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1.
Surveys at southwestern China were conducted from November 2004 to July 2005 in three habitat types. A total 3319 individual of 69 bird species were recorded. Although urbanization was presumed to be responsible for decreasing species richness and diversity, our results showed bird species richness, diversity and density in urban habitats were not different in rural habitats. Whereas, the wasteland with low human disturbances, was the lowest bird species richness, diversity and density than others habitats. We inferred habitats structural complexity, large forest patches, native trees and human litter sustain many bird species in campus and park. However, human disturbances, habitats substrate and predation from domestic animals may reduce species richness and diversity. Therefore, we suggested that high vegetative cover should be in urban areas, because it may increase the number of bird species, support larger populations of insectivores, and perhaps create suitable habitat for some ground nesters. Moreover, by recreating or preserving natural islands decreased human disturbance and predation from domestic animals.  相似文献   

2.
The distribution of ant species was studied across different types of semi-natural grasslands in a mosaic landscape in which data on land use history and conservation values were available. The twenty-nine grasslands selected were non-fertilised and had an uninterrupted history of management, but they differed from each other in soil texture and grazing practices and were therefore sub-divided into six different types. Species abundance of mound-building ants were investigated in these grasslands in 2003. Additionally, ants were sampled using the pitfall trapping method in 13 semi-natural grasslands (in 2003 and 2005). Ant species richness and nest frequency of individual ant species differed between the different types of grassland and was associated with soil texture and grazing practices. The results also showed that even small grasslands have a very high ant species richness. This study showed that for the conservation of ants, habitat diversity and heterogeneity rather than habitat size are of great importance. I conclude that different types of semi-natural grassland contribute to heterogeneity in the farmland landscape and, thus, support higher ant diversity at the landscape scale.  相似文献   

3.
The types, frequency, and intensity of human interference with forests markedly affect the vegetation dynamics. Assessment of the impact of anthropogenic disturbances on forest diversity and structure is one of the central issues related to human behaviour and forest ecosystems and management. Both species diversity and density are very sensitive to local anthropogenic disturbance, which can be reduced depending on land-use systems. We used 10 line transects of 500 × 10 m to record and measure all plants ≥10 cm girth in some of the remaining forests surrounding villages in Tripura, Northeast India. To predict the effects of anthropogenic pressure on species richness and forest structure, we recorded and scored all ongoing disturbances in all transects of the forests. Although our study did not show any significant effects on the mean number of species, all diversity indices were significantly affected by disturbance. Total stem density (F = 128.60, p < 0.0001) and basal area (F = 65.30, p < 0.0001) of the forest stands were significantly affected by disturbance. Disturbance significantly (F = 84.81, p < 0.0001) impacts the abundance of mature voluminous trees removed by extensive illegal logging. Further, stem density at the middle (F = 10.01, p < 0.05) and upper (F = 131.70, p < 0.0001) canopy stories was also reduced by high disturbance intensity. The present analysis will be useful to policy-makers and planners for implementation of sustainable forest management at both the local and regional scale.  相似文献   

4.
This study aimed to assess Japan’s recent “local production for local consumption” (LPLC) movement, with a special focus on vegetables in the Osaka city region of central Japan. After collecting statistics and spatial data, we conducted a multi-scale analysis of vegetable production and consumption along with the associated energy consumption, using geographical information system software at three spatial scales along the vegetable flow paths: national, regional, and local. Vegetables consumed in the Osaka city region came from prefectures throughout Japan, and we mapped the foodshed within this region at 1-km spatial resolution, as well as the distribution of farmland, farmers’ and other markets. We also conducted a scenario analysis for reduced energy consumption through organic farming and the utilization of abandoned farmland near a city to replace food imports from distant areas. We found that the large majority of vegetables consumed in the Osaka city region currently come from remote prefectures, and that this is associated with a high level of energy consumption. Inside the Osaka city region, peri-urban vegetable farming contributes to regional vegetable provision, resulting in an approximately 70 % production/consumption ratio within an 80-km radius of the urban center; if all of the area of abandoned farmland were restored to production, this ratio would increase to approximately 75 %. Organic farming activities that bring together farmers and urbanites are emerging in many parts of the study area, contributing to increased LPLC. Scenario analysis suggested that a decrease of more than 1 × 106 GJ of energy inputs could be achieved through wider adoption of local organic farming for local consumption and complete utilization of abandoned farmland in the Osaka city region.  相似文献   

