首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 514 毫秒
1.
Riparian zones are a characteristic component of many landscapes throughout the world and increasingly are recognised as key areas for biodiversity conservation. Their importance for bird communities has been well recognised in semi-arid environments and in modified landscapes where there is a marked contrast between riparian and adjacent upslope vegetation. The value of riparian zones in largely intact landscapes with continuous vegetation cover is less well understood. In this study, birds were surveyed at 30 pairs of riparian and adjacent non-riparian sites in extensive mesic forests of the Victorian Highlands, Australia. Riparian sites were floristically distinct from non-riparian sites and had a more complex vegetation structure, including a mid-storey tree layer mostly absent from non-riparian sites. Bird assemblages at riparian sites had significantly greater richness, abundance and diversity of species than was recorded at adjacent non-riparian sites. Species composition also differed significantly between these habitat types. Compositional differences in assemblages were due to a suite of distinctive species in each habitat and to significant contrasts in the densities of species that occurred in both habitat types. Many species (36%) attained a significantly greater abundance in riparian habitats. The distinctiveness and richness of the riparian avifauna contribute to the diversity of continuous forest landscapes. The spatial patterning of the avifauna, the occurrence of complementary assemblages, the presence of rare species and the potential for riparian habitats to serve as refuges, all point to the value of riparian zones and highlight the importance of landscape-level planning and management for avifaunal conservation.  相似文献   

2.
北江干流河岸带不同植被类型植物物种多样性分析   总被引:1,自引:0,他引:1  
以北江干流河岸带4种典型植被类型(竹林、草地、混交林和桉树林)为研究对象,采用样方法调查分析其群落特征和物种多样性,运用冗余分析(RDA)探讨北江河岸带植物物种多样性与环境因子之间的关系。结果表明:北江河岸带植物物种受热带季风气候影响,植物种类繁多,共调查到59科116属136种植物,群落科属组成分散;4种植被类型的物种丰富度、Shannon-Wiener多样性和均匀度指数变化规律一致,均以混交林最高,竹林次之,桉树林最低,但各植被类型间差异并不显著,说明北江河岸带不同植被类型维持物种多样性的异质性较小,其作用更多体现在为不同物种提供栖息地;RDA结果显示,植物物种丰富度、均匀度和多样性指数与乔木层高度、草本层盖度和海拔均呈正相关,而与至河流距离和土壤含水量呈负相关,在选取的7个环境因子中,海拔对北江河岸带植物物种多样性的影响最大,土壤含水量影响次之,至河流距离影响最小。  相似文献   

3.
Habitat patches along river systems are often highly isolated and characterised by a high degree of heterogeneity at different spatio-temporal scales. The connectivity between river bank arthropod populations directly adjoining the river channel is often greatly disturbed due to river regulation. While flight-active arthropods easily disperse upstream, less mobile species are expected to show predominant downstream dispersal unless specific upward movements are prevalent. In linear river ecosystems, downstream drift of organisms may therefore prevail with subsequently strong asymmetrical gene flow. We analysed patterns of genetic variation within and among nine spatially structured populations of the highly stenotopic riparian wolf spider (Lycosidae) Pardosa agricola (Thorell, 1856) using Amplified Fragment Length Polymorphism (AFLP) markers. No evidence was found for downstream accumulation of genetic diversity. The high genetic diversity is hypothesised to be the result of historical drift processes. Nearby populations on the same river shore were less genetically differentiated compared with populations further away and/or on the opposite shore. This indicates that short-distance dispersal still occurs on river banks during low water flow levels, but at the same time that the river channel constitutes a physical barrier for species exchange between opposite shores. The rehabilitation of the riparian corridor will increase the amount of suitable habitat, the functional connectivity during periods of low flow-discharges and eventually riparian spider population persistence.  相似文献   

