小兴安岭五种林型早春草本植物多样性及其环境解释

早春草本层植物作为草本层动态变化的早期阶段,是森林的重要组成部分,对于维持森林生态系统功能及其多样性具有重要意义。为探究小兴安岭地区早春草本层植物对人为干扰后引起的林型改变的响应,以黑龙江凉水国家级自然保护区内的五种林型(白桦次生林(Betula platyphylla)、红松(Pinus koraiensis)人工林、落叶松(Larix gmelinii)人工林、阔叶红松择伐林以及阔叶红松林)为研究对象,分析林下早春草本层植物多样性的差异及其影响因素。结果显示：(1)研究区林下早春草本层植物共60种,隶属26科52属,林下优势种主要以银莲花(Anemone cathayensis)、东北羊角芹(Aegopodium alpestre)为主,五种林型早春草本层植物组成相似度较高;(2)五种林型不同生活史对策早春草本层植物的密度、盖度以及多样性指数均呈现显著差异;(3)土壤pH对早春生长期植物的密度、盖度及多样性指数,林下光对早春开花植物的密度和盖度以及早春展叶植物的多样性指数具有较高的解释率;(4)早春生长期植物的密度、盖度及多样性指数与土壤pH呈显著的正相关关系,其多样性指数与土壤全...     

长白山红松阔叶林林冠空隙特征的研究

将林冠空隙干扰作为红松阔叶林动态维持的重要因素,对长白山红松阔叶林林 冠空隙的形成方式、出现频度、分布格局、结构及林冠空隙内形成本的数量、年龄分布、种 群特征等进行了系统分析．结果表明．长白山阔叶红松林多数林冠空隙由双形成本形成, 每个林冠空隙拥有的形成木为２．４４株;林冠空隙形成的速率为０．９２个ｈｍ２·ａ－１,林冠空 隙干扰的间隔期（周转期）为７５１ａ;扩展林冠空隙面积大多在１００～６００ ｍ２之间,其中以 ４００～５００ ｍ２所占比例最大．冠空隙在５０～３５０ ｍ２之间,其中以２００～２５０ ｍ２所占比例最 大;每个形成本所形成的扩展林冠空隙平均面积为 １４１ ８２ ｍ２,形成的冠空隙面积平均为 ６７．６３ ｍ２．     

辽宁白石砬子保护区早春类短命植物研究

调查和分析了白石砬子保护区早春类短命植物物种组成的数量特征,应用物种丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson优势度指数,定量描述了不同林型下早春类短命植物的物种多样性.结果表明:研究区有早春类短命植物12种2变型,隶属7科11属.黑水银莲花是早春类短命植物层片的优势种.花曲柳林下早春类短命植物物种数最多,枫桦林、红松阔叶林、落叶松林次之,蒙古栎林、杂木林、鱼鳞云杉臭冷杉林最少.多样性指数的变化趋势总体上表现为针阔混交林>落叶阔叶林>针叶林.均匀度指数的变化与多样性指数的变化趋势基本一致,与优势度指数的变化趋势相反.红松阔叶林下早春类短命植物物种多样性最高且各物种均匀分布,层片结构稳定.     

长白山红松阔叶林林冠木竞争生长及林冠空隙动态研究

以长白山红松阔叶林林冠木的年龄资料为基础,分析林木冠重叠与年轮径向生长的关系;通过林冠空隙边缘人隙边缘株的干扰释压分析,揭示林冠空隙集中形成的动态规律。红松林相邻林木间理论树冠重叠率与年轮径向生长呈显著负相关,不同树种间存在不同的竞争和协同关系;红松林中除个别小空隙是经过一个集中形成期形成外,大部分空隙是经过２－３个集中形成期形成的,１９００－１９２０和１９１０－１９３０是大部分空隙的集中形成期。     

山西霍山灌丛空隙草本植物物种多样性与更新

采用物种重要值和物种多样性指数,分析了山西霍山灌丛空隙内主要草本组成及其多样性随灌丛空隙面积梯度的变化规律。结果表明:在自然状况下形成的10 m2的灌丛空隙最多,占51.2%。灌丛空隙内草本植物的重要值高于灌丛下草本,且以10~20 m2的空隙为最高。主要草本可分为3类:(1)对灌丛空隙更新反应不明显的草本,(2)对灌丛空隙有正更新反应的草本,(3)对灌丛空隙有负更新反应的草本。灌丛空隙内的物种丰富度、多样性指数和均匀度指数均高于灌丛下,而生态优势度均小于灌丛下,呈现"单峰型"的变化趋势,且在10~20 m2达到峰值。因此,适宜大小的灌丛空隙是森林生态系统草本层植物多样性维持的重要途径。     

