云南蒋家沟流域不同海拔梯度土壤种子库特征

为了解云南蒋家沟流域土壤种子库在不同海拔梯度上的变化特征,明确种子库对植被垂直带谱的响应性机制及群落恢复潜力,选取蒋家沟流域8条海拔带[Ⅰ(2700~2900 m)、Ⅱ(2500~2700 m)、Ⅲ(2300~2500 m)、Ⅳ(2100~2300 m)、Ⅴ(1900~2100 m)、Ⅵ(1700~1900 m)、Ⅶ(1500~1700 m)、Ⅷ(1300~1500 m)]为研究对象,对其植物群落土壤种子库的数量特征、物种组成、物种多样性及种子库相似性进行研究。结果表明:Ⅲ、Ⅱ海拔带的平均物种数和种子密度显著高于Ⅶ、Ⅷ海拔带,土壤种子库种子密度与物种数量随海拔降低而逐渐减少;Ⅰ、Ⅱ、Ⅲ海拔带的Margalef丰富度指数(M)大于5.000,Ⅶ、Ⅷ海拔带M小于3.000。种子库萌发物种以菊科和禾本科草本植物为主,海拔2300 m以上以多年生草本植物占优势,海拔2100 m以下则以1年和2年生草本植物占优势。各海拔带物种分布均匀性较好,除Ⅵ海拔带外,其余海拔带Pielou均匀度指数(J)均大于0.900。Ⅲ海拔带的Simpson优势度指数(D)和Shannon-Wiener多样性指数(H)最高,分别为0.942和3.006;Ⅶ海拔带的D和H最低,为0.810和1.720。除Ⅶ、Ⅷ海拔带以外,其余海拔带的土壤种子库均与临近海拔带种子库相似性最高,Sorensen相似性系数(CS)为0.400≤CS<0.550,且整体上表现为随海拔升高CS逐渐减小的趋势。蒋家沟流域植被群落土壤种子库的变化受海拔梯度的影响,与蒋家沟流域内气候的垂直地带分布具有一定的关系。     

干旱河谷边坡海拔变化对土壤种子库的影响

为更好地利用土壤种子库进行植被的自然恢复更新实践,利用"萌发幼苗法"测定海拔差异对岷江干旱河谷灌丛植被土壤种子库特征的影响,相应地上植被的特征采用样方法进行调查。结果表明:各海拔的土壤种子库库容量和物种丰富度随土层加深而减小;海拔间隔100 m以上时,土壤种子库和地上植被的物种组成更易呈现出显著的差异性;3个样地中,各海拔的土壤种子库和地上植被的物种组成频数均呈显著的负相关,表明海拔这一局部环境因子对土壤种子库和地上植被物种组成关系的影响不明显,岷江干旱河谷局部地段土壤种子库的特征可能由河谷整体环境所决定。     

北京西山地区火烧迹地植被恢复研究

在土壤性质分析的基础上,应用丰富度、多样性、相似度指标,研究了火烧迹地植被恢复情况,并与未过火林地做出了比较,讨论了北京西山地区火烧迹地土壤性质的变化与植被恢复之间的关系。结果表明:1)火烧迹地土壤的土粒密度增加,pH值呈上升趋势,土壤有机质减少,全氮增加,有机质的C/N比值在15左右。2)火烧迹地上植被的物种丰富度、Simpson指数、Shannon-Wiener指数高于未过火林地,火烧迹地与未过火林地更新层的物种丰富度相差不大,灌木层和草本层的物种丰富度和多样性则是火烧迹地上较高。3)火烧迹地与未过火林地土壤性质的差异导致了植被的差异,植被恢复也对土壤性质的变化产生了影响。     

