Structural peculiarities of forest litter in water protective pine stands in wet sites of Zhytomyr Polissia

The results of the study of the fractional composition, structure and formation of forest litter in water protection pine plantations, which grow in the predominant moist forest vegetation conditions of Zhytomyr Polissia, are presented. The age range of stands varies between 18 and 85 years. It is established that water-protected pine stands in wet hygrotopes accumulate significant reserves of forest litter, which ranges from 33.0 t/ha in young plantations 77.0 t/ha in mature stands. The distribution of forest litter throughout area in most stands is uniform, although in young plantations its greater share is accumulated between rows. In terms of composition, the forest litter of pure pines is characterized by a medium dense structure, and in pines with an admixture of deciduous species, the litter is usually loose, due to the presence of annual fallen leaves in its upper horizon. The thickness of forest litter between rows of young plantations varies within and 2.6-2.9 cm without its clear distribution on the horizons. In medieval plantations, the horizons of the litter are already clearly distinguished. The total thickness of the litter is 4.0–4.3 cm. In the pre mature and mature pine stands the thickness of the forest litter profile varies between 6.0–6.3 cm. In the stands of older age groups the forest litter has mainly a three-layer structure. The trend of intensive accumulation of forest litter in the conditions of wet boreal and sub boreal conditions with the age of maturity is revealed. In pre mature plantations, the accumulation of litter slows down and in mature plantations; the processes of accumulation and decomposition of litter are leveled. The tendency of predominance of the active part and, accordingly, reduction of the inactive fraction of litter in the pre mature and mature plantations of wet sub boreal site compared to boreal conditions is indicated, which indicates more active processes of mineralization of litter in wet subboreal conditions.

Model of mixed effects of height dependence on tree diameters in pine stands

Основными исходными данными для определения запаса служат результаты обмеров диаметров и высот деревьев. Но обмеры диаметров деревьев на высоте груди выполнить намного проще, чем обмеры высот, поэтому ограничиваются замерами высот 15–25 деревьев. Цель исследования – по материалам измерения модельных деревьев в сосновых древостоях выбрать наиболее адекватную простую модель, которая передает зависимость между высотой деревьев и диаметром на высоте груди. Объектом исследования послужили сосновые древостои искусственного происхождения на постоянных пробных площадях в Лесной опытной даче Российского государственного агарного университета – МСХА имени К.А. Тимирязева. В работе используются данные обмеров деревьев на 17 постоянных пробных площадях с 1934 по 2005 гг. Возраст древостоев на момент проведения измерений от 50 до 125 лет. По итогам проведения 77 перечетов массив данных составил 1157 наблюдений. И модель фиксированных эффектов, и модель смешанных эффектов адекватно описали зависимость между высотами и диаметрами деревьев в культурах сосны. Но, как и ожидалось, первая модель имеет худшие значения метрик качества по сравнению со второй. Модель со смешанными эффектами более точно предсказывает значения высот по сравнению с моделью фиксированных эффектов. Недостающие значения высот большого количества деревьев на участке можно вычислить более точно с помощью модели смешанных эффектов, а не применения модели фиксированных эффектов или использования только фиксированной части (средний отклик) модели смешанных эффектов. Применение разработанной модели должно ограничиваться только в тех условиях, к которым относятся экспериментальные материалы The main data for the stock of research results is the diameter of measurements and heights of trees. But measurements of the diameter at breast height are much easier to perform than measurements of heights, therefore, they are limited to measuring the heights of 15–25 trees. The aim of the study is to select the most adequate simple model based on the measurements of model trees in pine antiquities, which conveys the relationship between the height of trees and the diameter at breast height. The object of the study was pine stands of artificial origin on permanent test plots in the Forest Experimental Station Russian State Agararian University – Moscow Timiriazev Agricultural Academy. The work uses data from tree measurements on 17 permanent sample plots from 1934 to 2005. The age of the stands at the time of measurements was from 50 to 125 years. As a result of 77 enumerations, the data array amounted to 1157 observations. Both the fixed effects model and the mixed effects model adequately describe the relationship between heights and diameters of trees in pine stumps. But, as expected, the first model has worse quality metrics than the second. The mixed effects model more accurately predicts heights from the fixed effects model. The missing heights of a large number of trees on a site can be calculated accurately using mixed effects models, rather than using fixed effects models or using only a fixed portion (mean response) of the mixed effects model. The application of the developed model should be limited only in those conditions to which the experimental materials are applied.

The damage caused by wind in middle-aged Scots pine stands on permanent thinning experimental plots

In July 2002, the very strong hurricane appeared in northern Poland, which caused destruction of forest cover of area more than 10,000 ha. The permanent thinning research plot in a 53-year-old pine stand located in Myszyniec forest district (150 km north of Warsaw) was lying on the edge of damaged area. The following treatments were tested on this plot: 1) control plot (without thinning); 2) schematic cut in 20-year-old stand, selective thinning to 40 years, then thinning from below; 3) schematic cut in 20-year-old stand, then selective thinning; 4) selective thinning in young stand (20–40 years), then thinning from below and 5) selective thinning all the time. A significant part of this plot was completely destroyed and in the other part of the plot, some trees survived. A small part of the plot resisted the wind attack. An analysis of the amount of destroyed trees (measured by basal area) showed no differences between particular silvicultural treatments. The level of damage differed between particular parts of the plot. Another plot located in Ostrów Mazowiecka forest district (100 km NE of Warsaw) with the same thinning treatments was touched by heavy wind in July 2011 when the stand was 62 years old. Unlike the hurricane of 2002, this storm did not destroy the experimental plot which was located outside the zone of heaviest calamity. Therefore, damage on this plot had point and group character. Although on particular measurement units, share of broken or fallen trees did not exceed 10% of total basal area, it can be observed that the lowest level of damage was noticed on plots with selective thinning in young age and thinning from below in older stand.

