THE IMPACT OF SHARE PARTICIPATION OF PINE AND SPRUCE ON INVENTORY INDICES OF MIXED FOREST STANDS

Mixed stands of spruce and pine of myrtillus y forest types occupy large areas of the forest fund of the Leningrad region. For the theory and practice of forestry it is important to know the impact of plantations on the density of wood in bunk mixed spruce-pine stands. In mixed stands of pine and spruce disks and cores of wood species were selected from the model tree to determine the basic density by the method of maximum water capacity. The study of basic wood density of pine and spruce in the coniferous bunk stands revealed that its rates are higher for both species in the mixed forest stand than in pure coniferous plantations in the region of the study. With the predominance of pines in the stand composition, its wood density is higher than in stands dominated by spruce. Density of pinewood increases from smaller to larger classes of stand diameters. Variability of wood density by diameter of trunk is higher in spruce than in pine in mixed stands. In stands, after cutting dilutes the density of pinewood is lower than in the plantation, which is not passed with felling. In the bunk spruce-pine the stand, to the age of maturity, larger mass of stem wood of coniferous species is formed than in the pure one-tier stands of pine or spruce. Developed regression equations depending on the density of the wood at a height of 1.3 m to the average density of trunk allow for a more accurate assessment of this parameter in mixed stands than previously published equations for pure stands of myrtillus forest types for the study area.

Abstract Pine- and spruce-dominatedmixed stands occupy a substantial part of the forested area. Depending on soil and hydrological conditions of different landscapes, stands of different forest types and tree stand composition dominate. Modern forestry is focused on growing monodominant stands, but it is worth noting that mixed stands have higher productivity and stability. This work is devoted to identifying the patterns of distribution of mixed stands by forest type in different geographic landscapes. For the study, two landscape districts of the Leningrad Region (Valdaysko-Tikhvinsky and Luzhsko-Volkhovsky) with landscape mosaics of different structure were selected. The dominant forest types and types of mixed forest stands were determined by summing the areas of each plant association. To carry out the calculations, data of the state forest inventory of the Leningrad Region were used. In the course of this study, it was found that blueberry forest type was the most common forest type in mixed stands. Most of the landscapes of the study region were dominated by spruce-deciduous stands, but in some landscapes with hilly relief, a predominance of spruce-pine stands was observed.

AbstractResearch on mixed forests has mostly focused on tree growth and productivity, or resistance and resilience in changing climate conditions, but only rarely on the effects of tree species mixing on timber quality. In particular, it is still unclear whether the numerous positive effects of mixed forests on productivity and stability come at the expense of timber quality. In this study, we used photographs of sawn boards from 90 European beech (Fagus sylvatica L.) trees of mixed and pure forest stands to analyze internal timber quality through the quality indicator knot surface that was quantitatively assessed using the software Datinf® Measure. We observed a decrease in knot surface with increasing distance from the pith as well as smaller values in the lower log sections. Regarding the influence of neighborhood species identity, we found only minor effects meaning that timber qualities in mixed stands of beech and Norway spruce (Picea abies (L.) H. Karst.) tended to be slightly worse compared to pure beech stands.

Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth with increases in stand density. Several models that incorporate competitive effects have been developed to predict tree and stand growth, but with simplified representations of competitive interactions. While these studies provided guidance useful for forest management, they contributed only partially to furthering our understanding of competitive mechanisms. Also, most competition studies were conducted in single-species stands. As competitive interactions occurring in mixed stands are characterized by a higher degree of complexity than those in single-species stands, a better understanding of these mechanisms can contribute to developing optimal management scenarios. The dynamics of forest stands with at least two species may be affected not only by competition, but also by facilitation or complementarity mechanisms. Thus, knowledge of the mechanisms may provide insight into the relative importance of intra- versus inter-specific competition and whether competition is symmetric or asymmetric. Special attention to the implementation of field experimental designs is warranted for mixed stands. While traditional spacing trials are appropriate for single-species stands, the examination of competitive interactions in mixed stands requires more complex experimental designs to examine the relative importance of species combinations. Forest productivity models allow resource managers to test different management scenarios, but again most of these models were developed for single-species stands. As competitive interactions are more complex in mixed stands, models developed to predict their dynamics will need to include more mechanistic representations of competition.

We studied the response of beaver (Castor canadensis Kuhl), moose (Alces alces L.), and snowshoe hare (Lepus americanus Erxl.) to clear-cutting in three blocks that had been logged 10 years ago. In a previous study, these species had been surveyed in the same blocks 2 years before and 2 years after logging. We also surveyed an uncut block of the initial experimental design that was logged more recently. Over the 10-year period, the shrub layer and available browse have improved markedly in clear-cut areas. As compared with logged coniferous stands, logged mixed stands had higher lateral cover (62% vs. ≈55%) and taller regeneration (>4 m vs. <3 m). Beaver density did not change over the period because its feeding habitat remained unchanged in the riparian forest strips. Moose densities increased 54%–87% in two harvested blocks as a result of both logging and stricter hunting regulations (selective hunting). Based on the rate of increase observed in a control block, we estimate that a 25% density increase in the mixed forest block can be related to logging, while selective hunting can solely be responsible for the change in the coniferous forest block. Snowshoe hare have started to reoccupy logged coniferous stands, but their relative density still remained less than half that of uncut stands. We conclude that, after 10 years, logged mixed stands already offer good habitat conditions for moose and snowshoe hare. Conversely, in logged black spruce (Picea mariana (Mill.) BSP) stands, habitat conditions still remain poor for snowshoe hare because of a lack of cover.

