Klimatski signali u kronologijama ranog drva, kasnog drva i širini goda hrasta kitnjaka (Quercus petraea (Matt.) Liebl.) iz Majdanpeka, sjeveroistočna Srbija

In this article, the dependence of the sessile oak (Quercus petraea (Matt.) Liebl.) radial growth (tree-ring, earlywood, and latewood widths) on climate (the mean monthly temperature and precipitation totals) was studied in the Majdanpek area, north-eastern Serbia. The growth response of the oak trees to the prevailing climate conditions was dendroecologically investigated, by applying the correlation and response function, as well as by pointer years analysis. The site chronology covered 159 years (1855-2013). We found that latewood and total tree-ring width contain the imprinted positive response to the amount of precipitation in summer months (June and July) of the current growing season. The earlywood width showed no direct dependence on climate data, but it was significantly affected by the previous-year latewood width. Moreover, 40 % of the variation in the latewood width is explained by the earlywood variation in the same season. The temperature was not found to have any significant effect on the growth of oak at the study site. The use of pointer years, determined by applying several calculation procedures, has highlighted previous results, indicating that the precipitation in summer months was the deciding climate factor leading to the occurrence of the years with exceptionally wide or narrow tree-rings and latewood. To enhance our understanding of the response of the sessile oak growth at south-oriented sites with a shallow soil profile to precipitation and temperature variations, and expand the current database and knowledge, future studies should be undertaken.U radu je proučavana ovisnost radijalnog prirasta (širine goda, širine ranoga i kasnog drva) hrasta kitnjaka (Quercus petraea (Matt.) Liebl.) o klimi (srednjoj mjesečnoj temperaturi i količini oborina) na području Majdanpeka, u sjeveroistočnoj Srbiji. Odziv radijalnog rasta hrastovih stabala na prevladavajuće klimatske uvjete istražen je dendrokronološki, primjenom korelacijske i odzivne funkcije, kao i analizom pokaznih godina. Kronologija staništa obuhvatila je 159 godina (1855. – 2013.). Otkrili smo da kasno drvo i ukupna širina goda sadržavaju utisnut pozitivan odziv na količinu oborina u ljetnim mjesecima (lipnju i srpnju) tekuće sezone rasta. Širina ranog drva nije pokazala izravnu ovisnost s klimatskim uvjetima, ali je na nju značajno utjecala širina kasnog drva iz prethodne godine. Nadalje, 40 % varijacija širine kasnog drva objašnjava se varijacijama ranog drva iz iste sezone. Na istraživanom staništu nije utvrđeno da temperatura ima značajan utjecaj na rast hrasta. Primjena pokaznih godina, koje su određene primjenom nekoliko računskih postupaka, potvrdila je prethodne rezultate upućujući na to da je prevladavajući klimatski čimbenik koji je doveo do pojave izrazito širokih ili uskih godova i kasnoga drva u pojedinim godinama bila količina oborina u ljetnim mjesecima. Da bi se sveobuhvatno razumjela reakcija rasta hrasta kitnjaka na promjene temperature i količinu oborina na južnim ekspozicijama i s plitkim profilom tla, trebalo bi provesti dodatne studije kako bi se proširila baza podataka i spoznaja

First Dendroclimatological Insight into Austrian Pine (Pinus nigra Arnold) Climate-Growth Relationship in Belgrade Area, Serbia

