Growth characteristics of sessile oak (Quercus petraea (Matt.) Liebl., Fagaceae) young crop in conditions of small size regeneration areas

In accordance with the biology of sessile oak that implies shade tolerance and the ability to regenerate in the closed stand canopy conditions in the monodominant sessile oak forests in Serbia, the natural regeneration of stands is mainly based on beforehand, spontaneously formed young crop and its gradual release from shade of the secondary species and mother trees by means of regeneration cuts on the areas of various size. In the conditions of small size regeneration areas on a site of a mesophilious variant of monodominant sessile oak forest (Quercetum petraeae Čer. et Jov. 1953. s.l) in the area of northeastern Serbia, a morphometric analysis was conducted on sessile oak young crop that was formed after successive mast years (2002, 2005, 2009 and 2011). In the oldest found young crop that was formed in the closed canopy conditions, the above-cotyledon-axis was on average 9.0 cm tall in the first year of its development while at age 15 years it was 55.0 cm with a root collar diameter of 6.3 mm. The morphology of the seedlings was typical of shade conditions (sciomorphic). The current annual height increment in the unchanged canopy conditions in the period from the 2nd to the 9th year of age was 1.0–2.6 cm. When the canopy conditions were changed, from 10th to 15th year, the current annual height increment was 1.4–10.9 cm. In the conditions of small size regeneration areas, the sessile oak young crop shows a specific norm of reaction of height growth in the first and in the following years of development and the main height growth type was one-flush growth

Polna struktura pajasena (Ailanthus altissima /Mill./Swingle) u zaštićenom prirodnom dobru ,,Bajfordova šuma” na području Beograda — osnova za biološku kontrolu širenja i plansku redukciju

Pajasen (Ailanthus altissima /Mill./ Swingle) je invazivna vrsta u Srbiji, koja ugrožava floristički biodiverzitet u prirodnim sastojinama i urbanim prostorima. To je svetloljubiva vrsta drveća, sa brzim rastom u početnoj fazi razvoja i ima izraženu adaptivnu sposobnost na različite uslove sredine otvorenih staništa. Sa pojavom ranog polnog sazrevanja i, pretežno, svakogodišnjeg uroda velike količine plodova, koji se lako prenose na veću udaljenost od matičnog stabla, pajasen brzo kolonizuje sastojine drugih vrsta drveća sa narušenom strukturom. To je dvodoma drvenasta biljka, sa jednopolnim i dvopolnim cvetovima. Primenom polnog dimorfizma kod pajasena, kao kriterijuma za selekciju stabala u proredi, može se uticati na širenje pajasena generativnim putem, a u okviru sastojinskog sklopa može se uticati na rast i održanje generativnog i vegetativnog potomstva. Diferenciranje rodnih-ženskih od nerodnih-muških stabala vrši se u fazi cvetanja na osnovu cvetno-plodnih cvasti, a odabir rodnih-ženskih stabala vrši se tokom cele godine na osnovu prisutnih plodova i cvetno-plodnih drški koje se dugo zadržavaju u krošnji po opadanja plodova. Polni dimorfizam ove vrste poslužio je kao osnova za utvrđivanje polne strukture stabala u zaštićenom prirodnom dobru ,,Bajfordova šuma” na području Beograda. Na 37,4 ha šumom obrasle površine evidentirano je 138 polno izdiferenciranih stabala pajasena u 2018. godini, što je potvrđeno i u fazi cvetanja 2020. godine. Na osnovu dendrometrijskog premera stabala 2018. godine prsni prečnici stabala su bili u rasponu 5-74 cm, a visine u rasponu 5-21 m. U okviru navedenog broja stabala zastupljenost rodnih-ženskih i nerodnih-muških stabala je približno podjednaka, ali prostorno varira. Evidentirana rodna-ženska i nerodna-muška stabala pajasena osnova su za monitoring invazije, a pored zdravstenog stanja i biološkog položaja u sastojinama osnova su i za plansku redukciju i gajenje u neinvazivnom obliku u zaštićenom prirodnom dobru ,,Bajfordova šuma”

Primena potpornih konstrukcija u sanaciji klizišta na regionalnom putu Stolice - Krupanj

Landslides can be triggered by different factors including changeable weather conditions, prolonged heavy rains, complex terrain, traffic loads, etc. This paper deals with the problem of landslide rehabilitation on the Stolice-Krupanj regional road that resulted from vehicle loads and soil saturated with water. The technical measures used in the rehabilitation of the landslide included a concrete retaining wall and a geogrid-reinforced soil structure. Based on data related to soil obtained from laboratory tests, slope stability before and after applying rehabilitation measures was tested in the GEO5 Geotechnical software. The stability of the concrete wall was examined analytically by calculating the factors of safety against toppling and horizontal displacement. Both technical measures of given physicalmechanical properties increased the stability of the slope.Na pojavu klizišta mogu uticati mnogi faktori: promenljivi klimatski uslovi; velika količina padavina u kratkom periodu; složenost strukture terena; opterećenja od saobraćaja, itd. Rad se bavi problemom sanacije klizišta na regionalnom putu Stolice - Krupanj, koje je nastalo usled opterećenja od vozila i zasićenja zemljišta vodom. Tehničke mere koje su primenjene za sanaciju klizišta su: betonski potporni zid i potporna konstrukcija od tla i geomreže. Na osnovu podataka o zemljištu iz laboratorijskih ispitivanja izvršene su provere stabilnosti kosina pre i posle primenjenih mera sanacije u programu GEO5, dok je stabilnost betonskog zida ispitivana analitičkim proračunom faktora sigurnosti na prevrtanje i horizontalno pomeranje. Obe tehničke mere, zadatih fizičko mehaničkih karakteristika, povećale su stabilnost padine

