【作者】 姜红英；

【导师】 王政权； 谷加存；

【作者基本信息】 东北林业大学 ， 森林培育， 2010， 硕士

【摘要】 森林细根的生产和周转作为陆地生态系统中碳和养分循环的重要组成部分已得到广泛认可。目前,大气N沉降在全球范围内持续增加,这将会对树木的细根动态和生长产生重大影响。因此,细根动态与土壤N有效性的关系也越来越受到生态学家的关注。本研究以18年生水曲柳(Fraxinus mandshurica)和落叶松(Larix gmelinii)人工林为例,施肥处理同时运用微根管对两树种进行连续五年的动态观测,结果表明：两树种的细根生产和死亡在施肥样地和对照样地均表现出明显季节动态。细根生产主要发生在夏季(6月-7月)；细根死亡主要发生在夏末和秋季(8月-10月)。相关分析表明,大气温度变化可以解释水曲柳细根生产量55%和落叶松细根生产量66%的变异,降雨量变化可以解释水曲柳细根生产量28%和落叶松细根生产量27%的变异。施肥后,使水曲柳细根生产和大气温度的相关性增加14%,降雨量相关性增加21%,落叶松变化很小。细根的死亡受环境因子影响较小,仅水曲柳在施肥后细根的死亡量与大气温度指数负相关。水曲柳细根生长量和死亡量均大于落叶松。随着观测时间的增加,两树种细根生产量和死亡呈逐年减低的趋势。综合5年平均生产量和死亡量发现,施肥使水曲柳生产量增加,死亡量降低；均降低了落叶松的细根生产量和死亡量,但是差异不显著(P>0.05)。在不同年际间,施肥降低了两树种2004年的细根生产量,有增加两树种2005-2008年细根生产量趋势。死亡量变化不同于生产量,施肥降低了两树种2004-2006年细根死亡量,增加了水曲柳2007-2008年细根死亡量和落叶松2007年细根死亡量。两树种细根生长和死亡均集中在0-20 cm土壤中,综合5年不同土层的细根平均生产量和死亡量发现,水曲柳0-20 cm细根生产量占年细根生产量的62%左右,死亡量占72%左右；落叶松0-20 cm细根生产量占年细根生产量的65%左右,死亡量占64%左右。施肥后,使水曲柳0-20 mm细根生产量和死亡量降低,30-40 cm细根生产量和死亡量增加。而落叶松0-20 mm和30-40 cm的细根生产量和死亡量均降低。在不同年际间,随着施肥时间的延长,水曲柳0-20 cm细根生产量和死亡量占年生产量比例均呈先减小后增加的趋势。2005年达到最小,而落叶松这种比例在5年内逐年减小。落叶松的细根周转率要明显大于水曲柳的细根周转率(P<0.05)。综合5年平均周转率发现,施肥降低了两树种细根周转率,但差异不显著(P>0.05)。在不同年际间,2004年,施肥使水曲柳细根周转加快,落叶松细根周转降低,但在2006-2008年均降低了两树种细根周转。直径大小影响细根生产、死亡和周转。0-0.5 mm细根生产量和死亡量以及周转率大于0.5-2.0 mm的细根。从细根5年平均生产量和死亡量以及周转率来看,施肥使两树种0-0.5 mm的细根生产量和死亡量降低,0.5-2.0 mm的细根生产量和死亡量增加。同时,施肥增加了水曲柳0-0.5 mm细根周转率,对0.5-2.0 mm细根没有影响；降低了落叶松0-0.5 mm细根5年的平均周转率,增加了0.5-2.0 mm细根5年的平均周转率。综合分析表明：两树种细根的生产、死亡和周转可能受树种内在因素和外在环境因素的相互作用控制。更多还原

【Abstract】 Root production and turnover is an important component of the C and nutrient budget in the terrestrial ecosystems. N deposition continue increasing all over the world, which have an important effect on root dynamic and growth. So the relationship between root dynamic and soil available nitrogen is a major issue of ecologist. In the study, manchurican ash (Fraxinus mandshurica) and davurian larch (Larix gmelinii), two of the important forest trees in northeastern China, were used as the experimental materials. Fine root dynamic was monitored in situ by minirhizotron technique across five years. The main results were below:Root production and turnover showed obvious seasonal dynamic in control and N fertilization plots in the two plantations. Root production occurred in June and July primarily, root death occurred from August to October. Correlation analysis showed the change of atmosphere temperature accounted for 55% and 66% of root production in ash and larch plantation. The change of rainfall accounted for 28% and 27% of root production in ash and larch plantation. The relationship between root production and atmosphere temperature were increased by 14% by N fertilization in ash plantation. The relationship between root production and rainfall were increased by 21% by N fertilization in ash plantation. The changes is tiny in larch plantation. The environmental factors have little effect on root death. There were significant negative correlation between root mortality and the atmosphere temperature.Root production and mortality in ash plantation was higher than in larch plantation. Root production and mortality were declining year by year across five years. N fertilization increased mean root production of five years, and decreased the root mortality in ash plantation. N fertilization have no significant effect on root production and mortality in larch plantation. N fertilization decreased root production in 2004, and increased root production in 2005-2008 in the two plantations. The changes of root mortality were differ from root production. N fertilization decreased root mortality in 2004-2006 in the two plantations, increased root mortality in 2007-2008 in ash plantation and in 2007 in larch plantation. Root production and mortality were foucus in 0-20cm of the soil in the two plantations. Root production accounted for 62% in 0-20cm of the soil, root mortality accounted for 72% in ash plantation of the five years.Root production accounted for 65% in 0-20cm of the soil, root mortality accounted for 64% in larch plantation. N fertilization root production and mortality decreased in 0-20cm of the soil in ash plantation, while increased in 30-40cm of the soil. N fertilization root production and mortality decreased in 0-40cm of the soil in larch plantation. The percent of root production and mortality in 0-20cm of the soil decreased across fertilization time. Root turnover rate was higher in larch plantation than in ash plantation. N fertilization decreased root turnover rate in the two plantations. N fertilization increased root turnover rate in 2004 in ash plantation, while decreased in larch plantation. N fertilization decreased root turnover rate in 2006-2008 in the two plantations.Root diameter effect root production, death and turniver. Root production, death and turniver was higher of 0-0.5 mm diameter than 0.5-2.0 mm. N fertilization decreased root production and death of 0-0.5 mm in the two plantations, while 0.5-2.0mm increased. N fertilization increased root turniver rate of 0-0.5 mm, have no effect on 0.5-2.0 mm root in ash plantation. N fertilization decreased root turniver rate of 0-0.5 mm, increased 0.5-2.0 mm root in larch plantation.As a whole, root production, death and turnover were controled by intermediate factor and experimental factor.更多还原