The rapid climate change-caused dichotomy on subtropical evergreen broad-leaved forest in Yunnan： Reduction in habitat diversity and increase in species diversity

Yunnan's biodiversity is under considerable pressure and subtropical evergreen broad-leaved forests in this area have become increasingly fragmented through agriculture,logging,planting of economic plants,mining activities and changing environment.The aims of the study are to investigate climate changeinduced changes of subtropical evergreen broad-leaved forests in Yunnan and identify areas of current species richness centers for conservation preparation.Stacked species distribution models were created to generate ensemble forecasting of species distributions,alpha diversity and beta diversity for Yunnan's subtropical evergreen broad-leaved forests in both current and future climate scenarios.Under stacked species distribution models in rapid climate changes scenarios,changes of water-energy dynamics may possibly reduce beta diversity and increase alpha diversity.This point provides insight for future conservation of evergreen broad-leaved forest in Yunnan,highlighting the need to fully consider the problem of vegetation homogenization caused by transformation of water-energy dynamics.

Change in Species Diversity during Recovering Process of Evergreen Broad-leaved Forest

Evergreen broad-leaved forestis one of the most important vegetation types in China.Because of the human activities,evergreen broad-leaved forest has been destroyed extensively,leading to degraded ecosystem.It is urgent to conserve and restore these natural forests in China. In this paper,the tendency and rate of species diversity restoration of the evergreen broad-leaved forest in Daming Mountain has been studied.The main resultsare as follows:(a)In subtropical mid-mountain area,species diversity in degraded evergreen broad-leaved forestcan be restored. Through analyzing b diversity index of communities in different time and space,it was found that the species composition of communities tend to be the same as that in the zonal evergreen broad-leaved forest.(b)The restoration rate of evergreen broad-leaved forest was very fast.Planting Chinese fir after clear-cutting and controlled burning of the forest,178 species appeared in a 600m^2 sample area after 20 years’natural recovering.Among the sespecies,58 were tree layer and the height of community reached 18m.The survey suggested that it would take only 20 years for the degraded forest to develop into community composed of lightdemanding broad-leaved pioneer trees and min-tolerance broad-leaved trees,and it need another 40~80 years to reach the stage consisting of min-tolerance evergreen broad-leaved trees.(c)Species number increased quickly at the early stage(2-20years)during vegetation recovering process toward the climax,and decreased at the min-stage (50-60 years),then maintained a relatively stable level at the late-stage (over 150 years).

Combined community ecology and floristics,a synthetic study on the upper montane evergreen broad-leaved forests in Yunnan,southwestern China

The upper montane evergreen broad-leaved forest in Yunnan occurs mainly in the zone of persistent cloud and has a discontinuous,island-like,distribution.It is diverse,rich in endemic species,and likely to be sensitive to climate change.Six 1-ha sampling plots were established across the main distribution area of the upper montane evergreen broad-leaved forest in Yunnan.All trees with d.b.h.>1 cm in each plot were identified.Patterns of seed plant distributions were quantified at the specific,generic and family levels.The forests are dominated by the families Fagaceae,Lauraceae,Theaceae and Magnoliaceae,but are very diverse with only a few species shared between sites.Floristic similarities at the family and generic level were high,but they were low at the specific level,with species complementarity between plots.Diversity varied greatly among sites,with greater species richness and more rare species in western Yunnan than central Yunnan.The flora is dominated by tropical biogeographical elements,mainly the pantropic and the tropical Asian distributions at the family and genus levels.In contrast,at the species level,the flora is dominated by the southwest or the southeast China distributions,including Yunnan endemics.This suggests that the flora of the upper montane forest in Yunnan could have a tropical floristic origin,and has adapted to cooler temperatures with the uplift of the Himalayas.Due to great sensitivity to climate,high endemism and species complementarity,as well as the discontinuous,island-like,distribution patterns of the upper montane forest in Yunnan,the regional conservation of the forest is especially needed.

