濒危植物白桂木土壤种子库的特征及动态

采用筛分法对天然林中白桂木土壤种子库进行了研究。结果表明:白桂木天然林土壤种子库种子储量少,最大储量为31.9粒/m2,约80%的种子储存于枯枝落叶层中,其土壤种子库的散布格局具有明显的集群分布特征,种子几乎全部分布于冠幅范围内。     

内蒙古大兴安岭兴安落叶松土壤种子库研究

对内蒙古大兴安岭成熟兴安落叶松纯林的3种不同采伐林分类型(原始林、渐伐林、皆伐林)的土壤种子库储量、质量及其垂直分布(枯枝落叶层、土层0~5cm和5~10cm)进行了研究,结果表明:不同的采伐林分生长状况,决定了不同的土壤种子储量,渐伐林种子储量最多,皆伐林种子储量最小;从种子库活力程度看,种子整体质量非常差,完整种子中大部分为空粒种子,各林分均为70%左右;土壤种子库中种子集中分布在枯枝落叶层中;各林分林下均有幼苗,表明兴安落叶松纯林土壤种子库种子具有一定的萌发能力。     

长白山杨桦次生林采伐林隙种子库特征

研究长白山杨桦次生林不同大小采伐林隙的土壤种子库特征.结果表明:杨桦次生林非林隙林分中种子库储量远高于林隙,但多样性比林隙低;不同大小林隙内的种子库储量差异显著,其中50～100 m2大小的林隙内种子库储量最大;随林隙形成时间的延长,林隙内的种子库储量减少,但多样性有所增加;林隙内不同部位间的种子库储量变化较大,且丰富度大小同个体密度大小的变化不一致;种子库中优势种突出,水曲柳、紫椴、山槐与色木槭4个树种的种子数量占种子总量的74.3%以上;地表凋落物层对种子落入土壤有明显的阻滞作用;在林隙形成初期,种子库的组成及数量主要由腐殖质层种子库决定,但随时间的推移枯枝落叶层种子库对整个种子库的贡献越来越大;林隙内土壤种子库同地上更新幼苗相似性不大.     

城市近郊林土壤种子库研究

对沈阳、抚顺两城市交接的近郊林区不同林分类型土壤种子库进行研究.结果表明:不同林分类型土壤种子库均具有较好的储量和活力,其储量大小顺序为:乔木林地＞灌木林地＞宜林荒地,土壤种子库物种多样性指数大小顺序为:灌木林地＞乔木林地＞宜林荒地,种子种类以乡土树种为主;数量化分析表明坡位对乔木林地及灌木林地中土壤种子库储量和活力影响较大,而植被覆盖度对宜林荒地中土壤种子库储量和活力影响较大.     

民勤绿洲外围人工梭梭林种子库研究

通过对石羊河下游民勤绿洲外围人工梭梭林土壤种子库特征调查分析,结果表明：种子分布在时间上,4月份158．0粒／m2,8月份86．6粒／m2,8月份的种子量只是4月份的54．8％;在种子水平分布上,种子分布规律是沙丘背风坡〉丘间滩地〉沙丘迎风坡〉沙滩地;在垂直分布上,0—2cm土层中分布植物种子总量的87．8％,2—5cm土层中分布植物种子总量的11．6％,5cm以下的土层中只分布植物种子总量的0．06％。梭梭林土壤种子库平均储种量为122．3粒／m2,其中,梭梭种子的平均储量为28．9粒／m2,最小储量为1．6粒／m2,最大储种量为56．1粒/m2。梭梭林土壤种子库中约80％的梭梭完整种子的生活力极低,但林中仍有梭梭幼苗分布,说明土壤种子库的梭梭种子具有一定的萌发能力。梭梭林土壤种子库储量为中等水平,并具有一定的萌发能力,能够为开展封沙育林草提供基本条件。     

