Biological properties of trees
Rooting ability. Rooting ability (rooting soil) it is the property of trees to produce a large amount of roots in order to obtain the greatest possible contact with the soil. The high root development capacity is characteristic of fast-growing trees. Poplar roots, for example, show great expansion under impermeable surfaces, which can even be damaged by them.
Growth rate in youth. This feature is especially important for city trees. Trees that grow fast in their youth can withstand and overcome various threats that occur in the adolescent period more easily - both unfavorable growing conditions, and mechanical damage. In addition, we quickly obtain the necessary mass of green. In urban conditions (Warsaw) crown volume and dbh of several species of aged trees 5, 10 i 15 years after planting, they are different and show different growth dynamics. The greatest increase was observed in the silver maple.
The dbh is the diameter of a tree trunk in height 1,3 m from the ground.
Productivity. In forestry, this term denotes the amount of growth in the mass of wood of a given tree species, in green areas it refers to the production of green plant mass, which is strongly correlated with the above process (the volume of the leaf mass). It needs to be highlighted that, that this property of trees in particular depends not only on the genetically determined properties of the species, but also on the environmental conditions and the treatments carried out.
Wound healing ability. This is a species dependent property, development period, Seasons, health and environmental conditions. In general, deciduous trees heal wounds better than conifers, because they contain more backup material in the trunk and branches, have more sleeping buds, and a greater possibility of delivering - via phloem - building materials - assimilation products - to the healing tissue. Conifers, on the other hand, "have" the resin, which can flood wounds and prevent infection. Similar comments also apply to the roots.
Susceptibility to diseases and pests. It is a property that varies greatly in time and space. Overall it can be said, that in the city trees are weakened by unfavorable living conditions. It makes it, that they are more susceptible to attack by pathogenic fungi and pests (usually insects). So, as a rule, we are dealing with a complex of unfavorable abiotic and biotic factors.
Suitability for use in urban conditions and for street filling - this is a comprehensive "feature" of a given species related to particular, previously discussed, biological requirements and properties. Positive rating in the penultimate column of the table 2 testifies to the tree's resistance to burdensome urban conditions, longevity, relatively low maintenance costs, etc.. The suitability of trees for planting streets is essentially the same as that for cultivation in urban conditions. However, for the safety of people and vehicle traffic, breaking off of branches as well as falling leaves and fruit should also be taken into account. For example, ash-leaf maple, due to its fragile wood and easily decomposed by fungi, is particularly dangerous on roadways.
The knowledge of the influence of harmful factors that have become more and more intense in recent years is still incomplete. This is especially true of air pollution and soil salinity.
Requirements and properties of the species collected in the table 2 were compiled on the basis of existing information in the field of dendrology and silviculture. At the same time, efforts were made to take into account specific urban conditions. Seems, that the list in question can be used not only in tree maintenance, but it can also be useful when designing plant sizing for cities.
