Zbornik gozdarstva in lesarstva 80 (2006), s. 97 - 109 INTRODUCTION UVOD Tree growth is limited to localized regions of specialized tissues, called meristems (e.g. KOZLOWSKI / PALLARDY 1997b). Their activity and hence growth is in temperate and boreal climatic zones restricted to the period of warm months (KOZLOWSKI 1971; LARSON 1994; KOZLOWSKI / PAL- LARDY 1997a; DESLAURIERS / MORIN 2005). Enviro- nmental conditions play an important role in controlling tree growth, but precise relationship between climate and begin- GDK: 56+111.8:174.7 Picea abies(497.12*02 Pokljuka)(045)=20 Prispelo / Recived: 24. 08. 2006 Izvirni znanstveni članek Sprejeto / Accepted: 24. 10. 2006 Original scientifi c paper USE OF DIFFERENT GROWTH PARAMATERS OF NORWAY SPRUCE (Picea abies (L.) KARST.) TO STUDY TREE RESPONSE TO CLIMATE Tom LEVANIČ1, R. JALKANEN2, J. GRIČAR3, M. GAGEN4, Primož OVEN5 Abstract In the paper, potential analysis of various growth parameters of Norway spruce are introduced at the macro and micro levels. Dendroecological measurements give information as to xylem growth ring widths, their density and content of stable isotopes in the xylem growth rings. Needle trace method of the terminal annual shoot allows retrospective view into needle density of the terminal annual shoot and consequently reconstruction of the several parameters linked to the needles and air pollution. Using pinning method, it is possible to follow intra-annual dynamics of the radial growth of trees at the cellular level and furthermore investigate the effect of climatic factors on cambial activity. Key words: Norway spruce, Picea abies, multiproxy analysis, Pokljuka, Slovenia, dendroecology, pinning, needle trace method UPORABNOST RAZLIČNIH RASTNIH PARAMETROV NAVADNE SMREKE (Picea abies (L.) KARST.) ZA ŠTUDIJ ODZIVA DREVES NA KLIMO Izvleček V prispevku so predstavljene možnosti analize različnih rastnih parametrov navadne smreke na makro in mikro nivoju. Dendroekološke meritve nam dajo informacijo o širinah branik, gostotah branik in vsebnosti stabilnih izotopov ogljika v njih na nivoju branike ter jih retrospektivno povezati z različnimi okoljskimi informacijami. Metoda preučevanja sledi iglic terminalnega poganjka nam omogoča rekonstrukcijo gostote iglic terminalnega poganjka in posledično analizo številnih parametrov, vezanih na iglice in zračno polucijo. Z metodo pinning je mogoče slediti intraanualno dinamiko debelinske rasti drevesa na celičnem nivoju in nadalje raziskati vpliv klimatskih dejavnikov na kambijevo aktivnost. Ključne besede: navadna smreka, Picea abies, multiproksistična analiza, Pokljuka, dendroekologija, metoda pinning, metoda sledi iglic 1 doc.dr. T. L., Gozdarski inštitut Slovenije, Oddelek za rast in gojenje gozda, Večna pot 2, SI-1000 Ljubljana, SLO 2 dr. R. J., METLA Rovaniemi Research Unit, Eteläranta 55, FIN-96300 Rovaniemi, FINLAND 3 dr. J. G., ., Gozdarski inštitut Slovenije, Oddelek za rast in gojenje gozda, Večna pot 2, SI-1000 Ljubljana, SLO 4 dr. M.G., University of Swansea, Department of Geography, Singleton park, Swansea, SA2 8PP United Kingdom 5 prof.dr. P. O., Biotehniška fakulteta, Oddelek za lesarstvo, Rožna dolina c. VIII/34, SI-1001 Ljubljana, SLO ning, culmination and termination of growth is only fragmen- tary understood. At the time of increasing threats of global climatic changes, which will not avoid forests, relevancy of this knowledge is increasing (KAJFEŽ-BOGATAJ / BER- GANT 2005a, b). It is a tool for understanding past climatic and environmental events as a basis for prediction of develo- pment of forest ecosystems and forest-based industries in the future. Closely related goal of dendroclimatology is to identify the climate signal in tree-ring series and to use them to recon- struct past climate variation from several hundred to several thousand-year-long tree-ring chronologies (FRITTS 1976; SCHWEINGRUBER 1989). As opposed to traditional defi niti- on, the number of tree-growth variables employed in contem- porary dendroclimatological studies is increasing. Similarly, needle-related