凉风坳亚热带次生常绿阔叶林土壤种子库和种子雨的特征研究

选择四川省沐川县凉风坳亚热带次生常绿阔叶林为研究对象,在2004年5月、2004年12月和2005年5月对其林下土壤种子库、种子雨以及种子天然萌发状况等方面进行系统调查及分析研究。结果显示,种子下落前后土壤种子库储量,变动为643.2～889.2粒.m-2,物种和种子密度多年生草本物种均占优势。天然林土壤种子库Shannon-Wiener指数均在2004年5月最大,2004年12月次之,2005年5月最小;Simpson指数却和Shannon-Wiener指数H＇的变化趋势相反;Pielou均匀度指数在2004年12月有所降低,此后又升高。种子均呈明显垂直分布,其中0～2 cm土层种子数量最多,其次是枯枝落叶层,其数量随着土层加深而降低。土壤种子库年输入活力种子142.3粒.m-2,年输出活力种子268.9粒.m-2,动物取食是造成种子损失的主要原因。对照人工林土壤种子库物种和密度均低于天然林地;种子库与地上植被物种相似性系数,人工林较高,而天然次生常绿阔叶林较低。     

西南桦人工林与天然林土壤种子库特征初步比较

以西南桦人工林与天然林的土壤种子库为研究对象,采用室内萌发法对云南热区的西南桦人工林与天然林下0～10 cm深度的土壤种子库的种子储量及其垂直分布进行了研究。研究结果表明:①西南桦人工林有活力种子储量为2 027粒/m2,天然林有活力种子储量为3 043粒/m2;②西南桦人工林土壤种子库由21科38属的42种植物组成,其中乔木4种,占全部种类的0.69%;灌木16种,占7.70%;多年生草本10种,占14.90%;1 a生草本9种,占73.36%;藤本3种,占3.35%。西南桦天然林土壤种子库由24科43属的49种植物组成,其中乔木6种,占全部种类的10.56%;灌木15种,占18.31%;多年生草本14种,占4.38%;1 a生草本10种,占65.06%;藤本4种,占1.69%;③乔木、灌木的植物数量占总数的比例为天然林>人工林,而草本和藤本为天然林<人工林;④西南桦人工林与天然林土壤种子库有活力种子密度自上而下都呈现下降趋势,0～5 cm种子数量较5～10 cm多。     

兰坪铅锌矿区植被恢复初期土壤种子库的季节动态

通过萌发实验的方法对兰坪铅锌矿区3种尾矿恢复初期的植物群落(以下简称恢复群落,包括魁蒿群落、马桑灌丛、草地早熟禾人工草地)和1种对照群落(云南松林)土壤种子库的季节变化进行比较研究,结果显示:各群落雨季末期土壤种子库储量均高于旱季末期,其中,3种恢复群落种子库储量季节变化显著(p0.05),对照群落季节变化不显著(p0.05);各群落雨季末期土壤种子库物种多样性均高于旱季末期,3种恢复群落物种多样性均低于相应对照群落;各群落土壤种子的垂直分布均为上层中层下层;各群落土壤种子库优势种季节变化均较大,一些优势种仅出现于雨季末期或旱季末期;3种恢复群落2个季节土壤种子库的相似性指数高于对照群落。     

土壤种子库研究综述

指出了土壤种子库是存在于土壤中和土壤表面所有具有活力种子的总和,是植被生态学中的重要研究领域之一。总结土壤种子库的研究方法、种子库分类和大小、种子库与地面植被的关系的主要内容,并在此基础上探讨了土壤种子库未来研究方向和急需解决的问题。     

庞泉沟自然保护区河岸林群落的土壤种子库特征

以人工拣种结合种子萌发法研究了庞泉沟自然保护区9种河岸林群落的土壤种子库特征,结果表明: 9种群落的土壤种子库密度间于684±108 - 2 696±266粒·m^-2,69.27% - 88.65%的种子留存于0 - 5 cm的层次,沙棘灌丛的种子库密度最大,乌柳灌丛最小;离河岸10 m和20 m处的种子库密度大于岸边、离河岸30 m和40 m处;种子库包含的40种植物以多年生草本为主,灌木和草本种多为耐干扰种,存在典型的湿地植物,但种子储量以先锋种白桦最丰;辽东栎无完整种子,白桦、华北落叶松、云杉和油松的种子活力保持期为1 - 2年,多数草本的种子活力保持期超过2年;按照群落土壤种子库的相似性,将群落划分为林分开始期、林分排除期、下层再现期和老熟期4个演替阶段。演替后期群落的种子库密度、丰度以及与地上植被的相似性都小于前期群落。土壤种子库是森林自然更新及种群恢复的重要基础,本文对于研究地区河岸林的保护和重建具有重要的理论意义。     

