Background and Purpose: The declining and dieback of lowland oak forests as the result of global climate change, as well as the attack of various pathogenic organisms, industrial pollution, and other negative effects reduce acorn yield and will continue to do so in the future. As a result of this fact, the areas on which artificial regeneration will be applied by planting seedlings will have to be increased. The artificial regeneration process is more expensive than the natural one, so protection measures need to be applied to minimize the loss of young seedlings. Materials and Methods: Experimental plots were set up in the forest area of Spačva Basin. A completely randomized block design experiment in four repetitions was used, in which four variants of planting and protection of oak seedlings were examined. We tested polypropylene tree shelters and hydrophilic superabsorbent based on maize starch. Heights of the plants were measured by measuring tape, and survival was registered by numbering of dead and living plants. For statistical purposes, we have used analysis of variance (repeated measure ANOVA), which allows us to prove statistically significant difference between morphological traits of studied variants. Results: Two years after planting, the lowest level of survival was found in unprotected seedlings (79.5%), while tree shelters provided the best conditions for seedlings survival (88.75%). In the case with the hydrophilic granules Zeba the result is slightly worse. When analyzing average height in a particular case, significantly higher plants are recorded in cases where the polypropylene tree shelters are used. The average height, with tree shelters (128.27 cm), is more than three times higher than the unprotected seedlings (37.97 cm). The addition of hydrophilic granules did not show a statistically significant difference. In cases where the seedlings were not under the tree shelter protection, the effect of hydrophilic granules was also not statistically significant. Conclusions: Sheltering accelerated the height growth of the planted oaks substantially and also provided best conditions for seedlings survival. During the research period the usage of Zeba did not justify the purpose for which it was applied. Although the first results are promising in order to gain a complete insight into the potential of tree shelters it is necessary to record the changes and maintain the experiment for a further 2-3 years with quantification of other harmful factors that may appear (drought, game etc.) after which a more reliable judgment regarding their usefulness could be provided.
Background and Purpose:The process of joining the market competition by the company "Croatian Forests", managing state forests in Croatia, is related to the transformation of the company into a trading company. This means that beside the biological and ecological goals in managing forests, the special attention is to be paid to business operations with the highest economic outputs, reduced costs and increased income. In order to enhance the regeneration of pedunculate oak forests in present day changing ecological and challenging economic conditions, as our proposal, is implementation of one of the artificial methods of regeneration pedunculate oak forests by planting seedlings protected with polypropylene tree shelters. Materials and Methods:The paper deal with existing knowledge about the conditions and characteristics of two methods of oak stand regeneration and analyzed data of current norms, standards and prices for each of these methods. The analysis compared the two methods: method of regeneration with unprotected seedlings, and seedlings protected with polypropylene tree shelters. Results and Conclusions:The research results showed that in comparison to the common seedling planting method, this method of pedunculate oak stand regeneration on difficult terrains with complex stand conditions is ecologically and economically more beneficial. Abstract Citation: LIOVIĆ B, TOMAŠIĆ Ž, STANKIĆ I 2013 Ecological and Economic Advantages of Using Polypropylene Tree Shelters in Lowland Oak Forests. South-East Eur For 4 (2): 115-125 LIOVIC B, TOMAŠIĆ Ž, STANKIĆ I 116 SEEFOR 4 (2): 115-125 © CFRI http://www.seefor.eu
U radu se istražuje povezanost postupaka pridobivanja drva i kretanja natječajnih cijena drva na panju. Istraživanje je provedeno na uzorku koji obuhvaća jednu šumsku regiju u Rumunjskoj, a cilj je bio utvrditi u kojoj mjeri pokazatelji pridobivanja prodanog drva utječu na natječajne cijene. Korišteni podaci Regionalne uprave šuma Baia Mare (RFA Baia Mare), Maramureş (slika 1), koja se sastoji od 13 šumarija, čine ugovore o sječi kroz tri godine gospodarenja (2012–2014). Autori smatraju da se navedeni podaci mogu smatrati reprezentativnim za rumunjske uvjete te mogu poslužiti kao ogledni primjer za svrhu istraživanja u ovoj studiji. Na temelju uzorka od 1192 potpisana ugovora, koji su obuhvaćali više od 20.000 ha sječne površine i više od 600.000 m<sup>3</sup> užite drvne zalihe, na temelju deskriptivne statistike, dobiveni su modeli predviđanja budućih natječajnih cijena, ovisno o raznovrsnosti uvjeta pri pridobivanju drva. Značajke sustava pridobivanja drva kao što su: 1. vrsta sječe, 2. veličina sječine, 3. sječna gustoća, 4. dimenzije stabla, 5. nagib terena i 6. srednja udaljenost privlačenja drva, imali su prilično slab učinak na iznose natječajnih (početnih) (R<sup>2</sup> = 0,20) i prodajnih (ostvarenih) cijena (R<sup>2</sup> = 0,17), što pokazuje da se preostala varijabilnost cijena može odnositi i na druge čimbenike. Nije bilo jasno izraženih odnosa između odstupanja pokazatelja u sustavu pridobivanja drva i razlika u cijeni koju su ponuđači plaćali za kupnju drva na panju. Stoga je provedena detaljnija analiza cijena kako bi se vidjelo do koje se mjere cijene mogu objasniti promjenama u odnosu na ponudu i potražnju. Analiza je pokazala da je u razdoblju istraživanja došlo do povećanja potražnje drva na panju, istodobno i uz veću potražnju za vrstama četinjača. Rezultati ove studije mogli bi pomoći šumovlasnicima/šumoposjednicima pri gospodarenju šumama, ali i privatnim poduzetnicima u šumarstvu prilikom planiranja i vođenja njihovog poslovanja.
