Search results for "boreal"

Metagenomic insights into strategies of aerobic and anaerobic carbon and nitrogen transformation in boreal lakes

2015

Thousands of net-heterotrophic and strongly stratifying lakes dominate the boreal landscape. Besides their central role as emitters of greenhouse gases, we have only recently begun to understand the microbial systems driving the metabolic processes and elemental cycles in these lakes. Using shotgun metagenomics, we show that the functional potential differs among lake types, with humic lakes being particularly enriched in carbon degradation genes. Most of the metabolic pathways exhibit oxygen- and temperature-dependent stratification over depth, coinciding with shifts in bacterial community composition, implying that stratification is a major factor controlling lake metabolism. In the botto…

Pool choice in a vertical landscape: Tadpole‐rearing site flexibility in phytotelm‐breeding frogs

2021

Abstract Many species of Neotropical frogs have evolved to deposit their tadpoles in small water bodies inside plant structures called phytotelmata. These pools are small enough to exclude large predators but have limited nutrients and high desiccation risk. Here, we explore phytotelm use by three common Neotropical species: Osteocephalus oophagus, an arboreal frog that periodically feeds eggs to its tadpoles; Dendrobates tinctorius, a tadpole‐transporting poison frog with cannibalistic tadpoles; and Allobates femoralis, a terrestrial tadpole‐transporting poison frog with omnivorous tadpoles. We found that D. tinctorius occupies pools across the chemical and vertical gradient, whereas A. fe…

Early Aptian corals from Peñascal (Bilbao, N Spain)

2020

From two horizons in the lower Aptian Peñascal limestone Formation south of Bilbao 22 coral species are reported. The corals belong to the scleractinian families Actinastraeidae, Eugyridae, Haplaraeidae, Latomeandridae, and Solenocoeniidae, and the octocorallian family Helioporidae. The stratigraphic distribution of the species lies between the Berriasian to Cenomanian, but most species have a distribution between the Barremian and Albian. The faunas show most palaeobiogeographical relationship to faunas from the Hauterivian to Albian of the European Boreal, the Western Atlantic and the Western Tethys.

Late Pleistocene to Early Holocene natural and human influenced sediment dynamics and soil formation in a 0-order catchment in SW-Germany (Palatinate…

2013

This paper presents the dynamics of sedimentation processes and soil development of a steeply sloping 0-order catchment in the sandy Lower Bunter of the south-western mid-range mountains in the Palatinate Forest (Germany) during the transition period from the Late Glacial to the Early Holocene. Field investigations, chemical, physical, micromorphological and anthracological analyses revealed a complex palaeosol-sediment sequence along the thalweg of a dry valley, where a significant amount of the sediment from the adjacent slopes had been captured. The deposition of aeolian sands in the lowermost sediment layer took place in the early Late Glacial. The subsequent sediments were deposited by…

Interactive effects of parasitism and predation on the behaviour of the amphipod Pallasea quadrispinosa

2006

Palaeoecological response to Greenlandian (Early Holocene) climatic changes: Insight from an abandoned-channel sequence of the Meuse River at Autreco…

2020

Abstract A Greenlandian (Early Holocene) palaeochannel of the Meuse River is described from Autrecourt-et-Pourron in the Ardennes region of northern France. During the Younger Dryas, fluvial deposits represent a high-energy, sinuous palaeochannel, but at the onset of the Holocene, progressive channel abandonment resulted in the establishment of a low-energy meandering river system. Well-dated studies using palynology, carpology, malacology and geomorphology reveal a Greenlandian succession of changes in fluvial dynamics and vegetation. Between 11,700 and 11,400 cal yr BP, warmer temperatures led to the development of a birch community (Betula sp.) within an open grassland, dominated by herb…

Stable carbon isotopic composition of peat columns, subsoil and vegetation on natural and forestry-drained boreal peatlands.

2018

We studied natural and forestry-drained peatlands to examine the effect of over 34 years lowered water table on the δ13C values of vegetation, bulk peat and subsoil. In the seven studied sites, δ13C in the basal peat layer was 1.1 and 1.2 ‰ lower than that of the middle-layer and surface layer, respectively. Furthermore, there was a positive correlation between the δ13C values of the basal and surface peat layers, possibly due to carbon (C) recycling within the peat column. In the same mire complex, natural fen peat δ13C values were lower than those of the nearby bog, possibly due to the dominance of vascular plants on fen and the generally larger share of recycled C in the fens than in the…

Reconstruction of palaeovegetation and sedimentation conditions in the area of ancient Lake Burtnieks, northern Latvia

2010

Palaeobotanical investigations were carried out with the aim of reconstructing the development of palaeovegetation and formation of sediments in the northeastern area of ancient Lake Burtnieks. Pollen and plant macroremain studies provide information on vegetation development in the surroundings of the lake, including Stone Age settlements of Braukšas I and Braukšas II. Results of the investigations indicate that the development of vegetation together with sedimentation conditions in the palaeolake have changed since the Younger Dryas until today. Vegetation composition varies in different parts of the ancient Lake Burtnieks area due to past changes in lake water level which reached differe…

The Spatial Distribution of Perch (Perca fluviatilis) Ectoparasites and the Effect of Chemical Water Quality Parameters on Ectoparasite Spatial Niche…

2018

Abstract Seasonal changes of abiotic factors and their influence on parasite occurrence have repeatedly been studied. Most of the studies have been conducted to evaluate the effect of water physicochemical parameters on changes in the intensity of infection, prevalence and component community of a number of parasite species. However, insufficient attention has been paid to the link between water quality parameters and spatial niche size of ectoparasites. The distribution of ectoparasite species on perch (Perca fluviatilis L.) was studied to establish whether seasonal changes of water quality parameters are associated with ectoparasite spatial niche size. The concentration of phosphates (PO4…

Nemoralisation of Pinus sylvestris and Picea abies Forest Stands in the Hemi-Boreal Zone: A Case Study from Latvia

2021

Abstract At the beginning of the 21st century, in extensively managed mature and over-mature conifer stands (Pinus sylvestris and Picea abies) in Latvia, establishment of native deciduous broad-leaved (Acer platanoides, Tilia cordata, Quercus robur and Ulmus laevis), as well as alien broad-leaved species (Acer pseudoplatanus and Tilia platyphyllos) has been observed. The establishment of deciduous broad-leaved species in coniferous stands is a process known as nemoralisation of coniferous stands, which is characterised by a large number of seedlings of broad-leaved species, young trees and the formation of a subcanopy layer in stands. Based on the age measurements of individuals of broad-le…