Many studies have proved that having nature experiences in forests is conducive to human physiological and psychological health. However, currently there is little research focusing on the effects of forest characteristics and the experiential characteristics of nature experiences on changes in health. In the study, three types of forest (mixed forest; deciduous forest; coniferous forest) and an urban site were used to measure the effects of these environments on participants’ physiological and psychological restoration after nature experience activities (sitting and walking activities). The study participants were 30 young adult students from Beijing Forestry University. Restorative effects were measured by physiological indicators (blood pressure and heart rate) and four psychological questionnaires (Profile of Mood States (POMS); Restorative Outcome Scale (ROS); Subjective Vitality Scale (SVS); Warwick-Edinburgh Mental Well-being Scale (WEMWBS)). Results demonstrated that all types of forest were beneficial to lower blood pressure and heart rate as well as to reduce negative feelings while boosting positive emotions. The mixed forest was more effective in lowering blood pressure and heart rate as well as increasing vitality. The levels of restoration and positive mental health increased significantly, while all subscales of the POMS (with the exception of vigor) decreased greatly in the coniferous forest. Relative to the sitting activity, obvious decreases in blood pressure and negative emotions were observed, while significant increases in restoration, vitality and positive mental health were observed after the walking activity. In conclusion, the impact on subjects’ health restoration varied with different forest characteristics, and the experiential characteristics of exposure may be helpful for creating supportive interventions and lifting the benefits of forest therapy as people interact with the forest.

We monitored 20 adult fishers (8 males, 12 females) to investigate the effects of season, sex, and site availability on rest-site selection by fishers at the southern extent of their range. Data on rest-site locations (n = 219) and random sites (n = 194) were collected from December 1989 through February 1991. Fishers rested in hardwood, softwood, and mixedwood forest types in proportion to their availability in summer; however, hardwoods were used less than expected in winter. Fishers used nests, cavities, and burrows in proportion to their availability in winter. In summer, however, nests were selected twice as often as expected, cavities were used less than expected, and burrows were not used. Male fishers tended to use larger cavity trees and mixed forest stands more often than females did. In winter, fishers were not restricted to coniferous forest types, as occurs at the northern extent of their range, because moderate snow depths did not restrict movement and prey may have been more available in other forest types. Fishers appeared to select rest-site types most suitable for thermoregulation and obtaining prey. Trees with diameter at breast height ≥ 32 cm may provide cavities for rest sites in hardwood-dominated forests.

The problems of joint cultivation of pine and fir, as well as the choice of the optimal composition of the target woods are examined. Collection of material for analysis of the commodity structure and forest indices of plantings was conducted in the summer of 2013 in Lisinsky teaching experimental forestry of Leningrad region in maturing stands of mixed conifer forest of sorrel type passed by thinning with intensity of 10 to 30 % in homogeneous soil conditions. Temporary sample plots measuring 0.25 hectares were laid by conventional forestry techniques considering OСT 56-69-83. Accounting of trees and calculation of the commodity structure of forest stands was conducted by conventional taxational methods.

The spatiotemporal distribution pattern of the aerosol optical depth (AOD) is influenced by many environmental factors, such as meteorological condition changes, atmospheric pollution, and topographic changes. Understanding the relationship between the vegetation land cover and the AOD would favor the improvement of forest ecosystem services. This quantitative research integrated remote sensing and ground survey data and used spatial statistical methods to explore the drivers that influence the AOD of the exurban national forest park and analyze the differences between various forest types. The driver analysis was carried out in the hot (Z ≥ 1.64) and cold (Z ≤ −1.64) spots of AOD in 2010 and 2017. Our results showed that (1) the forest type was proved to be the main factor contributing to the AOD pattern and (2) from 2010 to 2017, the average growth rate of broad-leaved forest, coniferous forest, bamboo, and shrub in hot spots was significantly higher than that in cold spots, while there was no significant difference in the mixed forest. The average growth rate of biomass densities of bamboo, coniferous forest, and mixed forest were higher than that of the shrub and broad-leaved forest. These findings provided the guidance for the rational allocation of tree species to increase the biomass and improve the ecosystem service values of forest parks.

The European heatwave of 2018 led to record-breaking temperatures and extremely dry conditions in many parts of the continent resulting in widespread decrease in agricultural yield, early tree-leaf senescence, and increase in forest fires in Northern Europe. Our study aims to capture the impact of the 2018 European heatwave on terrestrial ecosystem through the lens of a high-resolution solar-induced fluorescence (SIF) data acquired from the Orbiting Carbon Observatory (OCO-2) satellite. SIF is proposed to be a direct proxy for gross primary productivity (GPP) and thus can be used to draw inferences about changes in photosynthetic activity in vegetation due to extreme events. We explore spatial and temporal SIF variation and anomaly during spring and summer months across different vegetation types (agriculture, broadleaved forest, coniferous forest, and mixed forest) during the European heatwave of 2018 and compare it to non-drought conditions (most of Southern Europe). About one-third of Europe&rsquo;s land area experienced a consecutive spring and summer drought in 2018. Comparing 2018 to mean (2015-2017) conditions, we found a change in intra-spring season SIF dynamics for all vegetation types, with lower SIF during the start of spring followed by an increase in fluorescence from mid-April. Summer, however, showed a significant decrease in SIF. Our results show that particularly agricultural areas were severely affected by the hotter drought of 2018. Furthermore, the intense heat wave in Central Europe showed about 31% decrease in SIF values during July and August as compared to the mean over three previous years. Furthermore, our MODIS and OCO-2 comparative results indicate that especially for forests, OCO-2 SIF has a quicker response and possible higher sensitivity to drought in comparison to MODIS&rsquo;s fPAR and NDVI when considering shorter reference periods, which highlights the added value of remotely sensed solar-induced fluorescence for studying the impact of drought on vegetation.