In order to assess the impact of climate variations on Austrian pine forest in the Belgrade area, the radial growth of artificially-established Austrian pine trees and its dependence on temperature and precipitation was studied using dendroclimatological methods. The site is classified as Quercetum-frainetto cerris Rudski. Standard and residual chronologies were established and several common statistics were calculated. A dendroclimatic study was carried out using the correlation and response function analysis. The Pearson correlation coefficients between the chronology indices and 13 seasonal (3-month period) precipitation and temperature data were calculated for the period from 1959 to 2014. The applied response function analysis included 24 precipitation and temperature variables from October of the prior year to September of the current year. The results of the correlation analysis pointed out that there was a strong tendency towards a positive response to the summer and late summer/early autumn precipitation and a weak significant negative response to the spring and summer temperatures. Climate-growth relationships were further first studied using the response functions for the significant seasons that were detected from the correlation analysis and then for individual months from previous October to current September. These results also highlighted the findings that higher precipitation in the current summer months has a beneficial effect on the tree-ring width. The conducted correlation between the residual chronology and the Standardised Precipitation Evapotranspiration Index indicated that a high summer value of this drought index had a positive impact on the pine growth and reinforced the previously detected relevance of September as an important month for the Austrian pine growth. These preliminary results point out that some additional climate-Austrian pine growth studies (application of various tree-ring features, growth data with a much longer time span, more sites/stands, etc.) should be performed to obtain new and valuable knowledge important for the sustainable management of Austrian pine forests

Usporedna analiza utjecaja klimatskih čimbenika na radijalni rast autohtonih vrsta borova (Pinus spp.) u središnjoj Bosni i Hercegovini

In central Bosnia and Herzegovina, in the Zavidovići-Teslić area, the study of the radial growth of Austrian and Scots pine (autochthonous pine species) trees was conducted using the dendrochronological method in order to identify the differences between the species in terms of the influence of climatic variables on the tree ring formation. Trees were sampled in five experimental areas or five sites. The first site had a Scots pine stand, while the second had an Austrian pine stand, and the other three sites had mixed stands of Scots and Austrian pine. Cross-dating was conducted using visual on-screen techniques of CDendro software and statistical methods using Cofecha software. The tree ring series were standardized using the Arstan program and cubic smoothing spline. It produced Scots pine regional chronology, 145 years long (1870-2014), and Austrian pine regional chronology, 180 years long (1835-2014). Correlation analysis of the relationship between the index of tree-ring width and precipitation and temperature in the characteristic periods of the year showed a negative effect of temperature (except in winter months) and a positive effect of precipitation on the tree ring formation. The statistically significant dependence of the tree-ring width index on the SPEI indices indicates a significant impact of moisture deficiency on the tree ring formation in the period from June to August (r = 0.33 in June, r = 0.45 in July and r = 0.47 in August) for Scots pine and in the period from June to September (r = 0.36 in June, r = 0.43 in July, r = 0.47 in August and r = 0.30 in September) for Austrian pine. The analysis of the relationship between climatic parameters and the chronologies of Scots and Austrian pine shows similar relationships between radial growth and climate but the influence of climate is somewhat more pronounced in Austrian pine. In the study area, the radial growth of both tree species is significantly determined by climate conditions. In other words, the chronology of these species has a good climatic signal, especially the drought signal in the summer months.U Zavidovićko - Teslićkom području, u središnjoj Bosni i Hercegovini, dendrokronološkom metodom je proučavan radijalni rast stabala crnog i bijelog bora, autohtonih vrsta u pomatranom području. Cilj je bio identifikacija razlika između spomenutih vrsta glede utjecaja klimatskih čimbenika. Uzorci su uzeti iz stabala s pet lokaliteta. Na prvom lokalitetu je sastojina bijelog bora, na drugom crnog bora, a na ostala tri lokaliteta su mješovite sastojine. Standardizacija serija širina godova (radijalnih prirasta) obavljena je primjenom Arstan programa. Dobivena je regionalna kronologija bijeloga bora dužine 145 godina (od 1870. do 2014.) i regionalna kronologija crnoga bora dužine 180 godina (od 1835. do 2014.). Ispitivanje zavisnosti između indeksa širine goda i oborina odnosno temperature u pojedinim karakterističnim periodima godine, pokazalo je negativan utjecaj temperature (osim u zimskim mjesecima) na formiranje goda i pozitivan utjecaj oborina. Statistički značajna zavisnost indeksa širine goda od SPEI indeksa ukazuje na značajan utjecaj nedostatka vlage u periodu lipanj – kolovoz (r = 0,33 u lipnju, r = 0,45 u srpnju i r = 0,47 u kolovozu) za bijeli bor i periodu lipanj - rujan (r = 0,36 u lipnju, r = 0,43 u srpanju, r = 0,47 u kolovozu i r = 0,30 u rujnu) za crni bor na formiranje godova. Analiza odnosa klimatskih parametara i formiranih kronologija bijeloga i crnoga bora pokazuje slične odnose između širine goda i klime, ali je utjecaj klimatskih čimbenika nešto više izražen kod crnog bora, kojemu više odgovaraju uvjeti staništa na promatranom području. U promatranom području radijalni prirast stabala obje vrste drveća značajno je uvjetovan klimatskim čimbenicima, odnosno kronologije navedenih vrsta imaju dobar klimatski signal, a posebno signal suše u ljetnim mjesecima

