scholarly journals Horizontal structure of forest stands on permanent research plots in the Krkonoše Mts. and its development

2010 ◽  
Vol 56 (No. 11) ◽  
pp. 531-540 ◽  
Author(s):  
D. Zahradník ◽  
S. Vacek ◽  
L. Bílek ◽  
I. Nosková ◽  
Z. Vacek
Keyword(s):  
Large Scale ◽  
Juvenile Growth ◽  
Forest Stands ◽  
Mixed Stands ◽  
Artificial Regeneration ◽  
Horizontal Structure ◽  
Tree Layer ◽  
Spruce Stands ◽  
Evans Index ◽  
Developmental Phases

Horizontal structure on 38 permanent research plots is described for juvenile growth and developmental phases (natural seeding, advance growth, plantations) and tree layer of a parent stand. Hopkins-Skellam index, Pielou-Mountford index, Clark-Evans index and Ripley's K-function were computed. The results are presented separately for beech stands, mixed stands, spruce stands, stands in the timberline ecotone and relict pinewood. The numbers and distribution of natural and combined regeneration recruits are mostly sufficient from the aspect of ecological, environmental and production functions of forest. The horizontal structure of juvenile growth and developmental phases of natural and combined regeneration shows mostly clustering; it is random or moderately regular at places with a single dominant proportion of artificial regeneration. In the tree layer the horizontal structure of forest stands is mostly random to moderately regular. In the future silvicultural measures should be aimed to support the structure of homogeneous stands of younger growth phases that have originated on a large scale after the air-pollution disaster.

scholarly journals Regeneration of forest stands on permanent research plots in the Krkonoše Mts.

2010 ◽  
Vol 56 (No. 11) ◽  
pp. 541-554 ◽  
Author(s):  
S. Vacek ◽  
I. Nosková ◽  
L. Bílek ◽  
Z. Vacek ◽  
O. Schwarz
Keyword(s):  
Forest Regeneration ◽  
Developmental Stages ◽  
Forest Stands ◽  
Mixed Stands ◽  
Artificial Regeneration ◽  
Structure And Dynamics ◽  
Spruce Stands ◽  
Forest Limit ◽  
Environmental Limits ◽  
Stand Conditions

The article describes natural, combined and artificial regeneration on 38 permanent research plots in both Czech and Polish part of the Krkonoše Mts. The attention is paid to species composition, spatial (horizontal and vertical) and age structure of forest regeneration according to different stand and site conditions. Concerning the structure and dynamics of forest stands and their regeneration, the potential and prospects of regeneration according to particular developmental stages and stand types (beech stands; mixed stands: spruce-beech, fir-beech, spruce-fir-beech; spruce stands, stands in the ecotone of the upper forest limit and relict pine woods) were evaluated. In many aspects the plots show several similarities, nevertheless the regeneration in different site and stand conditions show clear differences in dynamics of development. The main differences are result of different ecological conditions, environmental limits and biological characteristics of dominant tree species.

scholarly journals Biological activity, nitrogen dynamics, and chemical characteristics of forest soils in the Šumava national park

2012 ◽  
Vol 49 (No. 7) ◽  
pp. 302-312 ◽  
Author(s):  
M. Svoboda
Keyword(s):  
Forest Soils ◽  
National Park ◽  
Large Scale ◽  
Ground Vegetation ◽  
Mountain Forest ◽  
Respiration Activity ◽  
Forest Sites ◽  
Tree Layer ◽  
Spruce Stands ◽  
Microclimatic Conditions

This paper deals with large-scale mountain forest decline in the Šumava National Park. The changes in biotic and abiotic properties of forest sites follow the tree layer disintegration. Changed microclimatic conditions such as intensity of irradiance, moisture and temperature of the top holorganic layers together with altered development of ground vegetation could strongly affect the values of microbiological respiration activity and the rates of nitrogen mineralization and nitrification. Soil substrates, built of organic mater, located on stony locations, are endangered by introskeletal erosion. This paper compares these features in pairs of research plots, consisting of dead or cut forest and of living stand. According to the results of this study, higher rates of organic matter decomposition, transformed dynamics of nitrogen and other nutrients and possible nutrient leaching from soil solutions were demonstrated in the forest floor under declined spruce stands. The extent and seriousness of these adverse processes for forest soils are strongly site dependent.

scholarly journals Distribution of the timber quality attribute ‘knot surface’ in logs of Fagus sylvatica L. from pure and mixed forest stands

2021 ◽  
Author(s):  
Kirsten Höwler ◽  
Torsten Vor ◽  
Peter Schall ◽  
Peter Annighöfer ◽  
Dominik Seidel ◽  
...  
Keyword(s):  
Fagus Sylvatica ◽  
Mixed Forest ◽  
European Beech ◽  
Forest Stands ◽  
Species Identity ◽  
Mixed Stands ◽  
Mixed Forests ◽  
Climate Conditions ◽  
Timber Quality ◽  
Positive Effects