Forest structure,productivity and soil properties in a subtropical ever-green broad-leaved forest in Okinawa,Japan

Structure, species composition, and soil properties of a subtropical evergreen broad-leaved forest in Okinawa, Japan, were examined by establishment of plots at thirty sites. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 5400 stems-ha^-1 （ -〉 3.0 cm DBH）; 64% of those stems were smaller than 10 cm DBH. The total basal area was 54.4 m^2-ha^-1, of which Castanopsis sieboldii contributed 48%. The forest showed high species diversity of trees. 80 tree species （≥ 3.0 cm DBH） from 31 families was identified in the thirty sampling plots. C. sieboldii and Schima wallichii were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were, 3.36 for Diversity index （H＇）, 0.71 for Equitability index （J＇） and 4.72 for Species richness index （S＇）, all of which strongly declined with the increase of importance value of the dominant, C. sieboldii. Measures of soil nutrients indicated low fertility, extreme heterogeneity and possible A1 toxicity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil exchangeable K^＋, Ca^2＋, and Ca^2＋/Al^3- ratio （all p values 〈0.001） and a negative relationship with N, C and P. The results suggest that soil property is a major factor influencing forest composition and structure within the subtropical forest in Okinawa.

Decomposition patterns of leaf litter of seven common canopy species in a subtropical forest： dynamics of mineral nutrients

Dynamical patterns of mineral elements during decomposition processes were investigated for seven common canopy species in a subtropical evergreen broad-leaved forest by means of litterbag technique over 2 years. The species studied are representative for the vegetation in the study area and differed significantly in chemical qualities of their litter. No significant relationships were found between decomposition rate （percentage dry mass remaining and decomposition constant k） and initial element cuncentrations.However, there were significant correlations betweeu the percentage of dry mass remaining and the mineral element concentrations in the remaining litter for most cases. The rank of the element mobility in decomposition process was as follows： Na = K 〉 Mg ≥ Ca 〉 N ≥ Mn ≥ Zn ≥ P 〉 Cu 〉〉 Al 〉〉 Fe. Concentrations of K and Na decreased in all species as decomposition proceeded. Calcium and Mg also decreased in concentrntion but with a temporal increase in the initial phase of decomposition, while the concentrations of other elements （Zn, Cu, AL and Fei increased for all species with exception of Mn which revealed a different pattern in different species. In most species, microelements （Cu, Al, and Fe） significantly increased in absolute amounts at the end of the litterbag incubation, which could be ascribed to a lange extent to the mechanism of abiotic fixation to humic substances rather than biological immobilization.

Tree species diversity and utilities in a contracting lowland hillside rainforest fragment in Central Vietnam

Background： Within the highly bio-diverse ‘Northern Vietnam Lowland Rain Forests Ecoregion＇ only small, and mostly highly modified forestlands persist within vast exotic-species plantations. The aim of this study was to elucidate vegetation patterns of a secondary hillside rainforest remnant（elevation 120–330 m, 76 ha） as an outcome of natural processes, and anthropogenic processes linked to changing forest values.Methods： In the rainforest remnant tree species and various bio-physical parameters（relating to soils and terrain）were surveyed on forty 20 m × 20 m sized plots. The forest＇s vegetation patterns and tree diversity were analysed using dendrograms, canonical correspondence analysis, and other statistical tools.Results： Forest tree species richness was high（172 in the survey, 94 per hectare）, including many endemic species（〉16%; some recently described）. Vegetation patterns and diversity were largely explained by topography, with colline/sub-montane species present mainly along hillside ridges, and lowland/humid-tropical species predominant on lower slopes. Scarcity of high-value timber species reflected past logging, whereas abundance of light-demanding species, and species valued for fruits, provided evidence of human-aided forest restoration and ‘enrichment＇ in terms of useful trees. Exhaustion of sought-after forest products, and decreasing appreciation of non-wood products concurred with further encroachment of exotic plantations in between 2010 and 2015. Regeneration of rare tree species was reduced probably due to forest isolation.Conclusions： Despite long-term anthropogenic influences, remnant forests in the lowlands of Vietnam can harbor high plant biodiversity, including many endangered species. Various successive future changes（vanishing species, generalist dominance, and associated forest structural-qualitative changes） are, however, expected to occur in smal forest fragments.Lowland forest biodiversity can only be maintained if forest fragments maintain a certain size and/or are connected via corridors to larger forest networks. Preservation of the forests may be fostered using new economic incentive schemes.

