Rapid Nutrient Research Articles

A Decrease in Oak Litter Mass Changes Nutrient Dynamics in the Litter Layer of a Central Hardwood Forest

Abstract The abundance of oak is declining in the central hardwood forest, resulting in structural and functional changes in the litter layer. We hypothesized that a decline in oak litter mass associated with a lower oak component will result in an increase in nutrient cycling rates in the litterlayer. To test this hypothesis, we compared mass loss and C, N, P, and Ca dynamics in pure oak litter and in litter made of 48% oak plus 52% five other deciduous species in a central hardwood forest in West Virginia. In 12 months of litter decomposition, pure oak litter decomposed more slowly,retained more C and N, immobilized more and subsequently did not release P, and released less Ca than litter consisting of 48% oak plus five other species. Annual stand-level nutrient fluxes in pure oak and in 48% oak plus five other species litter were correspondingly +4.1 and −4.4kg ha−1 N, +0.22 and −0.17 kg ha−1 P, and −9.3 and −16.7 kg ha−1 Ca. These results indicate that a decline in oak will cause more rapid nutrient cycling in the litter layer of affected central hardwood stands.

Variations and Controls of Sulfate Reduction in the Continental Slope and Rise of the Ulleung Basin off the Southeast Korean Upwelling System in the East Sea

Despite its importance in carbon mineralization pathways, relatively little is known about sulfate reduction along a continental slope and rise. We investigated the temporal and spatial variations and controls of sulfate reduction rates (SRRs) in the continental margin sediment of the Ulleung basin (UB), off the southeast Korean upwelling system in the East Sea. SRRs ranged from 1.22 to 8.07 mmol m−2 d−1 at the slope sites and from 0.69 to 3.18 mmol m−2 d−1 at the basin sites. These values were exceptionally higher than those observed within other marginal seas and were comparable to SRR values at the same depth range in the Peruvian and Chilean upwelling systems. The high sulfate reduction in the UB was attributable to enhanced primary production in the water column associated with coastal upwelling and a high export flux of large organic particles into the basin via the Ulleung warm eddy. The depth integrated SRR was approximately 4 times higher in the highly productive spring (4.91 ± 2.55 mmol m−2 d−1) than during the summer, which exhibited a stratified water column (1.28 ± 0.48 mmol m−2 d−1). In the meantime, despite the high organic carbon content (> 2.5% dry wt.) in the UB, the SRR was consistently suppressed in the Mn oxide-enriched (174 μ mol cm−3) surface sediments of the continental rise. Overall, these results indicate that the production of organic carbon in the water column and its subsequent deposition on the seafloor is the primary source controlling the temporal variability of sulfate reduction, whereas the Mn oxides that were enriched in the basin are responsible for the spatial variability of the SRR in the UB. Carbon oxidation in the UB accounted for approximately 30% of primary production and approximately 60% of the export flux, indicating that the continental slope and rise of the UB is a region of rapid organic carbon turnover and nutrient regeneration.

Coral mucus release and following particle trapping contribute to rapid nutrient recycling in a Northern Red Sea fringing reef

Mucus released by corals can function as an important energy carrier and particle trap in reef ecosystems with strong tidal currents. In fringing reefs with calm conditions, these processes may occur on smaller spatial scales. Observations of coral mucus dynamics in the Northern Red Sea revealed highly particle-enriched and negatively buoyant mucus strings attached to ∼27% of coral colonies for up to 79 min. Mucus strings of the scleractinian coral genus Acropora exhibited three orders of magnitude higher particulate organic carbon and nitrogen concentrations when compared with freshly released coral mucus, which confirms efficient particle trapping. After detachment from the coral surface, more than 95% of mucus strings rapidly descended to the reef sea floor within less than 1 m. Such mucus-induced transport may account for 21–25% of the total sedimentary particulate organic matter supply. In situ and laboratory analyses of planktonic and benthic microbial degradation of mucus strings showed high rates of up to 16 and 26% particulate organic carbon h–1, respectively. These findings suggest a newly discovered, tight sediment–water coupling mechanism via coral mucus that may contribute to rapid nutrient recycling in oligotrophic fringing coral reefs.

