scholarly journals ԿԱՂՆՈՒ ՀԱՄԱԿԵՑՈՒԹՅՈՒՆՆԵՐԻ ՎԵՐԱՐՏԱԴՐՈՒԹՅԱՆ ԽՆԴԻՐՆԵՐԸ ՀԱՅԱՍՏԱՆՈՒՄ

2021 ◽  
pp. 58-61
Author(s):  
H. P. Khurshudyan ◽  
K. A. Gharakhanyan ◽  
R. S. Petrosyan
Keyword(s):  
Adverse Effect ◽  
Forest Management ◽  
Tree Species ◽  
Human Factor ◽  
Oak Forest ◽  
Oak Seedlings

The aim of the research is to study the natural regrowth of the oak and to detect the most endangered forest areas. As compared to the data recorded in 1990, the oak seedlings and saplings have considerably decreased and unfavorable succession of tree species in the oak-forest have occurred as a consequence of adverse effect of human factor and improper forest management. To prevent the undesired processes it is recommended to conduct comprehensive research and to present scientifically justified reclamation ways.

scholarly journals Forest summer albedo is sensitive to species and thinning: how should we account for this in Earth system models?

2014 ◽  
Vol 11 (8) ◽  
pp. 2411-2427 ◽  
Author(s):  
J. Otto ◽  
D. Berveiller ◽  
F.-M. Bréon ◽  
N. Delpierre ◽  
G. Geppert ◽  
...  
Keyword(s):  
Forest Management ◽  
Tree Species ◽  
Near Infrared ◽  
Model Parameters ◽  
Earth System ◽  
Forest Thinning ◽  
Area Index ◽  
System Models ◽  
Maximum Change ◽  
Earth System Models

Abstract. Although forest management is one of the instruments proposed to mitigate climate change, the relationship between forest management and canopy albedo has been ignored so far by climate models. Here we develop an approach that could be implemented in Earth system models. A stand-level forest gap model is combined with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning on summertime canopy albedo. This approach reveals which parameter has the largest affect on summer canopy albedo: we examined the effects of three forest species (pine, beech, oak) and four thinning strategies with a constant forest floor albedo (light to intense thinning regimes) and five different solar zenith angles at five different sites (40° N 9° E–60° N 9° E). During stand establishment, summertime canopy albedo is driven by tree species. In the later stages of stand development, the effect of tree species on summertime canopy albedo decreases in favour of an increasing influence of forest thinning. These trends continue until the end of the rotation, where thinning explains up to 50% of the variance in near-infrared albedo and up to 70% of the variance in visible canopy albedo. The absolute summertime canopy albedo of all species ranges from 0.03 to 0.06 (visible) and 0.20 to 0.28 (near-infrared); thus the albedo needs to be parameterised at species level. In addition, Earth system models need to account for forest management in such a way that structural changes in the canopy are described by changes in leaf area index and crown volume (maximum change of 0.02 visible and 0.05 near-infrared albedo) and that the expression of albedo depends on the solar zenith angle (maximum change of 0.02 visible and 0.05 near-infrared albedo). Earth system models taking into account these parameters would not only be able to examine the spatial effects of forest management but also the total effects of forest management on climate.

scholarly journals Summertime canopy albedo is sensitive to forest thinning

2013 ◽  
Vol 10 (9) ◽  
pp. 15373-15414 ◽  
Author(s):  
J. Otto ◽  
D. Berveiller ◽  
F.-M. Bréon ◽  
N. Delpierre ◽  
G. Geppert ◽  
...  
Keyword(s):  
Forest Management ◽  
Tree Species ◽  
Structural Changes ◽  
Near Infrared ◽  
Canopy Structure ◽  
Model Parameters ◽  
Transfer Model ◽  
Forest Thinning ◽  
Crown Volume ◽  
The Difference

Abstract. Despite an emerging body of literature linking canopy albedo to forest management, understanding of the process is still fragmented. We combined a stand-level forest gap model with a canopy radiation transfer model and satellite-derived model parameters to quantify the effects of forest thinning, that is removing trees at a certain time during the forest rotation, on summertime canopy albedo. The effects of different forest species (pine, beech, oak) and four thinning strategies (light to intense thinning regimes) were examined. During stand establishment, summertime canopy albedo is driven by tree species. In the later stages of stand development, the effect of tree species on summertime canopy albedo decreases in favour of an increasing influence of forest thinning on summertime canopy albedo. These trends continue until the end of the rotation where thinning explains up to 50% of the variance in near-infrared canopy albedo and up to 70% of the variance in visible canopy albedo. More intense thinning lowers the summertime shortwave albedo in the canopy by as much as 0.02 compared to unthinned forest. The structural changes associated with forest thinning can be described by the change in LAI in combination with crown volume. However, forests with identical canopy structure can have different summertime albedo values due to their location: the further north a forest is situated, the more the solar zenith angle increases and thus the higher is the summertime canopy albedo, independent of the wavelength. Despite the increase of absolute summertime canopy albedo values with latitude, the difference in canopy albedo between managed and unmanaged forest decreases with increasing latitude. Forest management thus strongly altered summertime forest albedo.

scholarly journals Effect of Day or Night and Cumulative Shift Time on the Frequency of Tree Damage during CTL Harvesting in Various Stand Conditions