Na osnovi poznavanja dimenzijskih značajki skidera s vitlom (osnovne dimenzije, masa vozila, položaj točke težišta), razvijen je model procjene kretnosti skidera za privlačenje drva uz nagib terena na siguran, djelotvoran i okolišno prihvatljiv način. Model je zasnovan na graničnom nagibu kretnosti skidera temeljem vučne značajke vozila, koji povezuje dva istraživačka pristupa, 1) vozilo – teren (raspodjela sila ovisno nagibu i vučenom teretu) te 2) kotač – tlo (procjena vučnih značajki skidera temeljem indeksa kotača), uz poštivanje niza ograničenja proisteklih iz prethodnih istraživanja: i) rasterećenja prednje osovine vozila, ii) preopterećenja stražnje osovine vozila, iii) najmanje uzdužne stabilnosti skidera, iv) najmanje nosivosti šumskog tla te v) dopuštenog opterećenja pneumatika. Rezultati simulacijskog modeliranja procjene kretnosti skidera s vitlom Ecotrac 55V opremljenoga pneumaticima 12.4-24 pri privlačenju drva uz nagib terena, značajno se razlikuju s obzirom na uvjete nosivosti podloge te masu vučenih tereta. Kod manjih tereta, mase do 1 tone, kretnost skidera određuju kriteriji/ograničenja graničnoga nagiba kretnosti vozila (vučna značajka) i okolišne pogodnosti (najmanja nosivost podloge). Porastom težine tereta, osim nosivosti šumskog tla, odlučujući ograničavajući čimbenik kretnosti postaje odnos opterećenja prednje i stražnje osovine vozila (>1 : 3,5), koji ograničava kretnost skidera na terene nagiba <33 % kod tereta od 1,5 tone, tj. <20 % kod tereta od 2 tone. Kod tereta od 2,5 tone, na kretnost skidera, utječu kriteriji najvećeg dopuštenog opterećenja stražnje osovine skidera na nagibima <7 %.
In any planning, so even when planning the network of forest roads, it is an imperative to know the existing situation, and to have a detailed and accurate insight into the existing forest road network of the forest area in the process of opening, usually enabled by the forest traffic infrastructure registry. To validate the quantity of the existing forest traffic infrastructure (road density), it is necessary to precisely and unambiguously define the criteria for determining the density of existing forest traffic infrastructure. In Croatian forestry, the currently valid criteria for determining the density of primary forest traffic infrastructure are defined by the »Technical Requirements for Economic Roads« (Šikić et al. 1989), which are summarised in the Forestry Management Regulations (NN 111/06, NN 141/08) and (NN 79/15). The criteria mentioned are insufficiently precise and unclear, which leaves the forestry experts to make a series of subjective decisions in calculating the density of primary forest traffic infrastructure. To avoid/reduce any subjectivity, to obtain objective data and to make comparability of the calculated primary traffic infrastructure density of different management units, a set of completely criteria have been developed that will serve to accurately, objectively and transparently determine primary forest traffic infrastructure density. The criteria have been developed and described in detail in the Form for the Effectiveness Study of Primary Forest Road Traffic Infrastructure, an integral part of the Bylaw on measure implementation M04 »Investments in physical assets«, by-measure 4.3 »Grant for investments in development, modernization and customization of agriculture and forestry«, operation type 4.3.3. »Investments in forest infrastructure« from the Program of Rural Development in the Republic of Croatia in the period from 2014 to 2020 (NN 106/15, 65/17). The most frequent/characteristical examples of the application of criteria in determining the primary forest traffic infrastructure density are presented in the paper based on orthophoto maps together with photographs (image part of the primary forest traffic infrastructure registry from case studies).
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