques des arbres et du peuplement, incluant le volume, l'accroissement en volume des cinq dernieres annees et la profondeur mediane de la nappe phreatique (NPM) pendant la saison de croissance 1984, ont ete observees dans 69 peuplements de pin sylvestre (Pinus sylvestris L.) a l'interieur desquels trois sousplacettes ont ete etablies. Tous les peuplements etaient etablis sur des sols organiques profonds, moderement riches a pauvres, situes au centre de la Finlande (61[degrees]45'-62[degrees]26'N, 22[degrees]40'-28[degrees]29'E) et qui avaient ete draines environ 25 ans plus tot (1959-1961). Des modeles de prevision pour les fonctions fixes moyennes dans le cas de l'accroissement quinquennal en volume et de la NPM, de meme que l'estimation de la variance et de la correlation entre les effets aleatoires, aux echelles de la placette et de la sous-placette, ont ete estimes simultanement a l'aide d'une methode de regression bivariee. La correlation des residus du modele a l'echelle de la placette etait hautement significative. Le modele a ete utilise pour simuler l'evolution du volume du peuplement pendant une periode de 20 ans. Les simulations illustrent l'interaction dynamique entre le volume du peuplement, l'accroissement en volume et le niveau de la nappe phreatique. Ainsi, une NPM initialement basse a entraine une augmentation de la croissance du peuplement et du volume, ce qui a par la suite abaisse davantage...

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Gale Document Number: GALE|A185608860