Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd
In Sweden, harvesting pre-commercial thinning (PCT) stems for energy purposes is a interesting way of financing the high cost of preparing dense stands for a profitable first conventional thinning. This concept can be labelled bioenergy thinning. The aim of this study was to quantify the producti...
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| Formato: | Otro |
| Lenguaje: | sueco sueco |
| Publicado: |
2007
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| Acceso en línea: | https://stud.epsilon.slu.se/11970/ |
| _version_ | 1855571975301234688 |
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| author | Ersson, Back Tomas |
| author_browse | Ersson, Back Tomas |
| author_facet | Ersson, Back Tomas |
| author_sort | Ersson, Back Tomas |
| collection | Epsilon Archive for Student Projects |
| description | In Sweden, harvesting pre-commercial thinning (PCT) stems for energy purposes is a interesting way of financing the high cost of preparing dense stands for a profitable first conventional thinning. This concept can be labelled bioenergy thinning.
The aim of this study was to quantify the productivity of a Vimek 404R light harvester with an accumulating Naarva-Grip cutting head during the bioenergy thinning of a self-regenerated stand west of Sunnansjö in Dalarna. The stand was birch-dominated, contained 15 371 stems/ha, and measured on average 4,6 cm Dbh and 7 m tall. Even though the driver was well experienced with the machine, the stand in question was the first one that he ever thinned in this manner. Nevertheless, the driver strived to accumulate as many stems as possible during each crane cycle and chose to cut taller stems in half so as to make the handling and forwarding of the harvested stems easier.
On average, the Vimek harvester required ca 57 effective hours per ha to harvest ca 56 ton dry matter (DM) per ha. Thus, the mean productivity measured 0,98 ton DM per effective hour, or expressed in other terms, 232 harvested stems per effective hour. The average Dbh of the harvested stems was 4,58 cm. Since there was between parcels only a small variation in stand characteristics, no statistical trend could be identified between productivity and mean height, mean Dbh and stem density. After the bioenergy thinning, there were on average 2 310 (mainly spruce) stems/ha left standing and ca 25 % of those stems was injured in some way. This high injury frequency was partly due to the form of the parcels as their form hindered an efficent work pattern, which also undoubtedly leads to a higher time requirement and lower productivity in general.
In spite of the high biomass content of the unthinned stand, the net cost of harvesting (felling-bunching) the juvenille stems with the Vimek 404R (with measured productivity) and then forwarding them to roadside with a Vimek 606 was very high. The machine system was calculated to cost almost eight times more per ha than if the same stand was PCT motor manually without harvesting the stems. However, the following could help to improve the productivity and make the concept more competitive compared with motor manual PCT: geometrical driving and crane patterns; stronger hydraulics in the harvester; a combination of mechanical bioenergy thinning and motor manual PCT where the latter is used to cut the smallest stems (<2,5 cm). |
| format | Otro |
| id | RepoSLU11970 |
| institution | Swedish University of Agricultural Sciences |
| language | Swedish swe |
| publishDate | 2007 |
| publishDateSort | 2007 |
| record_format | eprints |
| spelling | RepoSLU119702017-11-15T09:08:16Z https://stud.epsilon.slu.se/11970/ Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd Ersson, Back Tomas Dept. of Forest Resource Management Forestry production In Sweden, harvesting pre-commercial thinning (PCT) stems for energy purposes is a interesting way of financing the high cost of preparing dense stands for a profitable first conventional thinning. This concept can be labelled bioenergy thinning. The aim of this study was to quantify the productivity of a Vimek 404R light harvester with an accumulating Naarva-Grip cutting head during the bioenergy thinning of a self-regenerated stand west of Sunnansjö in Dalarna. The stand was birch-dominated, contained 15 371 stems/ha, and measured on average 4,6 cm Dbh and 7 m tall. Even though the driver was well experienced with the machine, the stand in question was the first one that he ever thinned in