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Wyświetlanie 1-2 z 2
Tytuł:
Zmiany zachodzące w drzewostanach Bieszczadów
Changes in the forests of the Bieszczady Mts.
Autorzy:
Dmyterko, E.
Bruchwald, A.
Powiązania:
https://bibliotekanauki.pl/articles/985915.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
lasy gorskie
Bieszczady
drzewostany
sklad gatunkowy
zmiany w drzewostanach
zmiany skladu gatunkowego
model wzrostu drzewostanu
modele ryzyka uszkodzenia
species composition
stand growth model
model allowable cut
wind damage risk model
forest threat
measure
Opis:
The aim of the study was to analyse (on the basis of the data from the State Forests Information System) the changes occurring in the Bieszczady forests in the period of 2007−2016. One of the processes taking place in the study area is the withdrawal of grey alder stands and the appear− ance of natural regeneration of mainly beech and fir, and in a smaller proportion spruce (fig. 1). Another natural process is the encroachment of fir and beech under the canopy of pine stands, which is favoured by fertile habitats that meet the ecological requirements of these two tree species. As a result of economic activity supporting these processes, alder and pine stands are being rebuilt relatively quickly, turning into fir or beech stands, and sometimes into mixed stands with the participation of other tree species, including spruce (fig. 1). The decline of spruce stands occurs on the dominant area in Poland: in Beskid Śląski and Beskid Żywiecki, the Kaszuby Forest or the Białowieża Forest. The main causes of this process are abiotic and biotic factors, including frequent droughts causing the lowering of the groundwater level and insect outbreaks, especially of bark beetles. The proportion of spruce in the Bieszczady Mountains is relatively small (about 10%), and the high fertility of the habitats compensates, to some extent, the relatively high moisture requirements of this tree species and probably these factors determined the lack of decline of spruce stands in the analysed area. In the last 10 years, the average age of forests in the Bieszczady Mountains increased from 77 to 83 years (tab. 2), mainly as a result of too low volume of harvested timber (fig. 3). Comparing the total harvested volume with the volume of allowable cut determined by the stand growth model, the harvest of the wood raw material was understated by about 25%. The aging of forests is also confirmed by changes in stands in age classes (fig. 2). The aging of the Bieszczady forests is correlated with the process of increasing the threat to these forests by wind (figs. 4−5). The wind damage risk factor increased over the next 10 years in the two highest threat level, and thus the area of threatened stands increased. The forest threat measure in the Bieszczady forests increased in general as well as in individual forest districts (fig. 6). The forests in two of these districts are currently among the most threatened in Poland.
Źródło:
Sylwan; 2018, 162, 05; 355-364
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ocena szkód w lasach Polski spowodowanych przez huragan w sierpniu 2017 roku
Assessment of the damage to Polish forests caused by a hurricane in August 2017
Autorzy:
Dmyterko, E.
Bruchwald, A.
Powiązania:
https://bibliotekanauki.pl/articles/978974.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
wind−caused damage
risk model
stand growth model
allowable cut
Opis:
On August 11−12, 2017, a hurricane passed from south to north of Poland causing considerable damage to forests, especially in regional directorates of the State Forests in Wrocław, Poznań, Toruń, Szczecinek and Gdańsk. By the end of 2018, the volume of wind−broken and wind−fallen trees and deadwood approximated to 9 million m3. In 9 forest districts the harvested volume exceeded 440 thousand m3, including two entities with over 1 million m3 each. The harvested volume was expressed as a percentage of allowable cut, calculated from the stand growth model. It showed possibile timber harvest in final and intermediate cuts in the absence of natural disasters (strong wind, intense drought, heavy snowfall, insect outbreaks, etc.). In many forest districts, timber harvest accounted for 100% of the allowable cut, with the maximum value approximated to 1100% of the allowable cut. The high salvage harvest of post−hurricane timber prevents the execution of other economic tasks, including plans of stand rebuilding. On the example of forest districts with the largest damage, the possibilities of selecting forests classified as the most threatened by wind were examined. The wind damage risk model for the stand was used to determine the value of wind damage risk factor Wr for each stand (values from 0 to 3; the higher value, the higher risk). The damage risk factor allowed to create six damage risk classes of a span of 0.5 each and to assign individual stands to one of the damage classes. The share of the area of stands and damaged stands in Wr classes was also determined. In the Lipusz Forest District the share of stands in VI class of Wr was 9.8%, and the area of damaged stands in this class was 98.3%. In the Rytel and Przymuszewo forest districts, the areal share of such stands was 10.7% and 5.1%, respectively, and almost all stands in this class were damaged by the hurricane. The areal share of forests in the highest Wr class was reported in the Gniezno Forest District accounting for 4.8% and the hurricane damaged 85% of their area. The wind damage risk model for the stand allows to identify forests where damage is very likely to occur. It is, therefore, possible to take action on the rebuilding of stands before the wind comes and thus reduce its negative effects. The cutting plan should include, in the first place, stands classified to the high wind damage risk factor.
Źródło:
Sylwan; 2020, 164, 05; 355-364
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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