Factors promoting larch dominance in central Siberia: fire versus growth performance and implications for carbon dynamics at the boundary of evergreen and deciduous conifers
Factors promoting larch dominance in central Siberia: fire versus growth performance and implications for carbon dynamics at the boundary of evergreen and deciduous conifers
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DOI：
10.5194/bg-9-1405-2012
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发表时间：
2012-04
期刊：
影响因子：
4.9
通讯作者：
E. Schulze;C. Wirth;D. Mollicone;N. Lüpke;W. Ziegler;F. Achard;M. Mund;A. Prokushkin;S. Scherbina
中科院分区：
文献类型：
--
作者：
E. Schulze;C. Wirth;D. Mollicone;N. Lüpke;W. Ziegler;F. Achard;M. Mund;A. Prokushkin;S. Scherbina
抽象的。研究了火和气候在决定冠层物种组成和地上碳储量方面的相对作用。测量是沿着从西伯利亚中部黑暗的针叶林地带延伸到东西伯利亚落叶松地带的横断面进行的，在那里云杉和冷杉占据了树冠。我们检验的假设是，树冠物种组成的变化是基于(1)仅基于气候驱动的表现，(2)仅基于火，或(3)基于火-表现的相互作用。我们的研究表明，在西伯利亚中部和东部没有发生火灾的情况下，常绿针叶树种倒卵云杉和西伯利亚冷杉是演替后期的天然树种。所观察到的物种在样带上的表现没有变化。火似乎是解释落叶松和土壤碳优势的主要因素。影响较小的是代表气候、当地水文和活动层厚度的经度。我们只能部分解释回火频率，这不仅与气候和土地覆盖有关，还与人类行为有关。在叶尼塞岭和通古斯卡上游之间，替代立地的火灾从300年减少到50年。反复的非林分替代地面火灾消除了冷杉和云杉的再生。自上次火灾以来，每隔100年，落叶松的百分比就会下降20%。单株树干生物量没有表现出随年龄增长而下降的迹象。胸径相对生长量为0.4 1±0.2 0%，材积随时间呈线性增长，其增长速率约为0.36tC ha−1 a r−1，与年龄级和树种无关。林分生物量达到约130tC ha−1(相当于约520m3ha−1)。落叶松的单株树龄超过600年。最大年龄和生物量似乎受到心材真菌腐烂的限制。落叶松、云杉老树和西伯利亚松树干腐病的发病率分别为60%和30%。对火灾和植物病害的未来作用进行了讨论。
Abstract. The relative role of fire and of climate in determining canopy species composition and aboveground carbon stocks were investigated. Measurements were made along a transect extending from the dark taiga zone of central Siberia, where Picea and Abies dominate the canopy, into the Larix zone of eastern Siberia. We test the hypotheses that the change in canopy species composition is based (1) on climate-driven performance only, (2) on fire only, or (3) on fire-performance interactions. We show that the evergreen conifers Picea obovata and Abies sibirica are the natural late-successional species both in central and eastern Siberia, provided there has been no fire for an extended period of time. There are no changes in performance of the observed species along the transect. Fire appears to be the main factor explaining the dominance of Larix and of soil carbon. Of lesser influence were longitude as a proxy for climate, local hydrology and active-layer thickness. We can only partially explain fire return frequency, which is not only related to climate and land cover, but also to human behavior. Stand-replacing fires decreased from 300 to 50 yrs between the Yenisei Ridge and the upper Tunguska. Repeated non-stand-replacing surface fires eliminated the regeneration of Abies and Picea. With every 100 yrs since the last fire, the percentage of Larix decreased by 20%. Biomass of stems of single trees did not show signs of age-related decline. Relative diameter increment was 0.41 ± 0.20% at breast height and stem volume increased linearly over time with a rate of about 0.36 t C ha−1 yr−1 independent of age class and species. Stand biomass reached about 130 t C ha−1(equivalent to about 520 m3 ha−1). Individual trees of Larix were older than 600 yrs. The maximum age and biomass seemed to be limited by fungal rot of heart wood. 60% of old Larix and Picea and 30% of Pinus sibirica trees were affected by stem rot. Implications for the future role of fire and of plant diseases are discussed.