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1.
A. Šimkūnas S. Valašinaitė V. Denisov A. Salytė 《Journal of Agronomy and Crop Science》2013,199(6):460-465
The study investigated the cultivars of non‐obligatorily requiring vernalization plant Festulolium braunii and assessed the influence of non‐hardy reproductive and hardy vegetative structures on overwintering effect. The study was conducted taking into account systemic relations between these types of structures. The results show the cultivars differ according to the percentage of headed and overwintered plants, when the cultivars with the most abundant heading – ‘Felopa’ and ‘Sulino’ – are also better at overwintering. The positive correlation between heading and overwintering characteristics was also observed, what seemed to be a rather new finding. It can be explained by systemic effect: non‐hardy later reproductive structures induce the post‐generative regrowth of vegetative shoots, which during shorter days halt development and become potentially hardy. More detailed interpretation is also provided including discussion of causal mechanisms of the detected phenomenon. The authors suppose that these mechanisms constitute a survival strategy for such perennial plants. The observed late heading which represents reproductive structures could be applied in plant breeding as a marker of winter‐hardiness among perennial grass plants which non‐obligatorily demand vernalization. 相似文献
2.
Emily Fobert Grzegorz Zięba Lorenzo Vilizzi Michael J. Godard Michael G. Fox Saulius Stakėnas Gordon H. Copp 《Ecology of Freshwater Fish》2013,22(1):106-116
Predictions of future climate change include shifts in patterns of precipitation, evapotranspiration and water run‐off, resulting in increased periods of drought as well as variability and intensity of rainfall events. In the United Kingdom, the non‐native North American sunfish, pumpkinseed Lepomis gibbosus (L.), is expected to benefit from these changes. We examine how hydrological variability induced by predicted changes in climate will affect the dispersal and spread of pumpkinseed in England by: (i) determining the relationship between discharge regime and pumpkinseed propagule pressure; (ii) examining a newly‐established pumpkinseed population following a flood event in 2007; and (iii) comparing the growth and life‐history traits of this new population with fish collected from the source population to demonstrate how the pumpkinseed's life‐history plasticity contributes to its success as a coloniser. Using Bayesian modelling, we determined that the number of pumpkinseed escapees is likely to increase with increasing discharge. The newly‐established pumpkinseed population showed fast juvenile growth, early age at maturity and small size at maturity. These traits differed significantly from the source population, specifically total length (TL) means at ages 1 and 2 were significantly greater in the new population, whereas TL at age 4 was significantly greater in the source population, and a significantly higher proportion of mature females were found at smaller size classes in the newly established pumpkinseed population. This study demonstrates the potential link between hydrological variability (current and future) and the dispersal of non‐native pumpkinseed, leading to the establishment of new populations. 相似文献
3.
Abstract – To address the dearth of information on tagging effects and long-term survivorship of tagged fish in native and introduced species, laboratory and field investigations were undertaken on three non-native fish species (pumpkinseed Lepomis gibbosus ; topmouth gudgeon Pseudorasbora parva ; pikeperch Sander lucioperca ) tagged with coded-wire (CW), passive integrated transponder (PIT), radio (RT) telemetry and/or acoustic tags (AT), with survivorship of native brown trout ( Salmo trutta ) examined in the field. Laboratory results revealed high survivorship following tag attachment/insertion and resumption of feeding within 24–48 h of tagging (all mortalities could be attributed to an unrelated outbreak of fungal infection), with retention rates being high in both pumpkinseed and pikeperch but low in topmouth gudgeon (excluded from field studies). In the field, short-term post-operation survival was high in pikeperch, pumpkinseed and brown trout. In pumpkinseed and trout, 100% of RT fish survived a 24–30 day tracking study, with 60% and 80%, respectively, recaptured alive at least 3 months post-tagging. Of PIT tagged pumpkinseed, 44% were recaptured (after 6–18 months), with small-sized, CW-tagged fish (0.38 g weight) captured up to 1 year after tagging. In pikeperch, all AT fish except one (the smallest specimen) survived their full expected tracking period (i.e. tag life) – the single lost specimen survived at least half of its expected tracking period (i.e. 6 month battery life). Overall, the tagging methods used were highly effective in pumpkinseed and pikeperch, showing good retention and survival, but PIT tagging of topmouth gudgeon was plagued by low survivorship and tag rejection. 相似文献
4.