Study on successions sequence of evergreen broad-leaved forest in Gutian Mountain of Zhejiang,Eastern China:species diversity

Using the widely adopted scheme of space-for-time substitution for investigating 16 typical plots distri-buted as a pattern of contiguous grid quadrates within a sampling plot,the expressions of Shannon-Wiener index(H)for species diversity,Pielou index(J_(sw),J_(SI))for evenness and Simpson index(D)for ecological dominance are employed to investigate the species diversity(SD)of four evergreen broadleaved communities in the successions sequence within the Nature Reserve of the Gutian Mountains.Results showed that in the successions process from the coniferous to the mixed coniferous-broadleaved,then to Schima superba and finally to Castanopsis eyrei forest,the arbor layer SD showed the Shannon-Wiener index(H)as 1.9670,2.4975,2.6140 and 2.4356,respectively,characterized by their rise before drop and the shrub(herb)layer SD shows the maximum to be in the mixed coniferous-broadleaved(coniferous)forest(H arriving at 2.8625(1.5334)).In the vertical structure,on the other hand,for the sequenced coniferous forest,coniferous-broad mixed forest and Castnaopsis eyrei forest,the number of SD ranges in a decreasing order from the shrub,arbor to herb layer in contrast to the SD in a decreasing order of Schima superba forest ranging from the arbor to shrub and then to herb layer,and during the succession,the herb layer exhibits the maximum range of SD change among these layers,with its variation coefficients of 0.1572,0.0806,0.0899 and 0.1884 for H,J_(SW),J_(SI) and D,in order,in sharp contrast to the minimal SD range in the shrub layer,with the corresponding figures of 0.0482,0.0385,0.0142,and 0.1553.

Belowground carbon balance and carbon accumulation rate in the successional series of monsoon evergreen broad-leaved forest

The balance, accumulation rate and temporal dynamics of belowground carbon in the successional series of monsoon evergreen broadleaved forest are obtained in this paper, based on long-term observations to the soil organic matter, input and standing biomass of litter and coarse woody debris, and dissolved organic carbon carried in the hydrological process of subtropical climax forest ecosystem—monsoon evergreen broad-leaved forest, and its two successional forests of natural restoration—coniferous and broad-leaved mixed forest and Pinus massoniana forest, as well as data of root biomass obtained once every five years and respiration measurement of soil, litter and coarse woody debris respiration for 1 year. The major results include: the belowground carbon pools of monsoon evergreen broad-leaved forest, coniferous and broad-leaved mixed forest, and Pinus massoniana forest are 23191 ± 2538 g·m?2, 16889 ± 1936 g·m?2 and 12680 ± 1854 g·m?2, respec- tively, in 2002. Mean annual carbon accumulation rates of the three forest types during the 24a from 1978 to 2002 are 383 ± 97 g·m?2·a?1, 193 ± 85 g·m?2·a?1 and 213 ± 86 g·m?2·a?1, respectively. The belowground carbon pools in the three forest types keep increasing during the observation period, suggesting that belowground carbon pools are carbon sinks to the atmosphere. There are seasonal variations, namely, they are strong carbon sources from April to June, weak carbon sources from July to September; while they are strong carbon sinks from October to November, weak carbon sinks from December to March.

Density Dependence of a Dominant Species and the Effects on Community Diversity Maintainance

In order to test whether density dependence influences community diversity, a combination of manipulative experimentation and plot surveys were done using Cryptocarya concinna, a dominant species in subtropical evergreen forest. Twelve pairs of 1 m^2 seedling plots were built around 12 adults, and plots were treated monthly with either a fungicide or a control. The surviving proportion of C. concinna seedlings at different stages was calculated, and an analysis was conducted on the impact of fungicide on seedling survival and species richness. Correlation between relative abundance and community evenness at different ages was analyzed using plot surveys. The results showed that fungicide treatment decreased species richness of the seedling community by pro- moting the recruitment of common species. Furthermore, census of a 25 m radius around adult C. concinna trees confirmed that the density of saplings increased with distance from adults. Relative abundance of C. concinna decreased with increasing age, and decreasing C. concinna dominance resulted in an increase in community even- ness. To avoid the appearance of a single optimum population, the dominance of C. concinna decreased with age via density dependence, and subsequently improved community species diversity.

