Jozef Pajtík

Possible causes of the recent rapid increase in the radial increment of silver fir in the Western Carpathians

Silver fir is one of the most productive and ecologically valuable native European tree species, however, it has been experiencing decline which has periodically occurred over its natural range. This paper aims to investigate the recent climate-growth relationships of silver fir (Abies alba Mill.) and its temporal change along the course of its life. Long-term tree-ring databases, as well as records on climate, atmospheric SO2, NO3 and acid concentrations from four different regions in the Western Carpathians were used. The results provide clear evidence of significant increase of silver firs radial increment over the entire Western Carpathian area since 1970-1980. The results indicated that the most probable factors behind the rapid recovery of tree radial increment were reductions in emissions of NO3 and SO2, alongside a significant increase in mean June, July and April temperatures.

Individual biomass factors for beech, oak and pine in Slovakia: a comparative study in young naturally regenerated stands

Biomass conversion and expansion factors (BCEF) which convert tree stem volume to whole tree biomass and biomass allocation patterns in young trees were studied in order to estimate tree and stand biomass in naturally regenerated forests. European beech (Fagus sylvatica L.), Sessile oak (Quercus petraea (Mattuschka) Liebl.) and Scots pine (Pinus sylvestris L.) stands were compared. Seven forest stands of each species were chosen to cover their natural distribution in Slovakia. Species-specific BCEF are presented, generally showing a steep decrease in all species in the smallest trees, with the only exception in the case of branch BCEF in beech which grows with increasing tree size. The values of BCEF for all tree compartments stabilise in all species once trees reach about 60–70-mm diameter at base. As they grow larger, all species increase their allocation to stem and branches, while decreasing the relative growth of roots and foliage. There are, however, clear differences between species and also between broadleaves and conifers in biomass allocation. This research shows that species-specific coefficients must be used if we are to reduce uncertainties in estimates of carbon stock changes by afforestation and reforestation activities.

THE RESEARCH SITE VRCHSLATINA - AN EXPERIMENTAL DESIGN AND THE MAIN AIMS

Abstract The research site “Vrchslatina” was established in the spring of 2009 with the aim of studying production processes and the structure of net primary productivity in young forest stands. The beech and spruce stands grown at the site were selected because they originated from natural regeneration and are nearly of the same age. In 2009, we established 5 research plots in each stand with the aim of measuring basic tree characteristics. Moreover, we excavated entire trees to construct allometric relations for the specific tree compartments. In the consecutive years (2010, 2011 and 2012), we also included grass communities dominated by Calamagrostis epigejos in our studies. Besides studying production processes of all tree compartments (i.e. for trees: foliages, branches, stem, coarse and fine roots, for grasses and herbs: below- and above-ground parts), we monitored several atmospheric characteristics, followed by soil characteristics and eventually added a measurement of soil respiration. The results indicated that forest stands (even though they were in their initial growth stages) sequestrated much more carbon than the grass communities. Moreover, we proved the considerable influence of climatic conditions (especially the sum of precipitation) in the particular years for net primary productivity.

MODELLING EFFECTS OF WEATHER CONDITION ON SEASONAL DYNAMICS OF THE STEM CIRCUMFERENCE INCREMENT IN A MIXED STAND OF NORWAY SPRUCE AND EUROPEAN BEECH