The current state of cooperation in private forestry in Lithuania is examined, with a focus on the analysis of objectives,
organisational structure and the ways forest owners’ cooperatives operate. A postal survey has been used as a main research
instrument, the questionnaire consisting of a series of multiplechoice close-ended questions. This paper provides insights
into the state forest enterprises and other private companies operating in the private forestry sector, and places forest
owners’ cooperatives in a broader context of the private forestry sector. A typical forest owner’s cooperative in Lithuania
has up to 10 members and about 20 clients to whom services are provided. The leaders of cooperatives indicate that the optimal
number of clients using their services should not exceed 40. The main stated objectives of cooperatives are the provision
of services to their members under the most attractive conditions, uniting members, and earning a profit for the members.
These activities of cooperatives revolve around timber harvesting and trade. It is concluded that the process of cooperation
of private forest owners in Lithuania is rather slow, although positive development can be observed. 相似文献
5.
Background
This study investigated seasonal changes in naturally acquired gastrointestinal nematode (GIN) infections on two Lithuanian goat farms with different parasite control practices.Findings
On both farms, nematode faecal egg counts (FEC) and larval cultures were obtained from 15 adult and 10 young goats at bi-weekly intervals from April 2012 to April 2013. Goats on farm A were dewormed with ivermectin (0.3 mg/kg body weight) in October/November 2012, whereas the animals on farm B were left untreated. Thirteen young goats were slaughtered in August/November 2012 and April 2013 and worm burdens in the gastrointestinal tract were enumerated. In goats from both farms, Teladorsagia, Trichostrongylus, Oesophagostomum, Chabertia and Haemonchus were the dominant GIN genera. Herbage contamination with infective third-stage larvae (L3) peaked in July/August and resulted in high FEC in September/October. Parasitological examination at slaughter showed that Teladorsagia spp. and Haemonchus contortus survived the winter, both in the abomasal mucosa as adults and as early fourth-stage larvae (EL4). Deworming on farm A significantly reduced FEC, especially of H. contortus, at the start of the grazing period compared with the untreated farm B (P < 0.05).Conclusions
Goats were heavily infected with several GIN throughout the year. Strategic anthelmintic treatment during housing significantly reduced nematode egg output, in particular by H. contortus, at the start of the grazing season. 相似文献6.
Gediminas Brazaitis Kęstutis Pėtelis Remigijus Žalkauskas Olgirda Belova Darius Danusevičius Vitas Marozas Gintarė Narauskaitė 《European Journal of Forest Research》2014,133(5):857-869
We analyse the relationships between the main Cervidae [moose (Alces alces), red deer (Cervus elaphus) and roe deer (Capreolus capreolus)] species and a complex of environmental factors in an extensive fragmented landscape of Central Lithuania. The highest determining positive influence on moose density was the proportions of wet forest sites. In forest complexes with fewer proportions of wet sites, the most important factor was the total forest area. The proportion of shrub cover, upland and dense undergrowth area, and road density also has significant effect on moose density. The total area of forest complexes has the highest determining positive influence on red deer density. The highest density of red deer was calculated in large forest complexes (>2,745 ha) with a <17.6 % proportion of pine and <36.5 % of deciduous forests. Other significant factors were core area, road density and urbanization level. Forest edge density has the highest influence on the roe deer populations. The highest density of roe deer was recorded on forest areas with >51 m ha?1 of edges in wet forest (>25.4 %) dominating areas. The proportion of deciduous, coniferous mixed and pine forest, also shrub and density of edges also had significant effect. 相似文献
7.
Scott D. Foster Arūnas P. Verbyla Wayne S. Pitchford 《Journal of Agricultural, Biological & Environmental Statistics》2007,12(2):300-314
The identification of quantitative trait loci (QTL) can be viewed as a subset selection problem. In a simulation study the
least absolute selection and shrinkage operator (LASSO) is shown to be a useful and powerful tool for QTL identification.
LASSO effects are embedded into a mixed model allowing simultaneous modeling of genetic and experimental effects. This provides
the flexibility to model the experiment in conjunction with the power of LASSO QTL identification. Estimation is performed
using an approximation to the restricted likelihood and modified Gaussian elimination. The extended mixed model is used to
analyze a cattle gene mapping dataset. 相似文献
8.