香格里拉亚高山不同退化程度森林群落土壤种子库的特征研究

2006～2007年采用种子萌发法,对香格里拉亚高山不同退化森林群落的土壤种子密度、丰富度,物种组成及地上植被组成开展了调查研究。结果表明:(1)亚高山土壤种子库中共有42个种子植物,种子密度为471～891粒/m2;(2)退化林地种子库中的物种密度依次为重度退化>极度退化>中度退化>轻度退化>未退化,物种丰富度依次为轻度退化>未退化>极度退化>中度退化>重度退化;(3)多年生草本植物在5类群落中均占绝对优势,只在未退化林地中发现木本植物;(4)土壤种子库及地上植被在物种组成上具有较小的Jaccard相似系数;(5)11月份物种数量及种子密度比4月份及7月份高;(6)0～5 cm表土种子库中具有较高的物种数量及种子密度;(7)种子扩散、地上植物的无性繁殖及人工造林是恢复香格里拉亚高山退化植被的有效途径。     

高黎贡山自然保护区东坡水平带蚂蚁群落研究

研究了高黎贡山东坡水平带蚂蚁群落特征，结果表明，除中南段2500m等高线外，东坡各水平带的不同位置均有特有种。在1000m、1500m、2000m、2500m等高线上，从北到南特有种数目依次递增，但北段1500m和2000m等高线出现特有种增高例外。在东坡不同海拔等高线上，大多数物种只在1个样地中表现为优势种，北段与南段的优势种通常不同。在1000m和2000m等高线上北段的优势种多于南段，而在1500m等高线上南段优势种多于北段，2500m等高线上不同地段优势种趋于相等。东坡水平带上物种数目和密度表现出普遍规律性。从北到南，1000m和2500m等高线上物种数目和密度依次递增，在1500m等高线上物种数目和密度依次递减。在1000m等高线上优势度、多样性和均匀度具有明显规律性。从北到南，优势度依次递减，多样性和均匀度依次递增，但在北段出现例外。在1500m、2000m和2500m等高线上，蚂蚁群落的优势度、多样性和均匀度缺乏规律性，可能与植被的次生化和片断化等因素有关。尽管东坡水平带上同一海拔植被类型相似，但是蚂蚁群落之间差异显著，相似性系数在0－0．50之间。山体下部1000m等高线上蚂蚁群落之间相似性较大，相似性系数在0．25－0．50之间。随着海拔增加，同一水平带上群落之间相似性减小。     

基于土壤种子库的植被自然恢复作用研究

利用退化荒草地附近种源地表层土壤,通过客土和人工播撒乔、灌木种子的方式对荒草地进行土壤种子库的补充,比较植被恢复地、种源地、对照裸地的土壤种子库组成、密度、多样性、地上植被生物量和土壤理化性质,研究土壤种子库对荒草地在植被恢复方面的改良作用,以便为今后退化土地的自然恢复提供理论依据。结果表明:植被恢复地土壤种子库物种数量比对照裸地增加6种,地上植被有常绿乔木及多种灌木物种出现,种子密度由843.75粒/m~2增加至3 645.83粒/m~2;土壤种子库Shannon-Wiener多样性指数和Margalef丰富度指数顺序由大到小均依次为:植被恢复地、种源地、对照裸地;与地上植被的相似性指数也由0.12增加到0.23;植被恢复地地上生物量分别是种源地和对照裸地的4.28倍、4.85倍;植被恢复地的持水量增加,土壤结构改善,有机质及N、P、K的含量均显著提高。     

高黎贡山自然保护区东坡水平带

研究了高黎贡山东坡水平带蚂蚁群落特征,结果表明,除中南段2 500 m等高线外,东坡各水平带的不同位置均有特有种.在1 000 m、1 500 m、2 000 m、2 500 m等高线上,从北到南特有种数目依次递增,但北段1 500 m和2 000 m等高线出现特有种增高例外.在东坡不同海拔等高线上,大多数物种只在1个样地中表现为优势种,北段与南段的优势种通常不同.在1 000 m和2 000 m等高线上北段的优势种多于南段,而在1 500 m等高线上南段优势种多于北段,2 500 m等高线上不同地段优势种趋于相等.东坡水平带上物种数目和密度表现出普遍规律性.从北到南,1 000 m和2 500 m等高线上物种数目和密度依次递增,在1 500 m等高线上物种数目和密度依次递减.在1 000 m等高线上优势度、多样性和均匀度具有明显规律性,从北到南,优势度依次递减,多样性和均匀度依次递增,但在北段出现例外.在1 500 m、2 000 m和2 500 m等高线上,蚂蚁群落的优势度、多样性和均匀度缺乏规律性,可能与植被的次生化和片断化等因素有关.尽管东坡水平带上同一海拔植被类型相似,但是蚂蚁群落之间差异显著,相似性系数在0～0.50之间.山体下部1 000 m等高线上蚂蚁群落之间相似性较大,相似性系数在0.25～0.50之间.随着海拔增加,同一水平带上群落之间相似性减小.     

