An investigation was carried out at the Muda rice fields, Peninsular Malaysia during four consecutive seasons of 2004 and 2005 to study the seasonal variation in the weed seedbank. Species composition with their dominance ranking and similarity between the species were recorded. A total of 577 seeds/sample (3337 seeds/m ) in 1/2004, 970 seeds/sample (5659 seeds/m ) in 2/2004, 928 seeds/sample (...

Geese are large, herbivorous birds that graze in huge flocks in ways that may have a considerable impact on vegetation. This is exemplified best in two subspecies of snow geese, the lesser and the greater, both of which have increased dramatically in numbers in recent decades. In arctic coastal salt marshes, moderate goose grazing on Puccinellia phryganodes enhances plant production, but if it ...

Crenarchaeal 16S rRNA sequences constituted over 70% of the archaeal clones recovered from three salt marsh sites dominated by different grasses. Group I.1a Crenarchaeota dominated at two sites, while group I.3b Crenarchaeota sequences were most abundant at a third site. Abundances of 16S rRNA genes related to "Candidatus Nitrosopumilus maritimus" differed by site and sampling date.

Ammonia-oxidizing archaea (AOA) play important roles in nitrogen and carbon cycling in marine and terrestrial ecosystems. Here, we present the draft genome sequence for the ammonia-oxidizing archaeon "Candidatus Nitrosopumilus salaria" BD31, which was enriched in culture from sediments of the San Francisco Bay estuary. The genome sequences revealed many similarities to the genome of Nitrosopumi...

A survey of the extracellular ATP levels of 86 heterotrophic bacteria showed that gram-negative bacteria of the genera Sulfitobacter, Staleya, and Marinobacter secreted elevated amounts of extracellular ATP, ranging from 6.0 to 9.8 pM ATP/colony forming unit (cfu), and that gram-positive bacteria of the genera Kocuria and Planococcus secreted up to 4.1 pM ATP/cfu. Variations in the levels of ex...

Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availabi...

Some deleterious effects of drought, soil salinity and other abiotic stresses are mediated by the generation of oxidative stress through an increase in reactive oxygen species (ROS) that damage cellular membranes, proteins and DNA. In response to increased ROS, plants activate an array of enzymatic and non-enzymatic antioxidant defences. We have correlated the activation of these responses with...