Search results for "Season"
showing 10 items of 1002 documents
Whole-lake experiments reveal the fate of terrestrial particulate organic carbon in benthic food webs of shallow lakes
2014
Lake ecosystems are strongly linked to their terrestrial surroundings by material and energy fluxes across ecosystem boundaries. However, the contribution of terrestrial particulate organic carbon (tPOC) from annual leaf fall to lake food webs has not yet been adequately traced and quantified. In this study, we conducted whole-lake experiments to trace artificially added tPOC through the food webs of two shallow lakes of similar eutrophic status, but featuring alternative stable regimes (macrophyte rich vs. phytoplankton dominated). Lakes were divided with a curtain, and maize (Zea mays) leaves were added, as an isotopically distinct tPOC source, into one half of each lake. To estimate the …
Effects of male removal on female foraging behavior in the Eurasian treecreeper
1997
In old, spruce-dominated forests of central Finland, Eurasian treecreepers Certhia familiaris divide their territories spatially during the breeding season. Females forage primarily on the upper parts of the tree trunks, while males use the lower parts of the tree trunks. In this study we removed males from eight territories in the early nestling period to see if the mate's absence would change the foraging patterns of the resident female. Widowed females foraged at lower heights, thus behaving more like paired males. These females also spent less time on each tree and on each foraging bout than did paired females. We conclude that male removal facilitated the change in a female's foraging …
Direct measurement of NO<sub>3</sub> radical reactivity in a boreal forest
2018
Abstract. We present the first direct measurements of NO3 reactivity (or inverse lifetime, s−1) in the Finnish boreal forest. The data were obtained during the IBAIRN campaign (Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget) which took place in Hyytiälä, Finland during the summer/autumn transition in September 2016. The NO3 reactivity was generally very high with a maximum value of 0.94 s−1 and displayed a strong diel variation with a campaign-averaged nighttime mean value of 0.11 s−1 compared to a daytime value of 0.04 s−1. The highest nighttime NO3 reactivity was accompanied by major depletion of canopy level ozone and was associated with strong temperature…
Seasonal pattern of mannitol and malate accumulation in leaves of two manna ash species (Fraxinus ornus L. and F. angustifolia Vahl) growing in Sicily
2002
The content of mannitol and malate was assayed enzimatically during spring, summer and autumn, in leaves of two species of ash traditionally cultivated in Sicily for the extraction of manna. The results suggest that in these species, under the local field conditions, mannitol has a more relevant role than malate in the response to summer drought.
PHENOLOGICAL ADAPTATION OF ANT-DISPERSED PLANTS TO SEASONAL VARIATION IN ANT ACTIVITY
2002
We studied a temperate plant community to examine whether the reproductive phenology of ant-dispersed plants is correlated with seasonal variation in seed dispersal activity of ants. We documented flowering and fruiting peak of 24 ant-dispersed and 251 non-ant-dispersed plant species. To characterize the activity of ants, we quantified the seasonal removal rates of greater celandine (Chelidonium majus) seeds. Ant-dispersed plants flowered on average 5.6 wk and fruited 7.1 wk earlier than those with other dispersal modes. This difference was not caused by variation in growth form or habitat. Mean fruiting peak of ant-dispersed plants was early July. Ant activity was especially high between M…
A critical view on temperature modelling for application in weather derivatives markets
2012
Author's version of an article published in the journal: Energy Economics. Also available from the publisher at: http://dx.doi.org/10.1016/j.eneco.2011.09.012 In this paper we present a stochastic model for daily average temperature. The model contains seasonality, a low-order autoregressive component and a variance describing the heteroskedastic residuals. The model is estimated on daily average temperature records from Stockholm (Sweden). By comparing the proposed model with the popular model of Campbell and Diebold (2005), we point out some important issues to be addressed when modelling the temperature for application in weather derivatives market.
Diet of the garden dormouse (Eliomys quercinus Linnaeus 1766) in orange groves: seasonal variation and use of available resources
2010
Abstract The aim of this study was to describe the feeding habits of the garden dormouse Eliomys quercinus in orange groves of eastern Spain. The study area was an extensive orange grove near Sagunto (Valencia, Spain). This study combines two different non-invasive methods, the study of food store remains and the macroscopic analysis of feces. A total of 527 feces and the food remains of 172 food stores were recollected from nest boxes. Each feces was classified into five categories according to its characteristics: arthropods, gastropods, oranges, plants, and others. Throughout the year, the garden dormouse consumed all these types of food. The most consumed prey in summer and autumn were …
Seasonal characterization of nutritional and antioxidant properties of Opuntia ficus-indica [(L.) Mill.] mucilage
2021
Abstract Opuntia ficus-indica fruit and cladodes are a source of mucilage, a carbohydrate complex, as well as of phytochemicals and other nutrients, useful in the food industry. Despite the environmental-based composition variability has been studied, there is no information on its seasonal variability, which is particularly important for its industrial use. In this study, some technological, nutritional, and bioactive properties of O. ficus-indica cladodes mucilage were analyzed during the seasonal growth period. Total proteins did not change during the whole period and the lipid content significantly decreased from winter to the onset of summer. The fatty acid profile showed high levels o…
Plants in the UK flower a month earlier under recent warming.
2022
Global temperatures are rising at an unprecedented rate, but environmental responses are often difficult to recognize and quantify. Long-term observations of plant phenology, the annually recurring sequence of plant developmental stages, can provide sensitive measures of climate change and important information for ecosystem services. Here, we present 419 354 recordings of the first flowering date from 406 plant species in the UK between 1753 and 2019 CE. Community-wide first flowering advanced by almost one month on average when comparing all observations before and after 1986 ( p < 0.0001). The mean first flowering time is 6 days earlier in southern than northern sites, 5 days earlier…
High Diversity of the Viral Community from an Antarctic Lake
2009
Viruses are the most abundant biological entities and can control microbial communities, but their identity in terrestrial and freshwater Antarctic ecosystems is unknown. The genetic structure of an Antarctic lake viral community revealed unexpected genetic richness distributed across the highest number of viral families that have been found to date in aquatic viral metagenomes. In contrast to other known aquatic viromes, which are dominated by bacteriophage sequences, this Antarctic virus assemblage had a large proportion of sequences related to eukaryotic viruses, including phycodnaviruses and single-stranded DNA (ssDNA) viruses not previously identified in aquatic environments. We also o…