首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
川滇高山栎灌丛萌生过程中的营养元素供应动态   总被引:4,自引:0,他引:4       下载免费PDF全文
萌生更新是森林更新的重要方式,是硬叶栎林受到干扰后植被恢复的主要机制。以位于青藏高原东南缘的川西折多山东坡川滇高山栎(Quercus aquifoliodes)灌丛为研究对象,调查分析了砍伐后灌丛萌生过程中基株根系和萌株生物量动态、营养元素含量,以及基株根系和土壤对萌株生长过程中的营养元素供应动态。结果表明,川滇高山栎灌丛平均地上和地下生物量分别为(11.25±0.92)t·hm-2和(34.85±2.02)t·hm-2,具有较大的根冠比(3.10:1);萌生过程中,萌株生物量呈线性增加趋势,以灌丛活细根生物量变化为最大,其次是活中根和活粗根,树桩和根蔸生物量变化最小;萌生过程中,灌丛细根和中根N、P含量表现为先增加、后降低的变化趋势,萌生初期树桩、粗根和根蔸中N和K的含量明显下降,根蔸中Ca含量略有下降,而P没有明显下降,根系Mg含量变化幅度较大,灌丛地下根系储存了较多的营养元素;土壤、树桩、粗根和根蔸是川滇高山栎灌丛砍伐后0-120天萌生生长的主要营养来源,砍伐后60天,萌株生长所需的营养除K元素主要来源于根系外,其余营养元素主要来源于土壤;在砍伐后60-120天,基株根系对萌株生长所需的N、K和Ca贡献较大,而对P和Mg的贡献较小;在砍伐后120-180天,根系除K元素对萌生生长还保持较大的贡献外,对其余营养元素的贡献均较小。高山栎林管理要注重加强地下根系的保护。  相似文献   

2.
六盘山四种森林生态系统的碳氮储量、组成及分布特征   总被引:2,自引:0,他引:2  
碳和氮是森林生态系统的重要组成元素,其含量有很大时空差异,并和立地及森林特征关系很大,需做大量的积累性调查才能得到其变化规律,尤其是加强在过去较少研究的西北地区的调查。在宁夏六盘山区选择华北落叶松(Larix principisrupprechtii)人工林、华山松(Pinus armandii)次生林、桦木(Betula platyphylla)次生林和野李子(Prunus salicina)灌丛4种典型森林,测定了乔木层(分不同器官)、灌木层、草本层、枯落物层、根系层(0—100 cm土壤)的碳、氮含量,分析了生态系统的碳、氮储量及成分组成和层次分布特征。结果表明,碳含量在不同乔木树种及其不同器官之间的差异不明显;但氮含量存在显著的树种差别和器官差异,以树叶的最高、树干的最低。灌木层和草本层的碳氮含量均表现为地上部分地下部分。各森林样地的乔木层、灌木层、草本层的碳含量依次降低,但氮含量依次增高;枯落物层的碳含量低于各植被层,但氮含量高于各植被层;根系层土壤的碳、氮含量则随土层增深而递减。包括活植被层、枯落物层和根系层土壤在内的华北落叶松人工林、华山松次生林、桦木次生林、野李子灌丛的生态系统碳储量依次为364.56、450.98、640.02、196.55 t/hm2,氮储量依次为27.86、36.19、47.02、15.99 t/hm2。所有4种森林生态系统的根系层土壤的碳氮储量均占整个生态系统总储量的绝大部分,其比例对碳储量为84.69%—93.92%,氮储量为98.09%—98.64%。从乔木层、灌木层、草本层、枯落物层到根系层(土壤),呈现出C/N比依次减小的趋势;根系层土壤和整个生态系统的C/N比分别为华北落叶松林的11.84和13.12、华山松林的10.76和12.56、桦木林的12.48和13.52、野李子灌丛的11.70和12.29。  相似文献   