time series (JALKANEN / KURKELA / AAL- TO 2002) are very useful in climate reconstructions, and poten- tially useful in reconstruction of carbon storage. Tree-growth and needle-related parameters are referred to as proxies. The seasonal dynamics of cambial activity and corre- sponding cell differentiation in trees can be followed by a variety of different methods, such as pinning, micro-coring, automatic dendrometers, sampling of intact blocks of tissu- es, etc. (WHITMORE / ZAHNER 1966; WOLTER 1968; WODZICKI 1971; SKENE 1972; ANTONOVA / STASO- VA 1993, 1997; BÄUCKER / BUES / VOGEL 1998; FOR- STER / SCHWEINGRUBER / DENNELER 2000; GINDL / GRABNER 2000; SCHMITT / MOLLER / ECKSTEIN 2000; DESLAURIERS et al. 2003; MÄKINEN / NÖJD / SARANPAA 2003; SCHMITT / JALKANEN / ECKSTEIN 2004; DESLAURIERS / MORIN 2005). The pinning method uses the ability of the cambium and its youngest derivatives to respond to a minute mechanical injury without affecting the physiological integrity of a tree (WOLTER 1968; SHIGO 1986). Pin insertion into the cambium causes minute wound reactions, which defi ne the increment reached by the time of pinning. Therefore, precise knowledge of the species-related anatomical response to wounding is necessary when applying this technique (WOLTER 1968; YOSHIMURA / ITOH / SHI- MAJI 1981; KURODA / SHIMAJI 1983, 1984b, a; KURODA / KIYONO 1997; SCHMITT / MOLLER / ECKSTEIN 2000; MÄKINEN / NÖJD / SARANPAA 2003; SCHMITT / JAL- KANEN / ECKSTEIN 2004). Apart from long chronologies, investigation of annual dynamics of wood formation received only little attention until last decade. Environmental factors, regulating wood formation in particular growing season are still not well understood and hence misleadingly interpreted in classical dendroclimatological studies. As a part of an EU project (Predicting Impacts on Natural Ecotones, PINE, of the 5th framework program), multiproxy approach was applied at three sites of spruce forests in Slo- venia and Austria in the years 2002–2005. This paper shortly introduces the applied methods and techniques in order to produce inter- and intra-annual chronologies of various stem- originated parameters of a single Norway spruce (Picea abies (L.) Karst.) tree from the experimental site Pokljuka, Slovenia. The purpose of the information gathered on only one tree was to demonstrate the possibilities of extracting different proxy data and use of them in further research. Results presented in this article are introductory rather than conclusive. MATERIAL AND METHODS MATERIAL IN METODE EXPERIMENTAL SITE AND TREE Five healthy Norway spruce (Picea abies (L.) Karst.) tre- es from Pokljuka (46º21’N, 13º59’E, elevation 1260-1290 m a.s.l.), northern Slovenia, were selected for multiproxy den- droclimatological studies in spring 2002 (Fig. 1). All trees were about 70 years old and approximately 35 m high. They were selected according to the following criteria: tree crown should be in the stand canopy and normally developed (social position 2 after Kraft’s classifi cation), stem should be without any visible mechanical damage, whereas root system should be more or less intact (at least 10m from any skidding trails). The site and the stand were considered to be moist, relati- vely cool in the summer and well suited for spruce growth. Soil on research plot is high in organic contents and shallow to medium deep (Rendzic Leptosol according to WRB 1998 soil classifi cation). The experimental stand represented an average natural spruce forest of that age in stand density and silvicultural status including thinning. Ground vegetation of the site was scarce partly due to very dense crowns and partly due to the infl uence of the repeated cattle grazing. In May 2003, the sample trees were felled and sectioned for several purposes described below. Examples of all the described proxies in the present study are illustrated and discussed based on one sample tree (tree No. 4). The test tree was 26.9 m tall and 26 cm in diameter at breast height. PROXIES INVESTIGATED Here, the introduced parameters