4.
The characterisation of geomorphological, hydrological and ecological properties of river systems represents a popular and important research direction in fluvial studies, particularly with regards to contemporary international environmental legislation. Recent research has also drawn attention to the unique ecological value and high level of environmental threat associated with groundwater-fed catchments, emphasising the importance of underlying rock type in the development of river typologies. A standardised field method for assessing physical river habitat quality known as River Habitat Survey (RHS) has been developed in the UK and provides an extensive data set of surveyed river reaches. This paper uses information from the RHS database to explore the influence of rock type on reach-scale sedimentological and vegetation characteristics. A range of reach-scale indices are derived from the RHS database for analysis, supported by landscape variables which provide detail on the catchment context. River reaches were then classified into broad lithological groups which reveal statistically significant differences along two key gradients in environmental conditions: an energy gradient associated with stream power and sediment calibre which is inversely related to in-channel vegetation roughness, and a riparian vegetation gradient that also reflects the inverse relationship between instream and riparian vegetation cover. The results emphasise the differences in reach-scale geomorphological and ecological structure between groundwater-fed and surface water-fed catchments, supporting the inclusion of underlying reach lithology in the development of river typologies.  相似文献   

5.
Invasive plants are, simply by occupying a large amount of space in invaded habitats, expected to impose a significant impact on the native vegetation and their associated food webs. However, little is known about the impact of invasive plants both on native vegetation and on different invertebrate feeding guilds at the habitat level. Yet, studies addressing multiple trophic levels, e.g. plant species, herbivores, predators and detrivores, are likely to yield additional insight into how and under which conditions invasive weeds alter ecosystem structures and processes. We set out to assess whether plant species richness and invertebrate assemblages in European riparian habitats invaded by exotic knotweeds (Fallopia spp.) differed from those found in native grassland- or bush-dominated riparian habitats, which are both potentially threatened by knotweed invasion. Our findings suggest that riparian habitats invaded by knotweeds support lower numbers of plant species and lower overall abundance and morphospecies richness of invertebrates, compared to native grassland-dominated and bush-dominated habitats. Total invertebrate abundance and morphospecies richness in Fallopia-invaded riparian habitats were correlated with native plant species richness, suggesting that there is a link between the replacement of native plant species by exotic Fallopia species and the reduction in overall invertebrate abundance and morphospecies richness. Moreover, biomass of invertebrates sampled in grassland and bush-dominated habitats was almost twice as high as that in Fallopia-invaded habitats. Large-scale invasion by exotic Fallopia species is therefore likely to seriously affect biodiversity and reduce the quality of riparian ecosystems for amphibians, reptiles, birds and mammals whose diets are largely composed of arthropods.  相似文献   

6.
Riparian zones are important for the many ecosystem services they supply. In settled areas, the vegetation of such zones is shaped by human land-use; this often creates conditions under which alien plant species thrive. Alien plants have been shown to induce large-scale changes in riparian habitats, and they pose a major threat to the continued provision of key ecosystem services. We used direct gradient analysis to assess correlations between land-use and the composition of vegetation along a riparian river corridor in the highly transformed landscape surrounding Stellenbosch in South Africa’s Western Cape Province. Vegetation plots were sampled along the entire length of the river from headwaters to estuary (ca. 40 km). Plant community composition was analyzed in relation to land-use data collected in the field, and additional land-use variables computed from digital land-cover data. Patterns of plant community structure were found to be directly related to land-use, with measures of cover, richness, and diversity differing significantly among land-use types. Portions of the riparian zone adjacent to agricultural land had the greatest level of alien plant cover, while areas bordered by urban land maintained the highest alien species richness. Areas adjacent to grazing and natural lands showed intermediate and low levels of invasion, respectively. Several native species were found to persist in areas with high abundance and diversity of invasive alien plants, suggesting that they will be valuable focal species for future restoration attempts. Due to the level of human-mediated change in many areas of the riparian zone, restoration to historic conditions over most of the river is not considered feasible. These areas should be recognized as examples of novel ecosystems, and management efforts should focus on restoring or creating desirable ecosystem functions, rather than on achieving assemblages comprising only native species.  相似文献   

7.
Riparian forests in the Sahel zone of Africa are of considerable importance for human resource use and for their ecological and conservation value. Typical riparian forest tree species are dependent on river flows and a shallow aquifer, and the community and population structure of riparian forests is related to spatial and temporal patterns of flooding at a site. Therefore, changes in hydrology caused by dams cause changes in floodplain vegetation. This paper explores the spatio-temporal complexity of these changes through an analysis of regeneration in a Nigerian floodplain affected by dams built in the early 1970s. The study shows that under certain conditions, and given sufficient time, riparian forests may be changing to forest types more characteristic of unflooded, upland areas. The results of the study have implications for the way in which the sustainability of developments downstream of large dams are analysed, suggesting that assessment of impacts must take place within temporal parameters relevant to ecological processes and at spatial scales that encompass spatial variation in floodplain ecosystems.  相似文献   