Abstract This study was aimed at modelling seasonal variation of stem circumference increments in a mixed stand composed of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.). Moreover, we focused on the quantification of the main climatic factors governing the increments. The measurements were performed at a site established at about 970 m a.s.l. from the locality of Vrchslatina (Central Slovakia). Data was collected from 20 European beech trees and 20 Norway spruce trees, from 2009 to 2012. The increments (measured at 130 cm above ground level) were recorded circa biweekly using manual band dendrometers. Lognormal function was used for the modelling of the seasonal trend of the increments. Hourly-based records of climatic variables such as air temperature, precipitation, and derived vapour pressure deficit were used for the modelling. The effect of climatic parameters on the seasonal variations of the increments was tested by including them directly into the lognormal function. The results suggest that while the sum of precipitation was a better predicting factor for spruce, the mean temperature was the better predictor for beech. In addition, both temperature and vapour pressure deficits also had an effect on the increments of spruce, but these parameters did not contribute to the explanation of the variability of increments for beech. Overall, the variability clarified by the final model was 72% for spruce and 78% for beech. At the same time, climatic parameters as a part of the model helped to explain 10% of the variability for the spruce (precipitations) and 3% of the variability for the beech (temperature). We also found lower variability in the increments of beech compared to spruce. This suggests that for the specific site conditions spruce are more sensitive to environmental conditions than beech Resumé Štúdia bola zameraná na modelovanie sezónnej dynamiky prírastku na obvode kmeňov stromov v zmiešanom poraste smreka obyčajného a buka lesného. Okrem toho sme sa zamerali na kvantifikáciu hlavných klimatických faktorov ovplyvňujúcich prírastok. Meranie bolo vykonané na lokalite Vrchslatina (stredné Slovensko) v nadmorskej výške 970 m n. m. Prírastky boli merané na 20 stromoch buka a 20 stromoch smreka od roku 2009 do roku 2012. Prírastok (meraný na 130 cm od úrovne terénu) bol meraný v intervale približne dva týždne pomocou manuálnych denrometrov. Lognormálna funkcia bola použitá pre modelovanie sezónneho prírastku. Záznamy o klimatických premenných, ako je teplota vzduchu, zrážky a deficit nasýtenia vodných pár boli získané z meteorologickej stanice umiest nenej priamo na lokalite. Vplyv meteorologických premenných bol testovaný ich zahrnutím priamo do lognormálnej funkcie opisujúcej sezónnu dynamiku prírastku a otestovaním odhadnutých parametrov rovníc. Výsledky ukazujú, že zrážky hrajú dôležitejšiu úlohu pre smrek, avšak teplota pre buk. Taktiež, teplota a VPD majú významný vplyv na prírastok smreka, avšak pri buku rastúcom v daných podmienkach sa ukázali ako nevýznamné. Celkovo, model vysvetlil 72 % variability prírastku smreka a 78 % buka (tab. 2). Meteorologické premenné vysvetlili 10 % variability prírastku smreka, no iba 3 % pri buku.