香格里拉亚高山大果红杉—高山栎群落种子雨与土壤种子库研究

采用随机取样的方法对香格里拉亚高山大果红杉、高山栎群落的种子雨和土壤种子库进行分析研究,结果表明,群落的种子雨由5个主要组成树种的种子组成,发生在每年的9~11月,强度为3 520粒/m2.土壤种子库由分属9科15属的17种植物组成,主要以多年生草本为主,且大约75%的种子均分布在较浅的土层.土壤种子库的物种组成与地上植被物种组成的相似性系数仅为0.042 6,表明土壤种子库与地上植被的相关性不明显.     

湖南近自然森林经营主要林分类型土壤种子库特征研究

采用野外取样与种子萌发相结合的方法对湖南近自然森林经营主要林分类型(杉木、马尾松林)土壤种子库特征进行了研究。结果表明,杉木林土壤种子库主要由16种植物组成,其物种组成以草本为主,马尾松林20种,其种子库组成包括乔、灌、草生活型的物种。地上植被作为土壤种子库中种子来源,与种子库物种组成具有较高的相似性。种子库萌发过程呈现先草本植物种子萌发后木本植物的现象。杉木林、马尾松林土壤种子库密度具有一定相似性,杉木林、马尾松林最大值均出现在0~10 cm土壤层,分别为434.7粒/m2、523.6粒/m2。杉木林、马尾松林土壤种子库Margalef丰富度指数在10~20 cm土壤层中最低,最大值均出现在0~10cm土壤层中。Shannon-Wiener多样性指数存在一定差异,在10~20 cm土壤层中,杉木林多样性指数为1.56,而马尾松林为1.34,为各层取样中多样性指数最低值。杉木林多样性指数最低值出现在枯枝落叶层,为0.70,多样性指数最高值均出现在0~10 cm土壤层中,分别为1.72、2.01。马尾松林土壤种子库在数量及质量上高于杉木林土壤种子库,马尾松林已逐渐演变为以马尾松占优势,青冈栎、香樟等乔木伴生的次生林,具有一定的林分自然更新能力。     

河西走廊中部沙漠人工梭梭林土壤种子库特征

采用野外调查和室内分析相结合的方法,对河西走廊中部沙漠人工梭梭(Haloxylon ammodendron)林土壤种子库进行研究。结果显示:(1)沙漠人工梭梭林中土壤种子库共统计到9个物种,隶属3科9属,以藜科植物最多,土壤种子库总体表现出科属组成较为集中、1年生草本的物种和密度占优势的特点;(2)在沙漠人工梭梭林土壤种子库中,0～2 cm层、2～5 cm、5～10 cm的物种数量分别为4种、5种、6种,其种子密度依次为54.71粒/m~2、58.00粒/m~2、132.86粒/m~2。物种数量和密度均呈现5～10 cm2～5 cm0～2 cm层的分布规律,5～10 cm层与2～5 cm、0～2 cm层密度差异明显。(3)不同土层种子库的Shannon—wiener、Simpson、Peilow指数变化趋势基本一致,随土层深度增加而增大,而Margalet指数和生态优势度指数与之相反;(4)种子库和地上植被的相似性系数在0.545 5～0.666 7之间,相似程度比较高。(5)从土壤种子库物种的生活型构成及各功能群优势度比例分析,整体上,种子库中以1年生植物的种子比例最高,达到86.13%;沙漠植被自我恢复的程度较低。     