Jednofazni asinhroni generator sa dva namotaja na statoru

The paper describes a particular realization of the single-phase asynchronous generator with a double coil on the stator, which is suited for applications in agriculture in cases where the safety mandates the use of low voltages. We provide basic elements of the design, define equivalent circuits and report the results of experimental testing.U radu je prikazana jedna posebna izvedba jednofaznog asinhronog generatora sa dva namotaja na statoru, pogodna za primenu u poljoprivredi u onim slučajevima gde je, radi zaštite od opasnog dejstva električne struje obavezna primena malih napona. Dati su osnovni elementi konstrukcije definisane ekvivalentne šeme i prikazani rezultati eksperimentalnog ispitivanja

Konstrukcija, karakteristike i primena u poljoprivredi elektromagneta za magnetnu obradu vode

This paper presents the characteristics of a special, transformer-type electromagnet MOV - 2 that can be used in the magnetic treatments of water, for the purpose of its further use in various fields of science, industry, agriculture and medicine. This electromagnet is the original technical solution. Its construction makes it possible to obtain high values of magnetic induction, to regulate magnetic field parameters and continuously adjust the length of the air-gap in which a tube containing water which is treated magnetically is placed. The use of magnetized water is applied to the field of agriculture.U radu su date karakteristike specijalnog elektromagneta transformatorskog tipa MOV – 2 za magnetnu obradu vode radi njene dalje upotrebe u raznim oblastima nauke, industrije, poljoprivrede i medicine. Elektromagnet je originalno tehničko rešenje koje svojom konstrukcijom omogućava dobijanje visokih vrednosti magnetne indukcije, regulaciju parametara magnetnog polja i kontinualno podešavanje optimalne dužine vazdušnog zazora u kome se nalazi cev sa vodom koja se magnetno obrađuje. Primena magnetisane vode konkretizovana je na oblast poljoprivrede