8.
Using pitfall traps, we evaluated the spatial and seasonal variance in arthropod abundance, species richness, higher taxonomic and species composition, and guild structure within the ground litter of seven sites in a relatively undisturbed rainforest in Panama. We examined each of these five arthropod-dependent variables at two spatial scales (a few meters and a few hundred meters) and one temporal scale (a few months encompassing dry and wet periods), against environmental variables including local illumination and plant composition. Trap catches (9458 arthropods collected during 630 trap-days) were high compared to similar studies in temperate forests. We observed spatial and seasonal differences in abundance, species richness and composition of litter-dwelling arthropods. Often these differences appeared weakly related to geographical coordinates. They reflected forest structure (basal area) and local plant composition, and less so illumination patterns or seasonal changes in radiation. Seasonal variance was high and may relate to surrogate variables accounting for seasonal changes in litter moisture. The composition of higher taxa and species was often predicted by different independent variables at the three scales studied. Guild structure was difficult to predict. Our study lead us to expect that litter-dwelling arthropods may be more seasonal than soil microarthropods in tropical rainforests; and that tropical litter-dwelling arthropods may also be more spatially variable and seasonal than their temperate counterparts. We also recommend that conservation studies using pitfall traps in tropical rainforests should focus on: (1) taxonomic resolution to understand the functional complexity of soil organisms; (2) spatial replication to address subtle changes in plant composition throughout the study area; and (3) seasonal replicates to be commensurate with seasonal changes in litter moisture.  相似文献   

9.
Can enhancement of garden habitat for native birds have conservation benefits, or are garden bird assemblages determined by landscape and environmental characteristics? The relative roles of vegetation structure, floristics and other garden attributes, and environmental and landscape controls, on the abundance and richness of bird species in 214 back or front gardens in 10 suburbs of Hobart, Tasmania, Australia, are addressed to answer this question. Birds were counted in each garden and the resources they utilized noted. Vascular plant species and other attributes of the garden were noted, along with rainfall, altitude, distance from natural vegetation, distance from the city and garden size. Garden floristics and bird assemblages were ordinated, and garden groups characterized by particular assemblages of birds identified. General linear modelling was used to determine the combinations of independent variables that best predicted the richness of birds and the abundance of individual bird species and groups of species. The models for bird richness, bird species and groups of bird species were highly individualistic. Although native birds showed a preference for native plants, they also utilized many exotic plants. Exotic birds largely utilized exotic plants. Variation in garden characteristics does substantially affect the nature of garden bird assemblages in Hobart, with weaker environmental and landscape influences. The fact that gardens can be designed and managed to favour particular species and species assemblages gives gardeners a potentially substantial role in the conservation of urban native avifauna.  相似文献   

10.
通过对潮白河流域22个断面的调查分析,根据潮白河河道断面形态、河岸土地利用类型及岸坡坡度等条件,将潮白河河道断面划分为:U形+缓坡、U形+陡坡、U形+陡坎、V形+陡坡和漫滩型,并对潮白河河岸植被缓冲带完整性进行了评价。结果显示,潮河河段内植被缓冲带完整性较差,以次不完整状况为主;白河河段内河岸植被缓冲带状况相对较好,大部分调查断面内植被缓冲带为基本完整及完整状态。针对潮白河河岸植被缓冲带存在的问题,提出了潮白河流域不同河岸带断面类型植被缓冲带的恢复对策。  相似文献   