Forest vegetation of Xishuangbanna,south China

Xishuangbanna of southern Yunnan is biogeographically located at a transitional zone from tropical southeast （SE） Asia to subtropical east Asia and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. The region, though surprisingly far from the equator and at a relatively high altitude, has a rich tropical flora and a typical tropical rain forest in the lowland areas. Based on physiognomic and ecological characteristics, floristic composition and habitats combined, the primary vegetation in Xishuangbanna can be organized into four main vegetation types： tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad-leaved forest and tropical monsoon forest. The tropical rain forest can be classified into two subtypes, i.e. a tropical seasonal rain forest in the lowlands and a tropical montane rain forest at higher elevations. The tropical seasonal rain forest has almost the same forest profile and physiognomic characteristics as equatorial lowland rain forests and is a type of truly tropical rain forest. Because of conspicuous similarity on ecological and floristic characteristics, the tropical rain forest in Xishuangbanna is a type of tropical Asian rain forest. However, since the tropical rain forest of Xishuangbanna occurs at the northern edge of tropical SE Asia, it differs from typical lowland rain forests in equatorial areas in having some deciduous trees in the canopy layer, fewer megaphanerophytes and epiphytes but more abundant lianas and more plants with microphyll. It is a type of semi-evergreen rain forest at the northern edge of the tropical zone. The tropical montane rain forest occurs at wet montane habitats and is similar to the lower montane rain forest in equatorial Asia in floristic composition and physiognomy. It is a type of lower montane rain forests within the broader category of tropical rain forests. The tropical seasonal moist forest occurs on middle and upper limestone slopes. It is similar to the tropical montane evergreen broad-leaved forest in the region in physiognomy, but differs from the latter in floristic composition. It is a vegetation type on limestone at high elevations. The monsoon forest in Xishuangbanna is a tropical deciduous forest under the influence of a strong monsoon climate and is considered to be a transitional vegetation type between a tropical rain forest and savanna in physiognomy and distribution. The tropical montane evergreen broad-leaved forest is the main montane vegetation type in the region. It is dominated largely by the families Fagaceae, Euphorbiaceae, Theaceae and Lauraceae. It differs from tropical lower montane rain forests in its lack of epiphytes and in having more abundant lianas and plants with compound leaves. It is considered to be a distinct vegetation type from the northern margin of mainland southeastern Asia, controlled by a strong seasonal climate, based on its floristic and physiognomic characteristics.

Community Dynamics of Seed Rain in Mixed Evergreen Broad-leaved and Deciduous Forests in a Subtropical Mountain of Central China

Seed dispersal is a key process within community dynamics. The spatial and temporal variations of seed dispersal and the interspecific differences are crucial for understanding species coexistence and community dynamics. This might also hold for the mixed evergreen broadleaved and deciduous forests in the mountains of subtropical China, but until now little existing knowledge is available for this question. In 2001, we chose to monitor the seed rain process of our mixed evergreen broad-leaved and deciduous forest communities in Mount Dalaoling National Forest Park, Yichang, Hubei Province, China. The preliminary analyses show obvious variations in seed rain density, species compositions and timing of seed rain among four communities. The average seed rain densities of the four communities are 2.43 ± 5.15, 54.13 ±182.75, 10.05 ±19.30 and 24.91 ± 58.86 inds/m^2, respectively; about one tenth the values in other studies in subtropical forests of China. in each community, the seed production is dominated by a limited number of species, and the contributions from the others are generally minor. Fecundity of evergreen broadleaved tree species is weaker than deciduous species. The seed rain of four communities begins earlier than September, and stops before December, peaking from early September to late October. The beginning date, ending date and peak times of seed rain are extensively varied among the species, indicating different types of dispersal strategies. According to the existing data, the timing of seed rain is not determined by the climate conditions in the same period, while the density of seed rain may be affected by the disturbances of weather variations at a finer temporal resolution.

