An investigation was conducted on distribution pattern, site condition and population structure of yew Taxus cuspidata Sieb. et Zucc. in Muling Forest Bureau of Heilongjiang Province, China in April, 2005. Results sho...An investigation was conducted on distribution pattern, site condition and population structure of yew Taxus cuspidata Sieb. et Zucc. in Muling Forest Bureau of Heilongjiang Province, China in April, 2005. Results showed that yew is mainly distributed under the main storey of natural mixed forest of conifer and broadleaf, the soil moisture content of the yew site is high （40%-60%）, the pH value of soil is relatively lower （4.7-5.5）, and that the population structure of wild yew is not rational, belonging to the degeneration population, which is one of the reasons leading to the population decline. Although the site conditions of Muling area are suitable for the growth of wild yew, the population of wild yew shows a decline tendency, due to the fact that the middle-sized adult yew trees have been cut, young yews are often grazed by wildlife, and that the trunks of adult yew tend to be hollow.展开更多
Understanding population structure provides basic ecological data related to species and ecosystems.Our objective was to understand the mechanisms involved in the maintenance of Quercus aquifolioides populations.Using...Understanding population structure provides basic ecological data related to species and ecosystems.Our objective was to understand the mechanisms involved in the maintenance of Quercus aquifolioides populations.Using a 1 ha permanent sample plot data for Q.aquifolioides on Sejila Mountain,Tibet Autonomous Region(Tibet),China,we analyzed the population structure of Q.aquifolioides by combining data for diameter class,static life table and survival curve.Simultaneously,the spatial distribution of Q.aquifolioides was studied using Ripley’s L Function in point pattern analysis.The results showed:(1) Individuals in Q.aquifolioides populations were mainly aggregated in the youngest age classes,that accounted for94.3% of the individuals; the older age classes had much smaller populations.Although the youngest age classes(ClassesⅠ and Ⅱ) had fewer individuals than Class Ⅲ,the total number of individuals in classes Ⅰ and Ⅱ was also greater than in classes Ⅳ to Ⅸ.In terms of tree height,fewsaplings,more medium-sized saplings and few large-sized trees were found.The diameter class structure of Q.aquifolioides populations formed an atypical ‘pyramid’type; the population was expanding,but growth was limited,tending toward a stable population.(2) Mortality of Q.aquifolioides increased continuously with age; life expectancy decreased over time,and the survivorship curve was close to a Deevey I curve.(3) The spatial distribution pattern of Q.aquifolioides varied widely across different developmental stages.Saplings and medium-sized tree showed aggregated distributions at the scales of 0–33 m and 0–29 m,respectively.The aggregation intensities of saplings and medium-sized trees at small scales were significantly stronger than that of large-sized trees.However,large-sized trees showed a random distribution at most scales.(4) No correlation was observed among saplings,medium-and large-sized trees at small scales,while a significant and negative association was observed as the scale increased.Strong competition was found among saplings,medium-and large-sized trees,while no significant association was observed between medium-and largesized trees at all scales.Biotic interactions and local ecological characteristics influenced the spatial distribution pattern of Q.aquifolioides populations most strongly.展开更多