3.
卧龙巴郎山川滇高山栎灌丛地上生物量及其模型   总被引:4,自引:0,他引:4  
川滇高山栎广泛分布于横断山地区,属于亚高山硬叶栎林,是中国植被非常特殊的类型。采用标准地法和样方收获法,对卧龙自然保护区5个海拔梯度的川滇高山栎灌丛生物量进行调查。结果表明,用地径(D)、树高(H)估测单株林木器官生物量的适合模型均为指数模型和幂函数模型,且以指数模型为最佳,相关系数为0.941~0.988;而用D2H估测单株林木器官生物量的适合模型均为直线和指数模型,以直线模型为最佳,相关系数为0.982~0.996;川滇高山栎灌丛总生物量为3.3891×104kg.hm-2,各层生物量排序为川滇高山栎层>枯枝落叶层>伴生灌木层>苔藓层>草本层,其生物量占总生物量百分率分别为77.92%、17.64%、2.14%、1.23%和1.07%;川滇高山栎种群平均总生物量为2.6408×104kg.hm-2,各器官生物量大小排序为根>干>枝>叶>皮,其生物量占种群总生物量的百分率分别为31.03%、29.85%、18.54%、18.54%和6.91%。  相似文献   

4.
喀斯特峰丛洼地不同植被类型碳格局变化及影响因子   总被引:4,自引:0,他引:4  
采用样方法研究了西南喀斯特峰丛洼地草地、灌丛、次生林、原生林4种植被类型碳格局及其土壤碳的影响因子。结果表明:草地、灌丛、次生林、原生林4类生态系统总碳储量分别为133.84、160.79、179.08和261.24 Mg C/hm2,其中植被碳储量为5.02、6.59、20.87和60.20 Mg C/hm2,占总碳储量的3.75%—23.04%,随植被正向发展而增加;地被物碳储量为1.76、0.95、2.60和0.82 Mg C/hm2,仅占总碳储量的0.32%—1.45%;土壤层碳储量为127.06、153.25、151.61和200.21 Mg C/hm2,占76.64%—94.93%,随植被正向发展呈增加趋势,但对整个生态系统碳储量贡献率减少;由草地向原生林发展过程中,地下部分碳储量均大于地上部分碳储量,地上部分所占比例逐渐提高,地下部分所占比例逐渐减少;相关分析表明,土壤有机碳含量、储量与土壤容重、土壤深度存在良好的线性关系,喀斯特峰丛洼地石灰土土壤有机碳含量与水稳性团聚的分布关系密切,土壤氮素是影响有机碳含量的主要因素,2 mm细根和土壤微生物对石灰土土壤有机碳的积累具有重要的作用。  相似文献   

5.
较系统地研究了鼎湖山黄果厚壳桂(Cryptocaryaconcinna)-鼎湖钓樟(Linderachunii)群落植物主要营养元素(P、K、Ca、Mg)的分配和生物循环特征。营养元素含量随群落层次、组分(器官)和元素不同而异。群落植物营养元素贮量为(kghm-2):P61.253,K928.764,Ca1212.771和Mg79.349。各元素贮量在不同层次中的大小分布序列为:乔木(94.3%-97.8%)>藤本(1.3%-4.1%)>灌木(0.8%-1.4%)>草本(0.05%-0.15%)。在乔木层,元素贮量则主要分布在树干和树枝两组分(38.6%-61.7%)。各元素在植物组分中的贮量序列为:Ca>K>Mg>P(根、干和皮)和K>Ca>Mg>P(其余器官)。群落植物营养元素年积累量为(kghm-2):P2.677,K41.550,Ca63.309和Mg3.693,其在群落植物中的分配格局与贮量的相类似。群落植物营养元素利用系数为:P0.18,K0.11,Ca0.09和Mg0.28;循环系数:P0.76,K0.61,Ca0.41和Mg0.84;周转期(a):P7.36,K15.12,Ca28.05和Mg4.30。  相似文献   

