舟山群岛典型植物群落物种组成及多样性

以舟山群岛特有树种普陀樟(Cinnamomum japonicum var.chenii)、舟山新木姜子(Neolitsea sericea)和全缘冬青(Ilex integra)等占优势的植物群落为研究对象,通过典型样地调查,对物种组成及多样性进行了研究。结果表明:7个植物群落共调查到维管束植物125种,隶属于62科100属,其中滨海特有植物有12科14属16种。地理成分多样,热带成分大于温带、亚热带成分。各层次优势种明显,乔木层主要有红楠(Machilus thunbergii)、普陀樟、全缘冬青和舟山新木姜子等,在更新层中普陀樟和红楠最具优势,而灌木层、草本层、藤本层的优势种取决于群落类型及其所处的环境。群落间各层次的物种丰富度指数(R),Shannon指数(H),Pielou指数(J)均有较大波动,一般与群落的演替阶段、所处岛屿的大小、离大陆远近以及人为干扰有关,其中R、H保持一致的变化趋势。舟山海岛最具代表性的普陀樟群落各层次的R、H均低于其他群落。     

浙江省厚叶石斑木天然群落特征分析

对浙江省9个厚叶石斑木〔Rhaphiolepis umbellata(Thunb.)Makino〕天然群落的物种组成、表型性状、物种多样性和群落相似性进行了调查分析。结果表明:浙江省厚叶石斑木天然群落的物种数量相对较少,共有维管植物39科58属63种;生活型以常绿木本为主,1年生和2年生草本所占比例最小;优势科包括山茶科(Theaceae)、禾本科(Gramineae)、百合科(Liliaceae)、菊科(Compositae)和蔷薇科(Rosaceae),优势属包括柃木属(Eurya Thunb.)、芒属(Miscanthus Anderss.)、石斑木属(Rhaphiolepis Lindl.)、山菅属(Dianella Lam.)和海桐花属(Pittosporum Banks)。根据灌木层优势种的重要值,9个厚叶石斑木天然群落可分为8个类型:滨柃〔Eurya emarginata(Thunb.)Makino〕灌丛、厚叶石斑木+檵木〔Loropetalum chinense(R.Br.)Oliv.〕灌丛、厚叶石斑木+海桐〔Pittosporum tobira(Thunb.)Ait.〕灌丛、滨柃+赤楠(Syzygium buxifolium Hook.et Arn.)灌丛、厚叶石斑木灌丛、厚叶石斑木+大叶胡颓子(Elaeagnus macrophylla Thunb.)灌丛、海桐灌丛和厚叶石斑木+滨柃灌丛。9个群落中,厚叶石斑木的叶片、果实和种子等表型性状变异丰富,叶长、叶宽、叶片长宽比、单果鲜质量和种子鲜质量分别为3.58~5.70 cm、1.38~3.01 cm、2.11~2.43、0.19~0.60 g和0.09~0.30 g,变异系数的均值分别为12.7%、17.5%、12.4%、24.4%和31.8%;灌木层和草本层的物种丰富度、Simpson指数、Shannon-Wiener指数和Pielou均匀度指数最高的群落分别是位于普陀区元山岛的群落Ⅲ和位于玉环县大鹿岛的群落Ⅶ。在各群落中,灌木层的物种丰富度和Shannon-Wiener指数总体上大于草本层,Simpson指数无明显规律性,草本层的Pielou均匀度指数大于灌木层。不同群落间植物种类变化明显,9个群落的相似性系数为0.160~0.625。研究结果表明:浙江省厚叶石斑木天然群落遗传多样性丰富。     

