EXPERIMENTAL STUDY CONCERNING THE MAIN INDEXES OF THE MACROSCOPIC STRUCTURE OF BLACK LOCUST (Robinia pseudacacia L.)

Mihaela POROJAN
Lecturer Dr.Eng. - Universitatea "Transilvania" din Brasov - Facultatea de Industria Lemnului
Address: B-dul Eroilor nr.29, 500036 Brasov, Romania
Tel: +40 268 412921/int. 192. Fax: +40 268 415315
E-mail: mporojan@unitbv.ro

Abstract: This paper presents the experimental results for the main indexes of the macroscopic structure of black locust (Robinia pseudacacia L.) harvested from two different geographic regions of Romania, respectively North - the Carei region and South - the Arges region. The pedo-climatic conditions, the environmental factors and forest growth parameters act as a whole and influence the development of the trees by generating a large variation of wood structure, physical and mechanical properties, from one species to another, within the same species from one tree to another, and even within the same tree. The main indexes of the macroscopic structure of wood are: the heartwood proportion, the sapwood proportion and the features of the annual rings. Based on these macroscopic features, which are directly and easily perceptible by a naked eye observation, one can appreciate the physical, mechanical and technological properties of wood, which make it able for different uses.
The performed experimental study revealed that the black locust wood from both geographic areas contains mainly heartwood, with an average percentage of 80%, the black locust wood originating from the South has the width of the annual rings and the width of the late wood area by approximately 9% higher than the same species from the North and, also the proportion of the late wood from the Southern trees is by approximately 5% higher.

Key words: black locust, macroscopic structure, heartwood, annual rings.

REFERENCES
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POROJAN, M. (2007). Contributii la studiul proprietatilor fizico-mecanice si tehnologice ale lemnului de salcam (Contributions to the Study of Physical, Mechanical and Technological Properties of Black Locust Wood). PhD Thesis. "Transilvania" University of Brasov.
*** SR ISO 4471-1993: Lemn. Prelevare de arbori de proba si busteni pentru determinarea proprietatilor fizice si mecanice ale lemnului din arborete omogene (Wood. Sampling of Trees and Logs for the Determination of Physical and Mechanical Properties of Wood from Homogenous Growth Areas).
*** STAS 2557-88: Lemn. Determinarea caracteristicilor inelelor de crestere (Wood. Determination of the Characteristics of Annual Rings).