5.
Green spaces considered natural remnants in urban environments play a key role in promoting environmental quality and forming a sustainable city. Nowadays, development of urban spaces has taken a hasty growth. In the meanwhile, the natural green spaces are severely damaged. The current study aims at investigating the trend of changes in green space of Tabriz City, the second large industrial city in Iran, on the basis of landscape ecology principles. In order to prepare the land-cover maps, Landsat TM and IRS LISS-III of the years 1989 and 2006 were applied. Alongside, landscape percentage metrics, the largest patch index, number of patches, patch density, edge density, total edge, class area and landscape shape index were also used to analyse the changes. Metric analysis of the landscape within the studied years revealed that a large part of the region has enjoyed a rapid growth (equivalent to 64.5 %) in constructions. As the obtained results showed, the smallest landscape percentage (3.9 %) in the study area is belonged to the municipal green space, while the largest landscape percentage (66 %) is allocated to the barren land. This shows that the constructions have not balanced with creation of new green spaces, and the lack of green space per capita continues to be felt.  相似文献   

6.
长江中游地区多尺度耕地景观格局演变特征   总被引:3,自引:0,他引:3  
揭示区域耕地景观格局多尺度演变特征有助于从区域层面全面解读耕地利用状况,可为区域耕地保护和生态环境建设提供重要参考。采用景观格局指数分析方法和数理统计手段,选取10个景观指数,从城市群、省域、流域3个不同空间尺度分析了长江中游1995~2014年耕地景观格局变化特征。结果表明:(1)1995~2014年间,长江中游耕地总面积以平均每年30821 km2的降速大量减少。其中,湖北、湖南、江西3省年均降速分别为18512、7026、5276 km2/a,武汉城市圈、长株潭城市群、环鄱阳湖城市群三大城市群年均降速分别为18003、4819、5616 km2/a。(2)不同省份耕地景观变化的方向和程度存在较大差异。湖南省耕地连通性先增后减,景观的破碎度先减后增,而湖北省和江西省耕地景观的连通性和破碎度变化趋势则与湖南省恰好相反,且变化强度明显弱于湖南省。(3)不同城市圈(群)耕地景观变化的方向和程度差异明显,作为工业化快速发展地区,长株潭城市群耕地景观变化的剧烈程度明显高于长江中游经济带内的其他两大城市圈(群)。(4)不同尺度耕地景观格局在数量、面积、聚集度、多样性方面差异较大。而城市圈(群)作为省内重点发展区域,其耕地景观格局及其变化与其所处省份大致相同  相似文献   

7.
为更好地理解河流廊道对城市景观生态的意义,研究计算了四川省邛崃市景观类型多样性空间聚类特征和河流廊道景观格局特征。结果表明:(1)局部空间自相关指数Getis Ord Gi*显示研究区土地利用景观类型多样性存在高值聚类区,其形状与研究区河流廊道分布格局近似。(2)河流廊道主要与农田和林地景观毗邻,其两侧300 m缓冲区内主要景观类型为农田和林地,且林地破碎度小;而道路廊道主要与农田和建设用地毗邻,其两侧缓冲区内主要景观类型为农田和建设用地,其景观更为破碎化。(3)地形因素对研究区西部山区土地利用景观格局影响较大,景观类型多样性统计热点区域分布于西部河流台地。邛崃市河流廊道在提高该地区土地利用景观类型多样性中起到积极作用,需要保护邛崃市河流廊道景观多样性,加强河流与自然景观的连通性  相似文献   

8.
Although the coastal salt marshes of Arabian Gulf have been altered extensively by human development activities, there is a paucity of data describing changes in the distribution and abundance of native coastal plant communities. The main objectives of this study are to determine vegetation condition, size structure, and conservation status of Nitraria retusa, a medicinal and salt-tolerant shrub, in disturbed and non-disturbed coastal salt marshes of Kuwait. Size measurements of Nitraria shrubs and nabkas, which are mounds of sediment developed around shrubs, were carried out in 50 quadrats (20 × 20 m2), randomly selected inside and outside Sabah Al-Ahmad Natural Reserve. Species richness and soil properties of nabkas and interspaces, the open areas between the nabkas, were also measured. The results revealed that nabkas of Nitraria in non-disturbed sites are more stable and rich in plant diversity than those in disturbed sites. Mean height and mean canopy diameter of Nitraria shrubs, total plant cover, and species richness are significantly higher in non-disturbed sites than disturbed sites, which indicate the positive influences of conservation for long term on vegetation structure and species richness. The results of soil analyses indicate the important role of nabkas in providing refuges for plant life and species diversity. The present study indicates that more than 50 % of the N. retusa community has been lost during the last few decades. Therefore, N. retusa should be considered an endangered species in Kuwait. The reduction in vegetation cover, a decline in species richness, and the overall degradation of salt marshes are attributed to human development activities along the coast of Kuwait. Effective conservation actions for threatened species in degraded coastal salt marshes of this region include establishment of protective enclosures, prohibitions on development that adversely affects native plant communities, and the planting native salt-tolerant shrubs to facilitate regeneration.  相似文献   