舟山新木姜子(Neolitsea sericea)幼苗对不同盐胁迫的光合生理响应

为评价舟山新木姜子(Neolitsea sericea)的耐盐性, 对其在不同盐胁迫下的光合生理特性进行实验研究。以舟山新木姜子2年实生幼苗为试验材料进行盆栽实验, 通过添加不同浓度的NaCl溶液, 设置4个不同土壤盐分处理(土壤含盐量分别为0、0.3%、0.6% 和 0.9%)。分别在第10 d、20 d、30 d、40 d, 测定舟山新木姜子幼苗在不同处理条件下的叶片叶绿素含量(Chl)、净光合速率(Pn)和最大光化学效率(Fv/Fm)等指标。结果表明：在不同处理之间, 在相同的胁迫阶段, 叶片Chl无显著性差异(P>0.05);在各胁迫阶段, 随着土壤含盐量的增大,叶片Pn、最大光合速率(Pnmax)和光饱和点(LSP)都呈现下降趋势。在轻度盐胁迫(0.3%)舟山新木姜子幼苗叶片Fv/Fm介于0.74—0.78之间, 与对照无显著性差异(P<0.05), 中度(0.6%)和重度盐胁迫(0.9%)最终都显著降低了叶片Fv/Fm; 在胁迫初期, 0.3%、0.6%和0.9%土壤盐分处理条件下Pnmax与CK相比分别下降了29.46%、52.51%、97.91%; 在胁迫初期, LCP随土壤含盐量的增加而升高, 0.3%土壤盐分处理条件下叶片LCP随胁迫时间的延长呈现先下降后上升的趋势。研究表明, 舟山新木姜子幼苗在轻度盐胁迫下(土壤含盐量0.3%)生长受到了一定程度的抑制, 但仍能正常存活, 表现出一定的耐盐性; 在中度(土壤含盐量0.6%)和重度盐胁迫下(土壤含盐量0.9%)则无法存活。该研究结果为该物种迁地保护和滨海盐碱地造林树种选择提供了理论科学依据。     

外马廊山岛植被特性与植物多样性

该研究对无居民海岛舟山外马廊山岛进行初步踏勘,了解该岛植被特征与植物多样性,探讨海岛植被与大陆植被的差异性,并对海岛植物的主要植物组成、生活型结构、地理成分、群落类型以及多样性和相似性进行了分析。结果表明:外马廊山岛面积小,共有33科51属55种植物,植物种类偏少,留存有普陀狗哇花,滨柃,厚叶石斑木等具有滨海特色植物,具有开发潜力。外马廊山岛热带成分较为明显,与附近地区较为相似。岛上群落优势种或建群种的科为山茶科,大戟科,松科等,与大陆的常绿阔叶林的优势种或建群种的优势科如樟科,金缕梅科,壳斗科,山茶科等不大相同。岛上植物主要以高位芽植物为主(58.18%),但较大陆常绿阔叶林的高位芽植物比例要低。外马廊山岛植物群落结构简单,植物多样性相对较低,物种丰富较低,主要原因在于生态适应性和演替过程的差异,岛上植物群落演替至稳定群落还需要相当一段时间。外来种比例占9.09%,外来种如黑松和红鸡竹能形成群落或在群落中具有较为明显的优势,并可能会造成一定的生态干扰。     

盐胁迫下外源NO对苜蓿幼苗生长及氮代谢的影响

为探寻增强苜蓿耐盐能力的调控途径,以甘农4号苜蓿品种为材料,采用NO供体硝普钠、NO清除剂c-PTIO及硝普钠类似物亚铁氰化钠处理苜蓿幼苗,研究盐胁迫下外源NO对苜蓿幼苗生长、光合特征、氮同化酶活性和氮代谢物含量的影响.结果表明: 外源NO能明显缓解盐胁迫对苜蓿幼苗生长及光合作用的抑制,单株干质量、叶绿素含量、净光合速率、蒸腾速率和可溶性蛋白含量增加;外源NO能增强硝酸还原酶、谷氨酰胺合成酶和谷氨酸合酶活性,抑制蛋白水解酶和谷氨酸脱氢酶活性, 降低叶片中游离氨基酸含量,提高硝态氮含量,加快铵的同化.NO供体SNP的类似物亚铁氰化钠对盐胁迫下苜蓿幼苗生长及氮代谢无调控作用;施用NO清除剂c-PTIO加剧了盐胁迫对苜蓿幼苗生长和氮代谢的抑制,添加外源NO能缓解c-PTIO的抑制效应.盐胁迫下,外源NO和内源NO均参与了苜蓿幼苗氮代谢的调控.     