of the tree No. 4 are: tree-ring width (TRW), maximum late-wood density (MxD), height increment (HI), stable carbon isotopes (ISO), sum- 98 Zbornik gozdarstva in lesarstva, 80 mer needle retention (NRS), needle age (AGE), needle shed (SHED), needle production (PROD), needle pool (POOL), and needle density (DENS), and intra-annual wood forma- tion (WF). Depending on the type of analysis, we sent sam- ples to different laboratories: tree-ring width measurements were done at the Slovenian Forestry Institute, densitometry at WSL Birmensdorf, Switzerland and isotopic composition at the Department of Geography, University of Swansea, United Kingdom. Height increments and needle proxies were produ- ced in Metla, Rovaniemi. The Department of Wood Science and Technology, University of Ljubljana analysed the intra- annual radial growth. MEASUREMENTS OF TREE-RING WIDTHS For tree ring studies, 5 mm thick cores and radial sections from stem discs were used. All samples were prepared ac- cording to the standard dendrochronological procedures well described in the literature (FRITTS 1976; SCHWEINGRU- BER 1989). Tree-ring widths were measured on a measuring table LINTAB (www.rinntech.com), equipped with PAST-4 dendrochronological software (www.sciem.com). Tree-ring series were crosschecked, verifi ed and synchronized against each other. ANALYSIS OF WOOD DENSITY For tree-ring density, WSL team used system provided by Walesch electronics (www.walesch.ch). Cores, 12 mm in thickness, or radial sections of stem discs were taken for this type of analysis. Samples were prepared on a double bladed saw and resin extracted with Soxlet apparatus (SCHWEIN- GRUBER et al. 1978a). X-ray images were processed accor- ding to the procedures developed at their own laboratory (see SCHWEINGRUBER et al. 1978b). Tree-ring density measu- rements gave a comprehensive set of different tree ring fea- tures – minimum density, maximum density, maximum late- wood density, minimum earlywood density, average tree-ring density, proportion of early- and latewood and fi nally tree-ring width (see Figure 2). (SCHWEINGRUBER et al. 1978b) Levanič, T., Jalkanen, R., Gričar, J., Gagen, M., Oven, P.: Use of different growth paramaters of Norway spruce ... 99 Fig. 1: Location of the plot on the Pokljuka plateau Slika 1: Lokacija raziskovalne ploskve Pokljuka (Slovenija) CARBON ISOTOPE COMPOSITION Both cores and discs were sampled for stable carbon is- otope analysis. The complete length (radius) of each core or disk was sampled. Each ring was located on the sample and separated using a very sharp chisel and razor blade. We did not separate earlywood from latewood considering that our objective was to quantify carbon isotope discrimination during the entire period of wood formation, therefore both early and latewood were used. We isolated α-cellulose from the slivers of wood through a series of chemical steps, using a modifi ed Loader batch processing technique (see LOADER et al. 1997 for details). Cellulose δ13C was analysed using Europa 20/20 isoto- pe ratio mass spectrometer coupled to an elemental analyser. Processing to cellulose and δ13C analyses were carried out at the Department of Geography, University of Swansea, Brita- in. Nitrous oxide was removed by gas chromatography and corrections for 17O (CRAIG 1954) were done for all runs. Pre- cision calculation was done on a total of 303 tree ring samples at Pokljuka and overall precision for δ13C was 0.01‰ (n=303). Stable carbon isotope ratio was calculated using equation 1. (1) The 13C/12C standard used at University of Swansea is PDB standard (Pee Dee Belemnite from an internal calcite structu- re from a fossil Belemnitella americana from the Cretaceous Pee Dee Formation in South Carolina, USA). HEIGHT INCREMENT AND NEEDLE TRACE ANALYSIS Height increment was measured as the lengths of the an- nual length of the terminal shoot. The dating of the annual terminal shoots was controlled with the counting of tree rings in the discs originating in irregular distanced along the stem. Once the annual terminal