9.
Conservation practitioners require strata specific, seasonal species densities for habitat management. Herein, we use stratified distance sampling in Kanha Tiger Reserve (KTR) with 200 spatial transects and an effort of 1200 km walk in the year 2013. Analysis was done to access (a) impact of human use and (b) effect of habitat and season on ungulate densities in KTR. While a single detection function for each species was used for estimating density within human-restricted core and multiple use buffer of KTR, species-specific seasonal detections were modelled for each habitat. Ungulate biomass was 4.8 times higher in the core area compared with the buffer zone. The core supported a herbivore density and biomass of 50 ± 4.80/km2 and 26,806 ± 2573 kg/km2, respectively. Chital were found to be most abundant, having a density of 30.1 ± 4.34/km2 and contributing 33 % of the biomass with a habitat preference for grasslands (106 ± 39/km2) in summer and winter. Sambar had highest density (15.4 ± 3.34/km2) in bamboo-mixed habitat, in both seasons. Gaur contributed 39 % of the ungulate biomass and showed a seasonal shift in density from sal forests (9.65 ± 3.55/km2) in summer to miscellaneous forests (8.13 ± 1.94/km2) in winter. Barasingha were restricted to grasslands with similar summer and winter densities of 1.56 ± 0.76/km2. Chousingha were rare (0.1 ± 0.04/km2), found mostly in miscellaneous forests and plateau grasslands. Grassland and bamboo-mixed forests supported 58 % of the total ungulate biomass. Management for an optimal habitat mosaic that maintains ungulate diversity, addresses the specific needs of endangered species and maximizes ungulate biomass is recommended.  相似文献   

10.
The potential for agricultural landscapes to support biodiversity may vary greatly based on agricultural land use. Current knowledge suggests that agricultural composition and intensity are dominant drivers of biodiversity in agricultural landscapes, with variable effects of agricultural configuration and landscape diversity. The aim of this study was to determine the relative effects of agricultural composition, intensity, configuration, and landscape diversity on the species diversity of six distinct bird guilds on the landscape scale in a large and complex landscape in Ontario, Canada. We found that agricultural configuration, specifically patchiness of croplands, and to a lesser degree forage lands, was the strongest predictor of bird diversity for three of the six bird guilds considered (forest, shrubland, and town). The effects of increased cropland patchiness were variable, with forest and shrubland bird diversity increasing from small to moderate patchiness, and town bird diversity declining from moderate to high patchiness. Grassland birds, a group of considerable conservation concern, increased near linearly with increased agricultural land cover in the landscape, highlighting the need to consider agricultural lands in conservation planning for this species group. Woodland bird diversity declined significantly with all increasing measures of agricultural intensity, including the proportion of high-intensity agriculture and larger patches of agricultural land. Wetland birds were unique from the other guilds, showing primarily a strong association between diversity of land cover types and guild-level bird diversity. Surprisingly, increased cover of agricultural lands, which we predicted to be a dominant driver of guild-level bird diversity declines due to habitat loss, had weak, non-significant effects relative to the other land use variable being tested, except for the positive association with grassland birds. Our findings suggest that a mix of management strategies should be employed to consider the varying effects of agricultural lands on different bird guilds, such as the inclusion of agricultural land in conservation strategies for grassland species and further managing the configuration of agricultural lands to enhance biodiversity of agricultural landscapes.  相似文献   

