极危植物百山祖冷杉的种子雨

The Seed Rain of Critically Endangered Plant Abies beshanzuensis

百山祖冷杉(Abies beshanzuensis)为浙江百山祖特有的极度濒危植物,野生母树仅存3株,其中1株散生,另外2株呈南北相邻生长。为了解百山祖冷杉种子雨的时空格局特征,布设33个1.0 m×1.0 m的种子收集框,对2017年、2019年产的种子进行收集,每半个月收集一次种子,结果表明:(1)2017年12月16日至2018年2月28日,共收集到6次种子,其中散生株1093粒、相邻两株1020粒。2019年11月31日至2020年1月16日,共收集到4次种子,其中散生株341粒、相邻的北株165粒。(2)母树种子千粒鲜质量变化较大,最小的为2017年相邻两株种子(25.87 g),最大的为2019年相邻的北株种子(39.21 g)。种子长度、宽度、厚度的最大值分别为14.5、6.8、4.1 mm,种翅长度和宽度的最大值分别16.4、13.7 mm。种子饱满率和千粒质量都表现出“先下降后提高”的趋势。北向的种翅、种子饱满率、千粒质量较大,而南向的则较小。种子性状与收集框距离之间没有明显的规律。(3)2017年种子,有前2次的高峰,前2次收集到的种子为总数的80%左右,而2019年种子仅有第1次是高峰,收集到的种子为总数的80%左右。在高峰之后,收集到的种子显著减少。存在种子“二次掉落”现象,延长了种子掉落时间。(4)随着收集框与母树距离的增大,收集到的种子减少。约98%的种子掉落在距离母树10 m的范围内。30 m框合计仅收集到4粒种子。(5)西向收集的种子总数最多,可能与西向地形较低有关。

Abies beshanzuensis is a critically endangered plant endemic species in Baishanzu Mountain,Zhejiang Province,and only three mother trees are remained,one is scattered,and the other two grow adjacent to the north and south.In order to understand the spatial-temporal pattern of the seed rain of A.beshanzuensis,33 seed collection frames were set up to collect the seeds produced in 2017 and 2019 once every half month.The results showed that:(1)From December 16th,2017 to February 28th,2018,1093 seeds from the scattered tree and 1020 seeds from two adjacent trees were collected using six times,while from November 31th,2019 to January 16th,2020,341 seeds from scattered tree and 165 seeds from the adjacent north tree were collected using four times.(2)The fresh weight of 1000 seeds of A.beshanzuensis varied greatly,with the minimum of two adjacent trees seeds in 2017(25.87 g)and the maximum of the adjacent north tree seeds in 2019(39.21 g).The maximum length,width and thickness of the seeds were 14.5,6.8 and 4.1 mm respectively,and the maximum length and width of the seed wings were 16.4 and 13.7 mm respectively.Both seed plumpness rate and 1000-seed mass showed a trend of“decreasing first and then increasing”.The seed wing,seed plumpness,and seed fresh weight were larger in the north direction,whereas those in the south direction were smaller.There was no obvious pattern between seed characters and the distance from the collection frames.(3)In 2017,there were two peaks of seed rain,and the seeds collected in the first two times were about 80%of the total.However,in 2019,there was only one peak of seed rain,and the seeds collected for the first time were about 80%of the total.After the peak,the number of seeds collected decreased significantly.There was a phenomenon of“secondary seed drop”,which prolonged the drop time of seeds.(4)The number of seeds collected decreased with the increases of the distance from the collection frame to the mother tree,98%of seeds fell within 10 m from the mother tree.Only four seeds were collected in the 30 m frames.(5)The number of seeds collected from the west was the largest,which might be related to the lower terrain in the west direction.