shoots were determined, a 15-cm- long piece was sawn in each annual shoot for needle-trace Fig. 2: Different parameters obtained in densitometric analysis (source: COOK / KAIRIUKSTIS 1989) Slika 2: Nabor možnih spremenljivk, ki jih dobimo pri densitometrični analizi (vir: COOK / KAIRIUKSTIS 1989) 100 Zbornik gozdarstva in lesarstva, 80 analysis according to Aalto and Jalkanen (1998). The Nee- dle Trace Method (NTM) (see KURKELA / JALKANEN 1990; JALKANEN / KURKELA / AALTO 2002) revealed retrospectively the needle and growth history of the analysed trees. PINNING AND INTRA-ANNUAL ANALYSIS OF WOOD FORMATION Selected tree was pinned weekly, from May 10th until Sep- tember 13th in the year 2002, and experiment was made accor- ding to the procedure described below. Six pinning holes were set in a semi-helical pattern along the stem of the tree at the same experimental date, using a needle that was 1.75 mm at its thickest part. The holes were marked and numbered. After the 2002 growing season, the pinned tree was felled and samples containing wound tissues were removed, fi xed in FEA (forma- lin-ethanol-acetic acid solution) and dehydrated in a graded series of ethanol (30%, 50% and 70%). Transverse sections of approximately 25 μm in thickness were prepared, using a Leica SM2000R microtome. They were stained with safranine and astra blue and mounted in Euparal. Microscopical observati- ons and measurements were carried out with a Nikon Eclipse E800 light microscope and Lucia G 4.8 image analysis system. We counted the number of the cells and measured the width of the xylem increment reached from the time of pinning in at least three radial fi les of tracheids. In addition, we counted the number of cells and measured the width of the xylem growth rings formed during the 2002 season on the extreme sides of the cross-sections that were free of a wound response. For description of the radial growth of tree No.4 at Poklju- ka in the growing season 2002, the Gompertz function was used. Seasonal dynamics of wood formation follow S-shape of growth that show two different development phases: a po- sitive exponential phase followed by a relative growth rate decrease (ROSSI / DESLAURIERS / MORIN 2003). Among different sigmoid growth models, the Gompertz equation seems the more appropriate for its asymmetrical shape. The infl ection point in Gompertz equation is reached at a lower level, resulting in a shorter positive exponential phase (ROS- SI / DESLAURIERS / MORIN 2003; KOTAR 2005). The Gompertz function can be written as growth function: where y = cumulative of increment is expressed in cells/width, t = day of the year, A = upper asymptote of the maximum number of cells/width, β = x-axis placement parameter, κ = rate of change parameter or increment function where y = weekly increment is expressed in cells/width RESULTS AND DISCUSSION REZULTATI IN DISKUSIJA TREE-RING PROXIES (TRW, HI, MXD, ISO) TRW and HI parameters are relatively easy and cost effec- tive to measure. TRW measurements are based on cores and stem discs, while height increments are part of NTM analysis (explained later in this article) and tree need to be cut down to get this information. In both parameters we can observe typical decreasing trend of both tree-ring widths and height increments in relati- on to tree age / calendar year. Correlation between TRW and HI is fairly high (r=0.78 ***), however, in some years we can observe disagreements (e.g. 1993, 2001). Since both proxies are correlated, one can be replaced by the other in studies that need multiple regression approach. Decreasing trend of both parameters can be removed with appropriate standardisation technique (Figure 3). MxD is a parameter which correlates well with summer temperature and precipitation. It can also be observed that there is no age-related trend, however, troublesome with this parameter is in its weak sensitivity since its variation is usu- ally very small. This parameter is more or less independent from tree-ring widths (r=-0.205 NS), height increment measu- rements (r=0.067 NS) and in weak correlation with measure- ment of stable carbon isotope content in tree rings (r=0.279*). Therefore, it can be used as one of the independent variables in multiple regressions (Figure 4). Levanič, T., Jalkanen, R., Gričar, J., Gagen, M., Oven, P.: Use of different growth paramaters of Norway spruce ... 