© 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...

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Background: Arbutus unedo is a valuable Mediterranean shrub as an ornamental plant as well as fruit tree. Fresh fruits of A. unedo are a good source of antioxidants, of vitamins C, E and carotenoids and also are characterized by the high content of mineral elements. Materials and Methods: The effects of gibberellic acid (GA 3 ) and cold stratification (CS) on seed germination performance were investigated in A. unedo seeds collected from three provenances in the Northern part of Greece. Seeds of each provenance were soaked in solutions of GA 3 (500, 1000 or 2000 ppm) for 24 h and subsequently were subjected to CS at 3 -5ºC for 0, 1, 2, and 3 months. Results: Non-stratified seeds of the three A. unedo provenances which were not treated with GA 3 solutions exhibited very low germination. However, seed germination was significantly improved after a one-month period of CS. Similarly, the non-stratified seeds of all three provenances became non-dormant after the treatment with 2000 ppm GA 3 and they germinated at high percentages. However, in untreated seeds with GA 3 , after a one-month CS period the seeds of the Pieria provenance exhibited higher germination percentage than that of Rodopi provenance seeds. Furthermore, in non-stratified seeds, the Pieria provenance seeds treated with GA 3 germinated at higher percentages and more rapidly than those of the other two provenances. Conclusion:The results indicated that untreated seeds exhibited very low germination at 20/25ºC. However, in all three provenances seed germinability was significantly improved by a one-month period of CS or treatment of seeds with 2000 ppm GA 3 . Furthermore, there was a considerable variability among seed provenances in response to the treatments which were applied.

IntroductionNowadays, the plethora of publications make difficult to evaluate them and apply an evidence-based research practice. The meta-analysis is essentially a quantitative systematic review. The cost is minimal, compared to the cost of basic research, while interest from the readers becomes greater.A meta-analysis includes formulation of the query, a thorough search of the literature, studies' evaluation and selection, as well as statistical composition of individual studies and interpretation of results (Borenstein et al., 2009). However, meta-analysis is inappropriate for studies with different methodology, subject to systematic errors and with incompatible results (Cooper, 2010).The aim of this work was to provide the necessary knowledge to foresters to carry out proper meta-analyses, with an example of Aleppo pine density responses to burning 12-144 months after fire and with no thinning treatments. Material and methodsThere is a number of researchers who have proposed specific instructions for the conducting a meta-analysis (Lipsey and Wilson, 2000;Borenstein et al., 2009;Cooper, 2010). Stages of a meta-analysis are described below. Problem definitionForms of research findings, which are suitable to meta-analysis, are:1. Central tendency research (prevalence rates AbstractAim of study: Provision of the necessary knowledge to foresters in order carry out objective literature research, through meta-analysis.Area of study: Mediterranean. Material and methods:We describe in detail the methodology of meta-analysis. Then, we apply a meta-analysis in a set of independent studies of density of Aleppo pine (Pinus halepensis Mill.), a common forest species of the Mediterranean.Research highlights: Making high quality meta-analyses, can help foresters in making the most of individual forest studies by synthesize them. In this work:-We provide details on approaches for undertaking a meta-analysis.-We use a silvicultural example to demonstrate our idea.-We show how the method of meta-analysis could be applied to forestry also (besides the classical medical study reviews).-We have as ultimate goal the use of this article as a reference from other researchers as regards the application of meta-analysis to their area of expertise.

Preliminary height models, a volume model, a site index model and a survival analysis for Pinus halepensis Mill. in Chalkidiki (Northern Greece) were preliminarily developed based on measurements of 20 experimental plots established in 2010. The data for the height, volume and 'mortality' models consisted of 790 observations taken from 40 trees (20 dominant and 20 co-dominant). An equation derived from the hyperbolic function was selected to model the dominant height and the volume development. The height growth model was used as a guide curve to develop two site index curves. Mean dominant and codominant height was estimated at 10m (site I) and 7m (site II) (base age of 17 years). Kaplan-Meier survival and hazard functions applied for the 'mortality' analysis, confirmed the site index curves developed from the height model (SI10 and SI7).