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.

scholarly journals Constrained Urban Airspace Design for Large-Scale Drone-Based Delivery Traffic

Aerospace ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 38
Author(s):  
Malik Doole ◽  
Joost Ellerbroek ◽  
Victor L. Knoop ◽  
Jacco M. Hoekstra
Keyword(s):  
Traffic Congestion ◽  
Urban Areas ◽  
Large Scale ◽  
Cost Savings ◽  
Future Research ◽  
Fast Time ◽  
Potential Cost ◽  
Horizontal Structure ◽  
Traffic Demand ◽  
Demand Patterns

Large-scale adoption of drone-based delivery in urban areas promise societal benefits with respect to emissions and on-ground traffic congestion, as well as potential cost savings for drone-based logistic companies. However, for this to materialise, the ability of accommodating high volumes of drone traffic in an urban airspace is one of the biggest challenges. For unconstrained airspace, it has been shown that traffic alignment and segmentation can be used to mitigate conflict probability. The current study investigates the application of these principles to a highly constrained airspace. We propose two urban airspace concepts, applying road-based analogies of two-way and one-way streets by imposing horizontal structure. Both of the airspace concepts employ heading-altitude rules to vertically segment cruising traffic according to their travel direction. These airspace configurations also feature transition altitudes to accommodate turning flights that need to decrease the flight speed in order to make safe turns at intersections. While using fast-time simulation experiments, the performance of these airspace concepts is compared and evaluated for multiple traffic demand densities in terms of safety, stability, and efficiency. The results reveal that an effective way to structure drone traffic in a constrained urban area is to have vertically segmented altitude layers with respect to travel direction as well as horizontal constraints imposed to the flow of traffic. The study also makes recommendations for areas of future research, which are aimed at supporting dynamic traffic demand patterns.

Derivation of Pheromone-Based Larval Thresholds in Spruce Budworm Accounting for Distance to Defoliated Forest Stands

2021 ◽  
Author(s):  
Marc Rhainds ◽  
Ian DeMerchant ◽  
Pierre Therrien
Keyword(s):  
Boreal Forests ◽  
Large Scale ◽  
Choristoneura Fumiferana ◽  
Intervention Strategy ◽  
Spruce Budworm ◽  
Interactive Effects ◽  
The Novel ◽  
Forest Stands ◽  
General Guideline ◽  
Number Of Males

Abstract Spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is the most severe defoliator of Pinaceae in Nearctic boreal forests. Three tools widely used to guide large-scale management decisions (year-to-year defoliation maps; density of overwintering second instars [L2]; number of males at pheromone traps) were integrated to derive pheromone-based thresholds corresponding to specific intergenerational transitions in larval densities (L2i → L2i+1), taking into account the novel finding that threshold estimates decline with distance to defoliated forest stands (DIST). Estimates of thresholds were highly variable between years, both numerically and in terms of interactive effects of L2i and DIST, which limit their heuristic value. In the context of early intervention strategy (L2i+1 > 6.5 individuals per branch), however, thresholds fluctuated within relatively narrow intervals across wide ranges of L2i and DIST, and values of 40–200 males per trap may thus be used as general guideline.

scholarly journals Influence of trees and associated variables on soil organic carbon: a review

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Angom Sarjubala Devi
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Significant Negative Correlation ◽  
Mean Annual Temperature ◽  
Forest Stands ◽  
Mixed Stands ◽  
Silt Fraction ◽  
Different Types ◽  
Soil Climate ◽  
Associated Variables

AbstractThe level of soil organic carbon (SOC) fluctuates in different types of forest stands: this variation can be attributed to differences in tree species, and the variables associated with soil, climate, and topographical features. The present review evaluates the level of SOC in different types of forest stands to determine the factors responsible for the observed variation. Mixed stands have the highest amount of SOC, while coniferous (both deciduous-coniferous and evergreen-coniferous) stands have greater SOC concentrations than deciduous (broadleaved) and evergreen (broadleaved) tree stands. There was a significant negative correlation between SOC and mean annual temperature (MAT) and sand composition, in all types of forest stands. In contrast, the silt fraction has a positive correlation with SOC, in all types of tree stands. Variation in SOC under different types of forest stands in different landscapes can be due to differences in MAT, and the sand and silt fraction of soil apart from the type of forests.