蔊菜幼苗抗菌核病及抗旱和耐湿特性的鉴定

以3个甘蓝型油菜(Brassica napus L.)品种‘中油821’(‘Zhongyou No.821’)、‘中双9号’(‘ZhongshuangNo.9’)及‘中油杂2号’(‘Zhongyouza No.2’)为对照,采用离体叶片菌丝块接种法、人工模拟干旱和湿害胁迫处理法对蔊菜〔Rorippa indica(L.)Hiern〕的抗菌核病〔Sclerotinia sclerotiorum(Lib.)de Bary〕、抗旱和耐湿特性进行了鉴定。结果表明:菌核病菌接种后,蔊菜幼苗叶片的病斑直径为1.75 cm,极显著小于3个甘蓝型油菜品种的病斑直径(3.25～3.60 cm)。经干旱胁迫后,3个油菜品种的幼苗严重萎蔫,茎粗、根长以及地上部分、根和全株的鲜质量和干质量均极显著低于对照;蔊菜幼苗轻度萎蔫,仅茎粗和根鲜质量分别极显著和显著低于对照,其他生长指标与对照差异不显著;蔊菜幼苗各生长指标的伤害指数均显著或极显著低于3个油菜品种。经湿害胁迫后,蔊菜和3个油菜品种幼苗的总叶片数和绿叶数较对照明显减少、黄叶数增加,但蔊菜幼苗的黄叶数显著少于3个油菜品种;3个油菜品种幼苗的茎粗、根长以及地上部分、根和全株的鲜质量和干质量总体上显著或极显著低于对照,而蔊菜幼苗仅茎粗、根长和根干质量显著低于对照,其他生长指标与对照差异不显著;蔊菜幼苗的茎粗,根长,地上部分、根和全株的鲜质量以及根和全株的干质量的伤害指数均显著或极显著低于3个油菜品种。研究结果显示:蔊菜对菌核病的抗性及抗旱和耐湿性均强于供试的3个甘蓝型油菜品种,是十字花科(Brassiaceae)中对菌核病抗性强、抗旱耐湿的优质基因源。     

根系与叶片盐处理对枇杷幼苗生长及体内矿质元素分布的影响

在温室培养条件下,分别用根系和叶片Na Cl胁迫对甜土植物枇杷(Eriobotrya japonica)的幼苗进行处理,研究两种盐胁迫方式对其生长、矿质元素(Ca2+、Mg2+、Na+、K+、Cl-)和灰分含量在植物体各器官和叶片不同部位的影响。结果表明:在叶片盐胁迫下枇杷幼苗的叶片病斑较多分布于叶尖、叶缘,在根系盐胁迫下则较多分布于叶片中心区;根系盐胁迫促进枇杷幼苗的灰分含量积累,叶片盐胁迫则影响不大;两种方式盐胁迫枇杷幼苗体内的Na+和Cl-含量都呈极显著的正相关性;两种方式盐胁迫对枇杷幼苗的5种矿质元素含量影响相差不大,但它们影响矿质元素在植物中的重新分布;叶片盐胁迫对枇杷幼苗体内的离子毒害比根系盐胁迫的大。     

4种桦树幼苗耐盐性分析与评价

耐盐植物引种和培育是开发利用盐碱地的主要方式,具有重要的研究价值。本试验以哈萨克斯坦引进的吉尔吉斯白桦（Betula kirghisorum）、欧洲白桦（B.pendula）、毛枝桦（B.pubescens）和本地的白桦（B.platyphylla Suk.）1年生幼苗为试验材料,于2014年7月在东北林业大学进行中性盐（NaCl）和碱性盐（NaHCO₃）的胁迫试验,测定生长量、光合参数和叶绿素含量,并通过因子分析法,对比评价4种桦树幼苗的耐盐碱能力,筛选出综合性状优良的桦树树种,为耐盐植物引种和培育提供有价值的数据。结果表明：随着盐浓度的升高,桦树幼苗的高生长和光合效率受到显著抑制,而当浓度≥0.5%时,大部分幼苗枯死。株高增长量、基径增长量、净光合速率（P_n）、光能利用效率（SUE）、羧化效率（CUE）、表观量子效率（AQY）及叶绿素含量之间的相关性多数达到了显著水平;最后利用因子分析法分别构建了0.1% NaCl、0.3% NaCl、0.1% NaHCO3和0.3% NaHCO₃胁迫处理的综合评价公式,并分别筛选出了综合性状相对优良的单株,其中NaCl胁迫下较优单株为32、33、34、35;NaHCO₃胁迫下较优单株为262、263、264、35。综合比较认为,吉尔吉斯白桦对低中浓度的中性盐的抗性最强,本地对照白桦对低中浓度碱性盐的抗性最强,而吉尔吉斯白桦和毛枝桦对高浓度碱性盐抗性较强。     