Yield dynamics of natural pine stands in the Forest Experimental Station of the Timiryazev Agricultural Academy with 1860

Due to the longevity of forest vegetation, the problem of its age-related changes remains the least studied and most urgent. For 150 years, the Forest Experimental Station has been an experimental testing ground for a number of generations of foresters who have created experimental facilities to solve a number of pressing problems. On the example of natural pine stands with 1860, it was shown that in an urbanized environment, the life cycle of stands is accelerated, and their durability is reduced. At the same time, under the influence of negative factors (emissions from transport, enterprises, recreational load, etc.), a decrease in yield is observed.

Comparison of Scots pine growth dynamics in Polissya and Steppe zone of Ukraine

The goal of the study was to compare the dynamic changes in individual biometric indices of Scots pine in different natural zones of Ukraine, Polissya and Steppe. Scots pine stands were mainly concentrated in the Polissya zone, and their area was 3.6 times larger than that of forests in the Steppe zone, and the total wood stock by 4.6 times. The regression equations for biometric indices of artificial modal stands were developed. A comparison of the average height, diameter, and wood stock for pine stands of site index І^а, I, and II growing in Polissya and Steppe was made. It was found that the average differences in the average height (from 1.9 to 2.6 m) are observed at the age of 15–20 years. For the average diameter, the difference increases with age and the growth of the site index. The difference in the average stock is constantly increasing with age. At the age of 20 years this difference is 20–30 m³, and at the age of 120 years from 100 to 120 m³ depending on the site index. The developed growth models can be used in planning and prioritizing appropriate forestry activities for pine stands growing in specific regional conditions.

Role of soil fauna to litter decomposition in pine stands under Atlantic Forest biome

A produção de serapilheira e sua decomposição desempenham um papel importante no ciclo do carbono terrestre e na qualidade do solo, sendo um processo crucial envolvido na produtividade e funcionamento do ecossistema. Compreender esse processo em áreas comerciais de pinus ou invasões de pinus é crucial para projetar o manejo florestal ou a restauração de ecossistemas. Conduzimos um estudo em uma plantação comercial de pinus (Pinus taeda L.) no bioma da Mata Atlântica para investigar (1) a contribuição da fauna do solo para a perda de massa da serapilheira; (2) a atividade alimentar da fauna edáfica na serapilheira dentro das estações do ano. As bolsas de decomposição com acículas de pinus (5 g, peso seco) foram preparadas como tratamentos de exclusão para a fauna do solo de diferentes tamanhos, variando o tamanho da malha (2 mm e 0,06 mm). As bolsas de decomposição foram removidas após 60, 120, 180, 240, 300 e 365 dias para estimar as taxas de decomposição. Bait laminas foram expostos sazonalmente e horizontalmente na superfície do solo para determinar a atividade de alimentação da fauna na serapilheira. Encontramos: (1) nenhuma diferença na perda de massa da serapilheira e na taxa de decomposição quando a macrofauna do solo e a maior parte da mesofauna foram excluídas; (2) a atividade alimentar dos organismos da serapilheira foi maior no verão, provavelmente estimulada por uma combinação de alta temperatura e umidade. Em plantios comerciais de pinus, podemos concluir que a ciclagem de nutrientes é mais lenta do que em áreas naturais, o que está relacionado às características das acículas, descritas na literatura. Nossos resultados indicaram que a macro e a mesofauna do solo desempenham um papel menor na decomposição da serapilheira em plantios comerciais de pinus, indicando que o processo de decomposição em tais povoamentos está mais relacionada à atividade dos microrganismos.

The Structure of Saproxylic Beetle Assemblages in View of Coarse Woody Debris Resources in Pine Stands of Western Poland

Background: Resources of dying and dead trees, decaying fragments of stems, stumps and branches, i.e., coarse woody debris (CWD), are an important structural element of biocenoses and are drivers of biodiversity. The aim of this study was to describe assemblages of saproxylic beetles in pine stands of western Poland in view of dead wood resources. We present faunistic (species identity) and quantitative (species and individual counts) data from two types of stands: 1. unmanaged pine stands, in which no trees have been extracted for over 30 years, with processes connected with tree dying and self-thinning of stands being undisturbed, 2. managed pine stands, in which routine tending operations extracting trees are performed in accordance with forest management plans and naturally dying trees are removed in the course of tending and sanitary logging; Methods: Beetles were captured in the years 2013–2014 using window flight traps. Assemblages of saproxylic beetles were assessed based on the indices of dominance, diversity (the Shannon–Weiner index), and species richness (Margalef’s index) as well as the estimated habitat fidelity index, feeding habits, and zoogeographical distribution. Similarity between the assemblages was evaluated applying cluster analysis. Dependence between dead wood resources and the diversity and species richness indices were analysed; Results: A total of 2006 individuals classified to 216 species were captured. Assemblages show considerable similarity on the local scale. Higher values of species diversity indicators were observed in unmanaged stands, in which no sanitation cuttings are performed; Conclusions: The decision to refrain from sanitation logging in pine monocultures results in increased CWD resources, which nevertheless does not lead to a marked increase in the values of biodiversity indicators. Unmanaged stands were characterised by a high share of zoophagous, mycetophagous, and saproxylic species. In contrast, managed stands were characterised by a high share of xylophagous beetles.