共查询到18条相似文献,搜索用时 78 毫秒
1.
2.
通过对万人欢林场不同经营类型次生林林下物种丰富度与多样性的差异进行的试验研究,结果表明:以硬阔混交林为例,经抚育后的硬阔混交林Shannon-Wiener指数、Margalef丰富度指数、Pielou均匀度指数、Simpson多样性指数分别为1.92、3.85、0.62、0.67;未抚育的林分分别为0.88、0.92、0.63、0.46,无论是从物种丰富度还是多样性来说,抚育后的林分,明显高于未抚育林分。但软阔混交林各项数值差别不大,最有可能的原因是海拔高度影响生物多样性。 相似文献
3.
4.
我国种子植物物种丰富度空间分布格局的分析探讨 总被引:1,自引:0,他引:1
文章利用我国主要省(区)现有种子植物及空间、地形资料,通过通径分析和回归分析,发现中国种子植物物种丰富程度主要受纬度、土地面积、海拔幅度、山丘比(山地和丘陵面积占土地面积的比例)等因素影响,且呈现出一定的规律性:种子植物丰富度随纬度的增大而减小,随土地面积、海拔幅度、山丘比的增大而增大;物种密度随纬度和土地面积的增大而减小,随海拔幅度、山丘比的增大而增大。 相似文献
5.
通过分析广东省山茶科125种植物物种丰富度水平地带性格局,并对其进行环境解释,利用软件DMAP将广东省划分为72个0.5°×0.5°的经纬度网格,并将基于网格的物种丰富度表现出来,同时利用箱形图分析其水平分布格局.结果表明:广东省山茶科植物的分布中心位于粤北山区,表现出显著的经度(P=0.001 2)、纬度(P=0.004 9)地带性差异.对125种植物、72个网格和6个环境因子进行典范对应分析(CCA)表明:CCA排序轴第1轴主要代表温度的变化梯度,第2轴主要代表水分的变化梯度,说明水分、温度等因素共同影响山茶科植物在广东的生长和分布,其中年均最低温度是影响广东省山茶科植物丰富度水平地带性格局的最大因子. 相似文献
6.
通过对苏州市3所高中校园植物种类、数量的调查,分析了校园绿化植物的应用频率和物种丰富度。结果表明:这些高中校园共有144种植物,隶属于65科131属,其中乔木31种,占21.5%;灌木37种,占25.7%;草本73种,占50.7%;藤本3种,占2.1%。人工栽培的绿化植物92种,占植物总数的63.9%;杂草51种,占35.4%,其中狗牙根(Cynodon dactylon)、马尼拉草(Zoysia matrella)为主要杂草种。整体上校园植物资源丰富,但结构相对简单,布局不合理,建议增加植物种类,提高美化效果。 相似文献
7.
目的 试图给出确定森林群落树种丰富度的方法,解决物种丰富度测度问题,完善森林生物多样性研究的方法。 方法 采用Monod模型表达种-面积曲线,通过数学手段确定最小森林群落面积和最大树种数。 结果 用本研究提出的方法对不同气候带森林物种丰富度进行测算,结果表明:热带森林群落具有更高的最大树种数和更大的群落最小面积,物种丰富度随气候带由热带到寒温带逐渐减少。 结论 用最大树种数能够确切表达不同气候带森林群落树种丰富度,克服了现有研究中直接把不同大小调查面积上的树种数量视为树种丰富度的弊端。 相似文献
8.
为给南宁市行道树规划和建设提供参考,对南宁市主要道路的园林绿化状况进行全面踏勘,在5个城区中筛选出143条道路,对其行道树进行调查与分析。结果表明,南宁市共有行道树41种,隶属于21科31属,树种组成较丰富;常绿树种与落叶树种的比例为4.125∶1,乡土树种和引进树种的比例为2.154∶1。常用行道树有天桃木(Mangifera persiciforma)、雅榕(Ficus concinna)、秋枫(Bischofia javanica)、人面子(Dracontomelon duperreanum)和凤凰木(Delonix regia)等;天桃木(Mangifera persiciforma)和雅榕(Ficus concinna)的应用频度较高。行道树健康状况综合评分为81.68分,道路绿地达标率为83.11%,林荫路推广率为87.9%。除西乡塘区外,其他城区的行道树多样性指数与物种丰富度指数呈正相关;多样性指数表现为兴宁区>青秀区>良庆区>西乡塘区>江南区。季相树种在兴宁区中的应用较均衡;整体来看,南宁市行道树季相变化不明显;春、夏季景观效果相对较好,秋和冬季... 相似文献
9.