11.
While urban areas are increasingly recognized as having potential value for biodiversity conservation, the relationship between biodiversity and the structure and configuration of the urban landscape is poorly understood. In this study we surveyed birds in 39 remnant patches of native vegetation of various sizes (range 1-107 ha) embedded in the suburban matrix in Melbourne, Australia. The total richness of species within remnants was strongly associated with the size of remnants. Remnant-reliant species displayed a much stronger response to remnant area than matrix-tolerant species indicating the importance of large remnants in maintaining representative bird assemblages. Large remnants are important for other ecological groups of species including migratory species, ground foraging birds and canopy foraging birds. Other landscape (e.g. amount of riparian vegetation) and structural components (e.g. shrub cover) of remnants have a lesser role in determining the richness of individual remnants. This research provides conservation managers and planners with a hierarchical process to reserve design and management in order to conserve the highest richness of native species within urban areas. First of all, conservation efforts should preferentially focus on the retention of larger remnants of native vegetation. Second, where possible, riparian vegetation should be included within reserves or, where it is already present, should be carefully managed to ensure its integrity. Third, efforts should be focused at maintaining appropriate habitat and vegetation structure and complexity.  相似文献   

12.
Understanding how urban land-use structure contributes to the abundance and diversity of riparian woody species can inform management and conservation efforts. Yet, previous studies have focused on broad-scale (e.g., urban to exurban) land-use types and have not examined more local-scale changes in land use (e.g., the variation within “urban”), which could be important in urban areas. In this paper we examine how local-scale characteristics or fine-scale urban heterogeneity affect(s) the diversity, composition, and structure of temperate woody riparian vegetation communities in the highly urbanized area of Cincinnati, Ohio, USA. We use an information-theoretic approach to compare vegetation models and canonical correspondence analyses to compare species responses to urban variables. We found that urban riparian areas can harbor a high diversity of native canopy and shrub species (38 and 41, respectively); however, native and exotic woody plant species responded differently to urbanization. Exotic canopy species increased with the level of urbanization while native canopy and understory species declined. Understory species diversity displayed a greater response to urbanization than did canopy diversity, suggesting temporal lags in canopy response to disturbances associated with present and recent land-use changes. Certain native and exotic woody species represent ecological indicators of different levels of urbanization. Native species characteristic of pre-European settlement conditions were restricted to the wide riparian forests with little urban encroachment. Several native early-successional species appear tolerant to urbanization. Two exotic species, the tree Ailanthus altissima and the shrub Lonicera maackii, were the most abundant and ubiquitous woody species and appear to exploit urban disturbances. These exotic species invasions have the potential to modify forest composition and ecological function of urban riparian systems. In addition, altered hydrology may be a contributing factor as canopy and understory stem density of high-moisture-requiring species decreased with an increase in impervious surface and grass cover and with proximity to roads and railroads. In the face of urbanization, maintaining wide riparian forests and limiting building, road and railroad development within these areas may help reduce the invasion of exotic species and benefit hydrological function in temperate riparian areas.  相似文献   

13.
An important challenge for riparian management is to determine the extent to which landscape context influences the faunal assemblages of riparian habitats. We examined this challenge in the variegated landscapes of southeastern Queensland, Australia where riparian vegetation is surrounded by both extensive grazing and intensive cropping. We investigated whether riparian habitats adjacent to different landuses support similar bird assemblages. Three types of riparian habitat condition were sampled (uncleared ungrazed; uncleared grazed; cleared grazed) in four different land-use contexts (ungrazed woodland; grazed woodland; native pasture; crop) although only six of the 12 possible treatment combinations were available. Eighty percent of bird species responded significantly to changes in both riparian habitat condition and landscape context, while fewer than 50% of species were significantly influenced by landscape context alone. The influence of landscape context on the bird assemblage increased as the surrounding land use became more intensive (e.g., woodland to native pasture to crop). Riparian zones have been shown to have consistently high biodiversity values relative to their extent. These findings suggest it is not enough to conserve riparian habitats alone, conservation and restoration plans must also take into consideration landscape context, particularly when that context is intensively used land.  相似文献   

