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1.
常绿阔叶林是福建梅花山国家级自然保护区地带性植被。采用样带与典型群落调查法对区内的常绿阔叶林14400m2样地展开调查,并对植物多样性海拔梯度格局进行分析,结果表明:(1) 群落植物物种丰富度、Gleason丰富度指数、Simpson指数、Shannon Wiener指数和Pielou均匀度指数的均值分别为64.42、10.75、5.75、3.50、0.58,且这5种指数在各样带间差异极为显著,并随海拔的升高均呈单峰曲线变化,峰值出现在海拔700m~900m。(2) 群落各层次的植物物种丰富度、Shannon Wiener指数均呈现灌木层(包括幼树和层间植物)〉乔木层〉草本层的特征。乔木、灌木层物种丰富度与乔木层Shannon Wiener指数在海拔梯度上的样带间差异极显著,变化趋势与群落相似;灌木层与草本层Shannon Wiener指数以及草本层物种丰富度随海拔梯度变化不明显。因此,梅花山自然保护区常绿阔叶林植物物种多样性的海拔梯度格局呈现单峰分布,并支持中间高度膨胀模式(mid domain model)。  相似文献   

2.
In China, evergreen broad leaved forests (EBLFs) is one of the most important vegetation types which was widly distributed in subtropical area, and it plays a very important role in the global biological diversity and natural environment conservation also. In order to reveal species diversity and altitudinal gradient patterns of evergreen broad leaved forest in Meihuashan National Natural Reserve, Fujian Province. Five altitude transects were set up at a vertical interval of 200m between 375m and 1300m above sea level in the EBLFs distribution areas, and twenty four quadrats(14400m2) had been surveyed. Species richness(S), species richness index (dGl), Simpson index (D), Shannon Wiener index (H′), Pielou evenness index (J) had been used for analysis of species diversity and altitudinal gradient pattern of EBLFs. The average value of S, dGl, H′,J and D were 64.42, 10.75, 5.75, 3.50, 0.58 respectively. The difference of community species diversity index(S, dGl, D, H′, and J) was extremely significant between transects, and the altitudinal gradient patterns of species diversity presented the unimodal variable trend, with a peak in the mid altitude(700m-900m). The species richness and Shannon Wiener index of different layer were ranked as shrub layer (include young tree and the plants between layers)>arbor layer>herb layer. The species richness of tree and shrub layer, and Shannon Wiener index of tree layer were significantly different between at transects, and trends of altitude gradient was similar to community. The Shannon Wiener index of shrub layer and herb layer, and the species richness of herb layer did not change significantly along elevation gradient. Therefore, plant species diversity distribution pattern presented a unimodal variable trend along an elevation gradient, and supported “mid domain model” in EBLFs of Meihuashan National Nature Reserve.  相似文献   

3.
海拔梯度综合了温度、降水等气候因子,是影响物种多样性分布格局的重要环境因子,两栖动物多样性及其海拔分布格局一直是生物地理学和生态学研究的重要内容。为了全面掌握云南澜沧县两栖动物多样性现状及海拔分布格局,在调查并掌握澜沧县两栖动物多样性本底数据的基础上,根据地形地貌和生境的不同,在澜沧县99个10km×10km有效网格中按照分层抽样的方法选取45个网格,每个网格设置3-5条样线,于2016-2017年开展野外调查。调查共发现两栖动物1842只,隶属于2目9科30属60种,以树蛙科为主,占两栖动物物种总数的28.3%,其中云南纤树蛙(Gracixalus yunnanensis)为新种,清迈泽陆蛙(Fejervarya qingmaiensis)为中国新纪录种;调查到中国特有种有15种,三有保护动物有25种,受威胁物种有19种,其中极危物种1种,濒危物种4种,易危物种14种;澜沧县两栖动物在海拔600-2400m范围内均有分布,其中,在海拔1800-2000m之间的范围内调查到的两栖动物物种数目和多度均较高,其次是在海拔1600-1800m和1200-1400m范围内;本次调查记录到的两栖动物物种数是历史记录物种数的3倍,属数比历史记录多了1倍,铃蟾科为新记录科;丰富度较高的网格尤其是丰富度在20以上的网格均处于中高海拔,海拔相对较低和较高的网格丰富度相对较低;两栖动物多样性科、属、种的丰富度在海拔梯度上分布格局不太一致,种丰富度的海拔分布格局大体呈双峰型,是由包括平均降水量、平均温度和植被覆盖指数等环境因子的综合作用,各因子与物种丰富度相关性从大到小依次为平均降水量 > 平均海拔=平均温度 > 植被覆盖指数 > 水网密度指数 > 样线距离水域的平均距离 > 植被类型数量。研究摸清了澜沧县两栖动物的多样性状况,分析了两栖动物多样性海拔分布格局,为澜沧县生物多样性保护提供基础数据。  相似文献   