ABOVE-GROUND NET PRIMARY PRODUCTIVITY IN YOUNG STANDS OF BEECH AND SPRUCE

Abstract One of the expected consequences of climate change and its inherent phenomena to forest ecosystems is the gradual modification of their tree species composition (i.e. expansion of resistant species instead of less resistant ones). Climate change accompanied with increasing temperatures and a lack of precipitations may present a threat especially to spruce stands in the European part of the temperate zone. European beech is one of the possible forest tree species which might replace the potentially endangered spruce. In this paper, we observed, by using a combination of continual measurements and destructive whole-tree sampling, standing stocks of above-ground biomass (i.e. stem, branches, and foliage) and its annual net primary productivity (NPP) in naturally regenerated young stands of beech and spruce. We intentionally selected a site where the changing climate conditions are better suited to the ecological demands of beech rather than spruce (the species is dominant in the observed area). We recorded only small differences in the standing stock of stems of the beech, if based on tons per ha. However, this is in favor of spruce if based on cubic meters per ha. The largest difference between the species was found for the standing stock of foliage, spruce retained three times the biomass of beech. Also, beech allocated more carbohydrates to stem than spruce. On the other hand, we estimated nearly the same production of foliages and branches in both stands. Resumé V tejto práci sme pomocou kombinácií kontinuálnych meraní a deštruktívnych odberov vzorníkov sledovali a porovnali zásobu nadzemnej biomasy a ročnú primárnu produkciu (NPP) v prirodzene obnovených mladých porastoch buka a smreka. Na vybranej lokalite predpokladáme, že zmenené klimatické podmienky budú lepšie vyhovovať buku pred v súčasnosti prevládajúcim smrekom. Lokalita Vrchslatina sa nachádza v južnej časti Veporských vrchov v nadmorskej výške 977 m nad morom (48° 38΄ 50΄΄ N, 19° 36΄ 07΄΄ E). Priemerné ročné zrážky sa pohybujú okolo 900 mm, priemerná ročná teplota je 5,2 °C. Na sledovanej lokalite sme pozorovali odlišný priebeh rastu buka a smreka. Pri buku bola pozorovaná menšia medziročná mortalita, udržiaval sa až prehustený zápoj, v ktorom sa aj podúrovňové stromy snažili dostať do úrovne. Toto sa prejavilo na tvare kmeňov, ktoré sú tenké a vysoké. Štíhlostný koeficient sa pri stromoch so strednou hrúbkou a strednou výškou postupne zvyšoval od 1,19 do 1,40. Pri smreku dochádza k vyššej mortalite, vrastavé a podúrovňové stromy odumierajú z dôvodu nedostatku svetla. Stromy rastú viac do hrúbky, čo sa odráža aj na štíhlostnom koeficiente, ktorý bol po celé obdobie viac-menej konštantný a pohyboval sa v rozpätí 0,89 až 0,93 (tab. 1). Zásoby kmeňa sú pri smreku v jednotlivých rokoch o 3 - 10 m3.ha-1 väčšie ako pri buku (tab. 3). Po prepočítaní na sušinu je vplyvom rozdielnej objemovej hmotnosti (obr. 5) celková zásoba sušiny drevných častí (kmeň a konáre) väčšia pri buku (tab. 3). Najväčší rozdiel medzi drevinami je v zásobe asimilačných orgánov, ktorá je pri smreku viac než trojnásobná (tab. 3 a 4). Počas rastu dochádza pri obidvoch drevinách k zvyšovaniu podielu kmeňa a znižovaniu podielu asimilačných orgánov (obr. 2). Hlavný medzidruhový rozdiel pri pomerne vyrovnaných hektárových zásobách je v rozdelení nadzemnej biomasy medzi komponenty, kde buk alokuje do kmeňa viac asimilátov ako smrek (obr. 2 - 4). Pri porovnaní ročnej NPP asimilačných orgánov a konárov neboli zistené žiadne signifikantné rozdiely medzi sledovanými drevinami (obr. 6). Ukázali sme, že zásoby nadzemnej biomasy ako aj NPP buka a smreka boli v mladých plnozakmenených porastoch z prirodzeného zmladenia na danom stanovišti podobné (tab. 3 a 4).

Fine root standing stock and production in young beech and spruce stands

Abstract Fine roots (defined by a maximum diameter of 2 mm) and assimilatory organs are the compartments which rotate carbon much faster than any other tree part. We focused on quantification of fine roots in young European beech and Norway spruce trees growing under the same ecological conditions. Standing stock of fine roots was estimated by soil coring during 2009 - 2012. Fine root production was established by the in-growth bag method. Standing stock and productions of fine roots were comparable in both tree species. The quantity of fine root biomass (at a soil depth of 0 -50 cm) varied inter-annually between 6.08 and 7.41 t per ha in the beech and from 5.10 to 6.49 t per ha in the spruce stand. Annual production of fine roots (soil depth of 0 - 30 cm) was between 1.11 and 1.63 t ha-1 in beech and between 0.95 and 1.54 t.ha-1 in spruce. We found that fine root standing stock at the beginning of each growing season was related to climatic conditions in the previous year. Annual fine root production was influenced by the climatic situation of the current year. In general, a maximum standing stock of fine roots as well as a relatively slow fine root turnover is expected in young forest stands. Whereas production of fine roots prevailed over mortality in a favorable year (sufficiency of precipitations and slightly above-average temperatures in 2010), there was a reverse situation in an unfavorable year (drought episodes in 2011). We concluded that although both forest types represented contrasting turnovers of assimilatory organs (once a year and once in 5 years in beech and spruce respectively), fine root turnover rates were very similar (approx. once per four years). Resumé V ostatnom období sa výskum venuje jemným frakciám koreňových systémov drevín najmä z dôvodu ich výrazného prínosu pri obehu uhlíka v lesných ekosystémoch. Naše štúdium jemných koreňov (tieto sa definovali maximálnou hrúbkou 2 mm) sa sústredilo do bučín a smrečín v štádiu mladina, rastúcich na výskumnom objekte Vrchslatina. Pomocou dvoch metód, konkrétne pôdne vývrty (v hĺbke pôdy 0 - 50 cm) a vrastavé valce (v 0 - 30 cm) sa zis tila zásoba biomasy a nekromasy, ako aj produkcia jemných koreňov. Z týchto údajov sa odvodil ich obeh (vyjadrený ako pomer medzi produkciou a zásobou biomasy) a mortalita. Takéto sledovania sa vykonali počas štyroch rokov (2009 - 2012), pritom sa zohľadnili aj klimatické pomery, tzn. priemerné teploty vzduchu a úhrny zrážok. Výsledky poukázali na pokles zásoby biomasy jemných koreňov s hĺbkou pôdy, pritom výraznejší bol pri smreku (tzn. plytšia distribúcia jemných koreňov) než pri buku. Zásoba jemných koreňov bola mierne vyššia v bučine (priemer za roky 2009 - 2012 bol 6,57 t na ha) než v smrečine (6,01 t na ha), pritom medziročne výrazne varírovala. Ročná produkcia jemných koreňov bola veľmi podobná v obidvoch porastoch (priemer za roky 2009 - 2012 bol 1,37 t na ha za rok v bučine a 1,29 t na ha za rok v smrečine), pritom aj tu sa zistili veľké medziročné rozdiely. Kým v roku 2010 prevládala produkcia jemných koreňov nad ich mortalitou, opačná situácia bola v roku 2011. Zásoba, produkcia a mortalita jemných koreňov pravdepodobne súvisela s klimatickými pomermi v jednotlivých rokoch. Zvýšenú mortalitu jemných koreňov spôsobili najpravdepodobnejšie epizódy sucha. V obidvoch porastoch sa zistili podobné obehy jemných koreňov (približne jedenkrát za 4 roky). Pri porovnaní našich výsledkov s inými prácami sa konštatovali vysoké zásoby jemných koreňov, avšak nízke hodnoty ich obehu. Tento stav jemných koreňov pravdepodobne súvisí s mladým vekom sledovaných porastov, resp. s priaznivými pôdnymi pomermi na stanovišti.