东莞市亚热带常绿阔叶次生林优势种生态位特征研究

为了解广东省东莞市亚热带常绿阔叶次生林群落的生态位特征和演替现状,设置3个1 hm2样地,采用Levins生态位宽度和Pianka生态位重叠,对东莞市马山和银瓶山市级自然保护区的亚热带常绿阔叶次生林群落优势种进行生态位特征分析。结果表明,马山和银瓶山亚热带常绿阔叶次生林群落主要由樟科、芸香科、山茶科、鼠刺科、茜草科等树种组成。群落中山油柑(Acronychia pedunculata)、木荷(Shichima superb)、华润楠(Machilus chinensis)、黄樟(Cinnamomum parthenoxylon)、鼠刺(Itea chinensis)的生态位宽度较大,生态位宽度与频数关系密切。优势种生态位重叠值介于0~0.53,生态位重叠程度低,竞争关系较弱。3个样地所处演替阶段不同,银瓶山样地阳生树种与其他树种的生态位重叠值较大,马山样地中生性树种与其他树种的生态位重叠值更大,体现出常绿阔叶林从阳生树种建群到中生性树种建群的更替过程,为该区次生林的保护和管理提供科学依据。

南昆山自然保护区常绿阔叶林物种组成与群落结构

为探索南昆山自然保护区森林群落的物种组成和结构,利用样方调查法调查样地内胸径≥1 cm的木本植物,分析其群落树种组成、树种多度分布格局和径级结构。结果表明,样地内胸径≥1 cm的木本植物共有2576株,隶属35科60属98种,樟科、壳斗科和茜草科等6个优势科共有22属53种,华润楠、鸭公树和硬壳柯是优势树种;样地内稀有种16种,偶见种37种;树木径级遵从倒“J”形分布。表明该群落结构总体稳定,树木生长健康,样地没有明显的断层现象,群落总体上更新良好。研究结果为了解研究区森林生态系统和保护其生物多样性提供参考。

Tree species influences soil microbial community diversity but not biomass in a karst forest in southwestern China

Aims The relationships between plant species and soil microorganisms remain indeterminable in different ecosystems worldwide.In karst ecosystems,soil microbial(SM)community structure and their environmental driving factors are poorly explored,and the relationships between plant species and soil microorganisms are unclear.This study aimed to characterize the general patterns of SM community composition and biomass,and to explore the specific tree species and soil physiochemical properties highly related to SM community diversity and biomass in a karst forest.Methods The effects of tree species on SM community composition and biomass were firstly investigated on the basis of 212 soil samples collected from five dominant tree species(Lithocarpus confinis Huang,Platycarya longipes Wu,Itea yunnanensis Franch.,Machilus cavaleriei H.Lév.and Carpinus pubescens Burkill)through phospholipid fatty acid(PLFA)analysis of a karst evergreen and deciduous broad-leaved mixed forest in central Guizhou Province,southwestern China.The relationships between SM community structure and tree species and soil physiochemical properties were statistically analysed.Important Findings A total of 132 SM-PLFA biomarkers were detected.The average number of SM-PLFA biomarkers and microbial biomass in each soil sample were 65.97 and 11.22µg g^(–1),respectively.Tree species influenced the number of SM-PLFA biomarkers but not the SM biomass.The number of SM-PLFA biomarkers of C.pubescens was significantly higher than that of other species(P<0.05);the numbers of SM-PLFA biomarkers amongst other species showed no significant difference.Microbial biomass showed no relationships with the soil physiochemical properties of nutrient-rich surface soils but positively correlated(P<0.05)with soil organic carbon,nitrogen and phosphorus concentrations in deeper soils.The karst forest in the plateau-surface terrain of central Guizhou Province presented a low fungal-to-bacterial ratio,low microbial biomass storage and high microbial community diversity.Specific tree species affect the SM community diversity in this kind of karst forest.