14.
阿克苏河中游荒漠河岸林物种多样性与群落稳定性   总被引:1,自引:0,他引:1  
[目的]探究阿克苏河中游荒漠河岸林群落的物种多样性、稳定性及其之间的关系,在物种水平上对当前群落植物组成的复杂性及部分环境因子的关系进行探讨,为荒漠河岸生态系统的恢复提供理论依据。[方法]在样方调查的基础上,运用格局分析法,物种多样性指数与均匀度指数,聚类分析以及M.Godron稳定性测度对植物群落进行综合评估。[结果]阿克苏河中游荒漠河岸林主要的植物种群均呈现聚集分布的格局,群落结构简单,具有单寡种优势群落的特征。不同地段的植物群落物种分布较为均匀,但丰富度与多样性的高低略有起伏;荒漠河岸林植物群落根据环境因子的聚类结果可分为6个群丛,其中有3个群丛的物种多样性较低。物种组成与土壤水分的关联较为密切;当前植物群落尚未达到稳定阶段,物种多样性与群落稳定性者之间并无任何直接联系。[结论]单一以河水漫灌的方式促进该地区植物多样性的恢复具有一定的困难,考虑以胡杨、柽柳为主要格局,种植深根系的乔灌木以营造局部地区小气候,间接优化生境的方式对荒漠河岸林的植被恢复更为有利。  相似文献   

15.
Patterns of biodiversity are influenced by habitat features at multiple spatial scales, yet few studies have used a multi-scale approach to examine ground-dwelling beetle diversity patterns. We trapped and quantified ground-dwelling beetle assemblages at two spatial scales: (1) microhabitat elements, represented by open ground, ground under trees and ground next to logs and (2) macrohabitat, represented by three vegetation types in a box-gum grassy woodland in south-eastern Australia. Species richness and evenness was highest at samples from under trees and lowest at samples in the open. At the macrohabitat scale, species richness and evenness did not differ among vegetation types. Assemblage composition was significantly different between trees, logs and open elements. Assemblage composition was different only between vegetation types with contrasting high and low shrub cover. Estimation of true species richness indicated assemblages at logs may have a higher number of species compared to trees and open elements, and implied greater spatial heterogeneity in assemblages at logs. Significant spatial autocorrelation in beetle assemblages was detected for logs at up to 400 m, but not for ground under trees or in the open. In agreement with previous studies, a mix of vegetation types at the macrohabitat scale is important for beetle conservation. Assemblage composition, however, appears to be more closely linked with habitat elements at the microhabitat scale, where logs support a high diversity of beetle species. This strongly supports the idea that restoring logs to box-gum grassy woodlands would be useful for increasing beetle species richness and assemblage heterogeneity.  相似文献   

16.
基于巴江河和石林公园的协同保护利用,采用遥感和地理信息系统技术分析了2014年、1992年、1984年云南石林县巴江河岸1 000 m范围的影像或土地利用/土地覆被变化。30年来,巴江河岸土地利用/土地覆被结构显著变化,耕地面积保持56%以上,林地面积减少了54%、草地面积减少了95%。但住宅仓储工矿用地增加106倍,园地面积增加7.6倍、石砾地裸地面积增加1.7倍,土地利用结构严重碎化。这种变化的直接动力是居民用地和仓储用地等向河岸带集中。石林公园列为世界地质公园/世界自然遗产地提升了巴江河作为其缓冲区河流的地位,但并没有带来巴江河岸土地利用结构的优化。作为石林世界地质公园组成部分和石林县重要的景观河保育,以2014年土地利用结构为基础,应调整河岸土地利用结构,河岸带林地可增加77%,分别来自减少的57%裸地石漠化地,10%的耕地调整以及住宅和园地增加的10%绿化。由此可知,巴江河上游地段土地利用结构应优先调整。  相似文献   

17.
子牙河水系滨岸带植物群落结构及其与环境的关系   总被引:1,自引:0,他引:1  
梁雪  何萍  任颖  钱金平  戴霞 《水土保持通报》2017,37(1):292-296,303
[目的]以海河流域子牙河水系河流滨岸带植物为对象,研究影响植物群落结构和分布格局的主要环境因子,为相关研究提供依据。[方法]2013年6月,在子牙河水系干支流设置了94个滨岸带样地,调查植被结构和海拔、护岸类型、堤外土地利用类型等6个环境因子。[结果]子牙河水系滨岸带植物共249种,分属于51科,166属。山区河段滨岸带有199种植物,分属于43科,135属,优势物种有芦苇(Phragmites australis)、蒙古蒿(Artemisia mongolica)、荆条(Vitex negundo)、黄花蒿(Artemisia annua)等;平原河段滨岸带有36种植物,分属于22科35属,优势物种主要有芦苇(P.australis)、反枝苋(Amaranthus retroflexus)等,山区植物丰富度明显高于平原区。[结论]海拔高度和堤外土地利用类型与植物群落结构显著相关。水热条件和人类活动压力是影响植被构成的主要成因。  相似文献   