大穗结缕草幼苗耐盐生理机制及耐盐能力研究

以大穗结缕草为实验材料,采用不同质量分数的NaCl处理后,观察盐胁迫对其生长及生理生化指标的影响.结果表明:随着盐胁迫浓度增大,大穗结缕草幼苗株高、鲜重、干重都逐渐下降,而根容量和根冠比却逐渐上升;随盐胁迫浓度的增大,大穗结缕草幼苗叶片细胞质膜透性和MDA含量逐渐增加,脯氨酸含量持续升高;其多数生长和生理指标在≥2.0% NaCl盐胁迫浓度下与对照差异显著,且此时的脯氨酸含量是对照的10倍以上.研究发现,大穗结缕草幼苗地上部分对盐胁迫更敏感、受害更严重;通过体内脯氨酸积累来减轻渗透胁迫是其可能的耐盐生理机制;2.0%盐胁迫可能是大穗结缕草的最高耐盐浓度.     

盐胁迫下树种幼苗生长及其耐盐性

采用盆栽方法,以11个树种实生幼苗为材料,用不同浓度(0、3、5、8 g·kg-1和10 g·kg-1)NaCl溶液进行1次性浇灌处理,对盐胁迫下各树种的形态表现、生长及耐盐性进行了研究,结果表明:(1)当盐含量达到8 g·kg-1时,欧洲荚蒾、甜桦和光叶漆植株死亡,当含量增加到10 g·kg-1时,沃氏金链花植株死亡,其它各存活树种也均出现不同程度的盐害症状;(2)盐胁迫后,各树种的苗高生长量下降、生物量累积减少,且随着处理浓度的增加均呈下降趋势,其中榆桔、甜桦和光叶漆的降幅最大;(3)盐处理后,各树种的根冠比值增大,其中盐胁迫对光叶漆、银水牛果和沃氏金链花有显著影响(p<0.05);(4)综合分析各树种的生长和形态表现,认为日本丁香、银水牛果、三裂叶漆和豆梨具有高度耐盐性,沃氏金链花、金雀儿、鹰爪豆和榆桔具有中高度耐盐性,而欧洲荚蒾、甜桦和光叶漆具有中度耐盐性.     

NaCl胁迫对4种豆科树种幼苗生长和K~+、Na~+含量的影响

以合欢、刺槐、国槐和皂荚4种豆科树种盆栽实生幼苗为试验材料,研究了NaCl胁迫下4个树种幼苗的生长、耐盐临界浓度和Na+、K+含量的变化,并对其耐盐性进行了比较.结果表明:NaCl胁迫抑制了4个树种幼苗的生长,苗木的干物质积累量减小、根冠比增大,尤其对合欢和皂荚的影响较大;以相对干质量降至对照组50%时的NaCl浓度作为生长临界NaCl浓度(C50)指标,4个树种的耐盐强弱顺序为:刺槐(5.0‰)>国槐(4.5‰)>皂荚(3.9‰)>合欢(3.0‰);随NaCl浓度的增加,各树种幼苗根、茎、叶中Na+含量逐渐增加,K+含量先增加后减小(合欢根除外),而K+/Na+差异较大.相同浓度NaCl胁迫下,幼苗器官的Na+分布为根>茎>叶,K+因树种和NaCl浓度不同而各异,以叶片中较多,K+/Na+为叶>茎>根.NaCl胁迫下,刺槐的K+含量和K+/Na+较高,地上部分Na+含量较低,幼苗干物质量大,耐盐性较强;而合欢的K+/Na+较小,高浓度NaCl胁迫下地上部分的Na+含量较高,幼苗干物质量小,耐盐性较差.苗木地上部分对K+的积累和根部对Na+的滞留是影响豆科树种耐盐性能的主要因素.     

盐分和母树大小对黑松海防林种子萌发和幼苗早期生长的影响

研究了盐度(0、0.02、0.04和0.08 mol·L~(-1))和黑松母树大小对山东半岛北部海防林的主要造林树种黑松种子萌发和幼苗早期生长的影响.结果表明:盐度对黑松种子的发芽率有显著影响,随着NaCl浓度的升高,种子萌发率逐渐下降;盐分抑制黑松幼苗的早期生长,随着盐浓度升高,黑松幼苗的根长、芽长及根干质量均显著降低;母树大小在总体上对种子萌发率没有影响,但显著影响黑松幼苗的根长、芽长和芽干质量;盐度和母树大小的相互作用显著影响黑松幼苗的根长和芽长.而对黑松种子萌发率、幼苗根干质量和芽干质量的影响不显著.

