Search results for "SPECIES RICHNESS"

Biogeographical comparison of winter bird assemblages in urban environments in Finland

1996

We studied biogeographical variation of urban bird assemblages in Finland. Winter birds were censused by single-visit study plot method from thirty-one centres of villages or towns along 950 km latitudinal extent. A total twenty-eight bird species was observed and the average density was 61.2 ind./10 ha. The number of dominant species in study areas varied between two and seven and their proportion of the whole assemblage was over 70%. Species richness, but not the density of birds, decreased northwards in pooled data. Higher species richness in south than in north was mainly due to the higher amount of delayed migratory birds (e.g. waterbirds, finches) and southerly distributed bird specie…

Interspecific-Competition Strongly Constrains Species-Richness and Species-Abundance Evenness in a Tropical Marine Molluscan Community Inhabiting Cau…

2021

Increasing species-richness at the local scale (within species communities) is accommodated, first, by the diversification of the niches respectively associated to species. Yet, in case of excessive supply in colonizing species issued from the regional pool, the corresponding increase in the number of solicited niches may lead to some “niche-overcrowding” resulting in significant niche-overlaps. Then, second, strong interspecific competition for shared resource can arise, triggered by the density in individuals among those species co-occurring at niche-overlaps. Accordingly, the accommodation of species-richness within a local community involves a balance between (i) the positive contributi…

Heterogenic aquatic vegetation promotes abundance and species richness of Odonata (Insecta) in constructed agricultural wetlands

2019

Environmental and spatial correlates of community composition, richness and status of boreal lake macrophytes

2013

Abstract We assessed the relative roles of natural covariates, human disturbance (water quality and catchment land use) together with geography in driving variation in aquatic macrophyte community composition, richness and status among 101 lakes in southern and central Finland. In addition to all species together, we studied different growth forms (i.e. emergent and submerged macrophytes and aquatic bryophytes) separately. Partial redundancy analysis (taxonomic composition) and partial least-squares regression (species richness and status index) were employed to display the share of variability in macrophyte assemblages that was attributable to the environmental factors (both natural and hu…

Distribution patterns, ecological characteristic and conservation status of endemic plants of Tadzhikistan – A global hotspot of diversity

2011

Abstract Based on literature data and own fieldwork in Tadzhikistan (Middle Asia), the taxonomic structure, distribution, habitat preferences as well as conservation state of a group of 1486 species of vascular plants of endemic and sub-endemic character are presented. In addition to verifying the number of endemics, the present study has shown that Tadzhik endemics are the most numerous in the northwest of the country, in the Gissar-Darvasian and Zeravshan regions. An analysis of average richness of endemics per surface unit has revealed that Gissar-Darvasian F is the richest area. An assessment of the taxonomic similarity of geobotanical regions based on endemic species composition has sh…

Biotic homogenisation in bird communities leads to large-scale changes in species associations

2020

AbstractAimThe impact of global change on biodiversity is commonly assessed in terms of changes in species distributions, community richness and community composition. Whether and how much associations between species, i.e. the degree of correlation in their spatial co-occurrence, are also changing is much less documented and mostly limited to local studies of ecological networks. In this study, we quantify changes in large-scale patterns of species associations in bird communities in relation to changes in species composition.LocationFrance.Time period2001-2017.Major taxa studiedCommon breeding birds.MethodsWe use network approaches to build three community-aggregated indices reflecting co…

Energy and speleogenesis: Key determinants of terrestrial species richness in caves

2017

Abstract The aim of this study was to unravel the relative role played by speleogenesis (i.e., the process in which a cave is formed), landscape‐scale variables, and geophysical factors in the determination of species richness in caves. Biological inventories from 21 caves located in the southeastern Iberian Peninsula along with partial least square (PLS) regression analysis were used to assess the relative importance of the different explanatory variables. The caves were grouped according to the similarity in their species composition; the effect that spatial distance could have on similarity was also studied using correlation between matrices. The energy and speleogenesis of caves account…

The toughest animals of the Earth versus global warming: Effects of long-term experimental warming on tardigrade community structure of a temperate d…

2021

Abstract Understanding how different taxa respond to global warming is essential for predicting future changes and elaborating strategies to buffer them. Tardigrades are well known for their ability to survive environmental stressors, such as drying and freezing, by undergoing cryptobiosis and rapidly recovering their metabolic function after stressors cease. Determining the extent to which animals that undergo cryptobiosis are affected by environmental warming will help to understand the real magnitude climate change will have on these organisms. Here, we report on the responses of tardigrades within a five‐year‐long, field‐based artificial warming experiment, which consisted of 12 open‐to…

Polypore communities in broadleaved boreal forests

2012

The cover and extent of boreal broadleaved forests have been decreasing due to modern forest management practices and fire suppression. As decomposers of woody material, polypores are ecologically important ecosystem engineers. The ecology and conservation biology of polypores have been studied intensively in boreal coniferous forests. However, only a few studies have focused on the species living on broadleaved trees. To increase knowledge on this species group we conducted polypore surveys in 27 broadleaved forests and 303 forest compartments (539 ha) on the southern boreal zone in Finland and measured dead wood and forest characteristics. We detected altogether 98 polypore species, of wh…

Species richness of polypores can be increased by supplementing dead wood resource into a boreal forest landscape

2019

1. To prevent local species extinction and to counteract population declines, we must ensure species have access to resources they require for life. This can be done through ecological restoration where previously depleted resources are reintroduced. If the restoration is conducted as a one-off action in a large area, it resembles a natural resource pulse, which should lead to increased abundance of individuals, accompanied possibly by increased species richness. Species–energy relationship and underlying theory enable predictions about how different features of resource pulses affect species richness. 2. We conducted a large-scale, controlled, randomized and replicated field experiment to …