Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 3

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
w słowach kluczowych:  struktura społeczności
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
The influence of the shrub canopy on the spatial distribution of above and below ground arthropod communities in desertified ecosystems is largely unknown. Using the shrubs Hedysarum scoparium (H. scoparium) and Artemisia ordosica (A. ordosica) as model systems, the above and belowground arthropod communities were sampled by using pitfall trapping and hand-sorting, in order to examine the linkage between above and belowground arthropods across shrub microhabitats. Different profile layers harboured mostly distinct arthropod taxon and trophic groups that preferred specific microhabitats. Even the common taxa, including the Carabidae and Formicidae families, were found to have different abundance distributions in above and belowground soil layers across shrub microhabitats. Total abundance distribution was found to differ, while taxon-richness and Shannon-index distributions were similar in above and belowground parts across the shrub microhabitats. Markedly higher taxon-richness and Shannon-index values were found beneath the shrub canopy compared to the open spaces, particularly beneath the A. ordosica shrub canopy. The abundance distribution in above and below ground arthropod communities were affected by the shrub microhabitats along vertical and horizontal axes more than the richness and diversity of these communities. The A. ordosica shrub canopy (compared with the H. scoparium shrub) was found to have greater ecological implications on the spatial distribution of the arthropod communities. All these findings were expected to be helpful for the conservation of biodiversity, shrub plantation management, and desertification control.
The response of soil nematodes to simulated in spring, summer and autumn periods of warming and drought were studied in a grassland mesocosm experiment. The abundance, diversity and some community parameters of nematodes were analysed at different times after the end of the extreme events – 170 days after the spring treatment, 90 days after the summer treatment and 22 days after the autumn treatment. Among studied parameters the abundance of nematode trophic groups, taxonomic richness and diversity were found to be sensitive to changes in the soil system caused by extremes. Our results showed that warming and drought did not cause predictable shifts in nematode communities. Moreover the extremes’ after-effect was not unidirectional with time. The periods of warming and drought induced a positive or negative long lasting influence on nematodes, and the outcome seems to depend on season, the nematode trophic group or even the nematode taxon.
Conversion of land from wetland to agricultural management practices can lead to significant changes in nutrient rich topsoil, which may have an impact on microbial community structure in soils. However, little is known about how long-term (ca. 40 years) rice cultivation, one of major agricultural management practices in many regions, influence soil microbial biomass and community structure. Soil samples were collected from a wetland and paddy field in Anhui province in eastern China to examine soil physical and chemical characteristics and associated soil microbial biomass and community composition. Microbial community composition was assessed using phospholipid fatty acid (PLFA) analysis, terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes. Results indicated that soil moisture content, pH, soil organic carbon, total nitrogen and NH4[^+]-N contents were significantly lower in the paddy field in comparison to the wetland. Total microbial biomass showe showed a slightly significant decrease in the paddy field, however, there were significant shifts in the composition of the microbial communities based on the PLFA and T-RFLP fingerprintings in the both ecosystems. Signature PLFA analysis revealed that the sum of bacterial PLFAs and the relative proportions of Gram negative bacterial specific PLFAs significantly decreased in the paddy field, nonetheless, the relative numbers of actinobacterial, Gram positive and fungal PLFAs as well as the ratio between the bacterial and fungal PLFAs were not affected by the long-term agricultural management. These results revealed that long-term rice cultivations not only drastically decreased soil nutrients but also leaded to shifts in the soil microbial community structure, which would be helpful to provide a better understanding of wetland conservation and management practices.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.