Search results for "Richness"
showing 10 items of 447 documents
The preferences of saproxylic beetle species for different dead wood types created in forest restoration treatments
2010
Restoration by imitating natural disturbances is widely practised in boreal forests to increase the availability of habitats for specialized species. We studied the abundance and species richness of saproxylic beetles on different types of created dead wood during 2 years after restoration. The study was conducted on areas of a large-scale experiment in which Norway spruce ( Picea abies (L.) Karst.) forests were restored by controlled burning and partial harvesting with down wood retention in southern Finland. More beetle species were attracted to spruces than to birches and more species were attracted to burnt trees than to unburnt trees killed by girdling. Birch-living species consistent…
Species richness of migratory birds is influenced by global climate change
2007
Aim Global climate change is increasingly influencing ecosystems. Long-term effects on the species richness and composition of ecological communities have been predicted using modelling approaches but, so far, hardly demonstrated in the field. Here, we test whether changes in the composition of bird communities have been influenced by recent climate change. Location Europe. Methods We focus on the proportion of migratory and resident bird species because these groups are expected to respond differently to climatic change. We used the spatial relationship between climatic factors and bird communities in Europe to predict changes in 21 European bird communities under recent climate change.…
The global distribution of frugivory in birds
2009
Aim To examine patterns of avian frugivory across clades, geography and environments. Location Global, including all six major biogeographical realms (Afrotropics, Australasia, Indo-Malaya, Nearctic, Neotropics and Palaearctic). Methods First, we examine the taxonomic distribution of avian frugivory within orders and families. Second we evaluate, with traditional and spatial regression approaches, the geographical patterns of frugivore species richness and proportion. Third, we test the potential of contemporary climate (water–energy, productivity, seasonality), habitat heterogeneity (topography, habitat diversity) and biogeographical history (captured by realm membership) to explain geo…
The effects of small-scale disturbance on forest birds: a meta-analysis
2010
Small-scale disturbance is a significant process in all major forest biomes. Some silvicultural practices, particularly group selection harvesting, intend to emulate natural small-scale disturbance by harvesting small clearcuts in the continuous forest. We conducted a meta-analysis on the effects of small-scale harvesting on North American breeding forest birds. We extracted species richness and relative abundance of several functional bird groups and guilds from published studies and compared them between gap-dominated and unlogged forest as a function of forest type and the size and age of the gap. The abundance of many bird groups was higher in the gap-dominated than in the continuous f…
Disentangling the effects of area, energy and habitat heterogeneity on boreal forest bird species richness in protected areas
2009
Aim One of the few general laws in ecology is that species richness is a positive function of area. However, it has been proposed that area would merely be a proxy for energy. Additionally, habitat heterogeneity has been found to be an important factor determining species richness. Yet the relative importance of those relationships is little known, and it is still unclear how they are brought about. We aimed to dissect which factors drive the species richness of boreal forest birds, and to identify the most probable mechanisms. Location Forested protected areas in Finland. Methods Using bird line census data collected in 104 protected areas, we ran simultaneous autoregressive models to e…
Species Diversity and Distribution of Mammals in Riga
2003
The aim of this study was to investigate the species diversity and distribution of mammals in the territory of Riga. Our specific aims were to create a zonal division of Riga, and to classify habitats in unbuilt areas of the city. Riga was divided into four zones according to historical, economic and geographical features. Criteria of habitat classification were as follows: the size of a territory, anthropogenic load, soil and vegetation types and age. Sixteen types of habitats were distinguished. In the period 1999–2002, 27 mammal species of six orders were registered in the investigated territory of Riga. The number of animals and the diversity of species increased towards the periphery o…
Life-form adaptations and substrate availability explain a 100-year post-grazing succession of bryophyte species in the Moricsala Strict Nature Reser…
2013
Bryophyte species composition, richness and life-form distributions were studied in a succession after termination of land-use as meadows and pasture in the Moricsala Strict Nature Reserve. Detailed lists of bryophyte species in various vegetation types, which were produced in the early 1900s by Karl Reinhold Kupffer, were compared with those prepared from 2006 to 2010 to determine changes in species composition. Colonisations and extinctions of bryophyte species and life forms could be explained by increases in available substrates (living trees, dead wood, ground layer disturbance patches), and increasingly shaded conditions. In each forest type, the species diversity (alpha diversity) in…
Pesticide doses, landscape structure and their relative effects on farmland birds
2014
International audience; tAgricultural changes related to the intensification of farming practices and the simplification of land-scape elements often occur simultaneously. Their respective effects on biodiversity are thus difficult todisentangle and are poorly understood. This study assessed the relative contribution of each componentof agricultural intensification on taxonomic and functional bird communities.The bird communities studied were composed of 70 species, both farmland and non-farmland birds,found in 66 fields covering three main cereal departments of France. Herbicide dose was related to mea-surable negative effects on the Community Specialization Index (CSI). Overall, the propo…
Daurian pikas ( Ochotona daurica ) and grassland condition in eastern Mongolia
2003
Pikas ( Ochotona spp.) are burrowing herbivorous mammals believed to play a keystone role in determining the biodiversity of steppe ecosystems. Impacts of domestic livestock grazing on the distribution and abundance of the Daurian pika Ochotona daurica were investigated in eastern Mongolia where the species is widespread and abundant. Effects of pikas on plant species richness and vegetation coverage were examined at different distances from burrow systems. Daurian pikas were nearly absent from severely grazed study sites, and incidence of the species increased with decreasing grazing intensity. The number of occupied burrow systems and usage of burrows was higher in sites with lower grazin…
Is land-use change a cause of loss of pedodiversity? The case of the Mazzarrone study area, Sicily
2011
Anthropogenic soils created ex novo by land-us e change in large scale farming are, from a pedogenetic point of view, catastrophic events that bring the soils to time zero and change the natural pattern of the soilscape, remarkably, in some cases. The qu antitative aspects of pedodiversity of a soilsc ape in South-East Sicily, where some types of soils, in recent decades, have suffered a consistent reduction due to the transformations by large scale farming, are considered. The evolution of pedodiversity over a 53-year period (1955 to 2008 ) is examined using a dedicated statistical method and a space – time model based on Markov analysis and cellular autom ata in order to predict the evolu…