An ex situ germplasm collection of the endangered Cycas micronesica was established in a transition zone between biodiverse native forest and mature stands of the invasive species Leucaena leucocephala. Soil chemical properties were determined for the 2 tree cover types to inform management decisions. Total carbon, total nitrogen, calcium, and net ammonification were greater in native forest co...

We carried out a simulation experiment in a laboratory in order to study the effects of hydrostatic pressure from 0.1 MPa to 1.0 MPa on nitrogen cycles at the water-sediment interface of a freshwater reservoir. The results show that high hydrostatic pressure facilitates the release of nitrogen at the interface and ammonification, but has little influence on denitrification. And high hydrostatic...

The effects of floating macroalgae (250 g DW m(-2)) on photoautotrophic microbenthos were studied in a flow-through mesocosm with a parallel mesocosm without macroalgae serving as Control. Vertical microprofiles of O(2) at the sediment-water interface showed a immediate and complete suppression of photosynthetic activity of microphytobenthos (MPB) under the macroalgal canopy, resulting in a shi...

Analysis of data from the long term trash management trial at Mount Edgccombe (BTI) has shown that, after 59 ycars of green cane harvesting, with trash retention there was a significant incr-ease in soil organic matter content in thc surface 10 cm of soil compared with burning. The size of the microbial biomass, and its rcspiratory rate, dchytlrogenase activity and arginine ammonification rate ...

Wastewaters from baker’s yeasts industry effluent have a high organic contamination. The classical biological treatments under aerobic and anaerobic conditions lead to a good efficiency in removing the organic carbon, but regarding nitrogen efficiency is variable. To obtain a good efficiency in removing nitrogen, the effluents must pass through all different stages of nitrogen cycle (i.e. ammon...

Anthropogenic N deposition poses a threat to European Mediterranean ecosystems. We combined data from an extant N deposition gradient (4.3-7.3 kg N ha⁻¹ yr⁻¹) from semiarid areas of Spain and a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community. Soil organic N did not increase along the extant gradient. Nitrogen fixation de...

A perfusion technique was used to study the effects of l) simulated acid rain on the mineralization and nitrification of glycine (NH 2-N) or ammonium sulfate (NH4-N) by adjusting the pH of the perfusates to 3.0, 2.5, or 2.0 with H 2S0 4 ; and 2) 0, 50, I 00, 500, and I ,000 1-1-g Cd!g dry weight of soil on the mineralization and nitrification of NH 2-N, both in soil adjusted with H 2S04 to pH 3...

Denitrification and dissimilatory reduction to ammonium (DNRA) are competing nitrate-reduction processes that entail important biogeochemical consequences for nitrogen retention/removal in natural and man-made ecosystems. The nature of the available carbon source and electron donor have been suggested to play an important role on the outcome of this microbial competition. In this study, the inf...