Factors promoting larch dominance in central Siberia: fire versus growth performance and implications for carbon dynamics at the boundary of evergreen and deciduous conifers
The relative roles of fire and climate in determining canopy species composition andaboveground carbon stocks were investigated. Measurements were made along a transectextending from the dark taiga zone of Central Siberia, where Picea and Abiesdominate the 5 canopy, into the Larix zone of Eastern Si...
| Published in: | Biogeosciences |
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| Main Authors: | , , , , , , , , |
| Language: | English |
| Published: |
COPERNICUS GESELLSCHAFT MBH
2012
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| Subjects: | |
| Online Access: | https://publications.jrc.ec.europa.eu/repository/handle/JRC68624 http://www.biogeosciences.net/9/1405/2012/bg-9-1405-2012.html https://doi.org/10.5194/bg-9-1405-2012 |
| Summary: | The relative roles of fire and climate in determining canopy species composition andaboveground carbon stocks were investigated. Measurements were made along a transectextending from the dark taiga zone of Central Siberia, where Picea and Abiesdominate the 5 canopy, into the Larix zone of Eastern Siberia. We test the hypothesesthat the change in canopy species composition is based (1) on climate-driven performanceonly, (2) on fire only, or (3) on fire-performance interactions. We show that theevergreen conifers Picea obovata and Abies sibirica are the natural late-successionalspecies both in Central and Eastern Siberia, provided there has been no fire for an10 extended period of time. There are no changes in the climate-driven performance ofthe observed species. Fire appears to be the main factor explaining the dominance ofLarix. Of lesser influence were longitude, hydrology and active-layer thickness.Stand-replacing fires decreased from 300 to 50 yr between the Yenisei Ridge and theupper Tunguska. Repeated non-stand-replacing surface fires eliminated the regenera15tion of Abies and Picea. With every 100 yr since the last fire, the percentage of Larixdecreased by 20 %.Biomass of stems of single trees did not show signs of age-related decline. Relativediameter increment was 0.41±0.20% at breast height and stem volume increasedlinearly over time with a rate of about 0.36 tCha−1 yr−1 independent of age class and20 species. Stand volumes reached about 130 tCha−1 (equivalent to about 520m3 ha−1).Individual trees of Larix were older than 600 yr. The maximum age and biomassseemed to be limited by fungal rot of heart wood. 60% of old Larix and Picea and30% of Pinus sibirica trees were affected by stem rot. Implications for the future roleof fire and of plant diseases are discussed. JRC.H.3 - Forest Resources and Climate |
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