铜鼓岭国家级自然保护区植物多样性

铜鼓岭自然保护区地处海南岛东北部文昌县境内的滨海低丘陵。为全面了解其植物多样性及经过18年的保护后其植被变化特征,作者采用野外调查与植物群落学相结合的方法,对海南岛铜鼓岭保护区的各类植被多样性进行了调查。本次调查共记录到植物984种,隶属166科618属。其中海南特有种35个,如海南苏铁(Cycashain-anensis)、茶槁楠(Phoebehainanensis)、古山龙(Arcangelisiagusanhung)等;濒危保护物种12个,分别为:金毛狗(Cibotiumbarometz)、海南苏铁、蕉木(Oncodostigmahainanense)、白木香(Aquilariasinensis)、海南大风子(Hydnocarpushainanensis)、红花天料木(母生)(Homaliumhainanense)、粘木(Ixonantheschinensis)、毛茶(Antirheachinensis)、野生龙眼(Dimocarpuslongan)、野生荔枝(Litchichinensis)、苦梓(Gmelinahainanensis)、白桂木(Artocarpushypargyreus)。该保护区内的主要植被类型热带常绿季雨矮林、灌木林和红树林的Shannon-Wiener指数分别为4.7485、4.5876和1.8096,Simpson指数分别为0.9247、0.9206和0.6978。在热带常绿季雨矮林2,800m2的标准样地内,树高大于1.5m的乔木共有81种1,366个个体,重要值较高的物种分别为黄椿木姜(Litseavariabilis)、海南大风子、滨木患(Aryteralittoralis)、禾串树(Brideliainsulana)、无患子(Sapindusmukorossi)等,18年前的优势种鸭脚木(Scheffleraoctophylla)被黄椿木姜所替代。另外,种数—个体数分析得出3,300m2标准样方内高于1.5m的单个体种有20种,双个体种有13种,占标准样方内所记录物种总数的32.7%。总体来说,热带常绿季雨矮林群落发展稳定,灌木林有向次生林演替的趋势,红树林遭破坏严重,面积减小,多样性也不是很高。所以从植被角度来说对铜鼓岭自然保护区的保护是重要的。

天目山常绿阔叶林优势种群及其空间分布格局

常绿阔叶林是浙江省天目山国家级自然保护区重点保护植被类型,研究常绿阔叶林优势种群及其空间分布格局,可正确认识优势种群在常绿阔叶林中的地位和作用,为常绿阔叶林的保护和恢复重建提供理论依据。在天目山国家级自然保护区内,选择典型常绿阔叶林设置样地,样地大小100m×100m。用全站仪测定每株树木坐标。用优势度分析法确定群落优势种。采用Ripley’sK(d)函数分析优势种群空间分布格局和种间关联关系。结果表明,常绿阔叶林的优势树种数随大小级的增大而增加,但优势树种的聚集程度却降低。常绿灌木连蕊茶(Camelliafraterna)在幼苗、幼树中占绝对优势。在中树和大树中,以细叶青冈(Cyclobalanopsisgracilis)、青冈(Cyclob-alanopsisglauca)和短尾柯(Lithocarpusbrevicaudatus)为主,形成多优势种结构特征。连蕊茶、细叶青冈和青冈具有较稳定的显著聚集分布特征。豹皮樟(Litseacoreanavar.sinensis)和短尾柯的分布格局波动较大。从整体上看,5个优势种群的分布格局都呈显著聚集分布特征。连蕊茶与细叶青冈、短尾柯、豹皮樟,以及细叶青冈与短尾柯、青冈与豹皮樟都有较强的物种空间依赖性。青冈和短尾柯相互独立生长,有显著负关联性。同科、属的细叶青冈和青冈也表现出显著负关联性。研究认为,种间关联关系具有传递性,可以从已知3个种的两对种间关联关系推出第三对种间关联关系。已知种间关联关系越显著,且尺度范围越宽,那么种间关联关系传递的稳定性也越高。结果认为,常绿阔叶树种是天目山国家级自然保护区常绿阔叶林群落的优势种,优势种均呈显著聚集分布,多数优势种间有较强的种间关联性。