天然油松林与人工油松林物种结构等方面存在一定差异,其群落物种丰富度和最小面积也不同。本文对河北蔚县的天然次生油松林和人工油松林的物种丰富度及木本植物群落最小面积进行了探讨。结果表明,油松天然林乔木物种丰富度较人工林高,乔木幼苗幼树差距不大,灌木物种丰富度比人工林高,草本物种丰富度比人工林低。从总的物种组成来看,天然油松林与人工油松林具有较高的相似性。用8个模型对天然林和人工林木本植物种-面积曲线分别进行了拟合,并确定各自的最优模型,得出各取样比例时的最小面积。结果表明,当所取物种比例为0.6及以下时,天然林的最小面积小于人工林;而所取比例为0.7及以上时,天然林的最小面积大于人工林。 相似文献
10.
11.
We analyzed the relationship between species richness and biomass in natural forest communities at two similar sites on Mt. Xiaolongshan, northwest China. At both sites, a wide range of tree layer biomass levels was available by local biomass estimation models. In order to identify underlying mechanism of the species richness-biomass relationship, we included different water resource levels and number of individuals in each plot in our analysis. We sampled 15 and 20 plots (20 m ×20 m), respectively, at both two sites. These plots were sampled equally on the sunny slope and the shady slope. Species richness, number of individuals of each species and diameter at breast height (DBH) as a substitute of biomass of tree layer were recorded in each sample. At one site, the relationship between species richness and biomass was significant on the sunny slope, and this relationship disappeared on the shady slope due to more environmental factors. The relations between species richness and number of individuals and between number of individuals and biomass paralleled the species richness-biomass relation on both slopes. The difference in number of individuals-biomass relationships on the sunny slope and the shady slope revealed "interspecific competitive exclusion" even though the species richness-biomass relationships were not hump-shaped. At the other site, species richness was not related to biomass or to number of individuals. Our study demonstrated the importance of environmental stress and succession of community in the understanding of species diversity-productivity patterns. 相似文献
12.
Abelardo Aparicio Rafael G. Albaladejo Miguel Á. Olalla-Tárraga Laura F. Carrillo Miguel Á. Rodríguez 《Forest Ecology and Management》2008
While maximizing plant species richness continues to be central in the design, conservation and reforestation action plans, plant life histories are receiving increasing attention in assessments for the conservation of biodiversity in fragmented landscapes. We investigated the determinants of woody plant species (trees, shrubs and climbers) richness in the forest patches of the Guadalquivir river valley, a Mediterranean agricultural landscape with ∼1% forest cover. We analyzed three species richness variables, total, and those corresponding to species with short-distance (ballistic, barochorous, myrmecochorous and short-distance anemochorous) and long-distance (anemochorous, endozochorous, exozoochorous, hydrochorous and dyszoochorous) dispersal systems, which significantly characterize earlier and late successional stages, respectively. We selected eleven predictor variables related to habitat structure (patch area, shape, distances to the nearest patch and reserve, and general isolation), physical environment (temperature, precipitation, elevation, and lithological heterogeneity), and anthropogenic influences (disturbance and proportion of old-growth forest). We used ordinary-least-squares multiple regression (OLS) and the Akaike's information criterion (corrected for spatial autocorrelation) and derived indices to generate parsimonious models including multiple predictors. These analyses indicated that plant species richness increase primarily along with increasing patch area and decreasing disturbance, but also detected secondary effects of other factors when dispersal was considered. While the number of species with potential long-distance dispersal tended to increase in more isolated patches of areas with greater precipitation and lithological heterogeneity (e.g. highlands at the valley edges), the number of species with short-distance dispersal increased towards drier and less lithologically complex zones with shorter between-patch distances (e.g. central lowlands). Beyond emphasizing the need to consider dispersal in fragmentation studies, our results show that woody plant species richness would be favoured by actions that increase patch area and reduce anthropogenic disturbances particularly in lowland forests. 相似文献
13.
Comparison of fractal characteristics of species richness patterns among different plant taxonomic groups along an altitudinal gradient 总被引:1,自引:0,他引:1
This study was done using the non brown fractal model to quantify and compare the variations in the species richness of trees,
shrubs, herbs and all plants along an altitudinal gradient and to characterize the dominating ecological processes that determine
the variations.
Two transects were sampled far away from any anthropogenic disturbances along the shady slopes of the Dongling mountains in
Beijing, China. Both transects were continuous and 2 m wide, and every individual tree and shrub was recorded in each of them.
Discrete quadrats of 1 m × 1 m were located along the transects A and B for estimation of the herb species richness along
the altitudinal gradients. The level interval between the quadrats was 10 m and 25 m respectively. In this study, transects
A and B were combined into one transect AB, and 40 m was selected as the optimal quadrat length along the altitudinal gradients
for measuring the plant species richness patterns. Species richness in each quadrat was calculated using a program written
in Matlab 6.0.