11.
山区农业转型对于我国山区耕地可持续利用效率、土地整治方向以及生态建设方向具有一定的指导意义,渝东北生态涵养发展区是重庆市农用地整治项目的主要分区,通过定义作为农业转型产物的"规模农地"相关概念及其判读标准,旨在提出一种新的研究路径对重庆市典型山区地貌的耕地利用现状给予指导和改善意见。首先选取三峡库区腹地5个区县为研究区,并结合研究区实际对"规模农地"进行等级划分,利用Arc GIS10.2等软件通过景观格局指数、核密度测算、空间自相关等方法从斑块特征、数量分布、空间格局三方面对研究区内规模农地的空间分布规律进行探讨。研究表明:(1)不同类型规模农地斑块特征呈现一定的规律性,小规模农地斑块密度最大为6.004,大规模农地平均最近指数MNN值最低为643.401,且农地规模越大,面积加权平均斑块分维数AWMPFD值和聚集度AI值越高;(2)中、大规模农地数量多集中在奉节县,微、小规模则多集中在巫山县,且规模农地自身及其相互之间存在固定的邻接性规律,即同类斑块之间的邻接性与其斑块大小成反比,不同类型斑块之间则与之相反;(3)研究区规模农地整体空间分布主要集中在奉节县中部以及巫溪县东部,沿江流域的平坝地区分布相对密集,且不同类型规模农地在空间上存在明显的自相关性。  相似文献   

12.
为研究都市城郊耕地景观的演变历程,总结耕地景观演变模式进而为未来研究区的农业资源合理利用和优化调控提供可借鉴性措施,以重庆市沙坪坝区为例,按其地貌特征从东至西划分为东部丘陵A区、岩溶低山B区、中部浅丘C区、西部岩溶低山D区4个区域,以1979年的MSS影像、1988、1995、2001、2007和2010年5个时期的TM影像为基本数据源,采用景观指数和定量表征指标,分析了沙坪坝区耕地景观空间格局演变、空间分布变化幅度及其种植结构引起的耕地景观功能变化。结果表明:A、B、C、D 4区耕地平均斑块面积在1979~2010年有了较大程度的减小,相应的斑块数目有了显著的增加,斑块密度呈现逐步增加的趋势,多样性指数和均匀度指数除了A区在逐步减小外,其他3区均呈增大趋势,耕地景观总体的破碎化程度增加了。2001年以前,除了A区快速减少外,各区耕地面积相对稳定;2001年为界限至今,A、C两区耕地演变属于快速消退型,B、D区则属于逐渐消退型。从2003年到2007年研究区种植作物类型及各区功能定位有所变化,研究区正处于从传统都市城郊农业向现代都市农业的转变中。研究区耕地景观从东部主城核心区到西部缙云山区,呈现跳跃突变式演变的特殊模式  相似文献   

13.
The benthic macrofauna of the Segara Anakan lagoon, Java, Indonesia and its fringing mangroves were investigated between May 2004 and August 2006. This lagoon has been affected by various human activities for decades, in particular fishing, effluents from agriculture and industry, and illegal deforestation. In total, 163 taxa were identified, including 127 species occurring in the mangrove forest and 59 species in the subtidal. Mean density of macrobenthos was 2.5-fold higher in the central (881.8 ± 1,151.3 ind. m?2) than in the eastern mangrove site (356.3 ± 218.8 ind. m?2). Community structures differed significantly between these sites and showed a serial shift during the investigation period. Gastropods dominated the community in the central mangrove location, whereas sipunculids, polychaetes and gastropods had similar densities in the eastern site. Differences in community composition were best explained by three sediment properties: pore water salinity, δ13Corg, and Corg/N. It is suggested that small-scale heterogeneity of food availability and quality is a main factor determining the small-scale variability of the community composition. Compared to other Indo-West Pacific mangroves, species richness and densities are high. However, the dominance of specific taxa, especially of opportunistic species and the comparably low species richness in the subtidal of the lagoon may be attributed to the high sediment input by rivers in the central part and to the large-scale cutting of mangroves. Continuous tree logging will probably lead to a further spread of two fast growing understorey plants and thus to an increase of uniform swamp sites and a decrease of micro-habitats for benthic macrofauna. To our knowledge, this is the first detailed study on the spatio-temporal variation of benthic macrofauna in mangroves of Indonesia.  相似文献   