Endogenous Gibberellin Profile During Christmas Rose (Helleborus niger L.) Flower and Fruit Development

Gibberellins (GAs) were identified and quantified during flower and fruit development in the Christmas rose (Helleborus niger L.), a native of southeastern Europe with a long international horticultural tradition. Physiologically, the plant differs from popular model species in two major respects: (1) following anthesis, the initially white or rose perianth (formed in this species by the sepals) turns green and persists until fruit ripening, and (2) the seed is shed with an immature embryo, a miniature endosperm, and a prominent perisperm as the main storage tissue. GA1 and GA4 were identified by full-scan mass spectra as the major bioactive GAs in sepals and fruit. LC-MS/MS system in accord with previously verified protocols also afforded analytical data on 12 precursors and metabolites of GAs. In the fruit, GA4 peaked during rapid pericarp growth and embryo development and GA1 peaked during the subsequent period of rapid nutrient accumulation in the seeds and continued pericarp enlargement. In the sepals, the flux through the GA biosynthetic pathway was highest prior to the light green stage when the photosynthetic system was induced. Unfertilized, depistillated, and deseeded flowers became less green than the seed-bearing controls; chlorophyll accumulation could be restored by applying GA1, GA4, and, less efficiently, GA3 to the deseeded fruit. The sepals of unfertilized and depistillated flowers indeed contained very low levels of GA4 and gradually decreasing levels of GA1. However, the concentrations of their precursors and metabolites were less affected. These data suggest that a signal(s) from the fruit stimulates GA biosynthesis in the sepals resulting in greening. The fruit-derived GAs appear to be mainly involved in pericarp growth and seed development.

From bariatric to metabolic surgery in non-obese subjects: time for some caution

Severe obesity is associated with type 2 diabetes mellitus, and both resolve with weight loss after bariatric operations. Intestinal hormones have been identified which are stimulated by rapid nutrient delivery to the lower small bowel after certain weight-loss operations. These incretins stimulate secretion and hypertrophy of the pancreatic beta cells. Surgical procedures are now being performed to treat diabetes in adults of lesser weight, and the importance of ruling out latent autoimmune diabetes in the adult (a variety of type 1) is suggested, before experimenting with these procedures.

Satiety drinking tests: Effects of caloric content, drinking rate, gender, age, and body mass index

Objective. To compare the maximum tolerated volumes (MTVs) of drinking water and a nutrient liquid at different rates of drinking and to assess the best drinking test correlating with the symptom scores. Material and methods. Healthy volunteers were requested to drink water at a rate of 10 ml/min or a nutrient liquid drink at 100 and 20 ml/min on three separate occasions. Symptoms of bloating, nausea, and abdominal pain were assessed 30 min after the cessation of drinking using visual analogue scales. Results. The MTV of water was 1595±405 in males and 1327±308 in females (p<0.05). In rapid nutrient drinking, the MTV was 945±376 ml in males, whereas females tolerated 760±174 ml (p<0.05). In slow nutrient drinking, the MTV was 692±184 ml in males and 594±131 ml in females (p=0.051). Multiple regression analysis showed no influence of body mass index (BMI), age, or gender in slow nutrient drinking. However, drinking capacity was significantly influenced by gender, age, and BMI in rapid water drinking and by gender in rapid nutrient drinking. When the tolerated volumes for satiety drinking tests were compared, only males showed some significant positive correlations. Symptom scores were higher after slow nutrient drinking compared to the other two drinking tests. Conclusions. The rate of drinking and the caloric content affect the MTVs in satiety drinking tests. Slow nutrient drinking appears to be the best choice among the different satiety drink tests, as MTV in this test was not influenced by BMI or age and was associated with higher symptom scores.

