【摘要】 广西火桐自然种群存在严重的更新障碍，幼苗向幼树建成困难。基于此，本研究选取3株已结实的广西火桐开展研究，了解其种子雨特征、幼苗保存和生长特征及影响因素，并探明其自然更新受限因子。结果显示：（1）广西火桐种子雨出现在7月下旬，持续期为9 d,平均密度为23.31粒·m^-2,种子完整度和成熟度较高，平均萌发率为69.22%;（2）自然条件下的广西火桐当年生幼苗存活率极低，干旱缺水是导致幼苗死亡率高的主要因素；（3）广西火桐幼苗生长与土壤pH、全氮含量、速效磷含量、全钾含量和速效钾含量呈显著正相关（P<0.05）;（4）冗余分析表明土壤pH是影响幼苗生长的关键土壤因子；（5）位于林窗生境下的广西火桐幼苗生长状况优于林冠下和林冠边缘的生境，表明幼苗生长还与微环境中光照条件呈正相关。综上所述，广西火桐种子雨扩散时间极短，种子具有较高的萌发率。但当年生幼苗存活率极低，干旱缺水导致幼苗死亡率高是广西火桐自然更新的主要限制因子。此外，幼苗的生长不仅与土壤pH密切相关，还与生境中的温湿度和光照条件相关。研究结果可为广西火桐自然种群恢复和回归奠定基础。更多还原

【Abstract】 Firmiana kwangsiensis,a rare plant belonging to the Firmiana genus and found in the Karst regions of southern China, has obvious regeneration obstacles.Although much research on F.kwangsiensis has been reported, studies on its seed rain characteristics, seedlings growth and influencing factors remain lacking.To further understand the endangered reasons of the F.kwangsiensis,three seed trees were selected to investigate its seed rain characteristics, seedlings growth and influencing factors, and to explore the limiting factors of natural renewal in F.kwangsiensis.The results showed that:（1）The seed rain of F.kwangsiensis occurred in late July and lasted for only 9 days, with an average density of 23.31 seeds·m^-2.The seeds were highly complete and mature, and the average germination rate was 69.22%.（2）The survival rate of F.kwangsiensis seedlings under field conditions was extremely low, and drought was the main factor causing the large-scale death of seedlings.（3）The growth of F.kwangsiensis seedlings was significantly positively correlated with soil pH,total nitrogen content, available phosphorus content, total potassium content, and available potassium content（P<0.05）.（4）Redundancy analysis showed that soil pH was the key factor affecting the growth of F.kwangsiensis seedlings.（5）The growth status of F.kwangsiensis seedlings in the forest gaps was better than that under the crown canopy and at the canopy margins, indicating that the seedlings’ growth was also positively related to light in the micro-environment.In summary, the seed rain of F.kwangsiensis lasts for a short time, and the seeds have a relatively high germination rate.However, the survival rate of seedlings is extremely low.High seedling mortality caused by drought is the main factor restricting the natural regeneration of F.kwangsiensis.Additionally, the seedling growth is not only closely related to soil pH,but also to the temperature, humidity, and light conditions of the habitat.Our results could lay a foundation for the recovery and restoration of the wild population of F.kwangsiensis.更多还原