滇西北亚高山地区落叶松-高山栎混交林土壤种子库初步研究

采用随机取样的方法,对滇西北高山地区落叶松-高山栎针阔混交林的土壤种子库进行了研究。结果表明:亚高山地区落叶松-高山栎针阔混交林土壤种子库由分属9科17属的18种植物的种子组成,种子密度343粒/m2,其中75%的种子分布在0~5 cm的土层中。土壤种子库的物种组成与其地上植被物种组成相关不明显,相关系数仅为0.042 6。其树木群落种子雨由云杉、白桦和高山松等5个树种组成,密度为3 520粒/m2,发生时间集中在每年的9~11月。     

Native woody species regeneration in exotic tree plantations at Munessa-Shashemene Forest,southern Ethiopia

Regeneration of native woody species was studied in the plantations and the adjacent natural forest at Munessa-Shashemene Forest Project Area, Ethiopia. The aim of the study was to test the hypothesis that tree plantations foster regeneration of native woody species. A total of 60 plots, having 10 × 10 m area each, were studied in monoculture plantations of 4 exotic species (Cupressus lusitanica, Eucalyptus globulus, E. saligna, Pinus patula) and an adjacent natural forest. Ages of the plantations ranged between 9 and 28 years. Soil seed bank analysis was also undertaken from soil samples collected in each of the 60 plots to examine the similarity between the soil seed flora and aboveground vegetation. A total of 56 naturally regenerated woody species were recorded beneath all plantation stands with densities ranging between 2300 and 18650 individuals / ha in different stands. There was a significant difference among plantation stands with regard to understorey density (standard deviation: 4836 ± 1341). Vegetation diversity was assessed through analyses of floristic composition, species richness and abundance. Generally, seedling populations were the most abundant components of the regeneration in most of the plantation stands, forming 68 % of the total regeneration count in all stands. A total of 77 plant species represented by 44 herbs, 13 woody species, 8 grasses and 12 unidentified species were recorded in the soil seed bank from all stands. Similarity between the soil seed bank and aboveground flora was very low implying that the role of soil seed banks is negligible rather dispersal plays an important role in the process of regeneration. These results support the concept that forest plantations can foster the regeneration of native woody species, thereby increasing biological diversity, provided that there are seed sources in the vicinity of the plantations.     

Mangrove community recovery potential after catastrophic disturbances in Bangladesh

The objective of this study was to compare the variation in the soil seed banks and the aboveground vegetation in relation to three habitats, i.e., swamp forests, grassland and sand dunes within the Sundarbans mangrove forests of Bangladesh. We collected vegetation data (species and their percentage cover) by using quadrat sampling: 10 m × 10 m for swamp forests and 5 m × 5 m for grassland and sand dunes. We estimated the density of viable seeds of species in the seed bank by counting germinants from soil cores in a germination chamber. Species richness and composition of both aboveground vegetation and the soil seed banks differed significantly among habitats. We identified a total of 23 species from the soil seed bank. Of these, two were true mangrove species and the remaining were non-mangrove species, including halophytic grasses, herbs and mangrove associate species. Our results confirm that mangrove species do not possess a persistent soil seed bank. The presence of high-density non-mangrove and associated mangrove species in the soil seed bank implies that after frequent catastrophic disturbances which limit incoming propagules from adjacent forest stand, large canopy gaps can easily become invaded by non-mangrove and mangrove associate species. This would result in the formation of a cover of non-mangrove species and cryptic ecological degradation in mangrove habitats. We suggest that forest managers should actively consider gap plantations with mangrove species in the large canopy gaps created after catastrophic disturbances to counteract the invasion of non-mangrove species and cryptic ecological degradation.     

