【作者】 石新立；

【导师】 王传宽；

【作者基本信息】 东北林业大学 ， 生态学， 2010， 硕士

【摘要】 揭示树干呼吸(Rw)的时空变化规律及其影响因子,不但是模拟和估测森林碳收支的重要内容,而且对解释森林生产力的变化有重要意义。采用红外气体分析法于2008年5—9月份测定了自然条件下东北东部山区4个主要树种(红松Pinus koraiensis,兴安落叶松Larix gmelinii,白桦Betula platyphylla,水曲柳Fraxinus mandshurica)的Rw日进程,探索其Rw及其温度敏感系数(Qlo)的时间变化格局及其影响因子。此外,采用红外气体分析法于2008年与2009年5—10月份测定了自然条件下东北东部山区10个主要树种。除上述4个树种外,还以山杨(Populus davidiana)、胡桃楸(Juglans mandshurcia)、春榆(Ulmus propinqua)、蒙古栎(Quercus mongolica)、紫椴(Tilia amurensis)、五角槭(Acer mono)为研究对象,测定其RW的季节动态,旨在分析2008年与2009年RW的季节变化及比较年际间RW与Q10的种内种间差异及其影响因子。主要结果如下：树种、径级、月份及其交互作用均显著地影响RW。测定期间RW的总体平均值分别为：兴安落叶松(3.69μmol·m-2·s-1)、水曲柳(3.24μmol·m-2·s-1)、白桦(1.64μmol·m-2·s-1)、红松(1.62μmol·m-2·s-1).4个树种的RW的日变化(7月除外)大体上与树干温度(TW)变化一致,呈单峰曲线格局,但峰值出现时间因树种和月份而异,RW比TW滞后2—6 h。7月份的RW对TW的响应不明显,呈现S型或无峰的日变化格局。RW日平均的季节变化基本与TW和物候节律相符,呈单峰模式。虽然树种之间Q10的差异显著(波动在1.09—2.95之间),但所有树种Q10的季节变化格局一致,均在8月份达到最低值,9月份反弹达到最大值。而除白桦之外,同一树种不同个体的RW与其胸径之间呈显著的正相关关系,但这种关系的形式和相关程度却随树种而异。树种、径级、月份、年际及其交互作用均显著地影响RW。2008年与2009年大多数树种生长季的RW和TW存在显著的指数函数关系,RW对TW响应的敏感程度因树种和年际而异。10个树种RW季节变化基本与TW和物候节律相符,呈单峰模式,二者多于生长季中期(6、7月份)达到峰值。除红松和蒙古栎外,其余树种2008年的R10均大于2009年,而10个树种2009年的Q10均大于2008年(其平均Q10=3.08是2008年Q10=1.65的1.87倍)。同一树种不同个体的RW与其胸径之间有显著的正相关关系(除2008年的白桦、2008年与2009年的胡桃楸外),但这种关系的形式和相关程度却随树种和年际而异。兴安落叶松、水曲柳、山杨、胡桃楸、春榆与紫椴2008年的基于树干表面积的碳消耗量、生长季及全年呼吸环的碳消耗量均值及其9株样木全年碳消耗量均大于其2009年,这与2008年各树种生长季RW的均值大于其2009年这一结果相符；其余树种与之不符。红松、兴安落叶松、蒙古栎、紫椴与五角槭的碳消耗量与DBH呈显著的正相关关系,但二者之间关系的形式和相关程度亦随树种和年际而异。上述研究均表明,在构建森林碳循环机理模型时,应考虑RW及其温度敏感性随树种与时间的变化特性。此外,树干呼吸碳消耗量亦有随树种与时间变化的特性。更多还原