101 ISO is a parameter, with a very clear physiological back- ground and is directly connected with transpiration, carbon storage and water stress (FARQUHAR / O’LEARY / BER- RY 1982; FARQUHAR / EHLERINGER / HUBICK 1989). Generally we can expect that lower values are indicating less stress (less “heavier” δ13C is stored in plant body), while hi- gher values are connected with water stress. Expected value range is between -20‰ and -30‰ for C3 plants (all trees used in dendrochronology). Parameter does not correlate with tree- ring widths and height increments but slightly with maximum latewood density. Age trend is generally not present, so the- re is no need of standardisation. As such it can be used as an independent parameter in multiple regressions and also as an independent climate proxy (Figure 5). THE NEEDLE PROXIES Needle retention (Figure 6a), the Needle Trace Method (NTM) is able to produce needle-retention levels both for summer and winter. In this connection, summer needle-reten- tion chronology (NRS) is introduced. Needle retention descri- bes how many needle sets are present in the main stem at any Fig. 3: Tree-ring widths and height increment, spruce No. 4, Pokljuka, Slovenia Slika 3: Širine branik in višinski prirastki smreke št. 4 na Pokljuki, Slovenija Fig. 4: Maximum late-wood density, spruce No. 4, Pokljuka, Slovenia Slika 4: Maksimalna gostota kasnega lesa pri smreki št. 4 na Pokljuki, Slovenia 102 Zbornik gozdarstva in lesarstva, 80 Fig. 5: Stable carbon isotopes in tree rings – early- and latewood were not separated. Spruce No. 4, Pokljuka, Slovenia. Slika 5: Vsebnost stabilnega izotopa ogljika v braniko smreke št. 4 na Pokljuki, Slovenija – rani in kasni les nista bila analizi- rana ločeno. time. This is the fi rst time ever in unpolluted environments to launch a 65-year-long NRS chronology for spruce. Thus it is not known what the pattern should be. However, grown in more or less ‘normal’ conditions, this spruce may well indica- te the normal NRS pattern for Norway spruce (for spruce in a polluted environment, see SANDER / ECKSTEIN 2001). In the fi rst thirty years, NRS is increasing, then culminating and gradually declining. The pattern is similar to Scots pine (JALKANEN / AALTO / KURKELA 1995). Also the medi- um resolution variation seems to be the same in both species. Spruce indicates a 4 to 5-year period between the maximum within the whole-tree pattern. NRS pattern indicates some di- sturbances in spruce development in the early 1970s and at the end of 1980s. Highest mean NRS values up to 7.5 needle sets are met in the late 1960s. Long-term mean NRS for tree 4 was 6.5 needle sets. Needle age (Figure 6b) is able to produce chronologies for minimum, mean and maximum needle age of each needle-age class. Separately, the NTM calculates the average age of the attached needles at any time. In this connection, mean nee- dle age (AGE) is introduced. Its general pattern of long-term variation is the same as for NRS; AGE is fi rst increasing and then gradually decreasing. In fact, general patterns of AGE and NRS have to follow each other as needle age largely determines the number of attached needle sets. However, as AGE describes annual variation of each needle-age class, it has a different use in the description of the tree’s canopy or health history. As compared to NRS, mean AGE varies a lot. As the mean AGE of the entire tree number 4 was 6.0 ye- ars, annual maxima and minima were 7.4…7.3 in 1976, 1962 and 1951, and 4.3…5.2 in 1940, 1984 and 1960, respectively. Longest-living needle, born in 1954, was 11 years old. It is evident that AGE describes variations in growth conditions much better than NRS. Needle shed (Figure 6c) - opposite to the previous