Natural regeneration features of broad-leaved species under the canopy of coniferous stands in forest-steppe conditions

The age structure of the undergrowth was studied using the technique of constructing the age spectra of the adoles-cent population, which revealed the regularities of the natural pine recovery process. The aim of the study was to conduct a comparative analysis of the broad-leaved species renewal under the coniferous (pine) plantations canopy in forest-steppe conditions using the example of the Belgorod region. The research was carried out on 21 test areas using standard silvicultural techniques to assess natural regeneration effectiveness. Quercus robur L. and Ulmus laevis Pall. prevail among deciduous species in the second layer. Tilia cordata Miill, Fraxinus excelsior L., Acer platanoides L., Acer compestre L. reach less than 12%. (Betula pendula Ehrh., Populus tremula L.). The average number of young growth does not exceed 2000-2500 trees per hectare where the ones of medium height prevail (50%) and small height trees reach 22%. In the considered pine stands, Quercus robur L. young growth occurs more often. There is a growth that appeared from dormant buds at the root neck after the death of the seed unit. Units of normal vitality are found only among young growth younger than 5 years old or in communities with a disturbed stand structure.

The Introduction of Broad-Leaved Tree Species Drives The Process of Nutrient Cycling in Forest Soil

Background Pure cypress forests experience problems such as reductions in biodiversity, lowered capabilities for water and soil conservation, decreased underground productivity and land degradation. To improve the conditions of pure forests, we studied the effects of mixed gaps on the cypress (Cupressus funebris) pure forest, selecting the Chinese toon (Toona sinensis), which is a deciduous broad-leaved tree, as the mixed tree species. We examined the variations in the concentrations of C, N, and P and their ratios in plant tissues, litter and soils in different seasons in pure cypress forests with 4 different sizes of mixed gaps (50, 100, 150, 200 m2). Results The leaf N:P ratios of cypress and Chinese toon were 10.77 and 12.74, respectively, and N was the main limiting factor for tree growth in the study area. The N and P resorption rates of the cypress pure forest were 57.4% and 60.7%, respectively, and mixed gaps with Chinese toon increased the resorption rates. An analysis of correlations among leaf-litter-soil stoichiometry indicated that the correlations between the soil nutrient elements and the corresponding plant leaves and litter increased when the broadleaf tree species was introduced into the cypress pure forest. Conclusions These results indicate that the introduction of broad-leaved species was favorable for triggering the forest soil nutrient recycling process.

Deciduous Broad-Leaved Species (Quercus Robur, Tilia Cordata, Acer Platanoides and Ulmus Laevis) Forest Stand Productivity in Latvia

Climate forecasts indicate that in the future the climate will become more and more suitable for growth of broad-leaved tree species in Latvia. It is therefore very important to recognise and understand the growth potential of these broad-leaved stands in Latvia and the factors affecting the increment of growing stock. The results of the study showed high volume yield, as already 60- to 80-year-old stand stock could reach 500–600 m3·ha-1, and in later years even 700–1000 m3·ha-1. Similarly, the results of our study showed that the increment of the stock and growth potential of individual forest elements varied significantly between the various broad-leaved species. Significant factors were the age of the forest stand or forest element (a set of trees of the same species, in one layer and belonging to one generation), the indicators of competition (basal area and/or relative density) and the indicators of the social status of the forest element, namely, the ratio of the mean diameter of the forest element and the mean diameter of the dominant species of the upper layer of the stand and the sum of the basal area of the larger forest elements). No significant differences were found in growing stock and growth potential between monospecies and mixed stands and between simple and complex stands, neither at the level of the stands, nor at the level of the individual forest element.