Abstract：

Pinus thunbergii is the main forestation tree species of coastal protection forests in northern Shandong Peninsula of China. Its seed germination and seedling early growth were stud-ied under the conditions of different water salinity (0, 0. 02, 0. 04, and 0. 08 mol·L~(-1)) and mother tree sizes. With increasing sea water salinity, the seed germination rate, root-and plu-mule length, and the dry weights of root and plumule decreased significantly. Mother tree size had little effects on the seed germination rate, but affected the root-and plumule length and the plumule dry weight significantly. The interaction of sea water salinity and mother tree size affect-ed the root-and plumule length significantly, but less affected the germination rate and the dry weights of root and plumule.     

NaCl胁迫对4种豆科树种幼苗生长和K+、Na+含量的影响

以合欢、刺槐、国槐和皂荚4种豆科树种盆栽实生幼苗为试验材料,研究了NaCl胁迫下4个树种幼苗的生长、耐盐临界浓度和Na⁺、K⁺含量的变化,并对其耐盐性进行了比较.结果表明：NaCl胁迫抑制了4个树种幼苗的生长,苗木的干物质积累量减小、根冠比增大,尤其对合欢和皂荚的影响较大;以相对干质量降至对照组50%时的NaCl浓度作为生长临界NaCl浓度(C₅₀)指标,4个树种的耐盐强弱顺序为：刺槐(5.0‰)＞国槐(4.5‰)＞皂荚(3.9‰)＞合欢(3.0‰);随NaCl浓度的增加,各树种幼苗根、茎、叶中Na⁺含量逐渐增加,K⁺含量先增加后减小（合欢根除外）,而K⁺/Na⁺差异较大.相同浓度NaCl胁迫下,幼苗器官的Na⁺分布为根＞茎＞叶,K⁺因树种和NaCl浓度不同而各异,以叶片中较多,K⁺/Na⁺为叶＞茎＞根.NaCl胁迫下,刺槐的K⁺含量和K⁺/Na⁺较高,地上部分Na⁺含量较低,幼苗干物质量大,耐盐性较强;而合欢的K⁺/Na⁺较小,高浓度NaCl胁迫下地上部分的Na⁺含量较高,幼苗干物质量小,耐盐性较差.苗木地上部分对K⁺的积累和根部对Na⁺的滞留是影响豆科树种耐盐性能的主要因素.     

Slow Leaf Development of Evergreen Broad-leaved Tree Species in Japanese Warm Temperate Forests

Rates of light-saturated net photosynthesis (P_Nmax) and darkrespiration (Rd) on a leaf area basis, leaf dry mass per area(LMA), leaf nitrogen content on a leaf area basis (LNa) andinstantaneous nitrogen use efficiency (NUE=P_Nmax/LNa) were followedduring leaf development in six evergreen broad-leaved tree speciestypical of warm-temperate forests in Japan. These species wereCastanopsissieboldii, Quercus myrsinaefolia, Quercus glauca, Machilus thunbergii,Cinnamomum japonicumandNeolitsea sericea.When expansion of leafarea was complete, P_Nmax was about one third of its peak valueand increased for another 15 to 44 d. Rd at full leaf expansionwas about 1.5 to 3.5-times greater than steady-state rates.These facts suggest that leaf development was still underwayat the time of full leaf area expansion. Low P_Nmax at full leafexpansion was caused both by low leaf nitrogen content and lowNUE. P_Nmax increased with the increase in LMA during leaf developmentin all six species; data from the literature for other specieswith different life forms also indicated a similar tendency.The steady-state LMA varied markedly among species. Becauseleaves with larger steady-state LMAs need more resources fortheir construction, they will also need longer periods for maturation.We hypothesized that the period required for the attainmentof peak P_Nmax, the ‘leaf maturation period’, dependson the steady-state LMA. Plotting data from the present studytogether with those from literature for other plants acrossseveral life forms showed a strong positive relationship betweenleaf maturation period and steady-state LMA, supporting thehypothesis.Copyright 1998 Annals of Botany Company. Castanopsis sieboldii, Cinnamomum japonicum,delayed period, expansion period, full leaf expansion,Machilus thunbergii,maturation period,Neolitsea sericea, Quercus glauca, Quercus myrsinaefolia,steady-state LMA.     