江西九连山亚热带常绿阔叶林优势种空间分布格局

于江西九连山国家自然保护区设置4 hm2亚热带常绿阔叶林固定监测样地,用样方法对亚热带常绿阔叶林进行调查分析。应用点格局方法分析生境异质性是否影响树木分布并分析优势种红钩栲(Castanopsis lamontii)、米槠(Castanopsis carlesii)、罗浮柿(Diospyros morrisiana)和细枝柃(Eurya loquaiana)分布格局,对比存在生境异质性和排除生境异质性两种情况下优势树种不同生长阶段(幼树、小树、成年树)的空间分布格局以及不同生长阶段之间的空间关联性,探讨生境异质性之外的其它种群分布影响因子。结果表明:1)生境异质性效应显著影响九连山树木分布,4个优势树种在大尺度上存在明显的生境偏好;2)用完全随机零模型不排除生境异质性时,4个优势种总体及其不同生长阶段在0—30 m所有尺度上主要呈现聚集分布;3)用异质性随机零模型排除生境异质性后,4个优势种及其不同生长阶段的聚集程度显著下降,只在小尺度上(0—5 m)呈现聚集分布;4)4个优势种的幼树与小树均表现显著的正相关。红钩栲的成年树与幼树及成年树与小树总体表现不相关。米槠的成年树与幼树总体以无相关为主;成年树与小树之间总体呈正相关。小乔木罗浮柿的成年树与幼树之间在小尺度上(0—5 m)表现负相关或无相关,在较大尺度范围上总体表现正相关关系;小树与成年树在研究尺度上表现出正相关。灌木细枝柃的成年树与幼树,成年树与小树及小树与幼树之间在研究尺度范围内均呈现正相关关系;5)研究发现九连山优势乔木物种通过密度制约和Janzen-Connell效应释放空间,为其他物种共存提供条件,而优势灌木物种细枝柃没有表现出这两个效应。

广东大东山常绿阔叶林物种多样性分析

通过对大东山自然保护区常绿阔叶林８个群落的物种多样性进行测算，结果表明：处于中亚热带南缘的广东大东山常绿阔叶林物种多样性指数（Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ指数）为２．９５０～４．６７３；物种均匀度为０．４９９～０．７８２；生态优势度为０．０５０～０．０６７；对立木层和草本层的物种多样性指数、均匀度和生态优势度也分别作了测算。大东山常绿阔叶林物种多样性指数略高于海拔高度相近的八宝山而略低于南昆山。通过生物多样性的分析，对大东山的自然保护进行了讨论。

亚热带常绿阔叶林优势种个体及生物量的点格局分析

在广东康禾自然保护区的亚热带常绿阔叶林内设置4 hm2固定样地进行每木调查,分析群落优势种米槠(Castanopsis carlesii)和木荷(Schima superba)种群的年龄结构,并分别用Ripley's L函数和标记相关函数(mark correlation function)对种群个体和生物量空间点格局进行可视化解析。结果表明:1)米槠和木荷种群的径级结构为金字塔型,种群中有大量幼年个体,属增长型种群。2)米槠和木荷种群在0—50 m尺度上均呈聚集分布,说明生境异质性在种群空间格局形成中发挥重要作用。米槠种群聚集强度随空间尺度的增大逐渐增强,木荷种群在0—29.5 m尺度上聚集强度随尺度增大而增强,随后开始减小。3)米槠和木荷种群生物量分布格局与个体分布格局并不耦合,米槠生物量在个体间主要呈负相关,说明个体间存在显著的资源竞争。木荷个体间生物量分布相互独立,竞争不明显,显示出作为亚热带先锋树种的木荷有很高的资源利用效率。个体及生物量空间分布格局分析表明两个种群的分布模式均有利于实现物种共存。

菜阳河自然保护区天然植被物种多样性研究

采用植物群落学的原理和方法,对菜阳河自然保护区内的3种主要天然植被物种多样性进行研究 结果表明:植被型相同的群落间物种相似性程度较高,植被型不同的群落间物种相似性系数为山地雨林和季节雨林>山地雨林和季风常绿阔叶林>季节雨林和季风常绿阔叶林 季节雨林群落优势种明显,重要值集中在少数优势种上;山地雨林群落优势种不明显,重要值分布均匀;季风常绿阔叶林群落优势种明显,重要值分布不均匀 山地雨林群落物种丰富,多样性指数明显高于季节雨林群落和季风常绿阔叶林群落