4.
In order to identify the phlebotomine sandfly populations in Tunisian leishmaniosis foci, an entomological survey was carried out through three entomological seasons (2002-2003-2004) in 19 visceral and cutaneous leishmaniosis areas, located in six bioclimatic zones. Sandfly collections were based on light and sticky traps placed around human leishmaniosis cases. 8,722 phlebotomine sandflies belonging to 12 species were collected. The dominance of subgenus Larroussius species in northern foci, Phlebotomus papatasi in south-western foci and their co-dominance in the centre of the country is in accordance with the distribution of Leishmania infantum and L. major in Tunisia. The low density found in the historical zoonotic cutaneous leishmaniosis focus of Metlaoui in the south-west may indicate the high competence of the local populations. Studied phlebotomine settlements have showed a low specific diversity in most of the studied sites. In L. infantum areas, the dominant species were respectively: P. perfiliewi in the cutaneous leishmaniosis site of the humid bioclimatic stage, P. perniciosus in the cutaneous and visceral leishmaniosis foci of semi-arid and arid bioclimatic stages and P. longicuspis in the visceral leishmaniosis focus of saharan bioclimate. In the zoonotic cutaneous leishmaniosis foci, P. papatasi was a dominant species. In the well-known south-eastern foci of cutaneous leishmaniosis due to L. killicki, P. sergenti was a dominant species with P. perniciosus. In the central emerging foci of L. killicki, P. perniciosus was a dominant species in some sites whereas it was very rare in others. In these sites, the subgenus Paraphlebotomus was always present with a higher abundance of P. alexandri than P. sergenti.  相似文献   

5.
To evaluate the role of altitude on distribution pattern and diversity of entomofauna on miombo woodlands, four altitudes (850, 1,000, 1,250 and 1,400 m) were selected in a characteristic mountainous forest of Inhamacari in Mozambique in July 2015. In each sampling altitude, a linear transect with 16 yellow pan traps spaced 2 m apart was established for insect capture. Capture results allowed assessment of insect distribution by determination of insect abundance and relative frequency. Insect diversity estimates were determined by Shannon–Wiener and Simpson indices. Altitude similarity was assessed by the Jaccard coefficient. The chi-square test () was used to compare insect abundance and distribution along the altitudinal gradient. Altitude significantly affected insect abundance, relative frequency and distribution, with a nonlinear decrease with increasing altitude. Families Formicidae (Hymenoptera) and Cecidomyiidae (Diptera) were most dominant. Highest diversity and more families confined to unique altitudinal positions were found at 1,250 m while the lowest diversity was observed at 1,000 m.a.s.l. Among the altitudes, greater similarity was found between 1,000 and 1,400 m. In conclusion, altitude had a significant effect on insect family's distribution. However, further research is recommended in order to understand effect of vegetation composition and structure on insect diversity at different altitudes.  相似文献   

6.
Despite enormous diversity, abundance, and role in ecosystem processes, little is known about how butterflies differ across altitudinal gradients. For this, butterfly communities were investigated along an altitudinal gradient of 2700–3200 m a.s.l, along the Gulmarg region of Jammu & Kashmir, India. We aimed to determine how the altitudinal gradient and environmental factors affect the butterfly diversity and abundance. Our findings indicate that species richness and diversity are mainly affected by the synergism between climate and vegetation. Alpha diversity indices showed that butterfly communities were more diverse at lower elevations and declined significantly with increase in elevation. Overall, butterfly abundance and diversity is stronger at lower elevations and gradually keep dropping towards higher elevations because floristic diversity decreased on which butterflies rely for survival and propagation. A total of 2023 individuals of butterflies were recorded belonging to 40 species, represented by 27 genera and 05 families. Six survey sites (S I- S VI) were assessed for butterfly diversity from 2018 to 2020 in the Gulmarg region of Jammu & Kashmir. Across the survey, Nymphalidae was the most dominant family represented by 16 genera and 23 species, while Papilionidae and Hesperiidae were least dominant represented by 01 genera and 01 species each. Among the six collection sites selected, Site I was most dominant, represented by 16 genera and 21 species, while Site VI was least dominant, represented by 04 genera and 04 species.  相似文献   