Leaf litter decomposition of dominant tree species of Namdapha National Park, Arunachal Pradesh, northeast India

Rates of weight loss and nutrient (N and P) release patterns were studied in the leaf litter of the dominant tree species (Ailanthus grandis, Altingia excelsa, Castanopsis indica, Duabanga sonneriatioides, Dysoxylum binectariferum, Mesua ferrea, Shorea assamica, Taluma hodgsonii, Terminalia myriocarpa and Vatica lancefolia) of a tropical wet evergreen forest of northeast India. Nitrogen and phosphorus mineralization rate and decay pattern varied significantly from species to species. In general, the decay pattern, characterized by using a composite polynomial regression equation, exhibited three distinct phases of decay during litter decomposition—an initial slow decay phase (0.063% weight loss day−1), followed by a rapid decay phase (0.494% weight loss day−1) and a final slow decay phase (0.136% weight loss day−1). The initial chemical composition of the litter affected decomposition rates and patterns. Species like D. sonneriatoides, D. binectariferum, and T. hodgsonii with higher N and P content, lower carbon and lignin content, and lower C:N ratio and lignin:N ratio exhibited relatively faster decomposition rates than the other species, for example M. ferrea, C. indica and A. grandis. A slow decay rate was recorded for species such as M. ferrea, C. indica, and A. grandis. The initial N and P content of litter showed significant positive correlations with decay rates. Carbon and lignin content, lignin:N, and C:N showed significant negative correlations with decay rates. Soil total N and P, and rainfall, soil temperature, and soil moisture had positive correlations with decay rates. The rapid decomposition rates observed in comparison with other different forest litter decay rates confirm that tropical wet evergreen forest species are characterized by faster decomposition rates, indicating a faster rate of organic matter turnover and rapid nutrient cycling.

Erosion and Nutrient Loss on Sloping Land under Intense Cultivation in Southern Vietnam

AbstractTo help improve the well‐being of the local people, a joint Vietnamese‐UK team set out to establish a way of estimating soil and nutrient losses under different land management scenarios, using field data extrapolated through remote sensing and GIS, to obtain catchment‐wide estimates of the impact of land cover change. Immigration from remote provinces to the Dong Phu District of Binh Phuóc Province, about 120 km north of Ho Chi Minh City, has led to disruption of soil surface stability on easily eroded clayey sandstones, creating rapid nutrient depletion that affects crop yields and siltation in the channel of the Rach Rat river downstream. The poor farmers of the areas see crop yields drop dramatically after two or three years of cultivation due to the fertility decline. Soil loss varies dramatically between wet season and dry season and with ground cover. Erosion bridge measurements showed a mean loss of 85.2 t ha−1 y−1 under cassava saplings with cashew nuts, 43.3 t ha−1 y−1 on uncultivated land and 41.7 t ha−1 y−1 under mature cassava. The rates of erosion were higher than those reported in many other parts of Vietnam, reflecting the high erodibility of the friable sandy soils on the steep side‐slopes of the Rach Rat catchment. However, although the actual measurements provide better soil loss data than estimates based on the parameters of soil loss equations, a large number of measurement sites is needed to provide adequate coverage of the crop and slope combinations in this dissected terrain for good prediction using GIS and remote sensing.

Macro and micro nutrient limitation of microbial productivity in oligotrophic subtropical Atlantic waters