Direction-dependence,or anisotropy,of spatial distribution patterns of vegetation is rarely explored due to neglect of this ecological phenomenon and the paucity of methods dealing with this issue.This paper proposes ...Direction-dependence,or anisotropy,of spatial distribution patterns of vegetation is rarely explored due to neglect of this ecological phenomenon and the paucity of methods dealing with this issue.This paper proposes a new approach to anisotropy analysis of spatial distribution patterns of plant populations on the basis of the data resam-pling technique(DRT)combined with Ripley’s L index.Using the ArcView Geographic Information System(GIS)platform,a case study was carried out by selecting the popula-tion of Pinus massoniana from a needle-and broad-leaved mixed forest community in the Heishiding Nature Reserve,Guangdong Province.Results showed that the spatial pattern of the P.massoniana population was typically anisotropic with different patterns in different directions.The DRT was found to be an effective approach to the anisotropy analysis of spatial patterns of plant populations.By employing resam-pling sub-datasets from the original dataset in different direc-tions,we could overcome the difficulty in the direct use of current non-angular methods of pattern analysis.展开更多
The population size class structure, survival curve, height class structure and population distribution patterns of Ilex cornuta in Longgan Lake National Nature Preserve, Hubei Province, were investigated by using the...The population size class structure, survival curve, height class structure and population distribution patterns of Ilex cornuta in Longgan Lake National Nature Preserve, Hubei Province, were investigated by using the adjacent grid method. The result showed that the population age structure of I. cornuta was of middle-aging type, in the vertical space of population individuals, most of them lived in the shrub layer, and a small number of individuals entered the arborous layer. The distribution pattern of I. cornuta was analyzed by variance /mean ratio method, and the results showed that the distribution pattern of the population was the cluster type. This study can provide references for the further protection, research and development and utilization of I. cornuta .展开更多
为探究濒危植物海南紫荆木(Madhuca hainanensis Chun et F.C.How)的种群结构与动态特征,以海南岛尖峰岭林区内天然分布的海南紫荆木种群为研究对象,在充分野外调查的基础上,基于胸径(DBH)分析了种群的年龄结构,并分析了种群的动态指数...为探究濒危植物海南紫荆木(Madhuca hainanensis Chun et F.C.How)的种群结构与动态特征,以海南岛尖峰岭林区内天然分布的海南紫荆木种群为研究对象,在充分野外调查的基础上,基于胸径(DBH)分析了种群的年龄结构,并分析了种群的动态指数、静态生命表、存活曲线、死亡率曲线、消失率曲线、生存力和空间分布格局。结果表明:Ⅱ级(2.5 cm≤DBH<7.5 cm)和Ⅲ级(7.5 cm≤DBH<12.5 cm)个体数明显多于其他径级,Ⅴ级(17.5 cm≤DBH<22.5 cm)和Ⅵ级(22.5 cm≤DBH<27.5 cm)个体数较多。从种群动态指数看,该海南紫荆木种群呈现“衰退—增长—衰退”的动态变化趋势;忽略外界干扰时的种群动态指数(V_(pi))和考虑外界干扰时的种群动态指数(V_(pi)′)分别为17.86%和0.44%,种群对外界随机干扰所承担的最大风险概率(P_(max))为2.78%,说明该种群呈增长趋势,且对外界随机干扰的敏感性强。该种群的生命期望随着径级增大而降低,且存活曲线趋近于Deevey-Ⅱ型。种群的死亡率和消失率整体上随径级增大而升高,而存活个体数量则随着径级增大而减少。生存力分析结果显示:该种群在幼龄期易受到外界的影响,并在生长中后期面临较高的死亡风险,种群生存力较低。另外,从空间分布格局看,该种群呈聚集分布。综上所述,海南岛尖峰岭林区的海南紫荆木种群缺少幼苗个体,种群稳定性较差,易受外界干扰,建议通过原地保护、扩繁及人工补植幼苗等方式实现种群更新和恢复。展开更多
文摘An investigation was conducted on distribution pattern, site condition and population structure of yew Taxus cuspidata Sieb. et Zucc. in Muling Forest Bureau of Heilongjiang Province, China in April, 2005. Results showed that yew is mainly distributed under the main storey of natural mixed forest of conifer and broadleaf, the soil moisture content of the yew site is high （40%-60%）, the pH value of soil is relatively lower （4.7-5.5）, and that the population structure of wild yew is not rational, belonging to the degeneration population, which is one of the reasons leading to the population decline. Although the site conditions of Muling area are suitable for the growth of wild yew, the population of wild yew shows a decline tendency, due to the fact that the middle-sized adult yew trees have been cut, young yews are often grazed by wildlife, and that the trunks of adult yew tend to be hollow.