7.
土壤微生物群落结构沿海拔梯度的变异是微生物生物地理学分异和群落空间分布的重要内容,然而,热带森林土壤微生物多样性及其群落特征的海拔模式尚不明确。研究海南省尖峰岭自然保护区0—20cm和20—40cm土壤细菌多样性和群落组成沿海拔梯度(400—1410m)的变化及其与环境因子的关系。结果表明:在0—20cm土壤微生物生物量碳、生物量氮和生物量磷随海拔升高(峰顶降低)而增加,20—40cm土壤微生物生物量碳、生物量氮和生物量磷随海拔升高呈先升高后降低趋势;整体上,变形菌门、放线菌门、酸杆菌门、拟杆菌门、厚壁菌门在0—20cm中占优势,丰度总和占该层细菌总量的88.17%;变形菌门、放线菌门、酸杆菌门、厚壁菌门、绿弯菌门在20—40cm中占优势,丰度总和占该层细菌总量的90.82%;随海拔增加,0—20cm细菌多样性线性减少,20—40cm细菌多样性变化不显著;沿海拔梯度,0—20cm细菌群落组成可分为低(409—1018m),中(1018—1357m)和高(1410m)三个海拔聚集群落,20—40cm细菌群落组成随海拔无显著性变化;两土层细菌多样性与土壤pH显著正相关,土壤细菌群落组成在0...  相似文献   

8.
This study reports the distribution, ecotopes and fauna diversity of sandflies captured in five training bases on a military reserve in Manaus, state of Amazonas (AM). A total of 10,762 specimens were collected, which were distributed among 58 species, with the highest number recorded at Base Instruction 1 (BI1). A higher rate of species richness was found at the Base Instruction Boina Rajada and low levels of diversity associated with a high abundance index with the clear dominance of Lutzomyia umbratilis, Lutzomyia ruii and Lutzomyia anduzei were found at BI1. The abundance of Lu. umbratilis raises the possibility of outbreaks of American cutaneous leishmaniasis by the main vector of the disease in AM.  相似文献   

9.
Despite enormous diversity, abundance, and role in ecosystem processes, little is known about how butterflies differ across altitudinal gradients. For this, butterfly communities were investigated along an altitudinal gradient of 2700–3200 m a.s.l, along the Gulmarg region of Jammu & Kashmir, India. We aimed to determine how the altitudinal gradient and environmental factors affect the butterfly diversity and abundance. Our findings indicate that species richness and diversity are mainly affected by the synergism between climate and vegetation. Alpha diversity indices showed that butterfly communities were more diverse at lower elevations and declined significantly with increase in elevation. Overall, butterfly abundance and diversity is stronger at lower elevations and gradually keep dropping towards higher elevations because floristic diversity decreased on which butterflies rely for survival and propagation. A total of 2023 individuals of butterflies were recorded belonging to 40 species, represented by 27 genera and 05 families. Six survey sites (S I- S VI) were assessed for butterfly diversity from 2018 to 2020 in the Gulmarg region of Jammu & Kashmir. Across the survey, Nymphalidae was the most dominant family represented by 16 genera and 23 species, while Papilionidae and Hesperiidae were least dominant represented by 01 genera and 01 species each. Among the six collection sites selected, Site I was most dominant, represented by 16 genera and 21 species, while Site VI was least dominant, represented by 04 genera and 04 species.  相似文献   

