Search results for "Pinus"
showing 10 items of 159 documents
Nest modifications by the acorn ant Temnothorax crassispinus (Hymenoptera: Formicidae)
2019
Many ant species construct nests and during the process considerably influence the environment such as by changing soil structure and creating new habitat for other species. However, other ant species dwell in ready-for-use cavities. Ants of the genus Temnothorax inhabit small cavities such as acorns and under rocks, but under natural conditions, good nest sites are limited resources. During field and laboratory experiments, I studied how the acorn ant Temnothorax crassispinus (Karawajew, 1926) modifies nesting sites. Temnothorax crassispinus is a forest species, which typically lives in cavities in fallen twigs and acorns; colonies usually number from a few dozen to about 200 workers. Alth…
High winter survival rate of acorn ants inside artificial nest sites (Hymenoptera: Formicidae)
2022
Although most species of ants overwinter underground to avoid low temperatures, the acorn ants of the genus Temnothorax remain in nests situated at ground level. During a field experiment, I studied the winter mortality of acorn ants in nest sites situated aboveground, as well as in sites experimentally buried in the soil. Despite the low air temperatures (even reaching –19°C, recorded 1.5 m above the ground), the survivorship was very high: all of the 18 queens used in the experiment survived, while the survival rate of workers was 61.9-100%, and for most colonies it exceeded 95%. The rate of survival in the nest sites aboveground and those experimentally buried in the soil was similar. Su…
Acorn Ants May Create and Use Two Entrances to the Nest Cavity
2021
Many ant species construct large nests that are inhabited by numerous workers, but other species dwell in ready-for-use cavities and live in small colonies. Ants of the genus Temnothorax inhabit small cavities, e.g., in acorns, twigs, and under rocks. Although a preference for nest sites with a narrower entrance is known, recent studies have shown that they also use cavities with wider entrances and may modify the size of such entrances. As good cavities for nest sites are a limited resource, the possibility to modify a potential nest site, including a reduction in the size of the hole, should be a favorable matter for the ants. Through field and laboratory experiments, I studied the acorn …
Cost to the cavity-nest ant Temnothorax crassispinus (Hymenoptera : Formicidae) of overwintering aboveground
2013
Most species of ants inhabiting the temperate zone overwinter underground, whereas those of the genus Temnothorax remain in nests aboveground. I studied the cost of aboveground overwintering. Workers of Temnothorax crassispinus survived in higher numbers (median = 88%) in artificial nests experimentally buried at a depth of 5 cm than those in nests on the surface (48%) of the soil. The results support the hypothesis that overwintering aboveground could be a consequence of a limited supply of nests and/or the advantage of being able to respond quickly to warm temperatures in spring.
A comparative thermogravimetric study of waterlogged archaeological and sound woods
2010
Waterlogged archaeological woods Pinus pinaster and Fagus sylvatica L. were analyzed by using TG technique. Degradation processes ascribable to the holocellulose decay were evidenced at nearly the same temperature for sound and archaeological samples. The residual matters at 600 and 900 °C of the sound woods are much lower than those of archaeological waterlogged woods in agreement with the presence of inorganic materials encapsulated during the burial into the marine environment. It was proposed a new protocol to rapidly calculate the maximum water content parameter, which is related to the wood degradation state. TG experiments at variable heating rates were performed to obtain kinetic pa…
The Norway spruce genome sequence and conifer genome evolution
2013
Conifers have dominated forests for more than 200 million years and are of huge ecological and economic importance. Here we present the draft assembly of the 20-gigabase genome of Norway spruce (Picea abies), the first available for any gymnosperm. The number of well-supported genes (28,354) is similar to the >100 times smaller genome of Arabidopsis thaliana, and there is no evidence of a recent whole-genome duplication in the gymnosperm lineage. Instead, the large genome size seems to result from the slow and steady accumulation of a diverse set of long-terminal repeat transposable elements, possibly owing to the lack of an efficient elimination mechanism. Comparative sequencing of Pinu…
The contribution of ozone to forest decline
1995
More than 10 years of intensive research into forest decline in Germany has ascertained that the full extent of the visible damage cannot be explained by just one of the current hypotheses on forest decline. One of the prominent hypotheses is that chronic exposure of forest trees to ozone is probably one of the primary causes of forest decline. The aim of this paper is the critical review of a number of recent results dealing with the ozone hypothesis from a plant physiological point of view. The synopsis focusses on the effects of ozone on conifers because the most extensive data are available for coniferous trees, especially for spruce (Picea sp.) and pine (Pinus sp.) trees.
Invazīvo augu (Lupinus polyphyllus, Impatiens glandulifera, Echinocystis lobate) bioloģiski aktīvo vielu grupas un to izmantošanas potenciāls bioekon…
2022
Invazīvās augu sugas var veicināt ar ekosistēmu funkcionēšanu saistītas problēmas, radot ekonomiskus zaudējumus, kaitējumu cilvēka veselībai un samazinot rekreācijas resursu kvalitāti. Tās raksturo strauja un agresīva izplatīšanās, nomācot endēmiskās sugas. Pilnīgai invazīvo augu biomasas izmantošanai ir nepieciešams atrast ilgtspējīgus, bioekonomikā balstītus pārstrādes risinājumus, kas ļautu iegūt komponentus vai produktus ar augstu pievienoto vērtību. Darbā tika apskatītas dažādas daudzlapu lupīnas, puķu spriganes un adatainā dzeloņgurķa augu daļas. Augos tika noteikts kopējais polifenolu daudzums, novērtēta antiradikālā aktivitāte (DPPH), un lupīnās atrodamie alkaloīdi (GC-MS). Augstākā…
Rīgas gaisa piesārņojuma izplatības bioindikācija ar priežu skuju bojājumu novērtēšanas metodi
2018
Gaisa piesārņojums ir aktuāla problēma vides zinātnē, tas spēj ievērojami ietekmēt vides un sabiedrības veselību. Parastās priedes Pinus sylvestris fizioloģiskās īpatnības ļauj to veiksmīgi izmantot gaisa piesārņojuma bioindikācijā. Darba mērķis ir izpētīt Rīgas gaisa piesārņojuma izplatīšanās īpatnības pēc priežu skuju bioindikācijas rādītājiem uz apkārtējām teritorijām atkarībā no valdošo vēju virziena. Apkārt Rīgai bija izveidots parauglaukumu tīkls, katrā parauglaukumā novērtējot skuju nekrotizācijas pakāpi, dzīves ilgumu, ozona bojājumus. Konstatēts, ka attālumam no Rīgas nav saistības ar gaisa kvalitāti. Izmantotie rādītāji norādīja uz sliktāku gaisa kvalitāti parauglaukumos, kuri atr…
Data from: Inter-annual variation and long-term trends in proportions of resident individuals in partially migratory birds
2016
Partial migration – a part of a population migrates and another part stays resident year-round on the breeding site – is probably the most common type of migration in the animal kingdom, yet it has only lately garnered more attention. Theoretical studies indicate that in partially migratory populations, the proportion of resident individuals (PoR) should increase in high latitudes in response to the warming climate, but empirical evidence exists for few species. We provide the first comprehensive overview of the environmental factors affecting PoR and the long-term trends in PoR by studying 27 common partially migratory bird species in Finland. The annual PoR values were calculated by divid…