基金financially supported by the National Key Technology Support Program(Grant No.2013BAC04B01)the National Natural Science Foundation of China(Grant No.31460200)
文摘Understanding population structure provides basic ecological data related to species and ecosystems.Our objective was to understand the mechanisms involved in the maintenance of Quercus aquifolioides populations.Using a 1 ha permanent sample plot data for Q.aquifolioides on Sejila Mountain,Tibet Autonomous Region(Tibet),China,we analyzed the population structure of Q.aquifolioides by combining data for diameter class,static life table and survival curve.Simultaneously,the spatial distribution of Q.aquifolioides was studied using Ripley’s L Function in point pattern analysis.The results showed:(1) Individuals in Q.aquifolioides populations were mainly aggregated in the youngest age classes,that accounted for94.3% of the individuals; the older age classes had much smaller populations.Although the youngest age classes(ClassesⅠ and Ⅱ) had fewer individuals than Class Ⅲ,the total number of individuals in classes Ⅰ and Ⅱ was also greater than in classes Ⅳ to Ⅸ.In terms of tree height,fewsaplings,more medium-sized saplings and few large-sized trees were found.The diameter class structure of Q.aquifolioides populations formed an atypical ‘pyramid’type; the population was expanding,but growth was limited,tending toward a stable population.(2) Mortality of Q.aquifolioides increased continuously with age; life expectancy decreased over time,and the survivorship curve was close to a Deevey I curve.(3) The spatial distribution pattern of Q.aquifolioides varied widely across different developmental stages.Saplings and medium-sized tree showed aggregated distributions at the scales of 0–33 m and 0–29 m,respectively.The aggregation intensities of saplings and medium-sized trees at small scales were significantly stronger than that of large-sized trees.However,large-sized trees showed a random distribution at most scales.(4) No correlation was observed among saplings,medium-and large-sized trees at small scales,while a significant and negative association was observed as the scale increased.Strong competition was found among saplings,medium-and large-sized trees,while no significant association was observed between medium-and largesized trees at all scales.Biotic interactions and local ecological characteristics influenced the spatial distribution pattern of Q.aquifolioides populations most strongly.
基金This paper was supported by the National Natural Science Foundation of China(Grant No.30370254).
文摘Direction-dependence,or anisotropy,of spatial distribution patterns of vegetation is rarely explored due to neglect of this ecological phenomenon and the paucity of methods dealing with this issue.This paper proposes a new approach to anisotropy analysis of spatial distribution patterns of plant populations on the basis of the data resam-pling technique(DRT)combined with Ripley’s L index.Using the ArcView Geographic Information System(GIS)platform,a case study was carried out by selecting the popula-tion of Pinus massoniana from a needle-and broad-leaved mixed forest community in the Heishiding Nature Reserve,Guangdong Province.Results showed that the spatial pattern of the P.massoniana population was typically anisotropic with different patterns in different directions.The DRT was found to be an effective approach to the anisotropy analysis of spatial patterns of plant populations.By employing resam-pling sub-datasets from the original dataset in different direc-tions,we could overcome the difficulty in the direct use of current non-angular methods of pattern analysis.
基金Supported by the Team Project of Hubei Collaborative Innovation Center for the Characteristic Resources Exploitation of Dabie Mountains(2015TD06)
文摘The population size class structure, survival curve, height class structure and population distribution patterns of Ilex cornuta in Longgan Lake National Nature Preserve, Hubei Province, were investigated by using the adjacent grid method. The result showed that the population age structure of I. cornuta was of middle-aging type, in the vertical space of population individuals, most of them lived in the shrub layer, and a small number of individuals entered the arborous layer. The distribution pattern of I. cornuta was analyzed by variance /mean ratio method, and the results showed that the distribution pattern of the population was the cluster type. This study can provide references for the further protection, research and development and utilization of I. cornuta .