10.
采用样方调查法,研究了白龙江干旱河谷不同坡向主要灌丛群落沿着海拔梯度的结构特征、物种多样性的变化规律,旨在了解白龙江干旱河谷不同海拔梯度植被特征和物种多样性变化,为白龙江干旱河谷区域不同海拔植被恢复提供理论依据。研究结果表明:(1)不同海拔梯度同一坡向物种数不同,同一海拔不同坡向物种数也不同,随着海拔的升高不同坡向物种数表现为先增加后减少的趋势,同一海拔梯度内不同坡向主要植被类型也不同。(2)主要灌木群落α多样性在不同坡向随着海拔梯度的升高,表现出先升高后减小的趋势。不同坡向草本群落α多样性随着海拔的升高,也表现出先升高后减小的趋势。对主要灌丛α多样性指数进行相关性分析得物种丰富度指数对物种多样性贡献率最大,表现为丰富度指数(D1、D2)> 生态优势度指数(SN)> 种间机遇指数(H)> 群落均匀度指数(R)。(3)不同坡向主要灌丛群落β多样性Whittaker指数沿着不同海拔梯度变化不大,最大值出现在海拔1250~1650m;Routledge和Codyβ多样性指数在海拔1450~1650m出现最大值,但是大体呈现出波形变化。草本β多样性随着海拔的升高变化较大,阳坡植物的β多样性指数在海拔1050~1250m达到最大,阴坡和半阴半阳坡在海拔区间1250~1450m达到最大,半阴半阳坡的β多样性指数均大于阳坡。白龙江干旱河谷不同坡向、不同海拔梯度物种α多样性和β多样性都不同,且不同坡向随着海拔梯度的变化物种α多样性和β多样性呈一定的相关性,说明海拔和坡向是影响生物多样性主要因子之一。  相似文献   

11.
Abstract. As the composition of natural sugars in the diet of adult sandflies (Diptera: Psychodidae: Phlebotominae) may affect the development of Leishmania (Kinetoplastida: Trypanosomatidae) in sandfly guts, and so play an important role in the epidemiology of leishmaniasis, there is increasing interest in the sources of sugars for wild sandflies. Advanced chromatography techniques have provided indirect evidence that wild sandflies feed on honeydew, a substance released by aphids (Hemiptera: Aphididae) when feeding. Our objective was to determine whether sandfly density can be influenced directly by the local density of aphids. Aphid density was determined by counting absolute numbers of aphids on alfalfa stems in Purisima Valley, Peru, where sandflies transmit Leishmania peruviana causing Andean cutaneous leishmaniasis (uta). Sandfly relative abundance was measured using sticky trap sampling repeatedly in alfalfa fields. Lutzomyia verrucarum accounted for 92% of the total sandflies collected. As there was a female bias in sandflies collected close to houses, only the numbers of male sandflies were used in analysis. Most of the adult aphids found feeding on alfalfa were either Therioaphis trifolii forma maculata (97%) or Acyrthosiphon pisum (3%). By regression analysis, a significant relationship was found between the density of Lu. verrucarum males and the density of adults of both aphid species. This is the first ecological study to support the hypothesis that aphid honeydew may be a source of sugar for sandflies.  相似文献   

12.
The bionomics of phlebotomine sandflies (Diptera: Psychodidae) were studied for three years (2001-2003) in the Galilee focus of cutaneous leishmaniasis in northern Israel, where the causative Leishmania tropica (Kinetoplastida: Trypanosomatidae) is transmitted by Phlebotomus (Adlerius) arabicus Theodor and Phlebotomus (Paraphlebotomus) sergenti Parrot, comprising 22% and 8%, respectively, of the local sandfly fauna sampled by light traps. The predominant species overall was Phlebotomus (Larroussius) tobbi Adler & Theodor (51%) with lesser numbers of Phlebotomus (Adlerius) simici Theodor (11%), Phlebotomus (Larroussius) syriacus Adler & Theodor (5%), Phlebotomus (Larroussius) perfiliewi Perfil'ev (3%) and Phlebotomus (Phlebotomus) papatasi Scopoli (0.05%). Sandfly adult populations were prevalent from April to November and peaked between June and August, being more abundant through the summer in irrigated habitats, such as gardens and orchards, than in open grassland. Of the two cutaneous leishmaniasis vectors, P. sergenti preferred boulder mounds located at the outskirts of settlements, whereas P. arabicus was more abundant overall and near houses in particular. Females of all these sandfly species displayed a peak of activity after sunset (20.00-22.00 hours), whereas activity of males persisted longer through the night. Another slight increase in activity was noted before dawn (02.00-04.00 hours). Phlebotomus arabicus appears to be the main vector of L. tropica in the Galilee focus, due to its denser populations, more endophily and preference for peridomestic habitats than shown by P. sergenti in northern Israel.  相似文献   