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 743 ◽  
Author(s):  
Mariusz Bembenek ◽  
Petros A. Tsioras ◽  
Zbigniew Karaszewski ◽  
Bogna Zawieja ◽  
Ewa Bakinowska ◽  
...  
Keyword(s):  
Forest Management ◽  
Human Factor ◽  
Stand Density ◽  
Age Classes ◽  
Tree Damage ◽  
Thinning Intensity ◽  
Thinning Operations ◽  
Work Shifts ◽  
Pine Stands ◽  
Stand Conditions

Thinning is one of the most important tools of forest management, although thinning operations require the use of machines which ultimately cause damage to the remaining stand. The level of damage largely depends on the human factor, and a tired, less focused operator will create more injuries in the forest. With this in mind, the objectives of this research were to find out whether the probability of tree damage caused by an operator is also affected by: (1) the part of the day (dawn/day/dusk/night), and (2) the cumulative shift time. The research was carried out in pure pine stands of different ages, density and thinning intensities. Sample plots were selected that had an increasing number of trees per hectare and growing thinning intensities were applied. The same Komatsu 931.1 harvester was used for the thinning operations in each stand. In all the age classes combined, 5.41% of the remaining trees were wounded. There was a significant influence of the part of the day on the percentage of damaged trees, which was positively correlated with the cumulative shift time. Stand conditions, such as age class and stand density, as well as thinning characteristics—thinning intensity, number of harvested trees and productivity—have different effects on the distribution of damage intensity and on probability. The results may improve the planning of operators’ work shifts in forests of various ages and densities, allowing harvester productivity to be maintained while at the same time inflicting the lowest possible level of damage.

scholarly journals Stand structure indices as tools to support forest management: an application in Trentino forests (Italy)

2013 ◽  
Vol 59 (No. 4) ◽  
pp. 159-168 ◽  
Author(s):  
F. Pastorella ◽  
A. Paletto
Keyword(s):  
Spatial Distribution ◽  
Forest Management ◽  
Species Diversity ◽  
Species Composition ◽  
Tree Species ◽  
Stand Structure ◽  
Composite Index ◽  
Mutual Position ◽  
Tree Species Composition ◽  
North East

Stand structure and species diversity are two useful parameters to provide a synthetic measure of forest biodiversity. The stand structure is spatial distribution, mutual position, diameter and height differentiation of trees in a forest ecosystem and it highly influences habitat and species diversity. The forest stand and species diversity can be measured through indices that provide important information to better address silvicultural practices and forest management strategies in the short and long-term period. These indices can be combined in a composite index in order to evaluate the complex diversity at the stand level. The aim of the paper is to identify and to test a complex index (S-index) allowing to take into account both the tree species composition and the stand structure. S-index was applied in a case study in the north-east of Italy (Trentino province). The results show that the Norway spruce forests in Trentino province are characterized by a medium-low level of complexity (S-index is in a range between 0.14 and 0.46) due to a low tree species composition rather than to the stand structure (diametric differentiation and spatial distribution of trees).  

When drought meets forest management: Effects on the soil microbial community of a Holm oak forest ecosystem

2019 ◽  
Vol 662 ◽  
pp. 276-286 ◽  
Author(s):  
F. Bastida ◽  
R. López-Mondéjar ◽  
P. Baldrian ◽  
M. Andrés-Abellán ◽  
N. Jehmlich ◽  
...  
Keyword(s):  
Microbial Community ◽  
Forest Management ◽  
Forest Ecosystem ◽  
Soil Microbial Community ◽  
Holm Oak ◽  
Oak Forest ◽  
Soil Microbial ◽  
Management Effects

Retrospective analysis of growth A contribution to sustainable forest management in the tropics

IAWA Journal ◽  
2017 ◽  
Vol 38 (3) ◽  
pp. 297-S21 ◽  
Author(s):  
Neda Lotfiomran ◽  
Michael Köhl
Keyword(s):  
Forest Management ◽  
Tropical Forests ◽  
Tree Ring ◽  
Tree Rings ◽  
Tree Species ◽  
Sustainable Forest Management ◽  
Cedrela Odorata ◽  
Tree Ring Analysis ◽  
Hymenaea Courbaril ◽  
Ring Analysis

Reliable information on tree growth is a prerequisite for sustainable forest management (SFM). However, in tropical forests its implementation is often hampered by insufficient knowledge of the growth dynamics of trees. Although tree ring analysis of tropical trees has a long history, its application for SFM has only recently been considered. In the current study, we illustrate both the potentials and limitations of a retrospective growth assessment by tree ring analysis under the prevailing tropical conditions in a Surinamese rain forest. For this purpose, 38 commercial tree species were screened and grouped into three categories according to the visibility of their tree ring boundaries: (I) tree rings absent or indistinct, (II) distinct but partially vague tree rings which enable approximate age estimation, (III) very distinct tree rings. In 22 out of 38 commercial tree species distinct to very distinct tree ring boundaries could be identified. The anatomy of tree ring boundaries was described following Worbes and Fichtler (2010). Four species with distinct growth rings, Cedrela odorata, Hymenaea courbaril, Pithecellobium corymbosum and Goupia glabra, were studied in greater detail. Time-series analysis was used to characterise their radial growth. From the tree ring width, the annual diameter increment and cumulative diameter growth were calculated to find long-term growth patterns. Pithecellobium corymbosum and partially Hymenaea courbaril followed a typical S-shaped growth curve. By contrast, Goupia glabra and Cedrela odorata did not exhibit an age-related decrease of growth, but showed a constant linear growth over their entire life span. If based on more sample trees, such data can provide target-oriented information for improving SFM in tropical forests.

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