摘要
【目的】研究红锥母树种子雨、土壤种子库及幼苗更新的动态,以期探究其更新制约因素及机制。【方法】采用样线法布置种子雨收集器,分别收集2017、2018年的红锥种子雨和落叶,统计分析不同散种期的种子雨密度、质量、总量及落叶量。同时在母树林下的土壤中设置小样方,对枯落物层、0~5 cm腐殖层和5~10 cm土层取样,统计计算土壤种子库密度和完整种子数量,并在室内测定种子千粒质量和发芽能力。2018年5月,在母树的各取样点附近设样方,调查幼苗的更新情况。【结果】1)红锥种子雨从9月中旬持续至12月下旬,集中散种期为10—11月。2017年为种子大年:种子产量高,种子雨密度为(480.97±11.61)粒·m-2;种子质量好,完整种子数(433.86±12.65)粒·m-2,占种子雨总量90.20%±1.09%。2018年为种子小年:产种量低,种子雨密度为(126.37±12.04)粒·m-2;种子质量差,完整种子数(45.54±11.47)粒·m-2,约占种子雨总量36.04%±0.95%。2)2018年4月的土壤种子库主要源于2017年的种子雨,种子库平均密度为(360.09±10.43)粒·m-2,完整种子数(215.13±10.04)粒·m-2,占种子库总量的59.74%±8.56%。经室内发芽试验测定,种子库中完整种子的发芽率平均为28.53%±7.50%。自然萌发前,约(61.38±18.57)粒·m-2种子具有发芽能力;将种子埋于林下土壤保存至2019年4月时,发芽率降为2.85%±0.86%,约(8.59±1.90)粒·m-2种子具发芽力。种子库中63.79%±3.55%的种子分布于枯落物层。3)红锥当年生幼苗的更新频度平均为16%,林下更新的78株幼苗仅11株存活。其中,阳坡的母树更新幼苗数量明显大于阴坡,阳坡的幼苗出现频度为40%,阴坡的为0。【结论】红锥种子雨扩散动态与落叶散落过程一致,其种子库垂直空间分布差异显著,其中大部分种子落入枯落物层;种子发芽率及当年生幼苗存活率低,即使在种子大年后仍难以实现幼苗的建成。因此,种子发芽率低及枯落物阻隔等是导致红锥更新不良的主要因素。
【Objective】Castanopsis hystrix is a rare broadleaved tree species under the second grade national protection in China,and it is difficult to regenerate in nature.Our study aims to examine whether population regeneraion is limited by seedling recruitment.We investigated dynamics of seed rain,soil seed bank and seedling regeneration of C.hystrix.【Method】The line transect method was used to collect the seed rain and fallen leaves of C.hystrix in 2017 and 2018.Seed rain density,quality,total of seed rain and weight of fallen leaves in different seed dispersal stages were analyzed.At the same time,small plots were also set under the seed trees for collecting samples in litter layer,0-5 cm humus layer and 5-10 cm soil layer.The soil seed bank density and the number of full seeds were calculated then,and the germination capacity and the weight of thousand seeds were measured in laboratory.In May 2018,small plots were set around each of sampling seed trees to investigate the seedlings regeneration.【Result】1)Seed rain of C.hystrix lasted from the middle of September to the late of December,and its concentrated scatter period was from October to November.In 2017,it was a big year for producing seeds of C.hystrix,and the seed rain density was(480.97±11.61)seeds The seed quality was good,the number of full seeds was(433.86±12.65)seeds·m-2,accounting for 90.20%±1.09%of the total seed rain.In 2018,it was a small year for seed production,both seed production and full seeds proportion were lower than those in 2017.The seed rain density was(126.37±12.04)seeds·m-2,and the full seeds accounted for 36.04%±0.95%of the total seed rain.2)The soil seed bank in April 2018 was mainly from the seed rain in 2017,and the average density of soil seed bank was(360.09±10.43)seeds·m-2,of which full seeds accounted for 59.74%±8.56%.By indoor germination test in 2018,the average germination rate of full seeds was 28.53%±7.50%in seed bank.There were about(61.38±18.57)seeds·m-2 having germination potential before natural regeneration.However,when the seeds were buried into the forest soil till April in 2019,the germination rate decreased to 2.85%±0.86%,and only about(8.59±1.90)seeds·m-2 had germination capacity in seed bank.Approximate 63.79%±3.55%of seeds in the bank were mainly distributed in litter layer.3)The average renewal frequency of seedlings of C.hystrix was 16%,and only 11 of the 78 regenerated seedlings were survived.【Conclusion】The dynamics of seed rain diffusion is consistent with that of fallen leaves of C.hystrix.The vertical spatial distribution of soil seed bank is significantly different,and the most of the seeds fall into litter layer.The germination rate and survival rate of seedlings are low,it is still difficult for seedling recruitment even if after a big year of C.hystrix.Thus,low seed germination rate and litter barrier are the main influencing factors leading to the poor regeneration of C.hystrix.
作者
赵总
刘勇
田祖为
贾宏炎
赵蕊蕊
安宁
Zhao Zong;Liu Yong;Tian Zuwei;Jia Hongyan;Zhao Ruirui;An Ning(Key Laboratory for Silviculture and Conservation of Ministry of Education,College of Forestry,Beijing Forestry University, Beijing 100083;Experimental Center of Tropical Forestry, Chinese Academy of Forestry, Pingxiang 532600)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2020年第5期37-49,共13页
Scientia Silvae Sinicae
基金
中国林业科学研究院热带林业实验中心科学基金项目“红椎天然更新机制研究”(RL2015-03)
“十三五”国家重点研发计划“马尾松人工林近自然经营技术”(2017YFD0600304)
林业科技创新平台运行补助项目“广西友谊关森林生态系统国家定位观测研究站”(2016-LYPT-DW-079)。
关键词
红锥
种子雨
土壤种子库
母树
幼苗更新
Castanopsis hystrix
seed rain
soil seed bank
seed tree
seedling regeneration