13.
The aims of the study were to (a) investigate the effect of trapping methods on alpha diversity; and (b) enhance the knowledge of the sandfly assemblage in the state of Quintana Roo. Field work was undertaken in a tropical forest of southern Mexico from August 2013 to July 2014. Sampling was conducted monthly during three consecutive nights. For each trapping night, 12 different types of trap were operated from 18.00 to 24.00 hours in four transects. Measures of alpha community diversity were based on the quantification of the number of species (Chao 2, Jackknife 2, Clench's equation, Margalef's index) and the community structure, as well as the dominance (Simpson and Berger‐Parker indexes) and evenness (Shannon's entropy index, true diversity of the Jost and Pielou index). With a total sampling effort of 1728 night‐traps, 16 101 phlebotomine sandflies were collected; they represented two genera and 13 species. Diversity estimates of 100% (Chao 2 and Clench's equation) and 85% (Jackknife 2) of potential species in the study area were calculated. Shannon traps and CDC light traps indicated the largest number of species, but only Shannon traps showed the greatest abundance. This inventory of sandflies is an important activity to enhance our knowledge of sandfly assemblages and guilds. The ultimate goal of studying alpha diversity in sandflies would be to have a better understanding of the population dynamics and all complex networks of interactions that may, in turn, be associated with the epidemiology of the disease.  相似文献   

14.
2012年7月-2013年7月,对深圳梧桐山风景区昆虫资源进行系统调查,并对其群落结构进行分析。期间共采集昆虫标本2934号,鉴定出166种,隶属17目98科。通过对不同生境昆虫物种丰富度和多样性指数统计分析得出,亚热带常绿阔叶林昆虫物种多样性指数最高,为3.29;南亚热带常绿灌丛昆虫多样性指数最低,为1.88。各种生境昆虫物种多样性指数从大到小排列为:亚热带常绿阔叶林南亚热带针阔叶混交林南亚热带人工常绿阔叶林南亚热带常绿灌丛。不同生境昆虫群落相似性系数在0.0889-0.2690之间,随着植被构成和环境小气候的差别越大相似性系数越小,说明梧桐山风景区各个生境之间昆虫群落具有一定的独立性。通过对不同垂直地带昆虫物种多样性指数统计分析得出,海拔介于300-600 m地带昆虫物种多样性指数最高,为3.30,海拔900 m以上地带昆虫多样性指数最低,为1.06。不同垂直地带昆虫多样性指数从大到小排列顺序为:海拔300-600 m海拔600-900 m海拔100-300 m海拔900 m以上。  相似文献   

15.
采用样带网格调查方法和α、β多样性指数分析方法,研究了长白山河岸带原始林和次生林群落木本植物多样性沿海拔梯度分布规律及其对采伐干扰的响应.结果表明:不同海拔区域河岸带原始林群落均由11~13个树种组成,其在群落中的地位随海拔升高而发生变化,阔叶树种优势地位逐步被针叶树种所取代,采伐干扰不仅改变了群落树种丰富度及其在群落中的地位,而且使针叶树种取代阔叶树种的趋势有所增强;河岸带原始林群落物种多样性沿海拔梯度呈现出中、低海拔区域相对较高且比较恒定(2.454~2.544),高海拔区域(2.250)下降的分布规律,采伐干扰改变了其沿海拔梯度分布格局(波动型),加大了不同海拔区域群落间的波动性(2.174~2.692);河岸带原始林群落树种沿海拔梯度的变动速率相对较低(1.5~3.5),且群落相似性较高(0.85~0.94),采伐干扰使次生林群落树种沿海拔梯度的变动幅度增大(0.5~6.0),群落相似性下降(0.68~0.91),但次生林群落沿海拔梯度分布仍具有较高连续性.  相似文献   