Monika Vilkienė Dalia Ambrazaitienė Danutė Karčauskienė Zenonas Dabkevičius 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2016,66(8):641-646
ABSTRACTMineralization is the main organic matter conversion process, which leads not only to preservation of organic matter in the soil but also to its sequestration. Soil organic matter has equal value as mineral part if we want to improve soil quality or increase the yield. Because of intensive farming, irresponsible use of mineral fertilizers and natural factors, soil organic matter is decreasing. To counteract this process, different soil-friendly management practices and techniques, such as shallow tillage, no-tillage or direct drilling and application of additional organic matter are used. The objective of the present study was to assess the changes in the intensity of soil organic matter mineralization as influenced by primary soil tillage of different intensity in combination with organic matter incorporation. Long-term studies showed that land management practices differentiated the soil into two layers: upper (0–10?cm) layer containing more moisture and nutrients and lower (10–20?cm) layer comprising less moisture and nutrients. The conditions of aeration in the arable soil layer did not change under the effect of ploughing. In this soil, the rate of mineralization was lower than that in the ploughless tillage treatment. The most active mineralization of soil organic matter in the ploughless tillage treatment occurred in the autumn period, when high level of rainfall promoted the loss of nutrients from the topsoil layer. 相似文献
9.
Dissolved concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the influents and effluents of two municipal sewage treatment plants (STPs) were monitored over 16- (Umeå, Sweden) and 22- (?iauliai, Lithuania) day sampling periods. Sampling was performed using a passive sampling technique (semipermeable membrane devices; SPMDs) for sequestration of the dissolved (readily bioavailable) fraction of persistent organic pollutants (POPs). Removal efficiencies for individual low molecular weight (LMW) PAH compounds varied from 84% to levels at which the compounds were not detected in effluents from Umeå. The corresponding efficiencies of the ?iauliai plant were 33–95%. Measurements revealed that dissolved concentrations of most of the PCBs and some of the high molecular weight (HMW) PAHs increased during the conventional wastewater treatment at both plants. The release of dissolved PAHs and PCBs in the effluents from municipal wastewater treatment plants might increase the environmental contamination by readily bioavailable pollutants in the recipient waters; the rivers Umeälven and Kulpè. SPMDs were found to be suitable sampling tools for long-term (weeks-month) integrative monitoring of trace concentrations of the dissolved fraction of hydrophobic pollutants in the wastewater process, since the sampling and clean-up steps were easy to perform. 相似文献
10.
Darius Danusevičius Jurata Buchovska Vidmantas Stanys Juratė Bronė Šikšnianienė Virgilijus Baliuckas Gediminas Brazaitis 《European Journal of Forest Research》2013,132(1):137-150
The aim of this study was to elucidate the introduction history of P. mugo in the unique landscape of the Lithuanian seaside spit of Kursiu Nerija by assessing its genetic structure and the genetic diversity. The individuals were sampled in 12 populations within an area of 3 km × 50 km along the Lithuanian part of Kursiu Nerija. P. mugo was introduced over 200 years ago to prevent sand erosion by establishing a forest cover. Chloroplast DNA polymorphism of 220 individuals of P. mugo together with 18 P. sylvestris and 11 putative P. sylvestris × P. mugo hybrids was assessed by the aid of five microsatellite markers. The standard intra-population diversity indexes were calculated. The intra-specific variation between distinct morphotypes as well as the population differentiation within the most spread P. mugo ssp. rotundata morphotype was assessed based on the haplotype frequencies by hierarchical AMOVA, GST/RST test, UPGMA clustering and PCA methods. The genetic diversity of P. mugo in Kursiu Nerija was high (He = 0.95; 83 different haplotypes). All except one of the P. mugo populations sampled contained a notable share of private haplotypes. AMOVA revealed high intra-specific diversity but low differentiation between the P. mugo populations. Most of the haplotypic variance was within populations. The UPGMA clustering produced groups more corresponding to the sub-species morphotypes than the geography of the populations. There was no geographical pattern of reduction in genetic diversity towards the younger plantations. A strong candidate for a species-specific DNA marker was found. After several events of introduction, the genetic diversity of P. mugo in Kursiu Nerija is very high and is structured based on the sub-species morphotypes rather than geography. The high frequency of shared and notable frequency of private haplotypes in most of the populations indicate that the major part of the P. mugo material originates from a number of geographically and genetically related sources, which more likely are introductions from abroad that the local collections. The high frequency of private haplotypes in the northernmost populations leaves a possibility for minor introductions from other genetically distinct sources. The absence of private haplotypes in one of the sampled populations indicates the use of local seed collections. The large number of shared haplotypes provides a strong evidence for a geneflow among the P. mugo taxa. 相似文献