Typical nursery production practices, such as root pruning and transplanting, can alter tree root architecture and contribute to root systems that are too deep. In a study of field-grown liner production, root architecture was examined at each stage of the production process, from first year seedlings or rooted cuttings, through 4 to 5 year old branched liners. Depth and diameter of structural roots were recorded on ten replications each of Acer saccharum, Gleditsia triancanthos, Pyrus calleryana, and apple seedling rootstocks; Platanus ‘Columbia’ clonal rooted cuttings; and apple EMLA 111 clonal rootstock produced by mound propagation. By the time the liners reached marketable size, most natural lateral roots emerging from the primary root were lost. Simultaneously, adventitious roots were produced deeper on the root shank at the pruned end of the primary root. These changes in architecture result in the formation of an ‘adventitious root flare’ that is deeper in the soil than a natural root flare. The depth of this new root flare is dependent upon nursery production practices and may influence the ultimate depth of structural roots in the landscape.
Nursery production practices subject tree root systems to mechanical and environmental factors that are not imposed on plants regenerated naturally from seed. Architecture of undisturbed root systems of nine trees species commonly planted in urban landscapes was compared to root architecture of these tree species produced using common field nursery production practices. When young nursery production seedlings are root-pruned prior to replanting, the loss of the lower portion of the main root and lateral roots emerging from it, and initiation of adventitious roots from the cut end, alter the root system architecture. Nursery production plants have 7 to 48 percent fewer natural lateral roots that could develop into flare roots than undisturbed plants. New roots initiated from the cut end of the main root on nursery production plants can substitute for the loss of lateral roots, if accepted practices are followed. Root architecture of trees is established early. With minor exceptions attributed to the loss of small roots less than 1 mm diameter, there were no significant changes in the number of lateral roots over the 4 year period in both nursery production and undisturbed plants. This consistent number of roots also suggests that pruning the main root did not stimulate additional lateral roots above the pruning cut. Root architecture of liner stock produced in nurseries can be equivalent to undisturbed root systems. Index words: Structural roots, root pruning, bare root, root depth, taproot, root flare. Species used in this study: Norway maple (Acer platanoides L.); green ash (Fraxinus pennsylvanica Marsh.); littleleaf linden (Tilia cordata L.); red maple (Acer rubrum L.); European white birch (Betula pendula Roth.); Kentucky coffee tree (Gymnocladus dioicus L.); domestic apple (Malus spp.); red oak (Quercus rubra L.); Siberian elm (Ulmus pumila Jacq.).
The physical, chemical, and biological constraints of urban soils often pose limitations for the growth of tree roots. An understanding of the interrelationships of soil properties is important for proper management. As a result of the interdependence of soil properties, the status of one soil factor can have an effect on all others. Preventing soil damage is most effective and preferred. Cultural practices, such as cultivation and mulching, can be effective in improving soil properties. Soil additives, such as biostimulant products, have not proven to be consistently effective through research. The management challenge is to provide an urban environment that functions like the natural environment.
Root systems of nearly all trees in the built environment are subject to impacts of human activities that can affect tree health and reduce longevity. These influences are present from early stages of nursery development and throughout the life of the tree. Reduced root systems from root loss or constriction can reduce stability and increase stress. Natural infection of urban tree roots after severing has not been shown to lead to extensive decay development. Roots often conflict with infrastructure in urban areas because of proximity. Strategies to provide root space under pavements and to reduce pavement heaving have been developed, but strategies for prevention of foundation and sewer pipe damage are limited to increasing separation or improved construction.
In 1984‐85 a randorn sample of maried primigravidae in Aberdeen completed a 7‐d weighed diet survey in the seventh month of pregnancy. The results are compared with a similar local survey conducted in 1950/51 and with other recent studies in the United Kingdom. Daily intake of nutrients were less in 1984/85 then in 1950/51. Although it is likely that there has been a real reduction, problems arise about direct comparison of values because of methods of calculation. Both surveys came to certain conclusions, including that taller women ate more than shorter women, that birthweight was not associated with distary intake and that smokers had a significantly reduced intake of ascorbic acid. Although wives of non‐manual workers tended to have higher nutrient intakes than other wives, the difference only reached marginal significanc for ascorbic acid in 1950/51 and for protein and calcium in 1984/85. The wife's occupation was more discriminating than that of the husband, particularly in 1984‐85, although the changes in the occupational structure necessitated a redivision of occupations. In 1984/85, women in professional occupations ate significantly more of all items except energy, fat and thiamin compared with clerical and other workers. Although 34 years apart, the two surveys showed that the proportion of energy derived from fat was unchanged (38.5%) whereas the proportion of protein had increased, offset by a reduction in carbohydrate. There were no significant differences in the components of energy by occupational group in either survey, irresective of the classification used. Evidence indicates by NACNE (1983). The recent study adds to the accumulation evidence that the DHSS (1979) recommendations for the diet of pregnant women are unrealistic.
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