Tree Biomass, Growth and Nutrient Pools

A steady-state mass balance model (ForSust), developed to simulate potentially sustainable levels of tree biomass growth and related nutrient uptake dynamics, was applied to 17 jack pine sites across Canada. The model simulates potential tree biomass growth based on nutrient inputs from estimated atmospheric deposition (N, Ca, Mg, K) and soil weathering (Ca, Mg, K), and matches the resulting nutrient supply rates with calculated nutrient demand. Nutrient demand calculations are based on nutrient concentrations in wood, bark, branches, and foliage. Specifically, the model simulates sustainable annual increment (SAI) of biomass growth for stem-only and whole-tree (aboveground biomass) harvesting, and for recurring forest fire conditions. Calculated SAI levels were compared with field-estimated mean annual increments for aboveground forest biomass (MAI). For recurring forest fires, it was found that SAI values, as simulated, corresponded with the MAI field estimates in general. For whole-tree harvesting, SAI was lower than MAI for most but not all sites. For stem-only harvesting, SAI corresponded with MAI, but there was a greater scatter between SAI and MAI values than what appeared to be the case for the recurring forest fire scenario. Key words: Jack pine; whole-tree, stem-only harvesting; steady-state mass balance; forest biomass; N, Ca, Mg, K growth limitations; atmospheric deposition

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Investigation of culture conditions by Response Surface Methodology and kinetic modeling for exopolysaccharide production by Klebsiella oxytoca ICCF 419 strain, using lactose as substrate

ROMANIAN BIOTECHNOLOGICAL LETTERS ◽

10.25083/rbl/25.6/2033.2044 ◽

2020 ◽

Vol 25 (6) ◽

pp. 2033-2044

Author(s):

CATERINA TOMULESCU ◽

◽

MIŞU MOSCOVICI ◽

ROXANA MĂDĂLINA STOICA ◽

GABRIEL BUJOR ALBU ◽

...

Keyword(s):

Citric Acid ◽

Klebsiella Oxytoca ◽

Fermentation Medium ◽

Culture Conditions ◽

Biomass Growth ◽

Initial Value ◽

Substrate Consumption ◽

Polysaccharide Production ◽

Crude Polysaccharide ◽

Central Composite

The objective of this work was to optimize the bioprocess parameters, using Klebsiella oxytoca ICCF 419 to obtain an exopolysaccharide based on lactose as substrate. A kinetic study was employed and Logistic and Gompertz models were applied to describe the polysaccharide production, in relation with biomass growth and substrate consumption. The RSM methodology based on Central Composite Rotatable Design was used to evaluate and optimize the effect of lactose, corn extract, KH2PO4 and citric acid concentrations as independent variables on the polysaccharide production, biomass growth and substrate consumption as the response functions. The interaction effects and optimal parameters were obtained using Design Expert Software (version 9.0.6.2). The significance of the variables and their interactions was tested by means of ANOVA analysis with a 99% confidence level. The optimum culture conditions were determined and the model prediction was compared with experimental results. At an initial value of 23.45 for the C/N in the fermentation medium, the strain produces 17.41 g/L of crude polysaccharide and 2.53 g/L dry biomass. The EPS production was significantly influenced by lactose, corn extract and KH2PO4, while the citric acid had no influence. The biomass growth was influenced by the corn extract, KH2PO4 and citric acid.

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