Factors promoting larch dominance in central Siberia: fire versus growth performance and implications for carbon dynamics at the boundary of evergreen and deciduous conifers

• Published in: Biogeosciences
• Main Authors: SCHULZE Ernest Detlef, WIRTH Christian, MOLLICONE Danilo, VON LUPKE N., ZIEGLER Waldemar, ACHARD Frederic, MUND Martina, PROKUSHKIN A, SCHERBINA S
• Language: English
• Published: COPERNICUS GESELLSCHAFT MBH 2012
• Subjects: Tunguska; taiga; Siberia
• 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

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