Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 232

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 12 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  plantation
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 12 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Civilizational development requires seeking for more and more modern methods of satisfying growing needs of the society. Living standards grow together with economic growth and, as a result, demand for energy grows as well. This fact is tantamount with the necessity to look for alternative energy sources. Otherwise, our civilization will soon have to face degradation of natural environment and shortage of conventional energy resources. Under Polish conditions, crucial role in utilizing renewable energy is played by biomass, and its importance is going to grow over the years. The present study has assessed productivity of three willow clones: Tur, Ekotur and Turbo, grown in short rotations on farmland.
In accordance with the National Program for Increasing Forest Cover it is planned to augment Poland’s forest cover to 30% by 2020. This task involves afforestation of agricultural lands by pioneer species that have low habitat requirements, such as the silver birch or the Scots pine. Application of sawdust, clear cutting residues, compost bark and compost beneath tree roots contributed to better development of the assimilation apparatus. The use of mineral fertilizer stimulated tree growth as well as improved physical and chemical properties of soil.
Incidence of Armillaria root disease and the population structure of associated Armillaria spp. were studied in 5-17-year-old Scots pine plantations in west-central Poland. Two infection centres (1.14– 9.30 ha) in each of three forest districts (Siemianice, Zielonka and Złotów) were intensively sampled. Root collars were examined for mycelial fans, decayed wood, and rhizomorphs. Twenty two isolates of Armillaria ostoyae collected from epiphytic rhizomorphs from 20 living and two dead trees in the six infection centres were identified with somatic incompatibility group. Only one somatic incompatibility group for A. ostoyae was found. Twenty one isolates produced rhizomorphs on oak-wood discs submerged in a sand-forest soil substrate. Isolates from Siemianice formed the smallest rhizomorph networks and those from Złotów the most abundant. There were 16 different genets among 22 isolates of A. ostoyae distinguished by RAPD analysis. Genetic similarity among genets was 25.6–97.5%. The large diversity in A. ostoyae suggests that sexual reproduction may occur in nature more often than expected.
The ground-active arthropod diversity response to size of shrub plantations in desertified grassland ecosystems is largely unknown. In the study ground-active arthropods were collected by pitfall trapping beneath shrub canopy of very low, low, medium and high size, with adjacent mobile sandy land as a control. It was found that arthropod dominant taxa from mobile sandy land were significantly distinctive from those from plantations of different shrub size. A considerably lower Sørensen index (i.e., 0.25–0.48) was found between the arthropod communities from mobile sandy land and the canopy of either shrub size, than between those under low and medium/high shrub size (i.e., 0.62 to 0.69). The arthropod total abundance was significantly greater under the shrub canopy of very low size in comparison to that of low and medium shrub size and mobile sandy land, with the intermediate values under shrub canopy of high shrub size. Taxon richness and diversity of arthropod communities were distinctly lower under the shrub canopy of low size in comparison to very low, medium and high shrub size. The shrub size was found to have different effects on the density and richness distribution of arthropod trophic groups (i.e., predators, phytophagous, saprophagous, and omnivorous). It was concluded that shrub plantations could facilitate ground-active arthropod diversity recovery when they were afforested in mobile sandy land. There was a contrasting effect of shrub size on ground-active arthropod diversity recovery versus arthropod abundance when grazing was excluded.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 12 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.