Effects of Thinning in a Plantation of Poplar Clone I-214 withWide Spacing

U nasadu topole klona I-214, osnovanom pri razmaku sadnje 6 × 6 m u sistemu kvadratne veze na zemljištu srednje povoljnom za uzgoj topola, analizirani su učinci prorjede koja je izvedena 11 godina nakon osnivanja nasada. Prorjeda je imala selektivan karakter, odnosno izdvojena je grupa tzv. perspektivnih stabala u broju koji odgovara prosječnom razmaku od 8,5 × 8,5 m i uklonjeni su njihovi izraziti konkurenti. Uzgojno neperspektivna stabla i stabla zaostala u rastu, što je uglavnom posljedica naknadnih popunjavanja, također su uklonjena. Prorjedom su uklonjena 122 stabla po hektaru (46 %), 6,45 m2/ha (43 %), 66,08 m3/ha (42 %) i 2645 m2/ha (40 %) površine projekcije krošnje, što je jačina zahvata iznad tzv. kritične temeljnice. Sortimentna struktura prorjednog etata pri selektivnoj prorjedi povoljnija je od shematskih prorjeda u mlađim nasadima na povoljnijim staništima i daje 50 % tehničkog drva, 30 % celuloznog drva i 20 % otpatka. Nakon 5 godina na prorijeđenoj je površini srednji promjer po temeljnici veći za 10,6 %, volumen srednjeg stabla veći je za 21,9 %, a površina projekcije krošnje srednjeg stabla veća je za 59,0 % u odnosu na neprorijeđenu površinu. Nasuprot tomu, srednja visina po Loraju na prorijeđenoj je površini za 4,2 % manja u odnosu na neprorijeđenu površinu. Veći tečajni prirast promjera, volumena i površine projekcije krošnje stabala na prorijeđenoj površini ukazuje na mogućnost produžetka ophodnje i povoljniju sortimentnu strukturu u odnosu na kontrolnu površinu.Research was conducted in the experiment plot of euramerican poplar, clone I-214, which was founded with one year seedling type 1/1 with spacing 6 × 6 m in the square system on the alluvial soils of river Sava basin in which browning processes is expressed. Eleven years after the plantation establishment 3 blocks with two experimental plot of 0.2016 ha, which are separated by a so-called. protective order, were singled out. In the experimental plot all the trees were numbered and measured by two cross-dbh, with an accuracy of 1 mm, and height, with an accuracy of 1 dm. The crown projection radius of 8 positions, each rotated to 45o, were measured. On the three experimental plots (one in each block) selective thinning was carried out (PP-E), at which in each plots 50 % of trees were cut down, or the distance between the trees raised on average 8.5 × 8.5 m. Firstly, a collective called. promising trees set aside, in the number that corresponds to an average distance of 8.5 × 8.5 m, and their main competitors were removed. The trees behind in development, which is mainly due to additional filling in plantations two years after planting, are also removed because they were judged as silvicutural non-perspective. The remaining three experimental plots were control (PP-K). In each repetition trees for dendrometric analysis were sampled, the dominant one (dg20%) and a mean tree which has mean quadratic diameter (dg). In the 16thyears of plantation development diameters at breast height (dbh) and height of each tree were re-measured, sa well as crown projection radius. The development of mean and dominant trees showed that the investigated habitat is the medium favorable for the cultivation of the poplar clone I-214. Current increment of diameter, height and volume in the 11thyear was in the intensive phase, where volume increment has not yet culminated (Figure 1–3). As a suitable element of growth to determine the start of thinning operation on a biological point of view, can be ring width along the spindle tree. In the first five years the tree has had a full solitary growth, and from the seventh year there is a competitive relationship between trees in plantation, which is manifested by changing the ring width along the spindle tree (Figure 4 and 5). This means that before the seventh year thinning does not have any biological justification. Models 1 and 2 of volume tables, constructed measuring felled trees from thinning (Table 2), and which are the dependence of the volume of tree from diameter at breast height (model 1) and from the diameter at breast and height (model 2), proved to be equally good at calculating the volume per hectare in the 11thyear and more convenient compared to other tables and models (Table 3). To calculate the volume in the 16thyear two input volume tables can be successfully used (model 2), while the application of model 1 is limited at the 11thyear. In the 11th year at the experimental plot an average of 263–266 trees per hectare are found, which represents a survival rate of about 95 %. Total basal area averaged from 14.70 to 14.97 m2/ha, while volume was an average from 156.67 to 157.62 m3·ha-1. By applying the statistical t-test significant difference in the number of trees, basal area and volume per hectare was not determined within the experimental plots before applying the silvicultural treatments (Table 4). By applying thinning operation,122 trees per hectare (46%), 6.45 m2/ha (43 %) of the total basal area, 66.08 m3/ha (42%) of the total volume and 2645 m2/ha (40 %) of the the crown projection area were removed, which represent a strong procedure and is located above the so-called. critical basal area (Table 4, 13).Size of allowable cut in the thinning of 66.08 m3/ha was in the limits expected on the basis of previous research for the density of 278 trees per hectare and the habitat medium favorable for the development of poplar clone I-214. However, the assortment structureof allowable cut is more favorable compared to thinning in younger plantations in the more favorable habitats and produces 50 % of technical wood, 30% of pulpwood and 20 % of wastewood (Table 4, 9, 15). Between 11 and 16 years on both series of experimental plot the mortality of trees was not determined. Five years after application of thinning treatment a significant difference in the number of trees, basal area, volume and crown projection areas of trees per hectarewere determined between the experimental and control plots (Table 4). The significant difference in the mean diameters, heights and crown projection areas of the mean and the dominant trees (Table 5, 6), as well as between the diameter strucures (Figure 7) were also determined between investigated plots. For a period of 5 years after application of thinning operation at the experimental field current basal area and volume increment per hectare accounted 85 % of basal area increment and 75 % of volume increment of the control plots wich had the number of trees twice higher than experimental plots (Table 14). For five years of positive reactions to increase growing space of remaining trees on the experimental plots the size of the total basal area and volume of trees removed by thinning operation is not compensated: the total basal area and the volume per hectare amounted to 2/3, and the crown projection area amounted 87 % of the size of the control plot. The reaction of trees on experimental plot with thinning treatment for 5 years is great and is reflected in greater mean diameter by 10.6 %, greater mean tree volume by 21.9 % and increased the crown projection area by 59.0 % compared to control plot. In contrast, the mean Lorey’s height at the experimental plot with thinning treatment decreased by 4.2 % compared to control plot. This has contributed to the intensification of the current (average periodic) volume increment compared to the period before applying thinning operation. Greater assimilation apparatus of trees in the experimental plots with thinning tretament and higher current diameter and volume increment indicate the need to extend the production cycle at the best assortment structure compared to the control plot. The research results indicate the validity of efforts that the thinning operation in poplar plantations should be treated as a biological and an economic category. As a biological category the thinning operation contributes to accelerating the growth of the remaining phenotypically better established trees and achieve optimum production. As economic categories with thinning operation realized the previous crop, and it being understood that the assortment of allowable cut in the thinning cover cost cutting and the establishment of plantations with more trees. In this framework it is necessary to direct further research, because the poplar plantations,which are aimed to applying thinning operation, are flexible enough to allow adaptation to changing market conditions