Inter- and intra-annual dynamics of height increment in young beech and spruce stands in relation to tree size and weather conditions

Abstract We investigated the seasonal dynamics of height increment, as well as total annual height increment, in 2009-2013 on young stands of beech and spruce grown at the same site. The results showed that the inter-annual dynamics of basic stand characteristics, especially tree density, were more obvious in spruce than in beech stands. Much higher tree mortality in spruce was explained by a lower light intensity under the spruce stand canopy and higher tolerance of beech to shade. Large interspecific differences were also found in the timing of height increment. Specifically, the height increment of beech trees started earlier than those of spruce. Moreover, the terminal grew for longer in spruce (nearly 70 days) compared to beech (about 45 days). The comparisons between the courses of the height increment and the ambient factors suggested that global radiation played a principal role. In the beech stand, the maximum height increment rate occurred during the same days as the maximal global radiation in 2009 and 2011, while a decline of the height increment occurred simultaneously with a depression in global radiation in 2012. As for the spruce stand, its one-peak maxima in height increment were related to the maximum of global radiation in 2009 and in 2012. On the other hand, double-peak courses of height increment in 2010 and 2011 may have been related to sudden declines in global radiation. Interspecific differences in height increment timing might play a certain role in cases of unfavourable weather conditions, e.g. drought episodes in the middle part of the growing season when the height increment would be accomplished in beech but would still be ongoing in spruce. Abstrakt Počas rokov 2009-2013 sme sledovali sezónnu dynamiku výškového prírastku, ako aj celoročný výškový prírastok v bukových a smrekových mladinách rastúcich na totožnom stanovišti. Výsledky naznačili, že medziročné zmeny základných porastových charakteristík, a to najmä hustota porastu, boli výraznejšie v smrečine než v bučine. Omnoho vyššia stromová mortalita v smrečine sa vysvetlila nižšou intenzitou svetla pod korunovou vrstvou smrekov, resp. vyššou toleranciou buka na zatienenie. Veľké medzidruhové rozdiely sa zaznamenali v „načasovaní“ výškového prírastku. Konkrétne výškový prírastok bukov začal každoročne skôr ako výškový prírastok smrekov. Ďalej, terminál smrekov rástol dlhšie (približne 70 dní) v porovnaní s bukmi (45 dní). Porovnanie priebehov výškových prírastkov vzhľadom na prostredie naznačilo, že principiálny vplyv mala globálna radiácia. V bučine bola maximálna intenzita výškového prírastku počas dní s maximálnou úrovňou globálnej radiácia, a to v rokoch 2009 a 2011, zároveň pokles intenzity sa objavil simultánne s poklesom globálnej radiácie počas roku 2012. V smrečine intenzita výškového prírastku predstavovala jednovrcholovú krivku - s najvyššou intenzitou prírastku v dňoch maximálnych hodnôt globálnej radiácie počas 2009 a 2012. Na druhej strane sa zaznamenal dvojvrcholový výskyt maxím intenzity výškového prírastku smrekov v 2010 a 2011. Tento jav súvisel s dočasným poklesom globálnej radiácie v týchto rokoch. Medzidruhové rozdiely v načasovaní výškového prírastku môžu mať relevanciu v prípade výskytu nepriaznivých poveternostných podmienok. Napríklad pri epizódach sucha v polovici vegetačného obdobia, keďže výškový prírastok je vtedy už ukončený pri bukoch avšak na smrekoch ešte prebieha