Competition theory — science and application in mixed forest stands: review of experimental and modelling methods and suggestions for future research

2013 ◽  
Vol 21 (2) ◽  
pp. 71-84 ◽  
Author(s):  
Guy R. Larocque ◽  
Nancy Luckai ◽  
Shailendra N. Adhikary ◽  
Arthur Groot ◽  
F. Wayne Bell ◽  
...  
Keyword(s):  
Mixed Forest ◽  
Single Species ◽  
Experimental Designs ◽  
Competitive Interactions ◽  
Future Research ◽  
Relative Importance ◽  
Forest Stands ◽  
Management Scenarios ◽  
Mixed Stands ◽  
Individual Tree

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.

scholarly journals The contribution of natural and artificial regeneration at the restoration of fire-affected peri-urban forest of Thessaloniki (Northern Greece)

2017 ◽  
Vol 19 (1) ◽  
pp. 29-36
Keyword(s):  
Natural Regeneration ◽  
Urban Forest ◽  
Burned Area ◽  
Cupressus Sempervirens ◽  
Northern Greece ◽  
Mixed Stands ◽  
Artificial Regeneration ◽  
Pinus Brutia ◽  
Stem Quality ◽  
Cupressus Arizonica

<p>In this study, the post-fire regeneration of three coniferous species (<em>Pinus brutia, Cupressus sempervirens </em>and<em> Cupressus arizonica)</em> was examined in the peri-urban forest of Thessaloniki, Northern Greece. The wildfire took place in July 1997 and burned almost 60% of the forest vegetation. During the autumn of 2010, 34 experimental plots were established in all aspects within the burned area. In each experimental plot the following measurements were carried out: height, diameter at breast height and crown projection in two perpendicular diameters. The results show that the <em>Pinus brutia </em>individuals, most of which came from natural regeneration, presented the best growth, in relation to the two other species in all aspects. As for <em>Cupressus sempervirens</em>, equal parts of which came from natural and artificial regeneration was characterized by remarkable growth especially in the Northeastern aspect. Finally, <em>Cupressus arizonica</em> existed in all aspects except the Northeastern. It also presented a satisfactory development, especially on the Southern aspect. Fourteen years after the fire pure or mixed stands of the above mentioned species show vigorous growth and good stem quality. Finally, the rates of participation of individual forest species indicate that the restoration has been achieved mainly by natural regeneration.</p>

scholarly journals The condition of forest stands on afforested agricultural land in the Orlické hory Mts

2017 ◽  
Vol 63 (No. 1) ◽  
pp. 1-8 ◽  
Author(s):  
Cukor Jan ◽  
Baláš Martin ◽  
Kupka Ivo ◽  
Tužinský Marek
Keyword(s):  
Agricultural Land ◽  
High Growth ◽  
Dry Mass ◽  
Growth Potential ◽  
Forest Stands ◽  
Tree Biomass ◽  
Humus Layer ◽  
The Status ◽  
Spruce Stands ◽  
High Growth Potential

The paper presents an evaluation of the growth of newly established forest stands on former agricultural land and furthermore describes the state of the upper part of the soils in these stands in comparison with neighbouring grassland in the Orlické hory Mountains. The new Norway spruce stands show an extremely high growth potential, usually significantly higher in comparison with areas forested for more generations/rotations. The formation of the surface humus layer also showed fast progress, the amount of dry mass of soil organic matter reaching values almost typical of permanently forested sites. The soils of newly afforested lands tend to resemble the status of forest soil – there was observed a process of acidification and nutrient depletion, probably connected with accumulation of the tree biomass.

scholarly journals Development of forest soils in the Krkonoše Mts. in the period 1980–2009

2010 ◽  
Vol 56 (No. 11) ◽  
pp. 485-504 ◽  
Author(s):  
K. Matějka ◽  
S. Vacek ◽  
V. Podrázský
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Large Scale ◽  
Vegetation Change ◽  
Soil Conditions ◽  
Available Phosphorus ◽  
Mountain Range ◽  
Site Conditions ◽  
Tree Species Composition ◽  
Spruce Stands

This paper documents the development of soil conditions in the set of 32 permanent research plots in the Krkono&scaron;e (Giant) Mts. These plots represent an altitudinal gradient covering the ecosystems of beech, mixed beech-spruce and spruce stands. In all plots, representing the site conditions of the highest areas of the mountain range, standard soil pits were prepared and the soil sampling was performed in autumn of years 1980, 1993, 1998, 2003 and 2009. The results reflect extreme site conditions, soil acidification, large scale surface liming and in minor extent also different tree species composition of the stands. The general type of the soil-genesis is represented by the podzolisation, overlapping the other soil-genetic factors, including the tree species composition. Nevertheless, this development is mostly expressed in the spruce stands. The beech dominance and/or co-dominance are reflected especially by more efficient N-cycling, higher pH, S and V values and fluctuation and lower extractable Al3+ content. More efficient cycling in beech ecosystems is insignificantly documented for plant available phosphorus, calcium and magnesium contents; on the contrary higher dynamics for iron ions was registered in the spruce stands. The long-term soil dynamics with a hysteresis (evident on the base of ordination analysis) can be divided into some periods &ndash; processes of acidification (typical in the 1980's samples), liming (main effect in 1993 and 1998) and regeneration (2003, 2009). Other features, important for the soil development, are probably related to the vegetation change, but this relation is not statistically significant.

Sign in / Sign up

Export Citation Format

Share Document