Effects of Thinning in a Plantation of Poplar Clone I-214 withWide Spacing

U nasadu topole klona I-214, osnovanom pri razmaku sadnje 6 × 6 m u sistemu kvadratne veze na zemljištu srednje povoljnom za uzgoj topola, analizirani su učinci prorjede koja je izvedena 11 godina nakon osnivanja nasada. Prorjeda je imala selektivan karakter, odnosno izdvojena je grupa tzv. perspektivnih stabala u broju koji odgovara prosječnom razmaku od 8,5 × 8,5 m i uklonjeni su njihovi izraziti konkurenti. Uzgojno neperspektivna stabla i stabla zaostala u rastu, što je uglavnom posljedica naknadnih popunjavanja, također su uklonjena. Prorjedom su uklonjena 122 stabla po hektaru (46 %), 6,45 m2/ha (43 %), 66,08 m3/ha (42 %) i 2645 m2/ha (40 %) površine projekcije krošnje, što je jačina zahvata iznad tzv. kritične temeljnice. Sortimentna struktura prorjednog etata pri selektivnoj prorjedi povoljnija je od shematskih prorjeda u mlađim nasadima na povoljnijim staništima i daje 50 % tehničkog drva, 30 % celuloznog drva i 20 % otpatka. Nakon 5 godina na prorijeđenoj je površini srednji promjer po temeljnici veći za 10,6 %, volumen srednjeg stabla veći je za 21,9 %, a površina projekcije krošnje srednjeg stabla veća je za 59,0 % u odnosu na neprorijeđenu površinu. Nasuprot tomu, srednja visina po Loraju na prorijeđenoj je površini za 4,2 % manja u odnosu na neprorijeđenu površinu. Veći tečajni prirast promjera, volumena i površine projekcije krošnje stabala na prorijeđenoj površini ukazuje na mogućnost produžetka ophodnje i povoljniju sortimentnu strukturu u odnosu na kontrolnu površinu.Research was conducted in the experiment plot of euramerican poplar, clone I-214, which was founded with one year seedling type 1/1 with spacing 6 × 6 m in the square system on the alluvial soils of river Sava basin in which browning processes is expressed. Eleven years after the plantation establishment 3 blocks with two experimental plot of 0.2016 ha, which are separated by a so-called. protective order, were singled out. In the experimental plot all the trees were numbered and measured by two cross-dbh, with an accuracy of 1 mm, and height, with an accuracy of 1 dm. The crown projection radius of 8 positions, each rotated to 45o, were measured. On the three experimental plots (one in each block) selective thinning was carried out (PP-E), at which in each plots 50 % of trees were cut down, or the distance between the trees raised on average 8.5 × 8.5 m. Firstly, a collective called. promising trees set aside, in the number that corresponds to an average distance of 8.5 × 8.5 m, and their main competitors were removed. The trees behind in development, which is mainly due to additional filling in plantations two years after planting, are also removed because they were judged as silvicutural non-perspective. The remaining three experimental plots were control (PP-K). In each repetition trees for dendrometric analysis were sampled, the dominant one (dg20%) and a mean tree which has mean quadratic diameter (dg). In the 16thyears of plantation development diameters at breast height (dbh) and height of each tree were re-measured, sa well as crown projection radius. The development of mean and dominant trees showed that the investigated habitat is the medium favorable for the cultivation of the poplar clone I-214. Current increment of diameter, height and volume in the 11thyear was in the intensive phase, where volume increment has not yet culminated (Figure 1–3). As a suitable element of growth to determine the start of thinning operation on a biological point of view, can be ring width along the spindle tree. In the first five years the tree has had a full solitary growth, and from the seventh year there is a competitive relationship between trees in plantation, which is manifested by changing the ring width along the spindle tree (Figure 4 and 5). This means that before the seventh year thinning does not have any biological justification. Models 1 and 2 of volume tables, constructed measuring felled trees from thinning (Table 2), and which are the dependence of the volume of tree from diameter at breast height (model 1) and from the diameter at breast and height (model 2), proved to be equally good at calculating the volume per hectare in the 11thyear