Effect of soil waterlogging on below‐ground biomass allometric relations in Norway spruce

Abstract An increasing importance is assigned to the estimation and verification of carbon stocks in forests. Forestry practice has several long‐established and reliable methods for the assessment of above‐ground biomass; however, we still miss accurate predictors of below‐ground biomass. A major windthrow event exposing the coarse root systems of Norway spruce trees allowed us to assess the effects of contrasting soil stone and water content on below‐ground allocation. Increasing stone content decreases the root/shoot ratio, while soil waterlogging leads to an increase in this ratio. We constructed allometric relationships for below‐ground biomass prediction and were able to show that only soil waterlogging significantly impacts model parameters. We showed that diameter at breast height is a reliable predictor of below‐ground biomass and, once site‐specific parameters have been developed, it is possible to accurately estimate below‐ground biomass in Norway spruce.

Biomass allocation influenced by canopy closure in a young spruce stand.

Growth intensity of particular tree components is controlled by a variety of factors and as a consequence, biomass allocation also changes over time. Since the allocation of biomass controls the carbon regime in a forest stand, tree standing stock and biomass structure, with regard to tree components: fine and coarse roots, stem, branches and needles, were estimated in a young Norway spruce stand based on repeated tree sampling, soil coring and allometric equations (modelled for 2009 and 2013, i.e. for 12- and 16-years-old trees). Large differences were found between the two models in the contribution of the tree components to aboveground biomass. Between the first and fifth year of the experiment, below - ground to aboveground biomass ratio as well as short-lived to long-lived tree part ratio manifested decreasing tendencies. At the same time, the stand possibly reached the maximum standing stock of both needles and fine roots. It is concluded that for biomass allocation estimates in young stands, not only stand-specific but also time-specific allometric relations should be constructed and implemented. Further, there appears to be a canopy closure threshold beyond which biomass allocation is different from the situation in sparse young spruce stands.

Why was browsing by red deer more frequent but represented less consumed mass in young maple than in ash trees

European ash (Fraxinus excelsior) and sycamore maple (Acer pseudoplatanus) are considered amongst tree species as some of the most attractive forage for red deer (Cervus elaphus). The aim of this paper is to estimate branch and foliage mass browsing by red deer in young Sycamore maple and European ash in Central Slovakia and to analyze interspecific differences in browsing frequency and quantity. Altogether 665 ash trees and 701 maple trees were measured for height and stem diameter at the ground level. Red deer browsing, defined as leader shoot or lateral branch cropping, was recorded for all trees. A combination of the diameter of browsed branches and branch regression models allowed for the estimation of browsed (potentially consumed) mass by red deer. Results show that browsing occurred more frequently on maple (5 cases per tree) compared to ash (3 cases per tree); however, more total branch biomass was consumed in ash (10.7 g per tree) compared to maple (2.6 g per tree). This is because browsed branches were larger in ash than in maple. We assume that the difference in the size of browsed branches between ash and maple is relative to species-specific branch morphological and structural features.