14.
15.
In Central Europe, management of forests for multiple ecosystem services (ES) has a long tradition and is currently drawing much attention due to increasing interest in non-timber services. In face of a changing climate and diverse ES portfolios, a key issue for forest managers is to assess vulnerability of ES provisioning. In a case study catchment of 250 ha in the Eastern Alps, the currently practiced uneven-aged management regime (BAU; business as usual) which is based on irregularly shaped patch cuts along skyline corridors was analysed under historic climate (represented by the period 1961–1990) and five transient climate change scenarios (period 2010–2110) and compared to an unmanaged scenario (NOM). The study addressed (1) the future provisioning of timber, carbon sequestration, protection against gravitational hazards, and nature conservation values under BAU management, (2) the effect of spatial scale (1, 5, 10 ha grain size) in mapping ES indicators and (3) how the spatial scale of ES assessment affects the simultaneous provision of several ES (i.e. multifunctionality). The analysis employed the PICUS forest simulation model in combination with novel landscape assessment tools. In BAU management, timber harvests were smaller than periodic increments. The resulting increase in standing stock benefitted carbon sequestration. In four out of five climate change scenarios, volume increment was increasing. With the exception of the mildest climate change scenario (+2.6 °C, no change in precipitation), all other analysed climate change scenarios reduced standing tree volume, carbon pools and number of large old trees, and increased standing deadwood volume due to an intensifying bark beetle disturbance regime. However, increases in deadwood and patchy canopy openings benefitted bird habitat quality. Under historic climate, the NOM regime showed better performance in all non-timber ES. Under climate change conditions, the damages from bark beetle disturbances increased more in NOM compared with BAU. Despite favourable temperature conditions in climate change scenarios, the share of admixed broadleaved species was not increasing in BAU management, mainly due to the heavy browsing pressure by ungulates. In NOM, it even decreased and mean tree age increased. Thus, in the long run NOM may enter a phase of lower resilience compared with BAU. Most ES indicators were fairly insensitive to the spatial scale of indicator mapping. ES indicators that were based on sparse tree and stand attributes such as rare admixed tree species, large snags and live trees achieved better results when mapped at larger scales. The share of landscape area with simultaneous provisioning of ES at reasonable performance levels (i.e. multifunctionality) decreased with increasing number of considered ES, while it increased with increasing spatial scale of the assessment. In the case study, landscape between 53 and 100 % was classified as multifunctional, depending on number and combinations of ES.  相似文献   

16.
随着城市化进程的加快,空气污染问题已成为中国最主要城市问题之一,严重影响公众健康。当前微观尺度下空气监测点周围景观格局对PM25浓度影响的研究较少,以长株潭城市群为例,选取地形、污染源、人口、道路交通、土地利用与城市景观格局6大类预测变量,其中城市景观格局选取边缘密度、连续度、形状指数、斑块平均面积、蔓延度、均匀度指数7个景观指数,运用逐步线性回归模型,探究城市景观格局对PM25浓度的影响。研究结果显示:(1)所选取的土地景观格局指数可以解释研究区PM25浓度的732%的变异,模型拟合较好;(2)影响PM25浓度的土地利用类型包括建设用地、林地、草地与水体。微观尺度下城市各类型景观格局中连续度和形状指数对PM25影响显著,建设用地连续度越高,分布越集聚,PM25浓度越高;水体形状指数越小,形状越简单规则,越易降低PM25浓度;(3)城市整体景观格局中,景观聚集程度与景观多样性等因素对PM25浓度产生重要影响。减少景观内各类型斑块的离散分布,使各景观类型均匀分布于整体景观内,有助于降低PM25浓度。研究结果可为未来大气防治与城市规划提供参考依据。〖HJ1〗〖HJ〗〖JP+1〗  相似文献   

17.
2011年利用样线法对长江上游向家坝库区夏、秋季鸟类进行了实地考察,共记录110种鸟类,隶属15目39科。通过5个调查点、2个对照点不同生境鸟类的多样性研究发现:(1)夏、秋季库区不同生境鸟类的Shannon Wiener 指数较低,几乎均未超过1.5,鸟类物种多样性相对贫乏;(2)库区各生境鸟类Pielou指数均超过了0.75,说明库区环境虽以人工植被为主,但并不单调;(3)阶地疏林灌丛、竹林与常绿落叶阔叶混交林的鸟类相似性差异最小〖JP2〗,而二者与芦苇、荩草丛滩地的差异最大,库区鸟类在不同生境中的分布存在着显著不同。在上述研究的基础上,从物种多样性和河流景观保护的角度,对库区鸟类的不同生境类型进行多要素综合分析,结果显示: 山地森林生境的物种多样性相对丰富,生态价值最高,而河滩和阶地疏林灌丛、竹林生境具备一定的景观特色,也有相当的生态价值  相似文献   

