WOOD RESEARCH 57 (2): 2012 241-250 HARVEST-TIME RELATED BLUE-STAIN SPREAD IN LOGS IN THE FOREST OF ELATIA, GREECE Dimou Vasiliki Demokrition University of Thrace, Department of Forestry and Management of The Environment and Natural Resources Kavala, Greece (Received May 2010) ABSTRACT Picea abies and Pinus sylvestris logs, both debarked and with bark still on, are examined in relation to the rate they were affected by blue-stain in the forest. In total twelve trees were felled, six from each species, in three different logging sessions in the Elatia region, Drama. The trees were subsequently cut into logs which constituted the 12 experimental surfaces of the study. The surfaces were placed either on a skidroad on special platforms or inside the logging area. Data from two cross-sections performed in each log were taken at the end of every month, a process that lasted four, seven and four consecutive months respectively for the experimental surfaces resulting from each logging session. At the end of the research periods each log was cut mid- length and data were collected from this cross-section as well. KEYWORDS: Blue-stain, harvest-time, Picea abies, Pinus sylvestris. INTRODUCTION Associations between fungi and bark beetles of coniferous trees are numerous, and mainly involve the beetle genera Ips and Dendroctonus and the fungal genera Ceratocystis and Ophiostoma (Webber and Gibbs 1989). Many of these fungal species are collectively known as blue stain fungi (Whitney 1982). Some of these fungi are pathogenic and associated with aggressive bark beetles, thus causing severe damage to living trees (Bramble and Holst 1940; Mathre 1964; Molnar 1965; Horntvedt et al. 1983; Redfern et al. 1987). Blue-stain is the most common case of wood discoloration and appears mainly in the sapwood of conifers and especially Pinus nigra (Mantanis 2003). The color of the sapwood changes into blue to grey or bluish black either in its totality or in spots. The fungi that cause blue-stain are mostly ascomycetes and deuteromycetes (Schmidt 2006). Blue-stain appears mostly in conifers, usually pines (as well as in Abies, Picea, Pseudotsuga etc.), and more rarely in broadleaves (Fagus, Populus, Quercus, Fraxinus, tropical species etc.). It dramatically reduces timber value mostly because the appearance of wood products (e.g. sawn 241 WOOD RESEARCH timber etc.) is not attractive. Besides, the change in the color of the wood makes consumers doubt about its health and endurance (Abdullah et al. 2006, Tsoumis and Voulgaridis 1978). The most common discoloring fungi belong to the genera of Alternaria, Cadophora, Diplodia, Discula, Graphium, Hormodendron, Hormonemia etc. These fungi use starches and simple sugars found in sapwood for food. They cannot grow in heartwood since it does not contain the necessary nutrients (Knabe 2002). There is no blue-colored excretion by the fungi that attack wood, and the cell walls retain their natural light yellow color. The blue tinting of the wood is due to a purely visual phenomenon. Despite acquiring a dark color in maturation, fungal hyphae when new are colorless; however, when seen through the semitransparent cell walls they appear blue (Tsoumis 1973, Karanikola 2008). Blue-stain can attack standing, living or dead trees, which it reaches through various bark- eating insects (Kailidis 1990). MATERIAL AND METHODS The aim of the present study is to examine the spread rate of blue-stain and insect infestation in Picea abies, and Pinus sylvestris in association with the time of felling. In Greece, logging operations are performed in spring or at the beginning of summer, depending on weather conditions, or, in other words, they commence as soon as snow melts. The timber that is logged annually remains for quite a long time (in most cases for more than four months and occasionally for one year or even longer) on the forest road or a skidroad till it is sold, a fact that invariably results in its decay before it is sold. It must be mentioned here that although there are buildings belonging to the Forest Service inside the forest of Elatia which have been constructed in order that felling may be performed during the winter months, this has not taken place so far. The infestation in Pinus sylvestris stands is so extensive that quite often it is extremely difficult to locate a piece of completely healthy timber. The economic implications of this situation are apparent: after waiting for such a long time (100 years and more) till the trees are of tradable dimensions, the timber loses a great part of its value shortly after it has been cut (Tsoumis and Voulgaridis 1978). The problem is approached from four viewpoints: a) Infestation of round wood inside the harvest