二滩库区锥连栎林土壤种子库和幼苗格局初步研究

本文对二滩库区群落优势树种锥连栎林土壤种子库和幼苗分布格局进行了调查研究，结果表明：(1)锥连栎群落土壤种子库不存在霉烂种子，虫蛀种子的数目较少，仅为2.08个／m^2；而败育种子和种子壳数目相对较多，平均密度分别达到42．78个／m^2和42.96个／m^2。(2)锥连栎土壤种子库组成中完好种子的密度为0．28个／m^2；雨季已萌发的种子密度为0．92个／m^2。(3)土壤种子库各组成的垂直分布较为明显，随土层厚度加深而减少，但霉烂种子例外。(4)经测算，锥连栎种子散布后的主要命运是动物捕食和转移，种子的保存率和萌发率分别仅占到单个树木种子产量的0、59％和1．95％。(5)在锥连栎树木分布的上坡有较多的萌生苗，而下坡实生苗的数量较多。(6)距树干距离不同，萌生苗和实生苗的分布模式有差异。     

川西南山地高山栲种群种子雨和地表种子库研究

研究川西南山地区两个高山栲低密度种群的种子雨模式、种子雨过程中地表种子库动态和种群的幼苗状况,讨论种子产量、种子存留和种子对成苗的贡献.结果表明:1)种子雨持续时间超过2个月,但种子下落的高峰期存在样地间差异;2)该地区高山栲的种子产量很低,种子雨散落的密度不大(2.3～2.8个·m-2).3)在种子雨过程中,地表种子库各组成的动态不同,霉烂种子和萌发种子为零,完好种子和虫蛀种子有轻微的波动,完好种子的存留密度为0.13个·m-2;和它们相反,地表的壳斗和败育种子存在积累效应.4)动物捕食是地表种子损失的主要原因,两种群分别占91.3%和97.83%,地表种子的存留率仅为8.7%和2.17%.5)研究样地的高山栲种群低的种子生产量、地表种子存留率和幼苗建成困难等3个环节都限制了高山栲种群的实生更新.     

Changes in size of soil seed bank in Robinia pseudoacacia L. (Leguminosae), an exotic tall tree species in Japan: Impacts of stand growth and apicultural utilization

This study examined the factors that influence the size of a soil seed bank in Robinia pseudoacacia stands. We proposed two hypotheses: the amount of buried seeds of R. pseudoacacia is proportional to stand biomass rather than stand age, and apicultural utilization influences the size of the soil seed bank. R. pseudoacacia generally produces seeds with various degrees of physical dormancy. In addition, this tree is short-lived, and fecundity declines after 30–40 years in relation to tree vigor. However, R. pseudoacacia is intensively used in apiculture as an important honey source, and supply of honeybees by beekeepers could influence seed crops. We investigated 25 plantations in Hokkaido (Central, Hidaka, and Oshima) and in Nagano, Japan, where many naturally regenerated R. pseudoacacia stands occur. We found great variation in the size of the soil seed bank among stands, ranging from 13,757 to 6.4 seeds m⁻² per plot. A generalized linear mixed model revealed that both basal area (BA_Rp) and apicultural utilization best explained the size of the soil seed bank. Both the positive effect of BA_Rp and small contribution of stand age to the model implied that the soil seed bank is transitory, and will not persist for very long time. The large contribution of apicultural utilization to the size of the soil seed bank implied pollinator limitation under natural conditions. R. pseudoacacia often has large flower crops, and native pollinators can not keep up with the demand for pollination. Thus, the supply of honeybees by beekeepers should improve the pollination success of R. pseudoacacia. From these results, we conclude that we must consider stand history with respect to apicultural utilization if the land is harvested or a stand declines.     

我国干旱区草场种子库研究进展

土壤种子库是指存在于土壤上层凋落物和土壤中全部存活种子的总和。土壤种子库研究是植物种群生态学和植被生态学研究的热点之一。我国干旱区分布着大面积的草场，土壤种子库的研究对于草场的研究发挥着十分重要的作用。本文系统介绍了我国干旱区草场种子库研究的方法和内容，旨在为以后草场种子库的研究提供思路。