In this study a quantitative analysis of the low molecular carbohydrates (predominantly sucrose, fructose and glucose) in a series of lumber samples of Pinus sylvestris and Picea abies taken at various distances from the surface has been made. The increase of nitrogenous compounds towards the surface had been shown in a previous study. Several of the lumber samples showed a marked sugar accumulation at the surface, which correlated quite well with a corresponding nitrogen accumulation. In one case, the total amount of the three sugars was as high as 4.9% of the dry matter content in the 0-1 mm layer. It was of special interest to note that samples with high nitrogen and sugar contents also had a yellow surface colour, which probably formed during the drying process by the well-known Maillard reaction -a complex of reactions occurring when sugars and amino adds, peptides and proteins are heat-treated together.Growth of the mould fungus Penicilliurn brevicornpactum was well correlated with the content of nitrogen and low molecular carbohydrates in adjacent samples. The initial colonization was somewhat delayed in material from the outermost sapwood zone despite high nutrient contents indicating effects of antifungal compounds from the bark or toxic Maillard reaction products effective against germination. Growth of Aspergillus versicolor was likewise most elaborate on samples with the highest nitrogen and soluble carbohydrate content but the results also indicate a sensitivity to antifungal compounds present.

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The content of water-soluble substances and starch in the living tree stem at the time of felling influences wood durability during further utilization. The aim of the study was to describe the annual and seasonal fluctuations in the contents of stored carbohydrates and nitrogenous compounds. The contents of soluble sugars, starch, and nitrogen were measured in the outer sapwood (0-15 mm from cambium) of 65-yr-old Scots pine {Pinus sylvestris L.) trees during an annual cycle. To study the influence of growth conditions, samples were taken from different stands in Sweden, in one stand from a control and a fertilized block. The effect of the age of the trees on the content of stored substances was also considered by comparing young (10-15 yrs old) and older trees (40-65 yrs old). Determination of the carbohydrates was carried out using enzymatic analysis. The outer pine sapwood contained a higher content of low-molecular weight sugars during autumn and winter than during spring and summer. Starch content rose at the beginning of the growth period and decreased in autumn. The content of soluble sugars increased towards the cambium on all sampling occasions. Fructose and glucose were dominant sugars in all the stands studied. Seasonal changes of sucrose were different from those of glucose and fructose, in that the sucrose content was already decreasing in February. The variations in the nitrogen content of the sapwood were far smaller than those of the soluble sugars. No significant differences were found between the stands with regard to glucose, fructose and the sum of all three sugars. The fertilized block showed low content of sucrose and nitrogen. It is concluded that seasonal fluctuations are more important with regard to the sugar content than the effect of growth conditions. Data indicate a lower content of soluble sugars and nitrogen in the outermost sapwood of young trees as compared with older trees.

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The distribution of the water soluble substances in green wood and subsequent redistribution during drying, is of importance for the colonisation by microorganisms. In this study the influence of a fast and a slow drying schedule on the redistribution of low-molecular sugars in the wood of Scots pine (Pinus sylvestris L.) was investigated and for this purpose through-and-through sawn, 50 mm thick planks, were dried in a mobile batch kiln. Samples at different depths in the planks were chemically analysed. There is a considerably greater amount of sugars at the surface of the planks after the fast drying schedule compared with the slow drying schedule, but for both schedules there is always a high gradient of the sugars from the inside to the surface of the planks. Obviously, sucrose is very liable to be hydrolyscd during handling or/and drying. The distribution of the sugars along the height of the tree after drying is also given. A selective choice of the drying schedule could be a means to regulate the redistribution and thereby decreasing risk of deterioration.