| 摘要: |
| 【目的】揭示渭北黄土高原地区侧柏人工林种子雨和种子库的组成、质量、散布规律，为侧柏人工林恢复和持续经营提供理论依据。【方法】在陕西省永寿县槐坪林场选择未经抚育、经间伐抚育（强度约30%）的侧柏人工林和刺槐-侧柏混交林各设置3块固定样地，于2012-08-10每隔7 d收集1次种子雨, 2012-11及2013-08分别收集土壤种子库，采用种子萌发试验测定种子活力，并调查样地内天然更新的幼苗密度。【结果】研究区未经抚育的侧柏人工林种子雨从08-10开始，8月末至9月初达到高峰期，10-12结束；2012-11土壤种子库中完整种子占 47.18%，萌发率为17.30%；2013-08土壤种子库中完整种子数为0。经间伐抚育的侧柏人工林种子雨从08-10开始，09-07左右达到高峰期，10-05结束；2012-11、2013-08土壤种子库中完整种子分别占42.24%和13.48%，萌发率分别为29.10%和0。刺槐-侧柏混交林的种子雨从08-10开始，09-07-09-14达到高峰期，10-12结束；2012-11、2013-08土壤种子库中完整种子分别占53.85%和20.97%，萌发率分别为26.27%和0。3种类型样地的种子雨在起始期均以空粒、干瘪的不完整种子为主；进入高峰期，种子雨以完整、饱满种子为主。种子雨到达地面后，主要分布在枯枝落叶层，0～2 cm土层有少量分布，2 cm以下土层极少有种子分布。【结论】种子雨下落前种子库密度大大减少，完整种子的萌发率降为0，霉烂种子的比例大幅增加，这表明研究区人工侧柏不能在地面形成稳定有效的种子库。 |
| 关键词: 渭北黄土高原 侧柏人工林 种子雨 种子库 |
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| 基金项目:国家“十二五”黄土高原人工林可持续经营技术研究与示范(2012BAD22B0302) |
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| Seed rain and soil seed bank of Platycladus orientalis plantation in Weibei Loess Plateau |
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YU Ze-qun,LIU Jin-liang,YANG Ting-ting,et al
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| Abstract: |
| 【Objective】This study investigated the composition,quality and dispersal regularity of seed rain and soil seed bank of Platycladus orientalis plantation in Weibei Loess Plateau to provide theoretical basis for the recovery and continuing operation of Platycladus orientalis plantation.【Method】Three permanent plots were set in each population including tended (tending rate was about 30%),no-tended Platycladus orientalis plantations and Robinia pseudoacacia Platycladus orientalis mixed plantation in Huaiping forest farm of Yongshou county,Shaanxi province.Seed rain was collected every 7 days from August to October in 2012 and seeds in soil seed bank were collected in November 2012 and August 2013,respectively.Viability of seeds was measured using seed germination method and density of natural regenerated seedlings in each plot was investigated.【Result】The seed rain of no-tended Platycladus orientalis plantation started from 10th August,reached the peak in later August and early September,ended on 12th October.In November 2012,intact seeds accounted for 47.18% in soil seed bank with germination rate of 17.30%;while in August 2013,the number of intact seeds decreased to 0.Seed rain of tended Platycladus orientalis plantation started from 10th August,reached the peak at about 7th September,and ended on 5th October;In November 2012 and August 2013,intact seeds accounted for 42.24% and 13.48% respectively in soil seed bank with germination rate of 29.10% and 0.Seed rain of Robinia pseudoacacia-Platycladus orientalis mixed plantation started from 10th August,reached the peak during 7th September to 14th September,ended on 12th October;In November 2012 and August 2013,intact seeds accounted for 53.85% and 20.97% respectively in soil seed bank with germination rate of 26.27% and 0.At the beginning of seed rain,vacant and incomplete seeds were the majority in all the three kinds of plot;while intact seeds dominated during the peak time of seed rain.Soil seeds mainly distributed in the litter layer with little in soil layer of 0-2 cm and fewer in soil layer of >2 cm.【Conclusion】Density of soil seed bank reduced greatly,germination rate of intact seeds dropped to 0,and ratio of rotten seeds increased dramatically before the falling of seed rain,indicating that Platycladus orientalis plantations could not form stable and effective seed bank on the ground in Weibei Loess Plateau. |
| Key words: Weibei Loess Plateau Platycladus orientalis plantation seed rain soil seed bank |