and more convenient compared to other tables and models (Table 3). To calculate the volume in the 16thyear two input volume tables can be successfully used (model 2), while the application of model 1 is limited at the 11thyear. In the 11th year at the experimental plot an average of 263–266 trees per hectare are found, which represents a survival rate of about 95 %. Total basal area averaged from 14.70 to 14.97 m2/ha, while volume was an average from 156.67 to 157.62 m3·ha-1. By applying the statistical t-test significant difference in the number of trees, basal area and volume per hectare was not determined within the experimental plots before applying the silvicultural treatments (Table 4). By applying thinning operation,122 trees per hectare (46%), 6.45 m2/ha (43 %) of the total basal area, 66.08 m3/ha (42%) of the total volume and 2645 m2/ha (40 %) of the the crown projection area were removed, which represent a strong procedure and is located above the so-called. critical basal area (Table 4, 13).Size of allowable cut in the thinning of 66.08 m3/ha was in the limits expected on the basis of previous research for the density of 278 trees per hectare and the habitat medium favorable for the development of poplar clone I-214. However, the assortment structureof allowable cut is more favorable compared to thinning in younger plantations in the more favorable habitats and produces 50 % of technical wood, 30% of pulpwood and 20 % of wastewood (Table 4, 9, 15). Between 11 and 16 years on both series of experimental plot the mortality of trees was not determined. Five years after application of thinning treatment a significant difference in the number of trees, basal area, volume and crown projection areas of trees per hectarewere determined between the experimental and control plots (Table 4). The significant difference in the mean diameters, heights and crown projection areas of the mean and the dominant trees (Table 5, 6), as well as between the diameter strucures (Figure 7) were also determined between investigated plots. For a period of 5 years after application of thinning operation at the experimental field current basal area and volume increment per hectare accounted 85 % of basal area increment and 75 % of volume increment of the control plots wich had the number of trees twice higher than experimental plots (Table 14). For five years of positive reactions to increase growing space of remaining trees on the experimental plots the size of the total basal area and volume of trees removed by thinning operation is not compensated: the total basal area and the volume per hectare amounted to 2/3, and the crown projection area amounted 87 % of the size of the control plot. The reaction of trees on experimental plot with thinning treatment for 5 years is great and is reflected in greater mean diameter by 10.6 %, greater mean tree volume by 21.9 % and increased the crown projection area by 59.0 % compared to control plot. In contrast, the mean Lorey’s height at the experimental plot with thinning treatment decreased by 4.2 % compared to control plot. This has contributed to the intensification of the current (average periodic) volume increment compared to the period before applying thinning operation. Greater assimilation apparatus of trees in the experimental plots with thinning tretament and higher current diameter and volume increment indicate the need to extend the production cycle at the best assortment structure compared to the control plot. The research results indicate the validity of efforts that the thinning operation in poplar plantations should be treated as a biological and an economic category. As a biological category the thinning operation contributes to accelerating the growth of the remaining phenotypically better established trees and achieve optimum production. As economic categories with thinning operation realized the previous crop, and it being understood that the assortment of allowable cut in the thinning cover cost cutting and the establishment of plantations with more trees. In this framework it is necessary to direct further research, because the poplar plantations,which are aimed to applying thinning operation, are flexible enough to allow adaptation to changing market conditions

