The structure of stands is the one which gives the more complex information about the programe of the stand and its following evolution if there are no esential (unexpected) modifications which can totally change the initial programe. This paper studied a mixed stand of sessile oak and european beech for which its characteristics were established and then, through successive simulations, different tipes of thinnings were pictured for which the characteristics of the stand were calculated afterwords.  Appling different sistems of silvotechnical mesures influences the size of growth and the quality of the wood, meaning the ratio between the volume of thick and thin trees, of different species and qualities. The structure of a stand can be defined as an interaction sistem between the element obeyed to modifications. These interactions give the stand stability and durability in time. The structure appears as a general characteristic of the coexistence relations between the elements of the stand. The relations between the elements of the stand which define its structure can be of many types: gathering relations,asociation relations, size and domination relations. Each of these relation types distinctevly establish some characteristics of the structure of the stand. The gathering relations establish the consistence of the stands, the asociation ones-type of the mix, size and domination relations establish structure of the stand in a vertical plan. Structure of the stands is the result of the abiotic environment action and the interaction of the system elements. Among the complex interactions which influence the structure of the stand, the intraspecific and and interspecific relations have an important role. These interactions are obeyed to the capacity of the species for perpetuation in space and time. Among intraspecific relations the ones of embaresment and rivality can be mentioned and among interspecific relations the ones of favouring, embaresment and rivality are mentioned. The forming and the dynamics of the structure of the stands is given on one hand by the competition, favouring, embaresment relations, the intra and interspecific cooperation and on the other hand by the interactions with the abiotic environment, taking into acount the genetic features also. In the mixed stands, as in the case of European beech, European spruce and European silver fir stands, the competition, favouring and cooperation appear as interspecific rates. In the mixed stands the interspecific competition in minimum and the cooperation and favouring relations act in the way of asuring stability and perennity of the stands. As a result of the factors complexity which interfear in defining the structure of the stands it is necesary that on the basis of the concret conditions, the models which correspond to silvicultural conditions, social- economical and ecological functions of the stands to be established.

structure; stands; programme; thinnings; sessile oak; european beech

Presentation: oral