The roles of seedling salt tolerance and resprouting in forest zonation on thewest coast of Florida, USA

To determine whether the zonation of seven coastal tree species in north Florida correlated with the relative abilities of their seedlings to tolerate soil salinity, we subjected seedlings of Sabal palmetto, Juniperus virginiana var. silicicola, Quercus virginiana, Celtis laevigata, Ulmus spp., Acer floridanum, and Liquidambar styraciflua to a range of salinities (～0, 2, 4, 8, 15, and 22 g synthetic sea salt/L; up to 63% full strength seawater salinity) in a 6-mo greenhouse experiment. Pots with shoot-killed plants were flushed with freshwater for ≥5 wk to assess recovery. Salt tolerance was assessed as plant survival under saline conditions and as the ability to retain green leaf tissue under saline conditions. Using either criterion, the rank order of seedling salt tolerance correlated significantly (P ≤ 0.05) with that expected based on species zonation near the coast. Agreement was better, however, using retention of leaf tissue as an index of salt tolerance. Species from forest zones that were frequently exposed to tidal water retained green leaf tissue under saline conditions. Species from zones occasionally subjected to very high tides were shoot killed but resprouted following removal of salt from the root zone. Those restricted to zones exposed only to infrequent storm surges died at salinities ≥4 g/L. Thus, differential seedling salt tolerance was consistent with tree zonation and, although the ability of young seedlings to resprout following salt removal did not appear to allow tree establishment at the extreme seaward margin of the forest, it appeared important in intermediate zones.     

The reclassification of Lycopodiaceae (s. str.) in China

The fern-allied family Lycopodiaceae(s. str. ) in China is reclassified in the present paper. Six genera, fifteen species and three forms are recorded. The genus Pseudolycopodiella Holub (1983) is adopted, one new name, Lycopodium neopungens H. S. Kung et L. B. Zhang, is given to replace the invalid name L. pungens Desv., one new form is described: Palhinhaea hainanensis C. Y. Yang f. glabra H. S. Kung et L. B. Zhang, and nine names are treated for the first time as synonyms: L. annotinum L. var. brevifolium Christ( = L. zonatum Ching), L. annotinum L. var. aciculare Christ( = L. zonatum Ching), L. alticola Ching( = L. zonatum Ching), L. simulans Ching et H. S. Kung ex Ching( = L. japonicum Thunb. ex Murray), L. interjectum Ching et H. S. Kung ex Ching( = L. japonicum Thunb. ex Murray), L. taliense Ching(＝L. japonicum Thunb. ex Murray), L. pseudoclavatum Ching( = L. japonicm Thunb. ex Murray.), L. pseudoclavatum Ching var. yunnanense Ching( = L. japonicum Thunb. ex Murray), and L. centro-chinense Ching( = L. japonicum Thunb. ex Murray). The distribution of all the taxa is also given. Additionally, some taxonomic discussions are made and it is considered that there is no Diphasiastrum wightianum (Wall. ex Grev. et Hook. ) Holub( = Lycopodium wightianum Wall. ex Grev.et Hook. ) in the flora.     

Impacts of streaked shearwater (Calonectris leucomelas) on tree seedling regeneration in a warm-temperate evergreen forest on Kanmurijima Island,Japan

The ground vegetation of an evergreen broad-leaved Persea thunbergii-dominated forest on Kanmurijima Island has been heavily damaged by a ground-burrowing seabird, the streaked shearwater (Calonectris leucomelas). To clarify the effects of seabird trampling and burrowing on the recruitment of tree seedlings, 22 paired quadrats, protected and unprotected against seabirds, were laid out under various degrees of canopy coverage, ranging from heavy- to light-shade. Protection from seabird activities resulted in an increase in species richness of tree seedlings. Seabird activities had a significant effect on tree seedling diversity, while canopy coverage was shown to be important for herbaceous species diversity. Though seedling emergence of Persea thunbergii, the evergreen canopy dominant, was not affected by seabird activities and canopy coverage, that of Mallotus japonicus, a deciduous pioneer tree, was negatively affected by the both factors. Seabird activities and evergreen heavy-shade canopy negatively affected seedling survivorship of both species. Low survivorship in seedlings of the canopy species may doom the present-day warm-temperate evergreen forest of Persea thunbergii on the island. Mechanical impacts of trampling and burrowing and the resulting soil erosion may play an important role in forest regeneration and dynamics.     

11株不同生态条件下的根瘤放线菌的形态特征

1 引言 自1978年由美国的Callaham等首次成功地从香蕨木根瘤中分离出Frankia的离体培养以来,使放线菌结瘤植物的研究领域有了突破性的进展,据报道,近10年国内外的研究者已从10个属植物根瘤中获得Frankia菌株的离体纯培养。我们于1981年由四川