Storm event impact on organic matter flux, composition and reactivity in Taskinas Creek, VA

Carbon export from the land to the ocean are an important part of the global carbon cycle, linking terrestrial watersheds and the global carbon cycle. Burial of terrestrial organic carbon represents a long term sink for atmospheric CO2. Approximately 0.4 Pg Cy-1 is delivered to the global ocean from rivers, equally divided between POC and DOC. However, the amount of carbon entering the ocean is a small portion of the total amount entering rivers from the terrestrial environment, suggesting a large amount of processing in inland waters and estuaries. Most monitoring efforts have focused the processing of organic matter on baseflow conditions. However, recent studies have shown that POC and DOC exported during storm events, a small time period during a hydrologic year, can account for the majority of the annual carbon exported from small watersheds. This dissertation identifies the impact different magnitudes of storm events have on the source, composition and reactivity of organic carbon released to downstream waters from the terrestrial environment at Taskinas Creek, Virginia. The proximity of the Creek to the York River estuary, the changes in water table at the site, along with the small size of the watershed allowing opportunity to examine the connectivity between the watershed processes and delivery of organic matter made the site ideal for identifying how hydrology and environment alter POM and DOM export and reactivity. The sources, composition and flux of DOM and POM were measured during four storm events of different magnitudes to determine how events impacted the sources and fluxes of organic matter and the % reactive DOC exported. Events of different magnitudes with varying sources of DOC and POC had similar % reactive DOC that was not predicted using excitation emission spectroscopy. The events resulted in DOC fluxes 1.5-490 fold higher than baseflow. POC fluxes for storm were 6.7-55 times higher than DOC fluxes. Although the % reactive DOC did not increase during storm event conditions, coupled with the overall flux, storm events represent a considerable pulse of % reactive DOC to downstream waters, well above baseflow levels. When considered with increases in storm intensity due to climate change, storm event fluxes of reactive OM may have broad impacts on estuaries and the global carbon cycle through changes in carbon storage

European beech stem diameter grows better in mixed than in mono-specific stands at the edge of its distribution in mountain forests