16.
Aim This study assessed changes in diversity and assemblage composition in bryophytes and their associated invertebrates along altitudinal gradients in Australia and New Zealand. The importance of altitude in shaping these communities and for the diversity of both invertebrates and bryophytes was examined at different spatial scales, including local, altitudinal, regional and biogeographical. Location Samples were taken from four Australasian mountain ranges between 42° and 43°S: Mt Field and Mt Rufus, Tasmania, Australia, and Otira Valley and Seaward Kaikoura Mountains, South Island, New Zealand. Methods On both Tasmanian mountains, five altitudes were assessed (250, 500, 750, 1000 and 1250 m). At each location (mountain/altitude combination) two sites were chosen and six samples were taken. Six altitudes were assessed on New Zealand mountains (Otira: 250, 500, 750, 1000, 1250 and 1500 m; Kaikoura: 1130, 1225, 1325, 1425, 1525 and 2000 m). Bryophyte substrate was collected, and all samples were stored in 70% ethanol. Invertebrates were extracted from bryophytes using kerosene‐phase separation and all invertebrates were identified to family. At each location in Tasmania, all bryophyte species within six 25‐cm2 grids per site were collected and identified to species. Bryophytes from New Zealand were identified to species from the invertebrate sample substrate because of sampling constraints. Results Altitude did have a significant effect on diversity, however, no general trend was found along the altitudinal gradient on the four mountains. There were distinct differences in diversity between biogeographical regions, mountains, altitudes and sites. In Tasmania, Mt Field had the highest diversity in invertebrates and bryophytes at 750 m. In contrast, Mt Rufus had consistent low invertebrate and bryophyte diversity along the entire altitudinal gradient. There were also distinctive differences between locations in the composition of invertebrate and bryophyte communities in Tasmania. Along the two altitudinal gradients in New Zealand, Otira had highest diversity for both invertebrates and bryophytes at low altitudes, whereas Kaikoura had highest invertebrate and lowest bryophyte diversity at the highest altitude. Main conclusions There was an effect of altitude, however, there were no consistent changes in diversity or composition on the four different mountains. There was considerable local and regional variation, and, despite a strong sampling design, no underlying altitudinal trends were detectable. This study demonstrates the importance of examining a range of spatial scales if patterns in community structure along altitudinal gradients are to be studied. The implications of this study are discussed with reference to survey design, taxonomic resolution, climate change and conservation of habitat.  相似文献   

17.
根据大尺度的物种分布信息,利用聚类分析和数理统计的方法分析了云南哀牢山蕨类植物区系的垂直分布格局。研究结果表明,随着海拔的升高,热带区系成分所占比重呈显著递减趋势,而温带区系成分所占比重呈明显递增趋势。在整个海拔梯度上,东亚分布和热带亚洲分布成分始终占主导地位。区系过渡性随着海拔的升高呈先增强后减弱的单峰分布格局,平衡点出现于海拔1700 m左右。基于区系成分比重的聚类分析表明,在海拔1300 m,1900 m和2600 m左右,将海拔梯度上的蕨类植物分为4组,这与各海拔段内的物种组成和区系成分性质是一致的。  相似文献   

18.
西双版纳热带山地雨林的植物多样性研究   总被引:18,自引:1,他引:18       下载免费PDF全文
 根据6块样地的调查资料,分析了西双版纳热带山地雨林植物多样性特征。结果表明:在2 500 m2的样地上,西双版纳热带山地雨林群落共有植物物种99~181种。其中乔木层的物种丰富度(S)为54~113,Shannon-Wiener指数(H′)为1.648 7~4.049 1,Simpson指数(λ)为0.503 5~0.969 5,Pielou 均匀度指数(Jsw)为0.413 3~0.854 9。灌木层的S为35~89,H′为2.413 2~3.716 2,λ为0.762 7~0.958 2,Jsw为0.678 8~0.859 3。草本层的各指数值:S为31~65,H′ 为2.792 1~3.499 2,λ为0.902 0~0.938 2,Jsw为0.729 3~0.838 2。低海拔带上的山地雨林(Ⅰ号、Ⅱ号样地)的各指数值(H′、λ、Jsw)在群落不同层次中均表现为草本层 > 灌木层 > 乔木层,而物种丰富度在不同层次中无一定变化规律;高海拔带上山地雨林(Ⅲ号、Ⅳ号、Ⅴ号、Ⅵ号样地)的物种丰富度和多样性指数(H′、λ)表现为乔木层 > 灌木层 > 草本层,而均匀度指数(Jsw)在不同层次中则无一定变化趋势。高海拔带上的山地雨林乔木层和灌木层的物种丰富度、多样性和均匀度指数均明显高于低海拔带上的山地雨林,这是由于前者所处生境较为优越。沿着海拔梯度,群落乔木层的物种丰富度、多样性和均匀度指数均在中等海拔高度地带(约1 200~1 220 m)达到最高值,这是由于中等海拔高度的山地雨林位于生境条件最为优越的沟谷地带,而且与低地季节雨林毗邻,热带雨林植物成分丰富。  相似文献   