para- meters, the general pattern for needle shed (SHED) is fi rst decreasing and in latest decades increasing. Logically, when needle age increases, dying of needles are delayed, thus re- sulting in lowered SHED values. Long-term average in ideal growing conditions should theoretically be one because on average one needle set is lost and one new is born every year. In tree No. 4 long-term mean SHED was 1.0, indicating that the tree is in balance and that no extra strong outside fac- tor is infl uencing needle longevity. Minimum and maximum SHED, 0.2 and 1.6 needle sets, was met in 1952 and 1990, and in 1939, 1973, 1972 and 1988, respectively. Needle production (Figure 6d) - annual needle production (PROD) reveals the number of needles produced in the leader shoot. As compared to pines with short shoots attached in the long shoot, needles are directly attached to the long shoot in Levanič, T., Jalkanen, R., Gričar, J., Gagen, M., Oven, P.: Use of different growth paramaters of Norway spruce ... 103 spruce and fi rs. So the long-term mean PROD in the exam- ple tree, 441 needles, would result in a value of 220 short shoots in a 2-needle pine. At high latitudes PROD for Scots pine is below 100 to increase to over 200 in Estonia (PENSA / JALKANEN 2005), reaching nearly the 300-level in more southern latitudes with a vigorous growth (JALKANEN / LE- VANIČ 2001). In spruce, needles are produced particularly in the early years of the tree and clearly less towards the middle age. Whether the slight increase in the pattern of PROD du- ring the last 15 to 20 years is typical for spruce, is of silvi- cultural origin or is maybe related to climate warming, needs further studies. Needle pool (Figure 6e) - as shown above, spruce needles are on average six years old when they die. This means that, on average, there are attached needles from at least six needle- age classes. The number of needles in different annual shoots is called needle pool (POOL). In the Pokljuka case, POOL decreases continuously and rather linearly in time. Pool va- lues of above 4000 needles in the fi rst decades were dropped to about half towards the 1990s. So far, no long-term POOL chronologies of any species in ‘normal’ conditions exist to indicate normal POOL behaviour. Needle density (Figure 6f) - the number of needles of the long shoot per centimetre gives needle density (DENS). To produce DENS the NTM uses needle production and length of the sample, from which the needle traces are counted and which originates from the middle of the annual shoot (JAL- KANEN / AALTO / KURKELA 1998). Here DENS of spruce increases in time, starting from a level of 13 needles cm–1 in the 1930s and ending to a general level of 18 needles cm–1. DENS is not the same from year to year, and in fact DENS is a very good parameter to describe disturbances in tree’s history. Here the years of 1982–1983, and 2001 represent very well some unknown disturbances, during which DENS increases over to 30 needles cm–1. However, the found disturbances can occur just in this tree, being e.g. a breakage of the leader sho- ot. Therefore, to get reliable density history at stand level, more trees are needed. Furthermore, annual leader shoot is much more vulnerable to disturbances than tree ring formati- on; however, they both react to short and long summers. Due to different structures of needle attachments in pines, Scots pine normally has between 6 to 8 short shoots per long shoot centimetre (JALKANEN / AALTO / KURKELA 1998; SAL- a) b) 104 Zbornik gozdarstva in lesarstva, 80 c) d) e) f) Fig. 6: Needle proxies a. summer needle retention, b. needle age, c. needle shed, d. needle production, e. needle pool, and f. needle density. Analysed spruce No. 4 at Pokljuka, Slovenia. Slika 6: Različne spremenljivke, vezane na sledove iglic glavnega poganjka, ki smo jih dobili s pomočjo NTM metode: a. pole- tno zadrževanje iglic, b. starost iglic, c. letni odmet iglic, d. prirast iglic, e. zaloga iglic in f. gostota iglic. Analizirano drevo št. 4 na Pokljuki. Levanič, T., Jalkanen, R., Gričar, J., Gagen, M., Oven, P.: Use of different growth paramaters of Norway spruce ... 