6.
不同利用方式下潮棕壤交换性钙镁的剖面分布   总被引:7,自引:0,他引:7  
在水稻田、玉米地、撂荒地和人工林地4种土地利用方式下,对潮棕壤0~150 cm土层中土壤交换性钙(Ca)和交换性镁(Mg)的剖面分布及Ca/Mg的变化进行了比较研究.结果表明:不同利用方式下土壤交换性Ca含量及储量差异不明显;林地各土层的土壤交换性Mg含量均显著高于水稻田(P<0.05);交换性Mg储量大小依次为林地、玉米地、撂荒地和水稻田(P<0.05).不同利用方式交换性Ca/Mg随土层深度的增加而降低,40 cm以下土层水稻田Ca/Mg显著高于其他3种利用方式(P<0.05).土壤生态系统中Mg的优先固持、土壤管理以及植物自身的特性如生物量的循环速率、生物量在地上部分和地下部分的分配、根系的分布等,对土壤剖面中交换性Ca和交换性Mg的构成以及土壤交换性Ca库和Mg库的重建等起到重要作用.  相似文献   

7.
岷江上游两种生态系统降雨分配的比较   总被引:10,自引:1,他引:9       下载免费PDF全文
 植被的降雨分配作用对理解生态系统的水文功能具有重要的意义。该文对四川岷江上游岷江冷杉(Abies faxoniana)针叶林和川滇高山栎(Quercus aquifolioides)灌丛两种生态系统的降雨分配及降雨截留的影 响因素进行了研究,探讨了植被分配降雨及截留降雨的影响机制和影响因素。文中采用定位观测的方法研究降雨 分配。针叶林中冠层降雨截留占33.33%,树干茎流占0.07%,穿透雨占66.60%;而灌丛的冠层截留降雨为24.95% ,穿透雨为75.05%;针叶林地被物的蓄留水能力(1.746 mm)要大于灌丛地被物的持水能力(0.941 mm);针叶林土 壤的容积含水率(39.66%)也要高于灌丛土壤的容积含水率(38.19%);两种生态系统中的穿透雨率与降雨量的关系 均可用逻辑斯谛方程较好地模拟。文中还选取了降雨量、降雨强度、降雨持续时间、两次降雨的间隔时间和次降 雨期间的气温等5种因子分析影响两种生态系统降雨截留的主要因素。根据截留降雨与上述5种因子的偏相关分析 结果:针叶林冠层的降雨截留主要受降雨量、降雨持续时间和间隔时间的影响;灌丛的降雨截留主要受降雨量、 气温与降雨持续时间的影响。文中从当地的降雨特征与两种生态系统微气候差异的角度分析了两种生态系统降雨 分配及降雨截留影响因素差异的原因。  相似文献   

8.
研究比较了南亚热带6年生格木(Erythrophleum fordii)、马尾松(Pinus massoniana)幼龄人工纯林及马尾松与格木混交林生态系统碳氮储量及其分配特征。结果表明,生态系统总碳储量依次为马尾松-格木混交林(137.75 t/hm2)格木纯林(134.07 t/hm2)马尾松纯林(131.10 t/hm2),总氮储量则为格木纯林(10.19 t/hm2)马尾松-格木混交林(8.68 t/hm2)马尾松纯林(7.01 t/hm2)。3种人工林生态系统碳氮库空间分布基本一致,绝大部分储存于0—100 cm土壤层,平均占生态系统总储量的81.49%和96.91%,其次为乔木层(分别占17.52%和2.69%),林下植被和凋落物层所占比例最小。林地土壤碳主要集中于表土层,其中0—30 cm土层平均碳储量为52.52 t/hm2,占土壤总碳储量(0—100 cm)的47.99%,土壤氮的分布则无明显规律。相比于纯林,与固氮树种混交的营林方式表现出更大的碳储存能力。3种幼龄人工林生态系统较低的地上与地下部分碳氮分配比,表明其仍具有较强的碳氮固持潜力。  相似文献   