19.
植物物种多样性在海拔梯度上的变化规律以及物种多样性与生产力的关系是生态学研究的热点, 至今还没有得出一般性规律。本文以青海省海南藏族自治州贵德县的拉脊山(36°21′ N, 101°27′ E, 海拔3,389-3,876 m)和果洛藏族自治州的玛沁县军牧场山体(34°22′ N, 100°30′ E, 海拔4,121-4,268 m)为研究对象, 对植物高度、盖度、地上生物量和物种多样性随海拔高度的变化进行调查和统计分析, 以探讨青藏高原高寒草甸的物种多样性和地上生物量在海拔梯度上的变化规律及两者的关系。结果表明: (1)两条山体样带上地上生物量与物种多样性随海拔的变化规律一致: 随着海拔的升高, 地上生物量线性降低; Shannon-Wiener指数、Simpson指数和物种丰富度都呈单峰曲线, 在中间海拔最大, 而Pielou指数随海拔的升高线性增加。结合目前针对青藏高原高寒草甸的研究数据, 发现物种丰富度随海拔高度的变化均呈单峰曲线, 说明随着海拔的升高物种多样性先升高后降低可能是青藏高原物种多样性分布的普遍规律。(2)地上生物量与物种多样性的关系在两条山体样带上表现一致: 地上生物量随Shannon- Wiener指数、Simpson指数和Pielou指数的升高而线性降低, 但与物种丰富度不相关。综合两条山体样带所有样方数据, 发现地上生物量与Shannon-Wiener指数、Simpson指数不相关, 而随物种丰富度的升高线性增加。结合目前在青藏高原的相关研究数据, 发现地上生物量与物种丰富度呈S型曲线(logistic model)。  相似文献   

20.
《农业工程》2019,39(5):335-347
Among the various topographical factors, effects of altitudinal factor on species diversity, richness, composition and biological functions patterns are considerable. This study was done to investigate plant species richness along altitudinal gradient in the Asalem watershed basin, northern forests of Iran. For these purpose, 13 altitudinal transects were established from 100 to 2500 m, according to altitude ranges within 200 m intervals. Data collection was done in 216 circular plots of 1000-m2 area with a distance of 150 m from each other. In total, 576species of 325 genus and 96 families were recorded. The highest number of species was belonged to Asteracese، Fabaceae and Lamiaceae families. The results indicated that forbs with 414 species belong to54 families and ferns with 31 species belong to10 families were the largest and smallest group of plants in study area respectively. In herbaceous layer, the mean number of species was increased along altitudinal gradients (P ≤ 0.005). The lowest and highest value of species number was belonged to 500 and 2500 m altitudes, respectively. Generally, there was a gradual decline of species number at 100 to 500 m. Fitted models indicated that variation patterns at altitudinal gradients were significant and the proposed polynomial model had a high conformity with changes of species richness. The lowest value of species number in woody layer was belonged to 1900 m altitude and 2100 m had the highest value. Three peak points were recorded at the beginning, middle and the end of gradient, respectively. Sinusoidal models showed a correlation between species richness and altitudinal changes by high coefficient of determination. Results of β –diversity indicated that species change rate was fixed at 700 m altitude, but it was decreased by increasing altitude. Fluctuations of β diversity were followed of the sinusoidal models. In the study area, destructive factors including road construction, tourism and over-exploitation are a serious threat for the ecosystem and this study can be considerable to develop targeted strategies for conservation of plant diversity. In addition, study of habitat conditions in each altitudinal gradients is necessary to reconstruction stands with low species diversity and appropriate species selection to establish stands with high density.  相似文献   

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