【Abstract】 Exploring spatiotemporal dynamics and influencing factors of stem respiration (RW) is important for estimating and modeling forest carbon budgets, and helpful to understand variability of forest productivity. In this study, we in situ measured the RW of four major tree species in the temperate forests of northeastern China. The species were Pinus koraiensis, Larix gmelinii, Betula platyphylla, and Fraxinus mandshurica. Our objective was to examine diurnal courses of RW across the growing season in order to understand spatiotemporal patterns and influencing factors of RW and its temperature coefficient (Q10) for the four species. Each month during May and September of 2008, the diurnal course of RW and stem temperature at 1 cm depth under bark (TW) was measured every two hours with a Li-6400 infrared gas analyzer and thermocouple. Besides, the species were Populus davidiana, Juglans mandshurica, Ulmus propinqua, Quercus mongolica, Tilia amurensis and Acer mono except for the four tree species above. Our objective was to examine seasonal and yearly courses of RW across the growing season in order to understand spatiotemporal patterns and influencing factors of RW and its temperature coefficient (Q10) for the ten species. Each month during May and Otc. of 2008 and 2009, the seasonal course of RW and stem temperature at 1 cm depth under bark (Tw) was measured once each month with a Li-6400 infrared gas analyzer and thermocouple. For each species, nine trees were randomly sampled to cover the distribution range of tree diameter. A PVC collar (inner diameter 10.2 cm, height 5 cm) was cut and polished to fit the stem shape of each sample tree, and installed on the northward side at breast height. The collar was attached with silicon adhesive to the stem surface that was pretreated without causing any injury of the live tissues, and was kept continuously throughout the measuring period. The measured RW was calibrated with the collar volume and stem surface area of each sample tree. The main results below:Tree species, diameter at breast height (DBH), month and their interactions significantly influenced the RW.The grand means of RW during the measuring period for the Larix gmelinii, Fraxinus mandshurica, Betula platyphylla and Pinus koraiensis were 3.69μmol·m-2·s-1,3.24μmol·m-2·s-1,1.64·μmol·m-2·s-1, and 1.62μmol·m-2·s-1, respectively. The diurnal courses of RW for all tree species during the growing season (except for July) overall showed a "unimodal" pattern, largely in accordance with those of TW. However, the occurring time of the peak RW varied with species and month, and delayed to that of the Tw by 2—6 hours. In July, however, the diurnal course of RW displayed a"sinusoidal"or non-peak pattern. The seasonal variation of daily mean RW showed a bell-shaped curve pattern, with its maximum occurring in July for all species, which was in consistent with the seasonality of temperature and canopy penology. There was a consistent seasonal pattern of Q10 for all tree species, with its minimum occurring in August and maximum in September. The Q10 was significantly different among tree species, varying from 1.09 for Pinus koraiensis and 2.95 for Larix gmelinii. The mean RW for each individual tree was significantly positively correlated with DBH for all species except for Betula platyphylla. However, the equation and variability of this correlation varied with tree species.Tree species, diameter at breast height (DBH), month, year and their interactions significantly influenced the RW The relationships between RW and TW for all tree species in the growing season have showed exponential functions, varing with tree species and year. The seasonal variation of RW showed a bell-shaped curve pattern, with its maximum occurring in June or July for most of tree species, which was in consistent with the seasonality of temperature and canopy penology. R10 of 2008 for all tree species was larger than that of 2009 (except for Pinus koraiensis and Quercus mongolica), while the grand mean Q10 of 2009 (3.08) for the ten tree species was 1.87 times than that of 2008 (1.65). The mean RW for each individual tree was significantly correlated with DBH for all species except for Betula platyphylla of 2008, Juglans mandshurica of 2008 and 2009. However, the equation and variability of this correlation varied with tree species and year. The total stem respiration in the growing season for all tree species was linear with DBH. However, the equation and variability of this correlation varied with not year but tree species.The carbon cost based on stem surface, the grand mean carbon cost for each collar in the growing season and all the year, and the carbon cost all the year around of nine samples for Larix gmelinii, Fraxinus mandshurica, Populus davidiana, Juglans mandshurica, Ulmus propinqua and Tilia amurensis in 2008 was more than that of 2009, so were the grand means of RW for these tree species in the growing season. While the others did not belong to this. The carbon cost for Pinus koraiensis, Larix gmelinii, Quercus mongolica, Tilia amurensis and Acer mono was linear with DBH. However, the equation and variability of this correlation varied with tree species and year.The study above showed that the temporal and inter-specific variations of stem respiration and its temperature sensitivity should be considered in developing mechanistic models of forest carbon cycles. Besides, the carbon cost for stem respiration varied with species and time.更多还原