Growth characteristics of three-year-old Turkey oak (Quercus cerris L.) seedlings from natural regeneration under a dense canopy stand

A morphometric analysis was conducted on three-year-old Turkey oak seedlings naturally regenerated from 2015 mast year in a degraded stand at Fruška gora on the site of pedunculate oak, European hornbeam and Turkey oak with limes (Carpino betuli-Quercetum roboris (Anić 59) Rauš 1971 var. geograf. Tilia argentea + Tilia cordata B. Jovanović & Tomić (1980) 1997). The stand overstory consists of Turkey oak and silver lime. After the first growing season, the height of the above-cotyledon-axis was between 8.6 and 44.1 cm, and the seedlings morphology was typical for shade conditions. The height growth increment in the second growing season was 0.7–6.1 cm, and 0.5–5.4 cm in the third growing season. The total height of the seedlings at the end of the third growing season was 13.0–47.0 cm, with 3–6 leaves and root collar diameter between 2.0 and 3.9 mm. In the closed canopy conditions, the three-year-old seedlings were are able to survive in large numbers while showing a specific norm of reaction in the first and the upcoming years. The one-flush growth is the basic trait of the height growth. The results are pointing out to the Turkey oak ability of ontogenetic adaptation in the dense canopy conditions. This is an important trait in the process of natural regeneration of mixed-species stands

Some Elements of Ecological Adaptability of Tree-of-Heaven (Ailanthus altissima/Mill./Swingle) to a Habitat of Turkey Oak and Oak of Virgil (Quercetum cerridis- virgilianae B. Jovanović & Vukićević 1977)

Tree-of-Heaven (Ailanthus altissima /Mill./Swingle) is exotic, rapid-growing tree species that intensively colonises stands of other tree species and urban areas in its surrounding due to its high adaptability, early maturation and ability to produce large amounts of seed every year. Presence of A. altissima in the stand structure is an important factor of stand degradation and is related to rapid growth of the species, and consequently dominant position in the structure of native tree species stands. Today, A. altissima is one of the most invasive exotic tree species in Serbia. The invasion of A. altissima calls for new silvicultural approaches that should not only stop the invasion in the area, but also to reduce the presence of A. altissima in the stand structure to a more sustainable, non-invasive silvicultural system in the transitional period. In this respect, the knowledge about the elements of ecological adaptability of A. altissima to different habitats is important. Some elements of ecological adaptability of A. altissima were analyzed on a habitat of Turkey oak and Oak of Virgil (Quercetum cerridis-virgilianae B. Jovanović & Vukićević, 1977.) on loess and marl bedrock in the lower hills of Fruška Gora mountain (Serbia) where A. altissima colonized young stands. The research was conducted in a stand 17 years old on two permanent sample plots on eastern aspect and slope of 15° that are located on different landforms — the first plot was on a foothill (130 m a.s.l.) that is on the border with pedunculate oak and European hornbeam forest (Ass. Carpino betuli-Quercetum roboris (Anić 59) Rauš 1971) and the second plot in the shoulder close to the summit (170 m a.s.l.) that is a typical habitat of Turkey oak and Oak of Virgil. The mean and dominant heights and diameters of A. altissima differ between the plots in the foothill and the shoulder of the hillslope. This indicates to different ecological adaptability of A. altissima to this habitat

Growth characteristics of three-year-old Turkey oak (Quercus cerris L.) seedlings from natural regeneration under a dense canopy stand

A moprhometric analysis was conducted on three-year-old Turkey oak seedlings naturally regenerated from 2015 mast year in a degraded stand at Fruška gora on the site of pedunculate oak, European hornbeam and Turkey oak with limes (Carpino betuli-Quercetum roboris (Anić 59) Rauš 1971 var. geograf. Tilia argentea + Tilia cordata B. Jovanović & Tomić (1980) 1997). The tree layer in this 114-yearold stand consists of Turkey oak and silver lime. In the dense canopy conditions, the height growth of the seedlings during the first three years was characterized by monophase type growth. In the first year of growth, the height of the above-cotyledonaxis was between 8.6 and 44.1 cm, and the seedlings morphology was typical for shade conditions. The height growth increment in the second year of growth was 0.7– 6.1 cm, and in the third year 0.5–5.4 cm. The total height of the seedlings in the third year was 13.0–47.0 cm, with 3–6 leaves and the root collar diameter between 2.0 and 3.9 mm. In the closed canopy conditions, the three-year-old seedlings are able to survive in large numbers while showing a specific norm of reaction in the first and the upcoming years. The monophase type of growth is the basic trait of the height growth. The results are pointing out to the Turkey oak ability of ontogenetic adaptation in the dense canopy conditions. This is an important trait in the process of natural regeneration of mixed-species stands