Recent studies show that several tree species are spreading to higher latitudes and elevations due to climate change. European beech, presently dominating from the colline to the subalpine vegetation belt, is already present in upper montane subalpine forests and has a high potential to further advance to higher elevations in European mountain forests, where the temperature is predicted to further increase in the near future. Although essential for adaptive silviculture, it remains unknown whether the upward shift of beech could be assisted when it is mixed with Norway spruce or silver fir compared with mono-specific stands, as the species interactions under such conditions are hardly known. In this study, we posed the general hypotheses that the growth depending on age of European beech in mountain forests was similar in mono-specific and mixed-species stands and remained stable over time and space in the last two centuries. The scrutiny of these hypotheses was based on increment coring of 1240 dominant beech trees in 45 plots in mono-specific stands of beech and in 46 mixed mountain forests. We found that (i) on average, mean tree diameter increased linearly with age. The age trend was linear in both forest types, but the slope of the age–growth relationship was higher in mono-specific than in mixed mountain forests. (ii) Beech growth in mono-specific stands was stronger reduced with increasing elevation than that in mixed-species stands. (iii) Beech growth in mono-specific stands was on average higher than beech growth in mixed stands. However, at elevations > 1200 m, growth of beech in mixed stands was higher than that in mono-specific stands. Differences in the growth patterns among elevation zones are less pronounced now than in the past, in both mono-specific and mixed stands. As the higher and longer persisting growth rates extend the flexibility of suitable ages or size for tree harvest and removal, the longer-lasting growth may be of special relevance for multi-aged silviculture concepts. On top of their function for structure and habitat improvement, the remaining old trees may grow more in mass and value than assumed so far.The authors would like to acknowledge networking support by the COST (European Cooperation in Science and Technology) Action CLIMO (Climate-Smart Forestry in Mountain Regions—CA15226) financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. This publication is part of a project that has received funding from the European Union’s HORIZON 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 778322. Thanks are also due to the European Union for funding the project ‘Mixed species forest management. Lowering risk, increasing resilience (REFORM)’ (# 2816ERA02S under the framework of Sumforest ERA-Net). Further, we would like to thank the Bayerische Staatsforsten (BaySF) for providing the observational plots and to the Bavarian State Ministry of Food, Agriculture, and Forestry for permanent support of the Project W 07 ‘Long-term experimental plots for forest growth and yield research’ (#7831-26625-2017). We also thank the Forest Research Institute, ERTI Sárvár, Hungary, for assistance and for providing observational plots. Furthermore, our work was partially supported by the SRDA via Project No. APVV-16-0325 and APVV-15-0265, the Ministry of Science and Higher Education of the Republic of Poland, the Project “EVA4.0” No. CZ.02.1.01/0.0/0.0/16_019/0000803 funded by OP RDE and the Project J4-1765 funded by the Slovenian Research Agency and also by the Bulgarian National Science Fund (BNSF) and the Project No. DCOST 01/3/19.10.2018

Jet stream position explains regional anomalies in European beech forest productivity and tree growth.

The mechanistic pathways connecting ocean-atmosphere variability and terrestrial productivity are well-established theoretically, but remain challenging to quantify empirically. Such quantification will greatly improve the assessment and prediction of changes in terrestrial carbon sequestration in response to dynamically induced climatic extremes. The jet stream latitude (JSL) over the North Atlantic-European domain provides a synthetic and robust physical framework that integrates climate variability not accounted for by atmospheric circulation patterns alone. Surface climate impacts of north-south summer JSL displacements are not uniform across Europe, but rather create a northwestern-southeastern dipole in forest productivity and radial-growth anomalies. Summer JSL variability over the eastern North Atlantic-European domain (5-40E) exerts the strongest impact on European beech, inducing anomalies of up to 30% in modelled gross primary productivity and 50% in radial tree growth. The net effects of JSL movements on terrestrial carbon fluxes depend on forest density, carbon stocks, and productivity imbalances across biogeographic regions