9.
中国亚热带山地杜鹃灌丛生物量分配及其碳密度估算   总被引:1,自引:0,他引:1  
灌丛生态系统作为一个巨大的潜在碳汇,在全球碳平衡和气候调节中发挥着重要的作用。杜鹃(Rhododendron simsii)灌丛是我国亚热带山地最为常见的灌丛类型。该文采用群落调查和数学模拟方法,研究了亚热带山地杜鹃灌丛的生物量和碳密度。结果表明:1)灌木各器官最佳生物量估测模型的函数类型为幂函数和线性函数,自变量为D和D2H(D为基径,H为株高),所有模型均达到极显著水平;生长方程对茎生物量的拟合效果优于其对叶和当年枝生物量的拟合效果。2)灌木层平均生物量为20.78 Mg·hm~(–2),其中优势树种杜鹃和白檀(Symplocos paniculata)占93.63%;灌木层各器官生物量排序为茎根叶当年枝,根冠比为0.32,说明生物量更多地分配到地上光合器官,体现了灌木层植物对该区域温暖湿润的环境条件的适应。3)杜鹃灌丛群落平均总生物量为26.26 Mg·hm~(–2),灌木层、草本层和凋落物层生物量分别占79.14%、7.62%和13.25%,凋落物层生物量较高表明该研究群落具有较大的养分归还量。4)灌木层和草本层的地上生物量与地下生物量和总生物量之间存在极显著相关关系,这种关系可用于相互间的预测。5)杜鹃灌丛群落平均总生物量碳密度为11.70 Mg·hm~(–2),群落平均含碳率为44.55%,以往通过乘以转换系数0.5得到的灌丛碳密度比实际碳密度高出12.22%,导致对灌丛植被碳储量和碳汇能力的估测产生严重偏差。  相似文献   

10.
何斌  秦武明  余浩光  刘运华  覃林  覃永华 《生态学报》2007,27(12):5158-5167
对马占相思人工林6种营养元素(N、P、K、Ca、Mg、S)的含量、积累、分布和生物循环特点以及随林分年龄的变化趋势进行了研究.结果表明(1)林木不同组分营养元素含量的大小次序为树叶>干皮>活枝>枯枝或树根>干材;各组分和凋落物中营养元素含量以N最高,其次是Ca或K,然后是S和Mg,P最低;林地土壤中,以K的含量最高,其次是Ca、Mg、N和P,S最低;随林龄的增加,0~40cm土壤N、P和S含量呈增加趋势;(2)4年、7年生和11年生林分营养元素总积累量分别为1022.08、1997.08和2633.45 kg·hm-2,其中乔木层营养元素贮存量依次占73.64%、82.39% 和83.65%,林下植被层依次占13.74%、8.74%和6.20%,地表现存凋落物层依次占12.62%、8.87%和10.16%;乔木层以N积累量最大,占总贮存量的53.90%~60.07%,P最小,仅占0.90%~1.23%;(3)马占相思林中不同组分营养元素积累量的分配随林龄的增长发生变化,由4年生以树叶和树枝占主导,逐渐转移到7年生和11年生以干材和树皮为主导;(4)林分营养元素年积累量依次为7年生(235.06 kg·hm-2·a-1)>11年生(200.26 kg·hm-2·a-1)>4年生(188.16kg·hm-2·a-1);林木各组分营养元素年积累量总的变化趋势为树干>树叶>树枝>根系>树皮,同一组分各营养元素年积累量与各组分营养元素积累量变化顺序一致,即为N>Ca>K>S>M>P;(5)林分营养元素年吸收量分别为382.35、432.04 kg·hm-2·a-1和403.15 kg·hm-2·a-1,年归还量分别为194.19、196.98 kg·hm-2·a-1和202.89 kg·hm-2·a-1,营养元素的循环系数分别为0.51、0.46和0.50,利用系数为0.51、0.26和0.18,周转期为3.88、8.35和10.86.可见,马占相思人工林早期营养元素利用率低,归还速率较快,林分生长到近熟期(11a)时营养元素的周转期较长,但其归还速率仍然较快,有利于林地地力的恢复、维持和提高.  相似文献   

11.
Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.  相似文献   

12.
The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.  相似文献   

13.
Since 1999, four specific weevils (Coleoptera, Curculionidae) were released in the Republic of Congo against three exotic floating water weeds: Neochetina eichhorniae Warner and N. bruchi Hustache against water hyacinth, Neohydronomus affinis Hustache against water lettuce, and Cyrtobagous salviniae Calder and Sands against water fern. Recoveries of exotic weevils were made from all 24 release sites except one, and all four species have established and spread (up to 800 km for water hyacinth weevils). Within a few years of releases, control of water fern and water lettuce was such that fishing and navigation could be resumed, while reductions of water hyacinth populations were only beginning.  相似文献   

