© iForest -Biogeosciences and Forestry IntroductionSite quality assessment is the evaluation of the natural productive capacity of a forest site for a tree species. Site quality assessment is very important in forest management, because a site could support one species excellently while supporting poorly other species. The oldest and most widely used technique for evaluating site quality or productivity is the site index.Site index is the average total height of dominant and co-dominant trees at a specified reference or base age (Clutter et al. 1983). It is scarcely affected by various densities and species composition, relatively stable under various thinning intensities and is strongly correlated with volume. The principal uses of site index are: (1) to estimate the height at any given age from site index; (2) to estimate site index from height at any given age; (3) to stratify forest land into productive classes; and (4) to provide entry to yield tables (Wang & Payandeh 1995). However, the most common objective of site index investigations is to determine the height development pattern that the stand is expected to follow throughout its life-cycle (Clutter et al. 1983).Site index models are essential quantitative tools in forest management (Teshome & Petty 2000). Most of the techniques used to fit site index curves could be considered as special cases of three general development models, namely: (i) the guide curve; (ii) the difference model; and (iii) the parameter prediction method (Clutter et al. 1983). Among the various techniques for developing site index curves, the guide curve method has become popular in those cases where repeated measures through time on the same permanent plots are unavailable (Clutter et al. 1983, Nanang & Nunifum 1999.Oak forests covers 22.6% of the total forested area in Greece (Ministry of Agriculture 1992). According to Christensen (1997), Hungarian oak (Quercus frainetto Ten. syn. Q. conferta Kit.) is an important timber species in most mainland Greece, but not in the drier low elevation area in the southern part of the country. Moreover, Bergmeier & Dimopoulos (2008) refer that in mainland Greece Q. frainetto is the species that most frequently dominates in comparison with the other deciduous oaks.The aim of this work was to obtain site index curves for site quality assessment of degraded Hungarian oak stands in central Greece to be used in the management of current and future Hungarian oak stands. Materials and Methods Study areaThe study was conducted in degraded Hungarian oak stands located in an area of approximately 290 ha (of which 260 are forested) in central Greece (38° 53' N, 22° 03' E - Fig. 1). Data were collected at an elevation ranging from 650 to 750 m a.s.l. The substratum is flysch and the soil texture is loamy sand, clay-loam to loam (Xirogiannis 2001). According to the closest meteorological station (390 m a.s.l.), the mean annual rainfall is 873 mm and the mean annual air temperature is 15.16 °C (Xirogiannis 2001).In the past, tree branches in some location...