Direct gradient analysis was used to describe the overall trends in the species richness of trees, shrubs, herbs and other
plants with change in altitude, while the non-brown fractal model was used to detect more accurately their variations at various
scales along the gradient. The model assumed that each class of ecological processes affecting the distribution of a variable
could be represented by an independent spatial random function. Generally, ecological phenomena are determined not by a single
ecological process but by multiple ones. These processes act on ecological patterns within their own spatial scales. In the
non-brown fractal model, the spatial random functions are nested within a larger range of spatial scales. The relative contribution
of the spatial random functions to the spatial variation of a variable is indicated by a weighting parameter that has to be
greater than or equal to zero.
In this paper, we reached the following results and conclusions. Firstly, the direct gradient method describes the general
trends of trees, shrubs, herbs and all plants along the altitudinal gradient but is unable to provide further details on the
altitudinal variations in the species richness. The non-brown fractal model brought out the altitudinal variations in the
species richness of trees, shrubs and herbs at various scales and related them to the ecological processes. The sharp changes
in the double-log variograms suggest that the non-brown fractal model is suitable for characterizing the altitudinal patterns
in the species richness of trees, shrubs and herbs at various scales but is not appropriate for explaining the variations
in the plant species richness, since no significant changes were found in the double-log variograms in this case. Secondly,
for the trees, the double-log variogram was divided into two scale ranges (0–245 m and 245–570 m), with a fractal dimension
of 1.83 and 1.10, respectively, implying that changes in the tree species richness were random at small scales (0–245 m) and
almost linear at large scales (245–570 m) along the altitudinal gradients. This suggests that altitudinal variations in the
tree species richness are dominated by short-range processes at small scales and by long-range processes at large scales.
Thirdly, for shrubs and herbs, the double-log variograms exhibited three ranges (0–101 m, 125–298 m and 325–570 m), and the
fractal dimensions were 1.78 and 1.97, 1.56 and 1.43, and 1.08 and 1.25, respectively. The results indicate that, as in the
case of trees, species richness of shrubs and herbs are distributed randomly at small scales and change in a linear manner
at large scales although variations in the herb species richness is less heterogeneous than shrub species richness at large
scales. These results also indicate that species richness of shrubs and herbs change approximately like brown movement at
middle scales. The results also suggest that altitudinal variations in the specie richness of shrubs and herbs are dominated
by three ecological processes, short-range ecological processes at small scales, long-range ecological processes at large
scales, and brown fractal processes at middle scales. Interestingly, comparisons of the variations in the species richness
of shrubs and herbs reveal that shrubs and herbs present the same scale range in spatial variation in species richness but
display different trends in species richness along the altitudinal gradient, i.e. the shrub species richness decreased with
increasing elevation whereas the herb species richness peaked at the mid-high elevation. These patterns suggest that although
the scales at which the main processes affect patterns in species richness are the same, the processes are completely different,
or the processes are similar but the responses of the shrubs and herbs to the ecological processes are different. Finally,
the plant species richness did not show any obvious pattern along the altitude gradient and maintained a constant fractal
dimension across all scales, this is perhaps because the processes defining the patterns of plant species richness had similar
weights and acted over closely related scales.
__________
Translated from Acta Phytoecologica Sinica, 2005, 29(6): 901–909 [译自: 植物生态学报] 相似文献
14.
沈阳市建成区树种现状分析 总被引:6,自引:0,他引:6
通过对沈阳市建成区城市树木的调查分析发现:沈阳市的各土地类型中的树木分布不均。其中,被调查的256块样地中每公顷物种小于或等于5种的样地有113块,占总调查样地的44.14%,每公顷小于或等于10株的样地共43块,占总样地的16.80%;利用械种多度重要性排序及累积贡献率获得了不同土地类型中的主要树种;多个生物多样性指数表明,公园性质的绿地树种多样性最高,企事业单位用地与居住区用地次之,街道类用地较低,而商业金融用地最低;并对沈阳市的树种发展提出建议。 相似文献
15.
16.
Studies on the effect of forest loss and fragmentation on plant species richness at different spatial scales have yielded contradictory results that have been attributed to different ways to measure fragmentation. The main goal of this study was to investigate the independent and combined effects of forest loss and habitat fragmentation on woody species richness. Woody species were grouped according to their habitat requirements (forest specialists, forest generalists, non-forest and total woody species). We used regression models to investigate the effect of fragmentation and human occupation on woody species richness. The underlying factors were investigated by partitioning of the variation, i.e. decomposing the variation in species richness between the pure effects of forest loss, fragmentation and human occupation. The relationship between species richness and forest loss resulted extremely non-linear. The models for forest specialist, generalist and total woody species richness accounted for 35%, 31% and 33% of the total variance respectively. Model for non-forest species richness only accounted for 7% of the total variance. The largest fraction of variability in species richness was accounted by fragmentation variables for all groups (except for non-forest species). Results emphasize the larger independent effect of fragmentation over forest loss, suggesting that species variation is mainly conditioned by the spatial configuration of the habitat. 相似文献
17.