中国森林冠层生物多样性监测

林冠作为森林与外界环境相互作用最直接和最活跃的关键生态界面,承载了森林生物多样性的主体,在生物多样性的形成与维持以及生态系统功能过程中发挥着重要的作用,被称为地球的"第八大洲"。同时,林冠对气候变化和人为干扰高度敏感,在人类活动和全球气候变化加剧的背景下,森林生态系统正面临着严重的威胁,首当其冲的就是森林冠层。气候变化下的林冠生物多样性保护与可持续利用已成为现代生态学研究的热点问题,受到森林生态学、气候学、环境科学等研究领域的学者越来越多的关注。据此,中国生物多样性监测与研究网络以网络内拥有森林冠层塔吊的生物多样性监测样地为平台,建立了林冠生物多样性监测专项网。该专项网将参照国际标准,统一监测指标,规范监测标准,通过大尺度地带性森林冠层内植物(包括附生种子植物和附生孢子植物)多样性、动物多样性、微生物多样性及其动态变化的长期监测,结合林冠小气候环境特征监测,建立林冠小环境特征、植物多样性、节肢动物多样性和微生物多样性等4个动态更新的数据库,以阐明我国典型森林林冠生物多样性变化的规律,揭示其对森林生态系统功能过程的影响和对全球变化的响应。     

不同类型人工阔叶红松林高等植物物种多样性

采用Shahnon—Wiener多样性指数、均匀度指数和优势度指数等指标研究了辽宁东部山区人工营造20年生5种阔叶树水曲柳、刺愀、紫椴、色赤汤、白桦与红松形成的混交林及人工红松纯林内各层次高等植物物种多佯性,并对该6种林分的垂直结构进行比较。结果表明,人工阔叶红松混交林内植物种类丰富,数量较多;红松纯林内的植物种数仅为人工阔叶红松混交林的42％～52％,植物总数量只有混交林的11％～37％。人工阔叶红松林各层次高等植物物种多样性均好于人工红松纯林,但与原始阔叶红松林相比。人工阔叶红松林的物种多样性还较低。在林分垂直结构方面,人工阔叶红松混交林的成层现象明显,层次结构复杂,垂直多样性丰富;红松纯林只有1个主林冠层,灌木层、草本层较矮,林分垂直结构单一。     

长白山红松阔叶混交林森林天然更新条件的研究

研究长白山红松阔叶混交林森林天然更新的变化规律及其条件,红松阔叶混交林是长白山主要的森林类型,保存不多,对于研究以前森林经营有重要意义。研究的目的在于揭示红松天然更新规律及其与森林组成结构的关系。研究结果表明,红松阔叶混交林天然更新与森林群落类型,海拔,森林植物条件及人类活动等干扰极大关系,一般在陡坡或山脊上胡枝子作树红松林中,那里林冠郁闭度达到80％－90％或更大,林分中红松组成也更大,红松天然更新良好。每公顷有红松幼苗和小幼树万株以上,但是在郁闭的红松林冠下,很少能长大。在大部分的阔叶红松混次林中,除了林冠比较郁闭的地方外,针叶树包括红松在内的天然更新通常稀少,每公顷仅有幼苗幼树数千株,其中大部是阔叶树,随着海拔上升到一定范围,在更新中云冷杉的成分增加,老择伐迹地由于林下植被密,常常缺乏更新。74．2％耐荫树种的幼苗幼树是在林冠下观查到,它们70％以上分布于离立木2．5 m以内,这正好等于林木平均冠幅的半径,所以,红松和耐荫树种幼苗的更新最好是在郁闭的林分下。     

森林生态系统中草层植物的生态功能

综述了过去20年国内外有关森林生态系统中草层植物的生态功能研究。森林生态系统中的草层植物是指活的草本类植物及在一定高度（通常40cm)以下的乔灌木幼苗的总和,它和枯落物以及林下土壤共同构成森林生态系统中的林下层亚生态系统。森林生态系统中的草层植物具有明显增加生物多样性,防止水土流失,改良土壤结构,保持和提高土壤肥力,促进林木生长,改善林地小气候,加速生态恢复等方面的功效。其功能是相当强大且多种多样的,我国南亚热带森林生态系统中的草层植物研究应在以下方面进一步加强：1）草层植物与枯落物各自的生态功能与生态效益;2）人工林下的草层植物发生与演替规律;3）林下幼苗的更新演替规律;4）草层植物在复合农林业生态系统中的生态功能及其机理;5）加强草层植物的良种的选育和应用研究等。     

