兴安落叶松(Larix gmelinii)火后种子萌发影响因子

林火干扰是影响兴安落叶松林结构和功能的主要因子之一。兴安落叶松种群火后更新受多种因子的影响，并决定着该群落演替轨迹。通过在大兴安岭呼中自然保护区的火烧迹地内设置原位控制实验，利用增强回归树分析方法，量化研究了落叶松火后恢复初期不同影响因子（温度、有机质层厚度、覆盖度等）对种子萌发的相对重要性。研究结果表明：落叶松火后种子萌发的最主要影响因子为温度，第二影响因子为种源，第三影响因子为草本覆盖度，分别解释了幼苗数量变异的28.51%、22.40%、20.66%；各影响因子的相对重要性在不同地形条件下有明显差异：温度在山坡顶部和阳坡底部占有重要影响，种源在阳坡中部和阴坡中部最为重要，土壤含水量在阴坡底部占有重要地位。同时，去除土壤表面有机质可以显著提高种子萌发数量，去除地面杂草则会使种子萌发数量降低。从研究结果可知，落叶松火后种子萌发在不同地形（环境条件）下的限制因子不同，人工辅助需因地制宜采取相应措施，才能更有效地促进种子萌发与森林恢复。

A study on the influencing factors of Larix gmelinii post-fire seed germination

Fire disturbance exerts great influences on the structure and function of Larix gmelinii forest ecosystem. Post-fire regeneration of Larix gmelinii is affected by multiple factors, and determines the community succession trajectory. By setting in-situ experiment at burned area of the Huzhong natural reserve in Great Xing''an Mountains, we used BRT (Boosted Regression Tree Analysis) to quantify relative influence of driving factors (temperature, depth of organic layer, coverage, et al.) that influenced Larix gmelinii seed germination of post-fire tree recruitment. The results showed that three main factors of Larix gmelinii post-fire seed germination were temperature, seeds number, and coverage, which explained 28.51%, 22.40% and 20.66% of the seedling quantity variation, respectively. Significantly differences in relative influence of these driving factors on seedling quantity were found among different topographic positions:temperature had important influence at the top of slope and the bottom of sunny slope; seeds quantity was the most influential factor of seedling quantity at the mid of slope; and soil water content played the most important role at the bottom of shady slope. Moreover, removing the organic layer and weeding significantly increased quantity of seedlings. In summary, the germination of Larix gmelinii seeds were influenced by different factors under different topographic positions (environment conditions). Therefore, local conditions should be an importance concern when artificial regeneration was implemented to promote post-fire Larix gmelinii restoration.