area, b) Infestation of round wood placed on platforms on the skidroad c) Infestation spread rate in round wood in relation to the time of felling, and d) Impact of blue-stain infestation on timber quality. The results included in the present study refer to the blue-stain spread rate recorded after three experimental felling sessions, the first having been performed in July 2008, the second in November 2008 and the third in June 2009. The present research was carried out in the “Elatia” Forest, Prefecture of Drama (Fig. 1), at an altitude of approximately 1500-1580 m. More specifically, the experimental surfaces of Picea abies and Pinus sylvestris were placed in the location called ‘Phylakion 109’, forest section 140D and had the same aspect (North). Six healthy trees - two from each species - were cut in each 242 Vol. 57 (2): 2012 felling session, making up a total of 12 trees (6 Picea abies and 6 Pinus sylvestris – See Tab. 1). Each tree trunk was further cut into 4 one-meter-long logs that did not vary considerably in mean diameter and bark thickness. In each felling session 4 logs from each species were placed inside the harvest area and 4 on the skidroad on special platforms (Fig. 2) thus making up a total of 12 logs inside the harvest area and 12 logs on the skidroad platforms. In each of the above locations and in each felling operation, out of the four logs one was debarked (Fig. 3). In all cases, the lower part of the trunk, measuring 1 – 1.5 m in length, was not used in order to ensure a greater degree of homogeneity in the material (bearing in mind that this tree part is of greater diameter and bark thickness). In total, 12 trees were felled and 48 logs were cut, of which 36 were unpeeled and 12 debarked. Fig. 1: The Elatia Forest N-E of the Greek- Fig. 2: Arrangement of Picea abies and Pinus Bulgarian border. sylvestris experimental logs in research sites: on skidroad A) and in logging area B). In each location three logs are with the bark on and one log is debarked. Logs located on skidroad are placed on special platforms A). All logs are 1 m. long. Logs placed in one single location come from the same tree The 48 logs of the study were transported to the research sites (on the skidroad on top of special platforms and in forest clearings) where they were stacked in the manner shown in Fig. 3, which presents the treatment adopted as well (e.g. whether they were debarked or not). Observations of blue-stain spread were performed every month and lasted for four months as far as the first felling session is concerned, seven for the second felling session and four months for the third (total collection of data lasted for 15 months). More specifically, both cross-sections performed on the logs were photographed. At the end of the experimental period corresponding to each felling session (that is, 4 months for the first, 7 for the second and 4 for the third) all logs were cut mid-length and assessed for blue stain in this area as well. The percentage of infestation of each cross-section was measured with the use of Autocad software. 243 WOOD RESEARCH Tab. 1: Characteristics of experimental logs. Log groups: Pic. abies-Sk. road.: Picea abies on skidroad, Pic. abies-Stand: Picea abies in logging area, P. sylv.-Sk. road: Pinus sylvestris on skidroad, P. sylv: Pinus sylvestris in logging area. Treatment: pl./ (logs on platforms), debark: debarked log, bark on: log with the bark on, 1,2,3,4: number of logs in a single group, SE: south-east aspect of cross-section, NW: north-west aspect of cross-section. RESULTS AND DISCUSSION Results are included in Figs. 3 and 4, which show the evolution of blue-stain contamination at the log ends of Picea abies (Fig. 3) and Pinus sylvestris (Fig. 4) in the months of August, September, October, and November for the logs produced in the first felling session, December, January, February, March, April, May, and June for the second felling session and July, August, September and October for the third, observations being carried out every 30 days. In addition, the above figures show for each species the blue-stain spread in the logs placed on the skidroad platforms as well as in those that were placed inside the harvest area. Tab. 2, columns 3.1, 3.2, and 3.3, presents the evolution of blue-stain contamination in the middle of the logs (observations after 120, 210 and 120 days respectively for the first, the second and the third felling session.) Blue-stain spread in Picea abies cut in the first felling session was relatively small, especially in the logs placed on the skidroad platforms. The maximum increase recorded for the first felling 244 Vol. 57 (2): 2012 session reached 32.6 % and was observed after 90 days (end of October 2008).