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。     

Endozoochory by European bison influences the build-up of the soil seed bank in subcontinental coniferous forest

The faeces of large herbivores include viable seeds of many plant species. With dung decomposition, some seeds migrate into the soil and influence seed bank build-up. However, only a few papers report evidence of this process, and only from grasslands. In forest studies, this subject has so far been neglected. Therefore, I ask in this paper whether seeds present in the dung of European bison migrate to the forest soil seed bank and influence its build-up. I sampled soil from underneath European bison dung pats and from surrounding areas (control samples). Samples were divided into shallow (0–5 cm) and deep (5–10 cm) series. Soil seed bank content was studied in the greenhouse for 2 years. The shallow seed bank under dung pats was characterized by the highest species richness (49 species) and seed density (>2,000 m^?2). Urtica dioica, Juncus effusus and Carex remota showed a demonstrable increase in seed density in the shallow seed bank underneath dung. Three years after dung deposition, seeds of endozoochoric origin influenced the soil seed bank of coniferous forest. U. dioica, J. effusus, C. remota and other species of deciduous forests and grasslands (Agrostis capillaris, Milium effusum, Polygonum hydropiper, Polygonum mite, Scrophularia nodosa, Stachys sylvatica, Veronica chamaedrys) caused an increase in seed density (by 61 %) and species richness (by 33 %) of the shallow soil seed bank underneath dung in comparison with the control soil seed bank.     

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.     

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。     

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。     

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.     

林木抗旱生理研究进展

从林木的表型特征、生理生化特性、抗旱分子生物学与抗旱基因表达3方面对国内外林木抗旱性研究进行综述。当前国内外学者对植物叶茎根的表形特征、渗透调节、光合生理、叶绿素荧光变化、活性氧代谢、植物激素的研究较多, 而对受干旱胁迫下林木的分子生物学与基因表达研究相对较少。最后提出了林木抗旱生理研究的主要评价方法、研究指标、研究方法与内容。随着技术的发展及相关研究的深入, 抗旱分子生物学与抗旱基因等方面的研究将成为林木抗旱生理方面的热点。     

Implications of crude oil pollution on natural regeneration of plant species in an oil-producing community in the Niger Delta Region of Nigeria

The study evaluated the impact of crude oil pollution on natural regeneration of plant species in a major oil-producing community in the Niger Delta region of Nigeria. Three sites—unpolluted site(US), polluted and untreated site(PUS), and polluted and treated site(PTS)—were purposively chosen for the study. The seedling emergence method was used to evaluate soil seed banks in the various sites at two depths, 0 to 10 cm and 10 to 20 cm. Woody-plant species richness, abundance, and diversity were higher in the US seed bank than in the PUS and PTS seed banks. The highest number of non-woody plants was observed in the US, followed by the PTS, and then the PUS. Both species richness and diversity of non-woody plants were highest at the US, followed by the PUS, and lowest in the PTS. Woody species in the US seed bank were 87.5% and 80% dissimilar with those of the PUS and PTS at 0–10 cm and 10–20 cm respectively. No variation was observed between woody species in the PUS and PTS seed banks. Non-woody species at 0-10 cm US seed bank were 73.08% dissimilar with those of PUS at the two soil depths and 81.48/88.46% dissimilar with those of the 0–10/10–20 cm of the PTS respectively. At 10–20 cm, non-woody species of the US were 69.66% dissimilar with those from each of the two soil depths in PUS; and 73.91/81.82% dissimilar with those of 0–10/10–20 cm of the PTS respectively. Non-woody species variation between the PUS and PTS was higher at 10–20 cm than 0–10 cm. The poor seed bank attributes at the polluted sites demonstrates that crude oil pollution negatively affected the natural regeneration potential of the native flora because soil seed banks serve as the building blocks for plant succession. Thorough remediation and enrichment planting are recommended to support the recovery process of vegetation in the polluted areas.