Nemoralisation of Pinus sylvestris and Picea abies Forest Stands in the Hemi-Boreal Zone: A Case Study from Latvia

At the beginning of the 21st century, in extensively managed mature and over-mature conifer stands (Pinus sylvestris and Picea abies) in Latvia, establishment of native deciduous broad-leaved (Acer platanoides, Tilia cordata, Quercus robur and Ulmus laevis), as well as alien broad-leaved species (Acer pseudoplatanus and Tilia platyphyllos) has been observed. The establishment of deciduous broad-leaved species in coniferous stands is a process known as nemoralisation of coniferous stands, which is characterised by a large number of seedlings of broad-leaved species, young trees and the formation of a subcanopy layer in stands. Based on the age measurements of individuals of broad-leaved species trees, the establishment of some individuals into the studied coniferous stands occurred 40–50 years ago — in the 1970s–1980s. However, the predominant age of alien broad-leaved tree species in the study plots was 15–25 years, i.e. the introduction of large numbers of seedlings of these species in the coniferous stands occurred at the end of the 20th century. In this manner, in the final phase of the conifer replacement process, stable, mostly shade tolerant, mixed stands consisting of 3–4 species have formed, in which spruce is often found together with broad-leaved species.

Age-Based Survival Analysis of Coniferous and Broad-Leaved Trees: A Case Study of Preserved Forests in Northern Japan

Scientifically sound methods are essential to estimate the survival of trees, as they can substantially support sustainable management of natural forest resources. Tree mortality assessments have mainly been based on forest inventories and are mostly limited to planted forests; few studies have conducted age-based survival analyses in natural forests. We performed survival analyses of individual tree populations in natural forest stands to evaluate differences in the survival of two coniferous species (Abies sachalinensis (F. Schmidt) Mast. and Picea jezoensis var. microsperma) and all broad-leaved species. We used tree rings and census data from four preserved permanent plots in pan-mixed and sub-boreal natural forests obtained over 30 years (1989–2019). All living trees (diameter at breast height ≥ 5 cm in 1989) were targeted to identify tree ages using a Resistograph. Periodical tree age data, for a 10-year age class, were obtained during three consecutive observation periods. Mortality and recruitment changes were recorded to analyze multi-temporal age distributions and mean lifetimes. Non-parametric survival analyses revealed a multi-modal age distribution and exponential shapes. There were no significant differences among survival probabilities of species in different periods, except for broad-leaved species, which had longer mean lifetimes in each period than coniferous species. The estimated practical mean lifetime and diameter at breast height values of each coniferous and broad-leaved tree can be applied as an early identification system for trees likely to die to facilitate the Stand-based Silvicultural Management System of the University of Tokyo Hokkaido Forest. However, the survival probabilities estimated in this study should be used carefully in long-term forest dynamic predictions because the analysis did not include the effects of catastrophic disturbances, which might significantly influence forests. The mortality patterns and survival probabilities reported in this study are valuable for understanding the stand dynamics of natural forests associated with the mortality of individual tree populations.

PENGETAHUAN DAN UPAYA KONSERVASI KAYU SOWANG (Xanthostemon sp.) MASYARAKAT KAMPUNG DOYO LAMA DAN KAMPUNG HARAPAN PADA KAWASAN CAGAR ALAM PEGUNUNGAN CYCLOOP

This research was conducted to determine the knowledge and conservation efforts of the people of Doyo Lama villageand Harapanvillage. The research was carried out for three months, namely, from July to September 2020, using the observation method; interview method; documentation method; and literature study methods, and analyzed descriptively qualitatively. The results showed that knowledge about sowang wood (Xanthostemon sp.), is a traditional knowledge passed down from generation to generation orally. The people of Doyo Lama village call sowang by the name toang (meaning hard and strong), and Harapan village named howan(meaning wood that is durable and not easily weathered). The people of Doyo Lamavillage know two species of sowang wood, namely broad-leaved species and small-leaved species. The people ofHarapan villagealso recognize two species, namely the red-flowered species and the yellow-flowered species. The broad-leaved species and the red-flowered species are Xanthostemonnovoguineensis species. While the species with small leaves and yellow flowers are Xanthostemonpapuanus. Traditional knowledge and use of sowang wood by the people of Doyo Lama villageand Harapanvillage is decreasing, influenced by the development of modern life, because until now there have been no efforts and conservation activities for sowang wood in the two villages and there has been a shift in cultural values from traditional be modern. While the species with small leaves and yellow flowers are Xanthostemonpapuanus. Traditional knowledge and use of sowang wood by the people of Doyo Lama villageand Harapanvillage is decreasing, influenced by the development of modern life, because until now there have been no efforts and conservation activities for sowang wood in the two villages and there has been a shift in cultural values from traditional be modern. While the species with small leaves and yellow flowers are Xanthostemonpapuanus. Traditional knowledge and use of sowang wood by the people of Doyo Lama villageand Harapan villageis decreasing, influenced by the development of modern life, because until now there have been no efforts and conservation activities for sowang wood in the two villages and there has been a shift in cultural values from traditional be modern