鼎湖山森林群落多样性垂直分布格局的研究

根据鼎湖山10 m×1 200 m的植物固定样带调查,沿海拔梯度对植物群落分布格局及生物多样性特性进行了分析。结果表明,本固定样带有3个森林类型,5个群落类型,构成一演替序列,但在垂直梯度上有交错现象。生物多样性指数为:乔木层,中生性阔叶林>针阔混交林>阳生性阔叶林;草本层,针阔混交林>阔叶林。阳性草本植物为主的草本群大部分生长在阳性树种为主的阔叶林和针阔混交林下,但是林下微环境变化对草本层植物优势度的影响也较大,以耐荫植物为主的草本群在阳性树种为主的阔叶林和针阔混交林也有分布,表明相同群落类型林下小环境的变化。     

神农架巴山冷杉群落更新特点及影响因素

采用样方法对神农架自然保护区巴山冷杉群落更新特性、环境因子对其更新的影响进行了研究.研究表明:(1)林窗更新是巴山冷杉群落重要的更新方式,以红桦为代表的阔叶树种和巴山冷杉等耐荫树种在林窗内外均存在更新差异;(2)巴山冷杉在林窗更新中具有最大优势,3a以下的巴山冷杉幼苗数量占45.7%,随着年龄的增加下降明显,7a以上的幼树数量只占6.3%;(3)用SPSS将影响巴山冷杉更新的四类环境因子进行主成分分析表明,林窗面积、坡向、林窗微环境、乔灌草盖度依次是影响巴山冷杉幼苗生长和分布的主要因子;(4)林窗微环境因子的相关分析表明,在不同的生活史阶段,更新影响因子重要性不同,光照水平和土壤水分分别对幼苗和幼树的生长具有显著影响;(5)坡向和密度的相关分析表明在北坡巴山冷杉更新幼苗数量丰富,灌草层是巴山冷杉更新过程的潜在障碍.     

青海三江源地区三种天然圆柏林更新特征

为明确青海三江源地区3种天然圆柏林的更新特征及其主导影响因子,对天然林保护与经营提供参考,本研究评价了圆柏林天然更新等级,分析了林分因子和林地土壤因子对圆柏林天然更新的影响.结果 表明:3种天然圆柏林更新不良,更新潜力不足.大果圆柏林、祁连圆柏林和密枝圆柏林平均更新密度分别为332、279和202株·hm-2,更新个体...     

伏牛山自然保护区森林冠层结构对林下植被特征的影响

在伏牛山自然保护区典型地段设立样方,测定了森林生态系统内几种典型群落类型的冠层结构、光环境特征,调查了林下植被的特征,分析了它们之间的相互关系.结果显示:各群落的冠层结构和光环境有一定的差异,单因素方差分析表明,部分群落间的差异性达到显著水平;各群落灌木层物种丰富度、多样性和均匀度均高于草本层,而优势度正相反;线性拟合的结果表明,草本层的物种丰富度、多样性与冠下光合量子通量密度间呈极显著负相关,优势度与冠下光合量子通量密度间呈显著正相关,灌木层各参数与冠层结构特征间相关性不显著.研究表明,冠层结构的变化对草本层(包括更新幼苗)的影响显著高于灌木层.林隙/林窗或林中空地的出现可能对草本物种或其他阳性及先锋物种具有促进作用,而对优势种幼苗的萌发和定植产生负效应.推测在典型的落叶阔叶林生态系统演替进程中,林下光照强度可能不是最主要的限制因素,优势种种子的扩散、萌发和定植限制可能更重要.     

Tree diversity,composition, forest structure and aboveground biomass dynamics after single and repeated fire in a Bornean rain forest

Forest fires remain a devastating phenomenon in the tropics that not only affect forest structure and biodiversity, but also contribute significantly to atmospheric CO2. Fire used to be extremely rare in tropical forests, leaving ample time for forests to regenerate to pre-fire conditions. In recent decades, however, tropical forest fires occur more frequently and at larger spatial scales than they used to. We studied forest structure, tree species diversity, tree species composition, and aboveground biomass during the first 7 years since fire in unburned, once burned and twice burned forest of eastern Borneo to determine the rate of recovery of these forests. We paid special attention to changes in the tree species composition during burned forest regeneration because we expect the long-term recovery of aboveground biomass and ecosystem functions in burned forests to largely depend on the successful regeneration of the pre-fire, heavy-wood, species composition. We found that forest structure (canopy openness, leaf area index, herb cover, and stem density) is strongly affected by fire but shows quick recovery. However, species composition shows no or limited recovery and aboveground biomass, which is greatly reduced by fire, continues to be low or decline up to 7 years after fire. Consequently, large amounts of the C released to the atmosphere by fire will not be recaptured by the burned forest ecosystem in the near future. We also observed that repeated fire, with an inter-fire interval of 15 years, does not necessarily lead to a huge deterioration in the regeneration potential of tropical forest. We conclude that burned forests are valuable and should be conserved and that long-term monitoring programs in secondary forests are necessary to determine their recovery rates, especially in relation to aboveground biomass accumulation.     