105 MINEN / JALKANEN 2006), disturbances resulting clearly higher values (FERRETTI et al. 2002) INTRA-ANNUAL WOOD FORMATION Investigated spruce No. 4 started with cambial activity between 17-24 May 2002. We defi ned the onset of the wood formation by distinguishing between cambial cells and radi- ally expanding xylem cells in the callus that were found next to the xylem growth ring 2001. Radial dimensions of the cells in postcambial growth were larger compared to the cambi- al ones. Time for the beginning of late wood formation was defi ned qualitatively and corresponds to week 5-12 Jul 2002. At that time, the radial dimensions of the tracheids narrowed and thickness of the cell walls increased. Production of new cells in the cambium ended in the week between 26 Jul-2 Aug 2002. We determined the cessation of the regular cambial activity when the number of the cells of the current xylem increment 2002 coincided with the number of the cells in the intact part of the same growth ring aside the callus. Further- more, the xylem cells in postcambial growth were not present in the callus and the latest formed late wood tracheids below the callus were in the fi nal stages of differentiation (secondary wall formation and lignifi cation). Maximal weekly increment was detected in the 169th day of the year, irrespective if expressed in width or cell number increase. This is in accordance with Rossi et al. (2006), who reported a maximum growth rate for various tree species in temperate and boreal climatic zones around the summer sol- stice (172 day of the year) - the time of maximum day length, and not during the warmest period of the year, as previously suggested. With measurements of the xylem increments and counting the number of cells, two types of information were obtained. Cell number gives information on cell production capacity of the cambium on the xylem side. On the other hand, increase of width of xylem increment contains the data of both; the number of xylem cells produced in the cambium, as well as the increase of radial diameter of cells during postcambial growth. In this context, wider earlywood cells formed in the fi rst part of the growing season contribute more to the fi nal width of the xylem growth increment. This could explain the differences in the shape of both growth functions (Figures 7, 8). It has to be stated that deposition of the multilayered se- condary cell wall and lignifi cation do not contribute to the increase of xylem increment, but only to the accumulation of the biomass into the cell walls. Fig. 7: Intra-annual dynamics of wood formation expressed in cell number formed by the pinning date in experimental tree No. 4 at Pokljuka in the season 2002. Slika 7: Sezonska dinamika nastajanja ksilemske branike, izražena kot število celic, nastalih do dneva vboda z iglo pri drevesu št. 4 (Pokljuka) v rastni sezoni 2002. 106 Zbornik gozdarstva in lesarstva, 80 CONCLUSION Different proxy data obtained from a single Norway spru- ce show that this kind of information is useful in ecological, physiological and climatological studies. Tree ring widths, height increments, maximum latewood densities and stable carbon isotope contents are information directly connected with different environmental and climatic data. Therefore they can be used to analyse tree’s response to climate and environment (including response to extreme events) and as a so called “proxy data” in reconstruction of past environmental and climatic events for the periods before instrumental data. Different information regarding needles, their longevity and density could be obtained through the so called “Needle Trace Method”. This method is using needle traces of termi- nal shoot to reconstruct various needle parameters and, further on, to reconstruct environmental or climatic factors that in- fl uence height growth, needle production, needle longevity, needle shed, etc. This is the only method that is capable to reconstruct any of the needle parameters back in time and it proved to be useful in all kind of ecological and climatologi- cal research dealing with conifers (especially pine and spru- ce). The method itself is more precisely presented in Kurkela and Jalkanen (1990) and in Jalkanen et al.