Old Forests from Dobrogea’s Plateau

From the oldest times, the forest has been the main food, shelter and energy source, playing an essential role in the development of human societies. Old stands are characterized by their long life, large heights and diameters and by their help in conserving biodiversity. The surfaces occupied by old stands have decreased lately because of their wood mass high value which leads to exploitation. This is furthermore coupled with climate changes, urbanization and human influences. These stands occupy a surface of 128.500 ha in the forests from Dobrogea’s Plateau, where broad-leaved species are preponderant (Quercus sp., Fraxinus ornus, Tilia tomentosa, Acer sp.). As such, the present paper intends to characterize the oldest stands from Dobrogea’s Plateau with the help of forest management plans realized during 1993-2007. The main characteristics analyzed in this study for stands older than 120 years were: location, surface, height, diameter, structure, forest type, soil type, altitude, exposition, slope and consistency. Stand older than 100 years occupy only 4% of the total surface and are composed of linden, brown oak and pedunculate oak which grow and develop on common luvisols.

Upper pliocene diatom complexes and its significfnce to establish lower boundary of quarter (South of the Far East)

An analysis of the evolutionary distribution of diatoms in the outcrops of the Late Cenozoic shows that, upon reaching the level of the Annensky Horizon (Gelazian stage), the extinct species disappear almost completely. A predominance of the alluvial type of sedimentogenesis and reduction in the lake basins areas are clearly registered for deposits of the diatom zone Aulacoseira praegranulata var. praeislandica f. praeislandica. A cooling in the Late Pliocene with the pronounced temperature minimum at the level about 2,58 million years is fairly bright reflected in the ecological structures of diatomic associations (upper complex): the benthic arcto- and north-boreal flora predominates. Of that time, a total absence of the pollen of the broad-leaved species is also characteristic and paleo-landscapes become close to the Eopleistocene ones. From this moment on, the coexistence and expansion of the polar ice sheets begin (transition of planet from the “Green house” mode to the “Ice house” mode) which determine the formation of the modern climatic system of the Earth which emphasizes the globality of the palaeoclimatic event. From the lithological point of view, the bottom of the red rocks strata of the Annensky Horizon corresponding to the Gelazian stage bottom (2,58 million years) coincides with this boundary in the southern Primorye. The age changes of the Quarter boundary to this chronostratigrahic level is well founded.

DYNAMICS OF SOIL-VEGETATION COVER OF SMALL ISLANDS ZHELTUKHIN, MOISEEV, AND PAKHTUSOVIN HOLOCENE (THE EUGENIE ARCHIPELAGO, PETER THE GREAT BAY)

Проведено геоботаническое, почвенное и биостратиграфическое изучение малых островов архипелага Императрицы Евгении. Выполнена оценка современного состояния их экосистем. Определены основные факторы, влияющие на состав, структуру, разнообразие и динамику почвенно-растительного покрова в голоцене. Установлено, что в теплые эпохи увеличивалась лесистость, доминировали широколиственные леса с богатым видовым разнообразием пород, в холодные фазы древесная растительность становилась более разреженной, в ее составе преобладали березы и ольха, доля широколиственных пород сильно сокращалась. A geobotanical, soil and biostratigraphic study of the small islands of the Eugenie Archipelago was carried out. Assessment of the current state of their ecosystems has been made. The main factors determining the composition, structure, diversity and dynamics of the soil and vegetation cover in the Holocene have been determined. It is found that in warm epochs, forest cover increased, and broad-leaved forests with a rich diversity of species were dominant whereas in cold phases tree vegetation became more sparse, with birch and alder predominating in its composition, and the share of broad-leaved species was greatly reduced.