18.
河岸带滩地植被是维持河流系统健康的重要屏障.以浙江省龙游县灵山港边滩为研究对象,运用聚类分析和RDA约束性冗余分析等方法,分析中小河流边滩植被分布特征及其主要驱动因子,并建立各驱动因子对植被分布的响应关系.结果表明:灵山港滩地植被种类丰富多样,共有62种植被(被子植物61种,蕨类植物1种),其植被群落结构包括9种类型;滩地相对水面高差因子、滩地形态系数和水文特性是植被分布空间差异性的主要影响因子,各因子贡献率分别为37.50%、27.50%和16.82%,各因子对植被分布的驱动响应机制不同.其中:在滩地相对水平面高差因子作用下,植被从滩地外缘到滩地内部,耐水性由强到弱,丰富性由低到高,生物量由小到大;当边缘线发育系数SDI值处于2.0~4.0之间,且滩地狭长指数Pe/Pa值在0.12 ~0.3之间时,至少有60%的保证率使得滩地植被多样性维持在1.03 ~1.96的高水平;水文特性能够影响植被的形态特征和滩地的生境条件,水文作用下,滩地外围砂粒质量分数随着离水距离增大而逐渐减小,植被类型也会随着离水距离的增加,从喜湿耐冲型到中生型过渡.掌握滩地植被的分布特征及其影响因子,以期为河道生态修复,提供理论依据.  相似文献   

19.
Human alterations to aquatic ecosystems are leading to decreases in species richness and biomass and subsequent changes in community composition. In many cases species losses are non-random: species with traits poorly adapted to the new environmental conditions suffer greater losses. We used long-term data from a southern US river, the Kiamichi River, to evaluate the synergistic effects of regional climate patterns coupled with water management practices on freshwater mussel communities. Mussel communities in the river changed over the 15 year period of this study, with overall densities and species richness decreasing and community structure shifting from assemblages dominated by thermally sensitive to thermally tolerant species. These changes corresponded with a period of very low flows in the river caused by a combination of climate patterns (a regional drought) and local water management practices (decreased reservoir releases). These low flows, coupled with high summer air temperatures, changed the river in many locations from a continuously flowing river to a series of shallow, isolated pools where water temperatures sometimes exceeded 40 °C. Altered conditions led to higher mortality rates of thermally sensitive compared to tolerant species. We predict future shifts in river ecosystem function as mussel communities change in response to changing climate and water management.  相似文献   

20.
Quantifying plant biomass and related processes such as element allocation is a major challenge at the scale of entire riparian zones. We applied sub-decimetre-resolution (5 cm) remote sensing using an unmanned aircraft system (UAS) in combination with field sampling to quantify riparian vegetation biomass at three locations (320-m river stretches) along a mining-impacted boreal river and estimated the amounts of Cd, Cu, and Zn stored in the dominant species. A species-level vegetation map was derived from visual interpretation of aerial images acquired using the UAS and field sampling to determine species composition and cover. Herbaceous and shrub biomass and metal contents were assessed by combining the vegetation maps with field sampling results. Riparian zone productivity decreased from 9.5 to 5.4 t ha?1 with increasing distance from the source of contamination, and the total amount of vegetation-bound Cd and Zn decreased from 24 to 0.4 and 3,488 to 211 g, respectively. Most Cu was stored at the central location. Biomass and metal contents indicated large variation between species. Salix spp. comprised only 17 % of the total dominant-species biomass but contained 95 % of all Cd and 65 % of all Zn. In contrast, Carex rostrata/vesicaria comprised 64 % of the total dominant-species biomass and contained 63 % of all Cu and 25 % of all Zn. Our study demonstrates the applicability of UAS for monitoring entire riparian zones. The method offers great potential for accurately assessing nutrient and trace element cycling in the riparian zone and for planning potential phytoremediation measures in polluted areas.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号