title: Above-ground biomass and structure of pristine Siberian Scots pine forests as controlled by competition and fire.
abstract: The study presents a data set of above-ground biomass (AGB), structure, spacing and fire regime, for 24 stands of pristine Siberian Scots pine (Pinus sylvestris) forests with lichens (n = 20) or Vaccinium/mosses (n = 4) as ground cover, along four chronosequences. The stands of the "lichen" site type (LT) were stratified into three chronosequences according to stand density and fire history. Allometric equations were established from 90 sample trees for stem, coarse branch, fine branch, twig and needle biomass. The LT stands exhibited a low but sustained biomass accumulation until a stand age of 383 years. AGB reached only 6-10 kgdwm-2after 200 years depending on stand density and fire history compared to 20 kgdwm-2in the "Vaccinium" type (VT) stands. Leaf area index (LAI) in the LT stands remained at 0.5-1.5 and crown cover was 30-60%, whereas LAI reached 2.5 and crown cover was >100% in the VT stands. Although nearest-neighbour analyses suggested the existence of density-dependent mortality, fire impact turned out to have a much stronger effect on density dynamics. Fire scar dating and calculation of mean and initial fire return intervals revealed that within the LT stands differences in structure and biomass were related to the severity of fire regimes, which in turn was related to the degree of landscape fragmentation by wetlands. Self-thinning analysis was used to define the local carrying capacity for biomass. A series of undisturbed LT stands was used to characterise the upper self-thinning boundary. Stands that had experienced a moderate fire regime were positioned well below the self-thinning boundary in a distinct fire-thinning band of reduced major axis regression slope -0.26. We discuss how this downward shift resulted from alternating phases of density reduction by fire and subsequent regrowth. We conclude that biomass in Siberian Scots pine forests is strongly influenced by fire and that climate change will affect ecosystem functions predominantly via changes in fire regimes.
authors.affiliation: Max-Planck-Institut für Biogeochemie, P.O.Box 100164, D-07743 Jena, Germany e-mail: cwirth@bgc-jena.mpg.de, , , , , , DE.
authors.forename: C
authors.initials: C
authors.lastname: Wirth
authors.affiliation: Max-Planck-Institut für Biogeochemie, P.O.Box 100164, D-07743 Jena, Germany e-mail: cwirth@bgc-jena.mpg.de, , , , , , DE.
authors.forename: E-D
authors.initials: ED
authors.lastname: Schulze
authors.affiliation: Lehrstuhl Pflanzenphysiologie, Universität Tübingen, Auf der Morgenstelle 1, D-72076 Tübingen, Germany, , , , , , DE.
authors.forename: W
authors.initials: W
authors.lastname: Schulze
authors.affiliation: Max-Planck-Institut für Biogeochemie, P.O.Box 100164, D-07743 Jena, Germany e-mail: cwirth@bgc-jena.mpg.de, , , , , , DE.
authors.forename: D
authors.initials: D
authors.lastname: von Stünzner-Karbe
authors.affiliation: Department of Biophysics and Chemical Physics, Comenius University, Mlynska Dolina F1, SK-842 15, Bratislava, Slovac Republic, , , ,.
authors.forename: W
authors.initials: W
authors.lastname: Ziegler
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: I M
authors.initials: IM
authors.lastname: Miljukova
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: A
authors.initials: A
authors.lastname: Sogatchev
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: A B
authors.initials: AB
authors.lastname: Varlagin
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: M
authors.initials: M
authors.lastname: Panvyorov
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: S
authors.initials: S
authors.lastname: Grigoriev
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: W
authors.initials: W
authors.lastname: Kusnetzova
authors.affiliation: Max-Planck-Institut für Biogeochemie, P.O.Box 100164, D-07743 Jena, Germany e-mail: cwirth@bgc-jena.mpg.de, , , , , , DE.
authors.forename: M
authors.initials: M
authors.lastname: Siry
authors.affiliation: Max-Planck-Institut für Biogeochemie, P.O.Box 100164, D-07743 Jena, Germany e-mail: cwirth@bgc-jena.mpg.de, , , , , , DE.
authors.forename: G
authors.initials: G
authors.lastname: Hardes
authors.affiliation: Lehrstuhl für Pflanzenökologie, Universität Bayreuth, Universitätsstr. 30, D-95440 Bayreuth, Germany, , , , , , DE.
authors.forename: R
authors.initials: R
authors.lastname: Zimmermann
authors.affiliation: Sukachev's Laboratory of the Institute of Evolution and Ecology Problems, Russian Academy of Sciences, Leninsky Prospect 33, 117071 Moscow, Russia, , , , , , RU.
authors.forename: N N
authors.initials: NN
authors.lastname: Vygodskaya
keywords: Biomass; Forest fire; Key wordsPinus sylvestris; Self-thinning; Siberia