18.
The production of energy crops in Germany is a growing agronomic sector and is expected to occupy a substantial share of farmland in the near future. At the same time, there are concerns that energy crops might cause increased nitrogen pollution of soil water, surface water and groundwater. Therefore, the Federal State of Saxony, Germany, funded a study on potential effects of an intensified cultivation of energy crops. In frame of this study, we used the Web GIS-based model STOFFBILANZ to simulate N leaching from the rooting zone and N loads of surface water for a reference scenario and an energy crop scenario. For the reference scenario, we used data representing the crop cultivation for the year 2005 at municipality level. We found that the total loads for N leaching from the rooting zone of cropland are highest for the loess region (8,067 t year?1), followed by mountainous region (6,797 t year?1) and lowland (5,443 t year?1). However, highest N fluxes in the leachate from rooting zones have been simulated for lowland (40.6 kg ha?1 year?1) and mountainous region (37.1 kg ha?1 year?1), while nitrate concentrations of leachate were highest for the lowland (101.8 mg l?1). In terms of diffuse N input into surface water, the mountainous region is the most important source area (total N load 6,380 t year?1, flux 34.6 kg ha?1 year?1). Retention by in-stream processes accounts for 15 % (3,784 t year?1) of the total N load leaving the study area (25,136 t year?1). In the 2020 energy crop scenario, shares of rape and silage maize (id., ensiled corn) were limited for each municipality to a maximum of 25 and 33 %, respectively. The conversion of grasslands to crop farming was not allowed. Under these conditions, we found slight to substantial reductions of nitrogen loads for leachate from the rooting zone and for surface waters. The simulated reduction depends strongly on local conditions. Only small reductions (ca. 4–8 %) were found for the lowlands and mountainous regions of Saxony, while reductions for the loess region were substantial (ca. 22 %). A major outcome of our study is that the cultivation of energy crops might reduce N loss if certain preconditions are assumed, for example, without conversion of grasslands to crop farming. However, effects might vary widely depending on local conditions.  相似文献   

19.
目前为止缺少对鄱阳湖全湖冬候鸟的种群动态和群落方面的研究分析,拟通过对鄱阳湖冬候鸟群落多样性和种群动态的分析,为该地区冬候鸟及其栖息地保护提出建设性建议。2010~2012年冬季,通过采用直接计数法和样线法调查鄱阳湖湿地冬季碟形湖内的越冬鸟类群落结构。总共记录到越冬鸟类88种,另有29种属于文献报道但本次调查中未发现的种类。总共117种鸟类分别属于目、鹈形目、鹳形目、雁形目、鹤形目、鸻行目和佛法僧目。在鄱阳湖,种类和数量分布最多的是冬候鸟,达到78种。小天鹅、鸿雁、豆雁、白额雁、绿翅鸭和斑嘴鸭是鄱阳湖湿地越冬鸟类中的绝对优势种,鸟类个体数量最多的冬季蝶形湖泊主要包括鄱阳湖自然保护区的蚌湖、大湖池、沙湖和大汊湖,都昌县的黄金嘴,南矶山湿地自然保护区的白沙湖,余干县的林充湖和南湖,以及鄱阳县的珠湖。各种越冬鸟类在鄱阳湖湿地的种群数量分布差异主要是与各碟形湖水位的高低和食物的分布密切相关。只有在冬季开始后,使碟形湖洼地的水位逐渐降低,越冬鸟类才能够更有效的利用湖泊中的食物  相似文献   

20.
In the mountain forests of the Kahuzi-Biega National Park (KBNP), in the Democratic Republic of Congo, where Sericostachys scandens, a woody climbing plant in the Amaranthaceae family, is expanding, trees appear to be negatively affected by this liana. In order to contribute to the understanding of the links between the expansion of the liana and the decline of its hosts, we compared the density and the species richness of the trees of dbh (diameter at breast height) ≥5 cm from the plots invaded by S. scandens with those from parcels that are still free from the invasion. The results of the paired unilateral t test applied to the overall sample showed that the tree density is very low in the plots dominated by the liana (p < 0.01), but that species richness is not affected (p > 0.05). In the class with diameter [10–30 cm], the lowest density of trees corresponds to the plots colonized by S. scandens, compared to the places where the liana is not abundant (p < 0.01). Further, the density of trees is significantly lower (p < 0.05) in the classes with diameters [5–10 cm] and ≥30 cm, in plots dominated by S. scandens. In conclusion, the emergence of the liana S. scandens has a negative effect on the density of the trees in the mountain forest of the KBNP.  相似文献   

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