(2002). Intra-annual studies of cambial activity give data of wood formation at high resolution. This information is very useful in standard dendroclimatological studies. For correlations of temperatures of the current year and the widths of the xylem growth ring, the knowledge on the length of the growing sea- son is crucial. Otherwise, high correlations of the September temperatures and the xylem ring widths are meaningless since trees from temperate and climatic boreal zone at this time of the year do not grow anymore. POVZETEK V pričujočem prispevku predstavljamo metode in tehnike, ki smo jih uporabili za sestavo dolgih časovnih vrst podatkov o rasti debla smreke (Picea abies (L.) Karst.). Tako prido- bljene informacije lahko koristno uporabimo pri modeliranju odnosa med rastjo in klimo (še posebej v razmerah globalne- ga spreminjanja klime). Podatki, ki jih predstavljamo v tem prispevku, so bili zbrani za potrebe evropskega raziskoval- nega projekta PINE – Predicting Impact on Natural Ecotone (5. okvirni program EU) na Pokljuki in na Sorškem polju v Sloveniji. V projektu PINE smo sicer zbirali podatke na ve- čjem številu ploskev na transektu sever-jug od severa Finske do Slovenije na jugu. Fig. 8: Intra-annual dynamics of wood formation expressed as width formed by the pinning date in experimental tree No. 4 at Pokljuka in the season 2002. Slika 8: Sezonska dinamika nastajanja ksilemske branike, izražena kot širina prirastka, ki je nastal do dneva vboda z iglo pri drevesu št. 4 (Pokljuka) v rastni sezoni 2002. Levanič, T., Jalkanen, R., Gričar, J., Gagen, M., Oven, P.: Use of different growth paramaters of Norway spruce ... 107 TRW / ISO / HI / MxD Spremenljivke o širini branike (TRW), maksimalni gosto- ti kasnega lesa (MxD), vsebnosti stabilnega izotopa ogljika (ISO) in višinskega prirastka (HI) so podatki, ki nam govori- jo o odzivu drevesa na okoljske spremembe. Podatek o širini branike je izmed vseh štirih spremenljivk najlaže pridobiti, podatek o vsebnosti stabilnega izotopa ogljika pa najteže. V nasprotju z drugimi tremi podatki je podatek o višinskem pri- rastku, kjer merimo dejanske višinske prirastke glavnega po- ganjka, mogoče pridobiti samo s posekom drevesa in zatorej sodi med destruktivne vzorčne metode. Drugi trije podatki se lahko pridobijo iz debelih, 12 mm izvrtkov. NTM Podatke o iglicah smo izračunali s pomočjo t.i. metode NTM (ang. »Needle Trace Method«), to je metoda, ki upo- rablja sledi iglic glavnega poganjka za rekonstrukcijo oigli- čenosti glavnega poganjka. Iz tega osnovnega podatka pa lahko izračunamo množico različnih izvedenih spremenljivk, ki nam defi nirajo gostoto iglic na enoto mero, letno produk- cijo in abscisijo iglic, kronološko spreminjanje števila iglic glavnega poganjka, ipd. Metoda NTM je edina, ki uporablja numerične podatke o iglicah glavnega poganjka in prek tega sklepa na klimatske / okoljske razmere, v katerih so iglice na- stajale. Metoda je uporabna predvsem na smreki in boru ter je natančneje predstavljena v delu Kurkele in Jalkanena (1990) in Jalkanena s sodelavci (2002). Sezonska dinamika rasti ksilemske branike (WF) Z raziskavami sezonske dinamike kambijeve aktivnosti v teku enega leta dobimo visokoločljive podatke o nastajanju ksilemske branike. Z njimi je mogoče dopolniti in nadgraditi spoznanja o rasti drevesa, ki izvirajo iz klasičnih večletnih kronologij. Rezultati kažejo, da je poznavanje začetka in kon- ca kambijeve aktivnosti za dendroklimatološke študije ključ- no. V tem smislu so npr. korelacije septembrskih temperatur tekočega leta in širine branik nesmiselne, četudi so korelacije visoko značilne, saj drevesa iz zmernega in borealnega kli- matskega pasu največkrat v tem mesecu ne priraščajo več, ugodnim temperaturam navkljub. 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