不同间伐强度对辽东栎林群落稳定性的影响

对黄土高原地区近自然经营间伐强度为13.4%(弱度间伐)和30.0%(强度间伐)的辽东栎林进行样地调查,并以未间伐林为对照,研究间伐后第5年建群种的更新潜力、林地生产力、土壤肥力和物种多样性;应用模糊数学中的隶属函数方法对辽东栎林群落稳定性进行评价.结果表明：与对照相比,弱度和强度间伐使辽东栎林地的更新潜力分别提高了14.2%和20.2%;立木蓄积量分别减少了9.0%和23.8%,但灌木生物量分别增加7.3%和12.2%,草本生物量分别增加10.5%和31.6%.间伐样地的土壤肥力和物种多样性指数均高于未间伐样地.辽东栎林群落稳定性表现为：强度间伐＞弱度间伐＞未间伐.近自然经营采伐强度30.0%更适合黄 土高原地区辽东栎次生林的抚育管理.     

Burrowing seabirds affect forest regeneration, Rangatira Island, Chatham Islands, New Zealand

The forests of Rangatira Island (218 ha) in the Chatham Islands are a critical breeding site for a number of rare and threatened forest bird species, but are also home to more than three million seabirds, which could significantly affect forest regeneration processes. We surveyed the forests of Rangatira Island by establishing 40 permanent forest plots, estimated seabird density through burrow counts, and analysed soil properties. To determine if seabirds were impacting on forest regeneration, we established exclosures (0.25 m²) in 30 of the forest plots, and examined the role of canopy gaps in forest regeneration. The tallest current forest (c. 15 m), dominated by Plagianthus chathamicus, has mostly regenerated since stock were removed in 1959. Mean burrow density was estimated to be 1.19 per square metre, all soils were highly acidic (pH 3.36–5.18), and burrow density was positively correlated with soil phosphorus. Seedling density of woody species in seabird exclosures measured after 9, 24 and 33 months was significantly higher than in the adjacent non-gap plots, and seedling density was positively associated with reduced canopy cover. Seedling densities were also significantly higher in canopy gaps than in adjacent non-gap plots, but seabird burrow density was significantly lower in gaps. These results suggest that canopy gaps allow forest regeneration despite the negative impacts of seabird burrowing. However, the gap makers, largely senescing Olearia traversii, are slowly disappearing from the forests. The cohort of Plagianthus that has regenerated following farm abandonment may progressively collapse, allowing regeneration to continue in small openings, but there is also the potential for a catastrophic blowdown. This might have serious implications for forest-dwelling birds, invertebrates, and plants.     

亚高山暗针叶林不同林冠环境下华西箭竹的克隆可塑性

以亚高山暗针叶林3种林冠环境中以及暗针叶林林缘的华西箭竹（Fargesia nitida）为对象,对其无性系数量特征、无性系根茎特征、分株生物量以及分株形态特征进行了对比研究。结果表明：（1）林冠环境的差异导致了不同种群的基株密度和每基株分株数的显著差异,但林冠环境差异不影响分株密度。林冠郁闭度愈大,每基株分株数愈少,分株分布愈均匀。（2）不同林冠环境间。分株生物量、分株构件生物量和分株构件的生物量分配百分率均有显著差异。开敞的林冠环境有利于华西箭竹的生长和生物量积累。（3）随着林冠郁闭度的增加,华西箭竹通过增大分枝角度、叶生物量分配百分率、比叶面积和叶面积率以提高光能利用效率,有效适应弱光环境。（4）隔离者长度、隔离者直径和分枝强度在林缘和林窗环境中要显著大于林内环境;同级隔离者分枝角度随林冠郁闭度的增加而最大,其值在林下显著大于林窗和林缘,而异级隔离者分枝角度的变化则正好相反。研究表明,华西箭竹种群在不同的林冠环境中发生了明显的可塑性变化,这些可塑性变化是种群对林冠郁闭度差异的适应性反应的结果,有利于增强种群对环境中有限光资源的利用。     

Understorey gaps influence regeneration dynamics in subtropical coastal dune forest