14.
A molecular phylogeny of Hebeloma species from Europe   总被引:2,自引:1,他引:1  
In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.  相似文献   

15.
Parsimony analyses of the internal transcribed spacer regions of nuclear ribosomal DNA (ITS 1 & ITS 2) for 38 taxa sampled from the Phebalium group (Rutaceae: Boronieae) and two outgroups confirm that, with the exception of Phebalium sensu stricto and Rhadinothamnus, six of the currently recognised genera within the group are monophyletic. The data indicate that Phebaliums. str. is paraphyletic with respect to Microcybe, and Rhadinothamnus is paraphyletic with respect to Chorilaena. Rhadinothamnus and Chorilaena together are the sister group to Nematolepis. Drummondita, included as an outgroup taxon, clustered within the ingroup as sister to Muiriantha and related to Asterolasia.The phylogeny suggests that the evolution of major clades within a number of these genera (e.g. Phebalium) relates to vicariance events between eastern and south-western Australia. Leionema is an eastern genus, with the most basal taxon being the morphologically distinct Leionema ellipticum from northern Queensland. Leionema also includes one species from New Zealand, but this species (as with some others) proved difficult to sequence and its phylogenetic position remains unknown. Taxonomic changes at the generic level are recommended.The authors wish to thank Paul G.Wilson, PERTH, for advice and discussion, and Paul Forster, BRI, for collecting and providing material of Leionema ellipticum. The project was supported by a Melbourne University Postgraduate Award (to BM), the Australian Biological Resources Study (ABRS), Australian Systematic Botany Society and Wolf Den (Australia) Investments.  相似文献   

16.
17.
Ten species of rust fungi (Crossopsora 2, Maravalia 1, Pileolaria 1, Puccinia 1, Ravenelia 1, Sphaerophragmium 1, Uredo 2, and Uromyces 1) are newly recorded together with six new host plants in Thailand.Contribution no. 194, Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan  相似文献   

18.
19.
The evolution of larval head morphology in holometabolous insects is characterized by reduction of antennal appendages and the visual system components. Little insight has been gained into molecular developmental changes underlying this morphological diversification. Here we compare the expression of the segment polarity gene wingless (wg) in the pregnathal head of fruit fly, flour beetle and grasshopper embryos. We provide evidence that wg activity contributes to segment border formation, and, subsequently, the separation of the visual system and protocerebrum anlagen in the anterior procephalon. In directly developing insects like grasshopper, seven expression domains are formed during this process. The activation of four of these, which correspond to polar expression pairs in the optic lobe anlagen and the protocerebral ectoderm, has shifted to postembryonic stages in flour beetle and Drosophila. The remaining three domains map to the protocerebral neuroectoderm, and form by disintegration of a large precursor domain in flour beetle and grasshopper. In Drosophila, the precursor domain remains intact, constituting the previously described “head blob”. These data document major changes in the expression of an early patterning gene correlated with the dramatic evolution of embryonic visual system development in the Holometabola.  相似文献   

20.
Synopsis In a fourteen month study (May 1976 – June 1977) I examined the following characteristics of an intertidal bay goby (Lepidogobius lepidus) in Morro Bay, California, U.S.A.: annual and seasonal patterns of abundance, age composition and growth rates, survivorship and mortality patterns, and the reproductive cycle for female gobies. Fishes were collected with the aid of quinaldine and otoliths and ovaries removed. Age and growth rates were estimated from otolith annuli using a back calculation formula and a Brody-Bertalanffy growth curve. Mortality rates were derived using the methods of Heincke (1913), Robson & Chapman (1960), mean age, and a catch curve (Ricker 1975). A gonad index was used to describe the annual reproductive cycle. Results indicated that abundance fluctuated seasonally and that these fluctuations appeared to be caused by reproductive emigrations. Bay gobies reached an age of 7+ and a standard length of 87 mm. Growth was relatively constant (6 mm yr−1) until age 5, at which point it began to decline. The mean rates of survivorship, mortality, and instantaneous mortality were 0.75, 0.25, and 0.29 respectively. Mortality rates for individual age classes ranged from 0.13 to 0.51 and increased with age. This stock appears to reproduce mainly during the winter.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号