this manner. Nevertheless, the driver strived to accumulate as many stems as possible during each crane cycle and chose to cut taller stems in half so as to make the handling and forwarding of the harvested stems easier. On average, the Vimek harvester required ca 57 effective hours per ha to harvest ca 56 ton dry matter (DM) per ha. Thus, the mean productivity measured 0,98 ton DM per effective hour, or expressed in other terms, 232 harvested stems per effective hour. The average Dbh of the harvested stems was 4,58 cm. Since there was between parcels only a small variation in stand characteristics, no statistical trend could be identified between productivity and mean height, mean Dbh and stem density. After the bioenergy thinning, there were on average 2 310 (mainly spruce) stems/ha left standing and ca 25 % of those stems was injured in some way. This high injury frequency was partly due to the form of the parcels as their form hindered an efficent work pattern, which also undoubtedly leads to a higher time requirement and lower productivity in general. In spite of the high biomass content of the unthinned stand, the net cost of harvesting (felling-bunching) the juvenille stems with the Vimek 404R (with measured productivity) and then forwarding them to roadside with a Vimek 606 was very high. The machine system was calculated to cost almost eight times more per ha than if the same stand was PCT motor manually without harvesting the stems. However, the following could help to improve the productivity and make the concept more competitive compared with motor manual PCT: geometrical driving and crane patterns; stronger hydraulics in the harvester; a combination of mechanical bioenergy thinning and motor manual PCT where the latter is used to cut the smallest stems (<2,5 cm). Att skörda röjstammarna för bioenergiändamål är ett intressant sätt att finansiera röjningen av eftersatta röjningsbestånd då täta och höga ungskogsbestånd fördyrar den motormanuella röjningen. Detta koncept namnges här ”bioenergiröjning”. Syftet med denna studie var att tidsstudera en bioenergiröjande Vimek 404R med ett ackumulerande Naarva-Gripaggregat i ett tätt blandskogsbestånd väster om Sunnansjö i Dalarna. Beståndet var självföryngrat och hade ett stamantal på 15 371 st/ha. Den grundytevägda medel brösthöjdsdiameter och medelhöjd före åtgärd var 4,6 cm respektive 7 m. Trots att föraren var van med maskinen var detta det första bestånd som han bioenergiröjde på detta sätt. I medeltal skördades totalt ca 56 ton TS/ha och tidsåtgången vid bioenergiröjningen var ca 57 G0-tim/ha, vilket motsvarade en produktion på 0,98 ton TS/G0-tim. Vimekskördaren producerade i medeltal 232 avverkade stammar per G0-tim. Uttagets medeldiameter var densamma som hela beståndets. Utformningen av studiens parceller utgjorde ett hinder för ett produktivt arbetssätt och medförde bl.a. att ca 25 % av de i medeltal 2 310 kvarvarande stammarna per ha skadades vid bioenergiröjningen. Trots den stora biomassamängden per ha beräknades skörd och uttransport av röjstammarna med maskinsystemet kosta nästan åtta gånger mer än endast motormanuell röjning. Men med ett mer geometriskt kran- och körmönster, en skördare med starkare hydraulik och ev. en motormanuell förröjning av de klenaste stammarna (<2,5 cm) torde bioenergiröjning inom en snar framtid kunna bli konkurrenskraftigt med motormanuell röjning i liknande bestånd. 2007-03-19 Other NonPeerReviewed application/pdf sv https://stud.epsilon.slu.se/11970/1/ersson_b_171115.pdf Ersson, Back Tomas, 2007. Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd. UNSPECIFIED, Umeå. Umeå: (S) > Dept. of Forest Resource Management <https://stud.epsilon.slu.se/view/divisions/OID-260.html> urn:nbn:se:slu:epsilon-s-8808 swe |
| spellingShingle | Dept. of Forest Resource Management Forestry production Ersson, Back Tomas Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| title | Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| title_full | Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| title_fullStr | Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| title_full_unstemmed | Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| title_short | Produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| title_sort | produktivitet vid selektiv mekaniserad bioenergiröjning av eftersatta röjningsbestånd |
| topic | Dept. of Forest Resource Management Forestry production |
| url | https://stud.epsilon.slu.se/11970/ https://stud.epsilon.slu.se/11970/ |