Dominant understorey species influence forest dynamics by preventing tree regeneration at the seedling stage. We examined factors driving the spatial distribution of the monocarpic species Isoglossa woodii, a dominant understorey herb in coastal dune forests, and the effect that its cover has on forest regeneration. We used line transects to quantify the area of the forest understorey with I. woodii cover and with gaps in the cover. Paired experimental plots were established in semi-permanent understorey gaps with I. woodii naturally absent and in adjacent areas with I. woodii present to compare plant community composition, soil, and light availability between the two habitats. Isoglossa woodii was widespread, covering 65–95% of the understorey, while gaps covered the remaining 5–35% of the area. The spatial distribution of this species was strongly related to tree canopy structure, with I.␣woodii excluded from sites with dense tree cover. Seedling establishment was inhibited by low light availability (<1% of PAR) beneath I.␣woodii. When present, I. woodii reduced the density and species richness of tree seedlings. The tree seedling community beneath I. woodii represented a subset of the seedling community in gaps. Some species that were found in gaps did not occur beneath I. woodii at all. There were no significant differences between the sapling and canopy tree communities in areas with I. woodii gaps and cover. In the coastal dune forest system, seedling survival under I. woodii is dependent on a species’ shade tolerance, its ability to grow quickly during I. woodii dieback, and/or the capacity to regenerate by re-sprouting and multi-stemming. We propose a general conceptual model of forest regeneration dynamics in which the abundant understorey species, I. woodii, limits local tree seedling establishment and survival but gaps in the understorey maintain tree species diversity on a landscape scale.     

Impacts of non-native plant and animal invaders on gap regeneration in a protected boreal forest

In balsam fir (Abies balsamea)-dominated boreal forests of Gros Morne National Park, Newfoundland (Canada), non-native Cirsium arvense (Canada thistle) has invaded forest gaps. Its management is complicated by the lack of viable control techniques and an overarching issue of gap regeneration failure attributed to browsing by non-native moose (Alces alces). This study identifies the impacts of thistle invasion on balsam fir regeneration and explores protocols to re-establish fir in gaps invaded by thistle and moose. Fir seeds were planted into ten gaps (five natural; five anthropogenic) and the emergence, growth, herbivory damage, and survival of fir was determined for 2 years amongst five treatments (n = 50 plots; 32 seeds/plot): (1) thistle monocultures in gaps; (2) where aboveground thistle biomass was removed; (3) where above- and below-ground thistle biomass was removed; (4) non-invaded areas in gaps; and, (5) adjacent uninvaded forest edges. In addition, 432 fir seedlings (aged 15 months) were transplanted into four forest gaps within the above treatments and followed for 1 year. Results indicate that invasion of C. arvense negatively affects fir emergence and early survival, and may further contribute to continued balsam fir regeneration failure independent of future moose densities. However, older fir seedlings transplanted into thistle monocultures experienced a positive facilitative effect due to the protection thistle provided against small mammal herbivory. Restoration actions that combine moose density reductions with the planting of fir seedlings offers the most viable long-term strategy to re-establish the native forest canopy in thistle-invaded gaps and would likely lead to the eventual decline of shade-intolerant C. arvense.     

Understory development in canopy gaps of pine and pine-hardwood forests of the upper Coastal Plain of Virginia

Canopygaps are important in establishing a pool of natural regeneration in manytemperate forest ecosystems. Information on the role of gaps in loblolly pine(Pinus taeda L.) and pine-hardwood foreststands in the southeastern Coastal Plain of the United States is lacking.Accordingly, 12 small canopy gaps in mature pine and pine-hardwood standsin Petersburg National Battlefield, Virginia, were studied. Loblolly pineregeneration was significantly more abundant in canopy gaps as compared to theadjacent forest in both forest cover types. In four stands dominated by loblollypine, there were 750 saplings/ha in the gaps compared to only 125saplings/ha in the adjacent forest. Pine saplings dominated the regenerationspectrum in the gaps in the pine stands, while red maple (Acerrubrum L.) was more important in the adjacent forest. In fourpine-hardwood stands, regeneration in both the gaps and adjacent forestwas dominated by sweetgum (Liquidambar styracifluaL.) with importance values of 27% and 28%, respectively.There were no loblolly pine seedlings in the adjacent forest, but an average 313per ha in the gaps of the pine-hardwood stands. Within thegaps in both cover types, loblolly pine saplings were lower in stature thancompeting hardwood stems, leading to the conclusion that the gaps may form atemporary pool of pine regeneration. Without further stand disturbance, theprocess of gap closure may reduce the pine component to a secondary status, orperhaps eliminate it altogether.