Environmental context. The subtropical oceans comprise ~70% of the world’s ocean surface and profoundly affect global biogeochemistry and climate. They are characteristically low-nutrient regions, but, owing to their large extent and often rapid nutrient turnover, may contribute to greater than 30% of the total marine primary production. However, there remains long-standing uncertainty as to what individual or combination of resources, e.g. macro (N, P) and micro (trace metals) nutrients, limit or co-limit marine productivity and thus total carbon fixation in these spatially dominant gyre systems. Abstract. The subtropical oceans are characteristically low-nutrient low-chlorophyll regions, but owing to their geographical dominance and rapid nutrient cycling may contribute &gt;30% of the total marine primary production. The present study investigates the addition of P, Fe, Co and Zn on rates of primary production and heterotrophic bacterial production, through a combination of mesoscale in situ (P, and P + Fe) and in vitro (Co or Zn) bioassay incubation experiments. Results from the bioassay incubation experiments suggest that primary production and chlorophyll a biomass are limited by N and P in this oligotrophic region. However, both were increased further after addition of trace metal micronutrients in the order Fe + Zn ≥ Fe + Co &gt; Fe ≈ Co. In contrast, rates of heterotrophic bacterial production did not appear to be P, or significantly, P + Fe limited, although in situ rates did increase during the first 12 h of mesoscale P fertilisation (which were not mirrored in the mesoscale P + Fe addition). The addition of Co to unfertilised waters increased heterotrophic bacterial production and the numbers of heterotrophic bacteria, Prochlorococcus spp. and Synechococcus spp., suggesting Co limitation. Prochlorococcus spp. were the most abundant autotrophs. The highest increases in both heterotrophic and autotrophic carbon assimilation were shown after in vitro addition of either Co or Zn to mesoscale enriched P + Fe waters, suggesting multiple limitation of microbial growth rates in the subtropical oligotrophic north-east Atlantic.

한국 남해 마산만에서 수질환경의 계절적 변동과 기초생산 제한인자

Seasonal variations of various physicochemical components (temperature, salinity, pH, DO, COD, DOC, nutrients-silicate, DIN, DIP) and potential limiting factor for phytoplankton primary production were studied in the surface water of semi-enclosed Masan Bay. Seasonal variations of nutrient concentrations, with lower values in summer and winter, and higher in fall, are probably controlled by freshwater loadings to the bay, benthic flux and magnitude of occurrence of phytoplankton communities. Their spatial distributional patterns are primarily dependent on physical mixing process between freshwater and coastal seawater, which result in a decreasing spatial gradient from inner to outer part of the bay. In the fall season of strong wave action, the major part of nutrient inputs (silicate, ammonium, dissolved inorganic phosphorus) comes from regeneration (benthic flux) at sediment-water interface. During the summer period, high Si:DIN and Si:DIP and low DIN:DIP relative to Redfield ratios suggest a N- and secondarily P-deficiency. During other seasons, however, silicate is the potential limiting factor for primary production, although the Si-deficiency is less pronounced in the outer region of the bay. Indeed, phytoplankton communities in Masan Bay are largely affected by the seasonal variability of limiting nutrients. On the other hand, the severe depletion of DIN (relatively higher silicate level) during summer with high freshwater discharge probably can be explained by N-uptake of temporary nanoflagellate blooms, which responds rapidly to pulsed nutrient loading events. In Masan Bay, this rapid nutrient consumption is considerably important as it can modify the phytoplankton community structures.

Yeasts Isolated from Neotropical Wood‐Boring Beetles in SE Peru

ABSTRACTSome temperate wood‐boring cerambycid beetles harbor intracellular gut yeasts believed to augment host nutrition, but species belonging to the subfamily Lamiinae are thought to lack endosymbionts. Almost 49 percent of Neotropical cerambycid species are lamiines, therefore, comparatively few rain forest species would be expected to host symbiotic gut yeasts. This study reports the isolation of gut yeasts from closely related Neotropical lamiines. We investigated species that feed on trees in the Brazil nut family (Lecythidaceae), because host plant associations are relatively well known. Our objectives were to determine if gut yeasts were present and, if possible, infer their mode of transmission. We collected and dissected 18 beetle specimens from three tree species, including 17 cerambycids and one curculionid. Every insect specimen yielded a gut yeast. DNA sequence libraries were used for a rapid identification of the yeasts and their larval hosts. The cerambycids included five lamiine species and one cerambycine. Six ascomycete yeasts were isolated from their guts; we found no evidence of strict vertical transmission. Larval gut yeasts were genetically similar to yeasts previously isolated from insects associated with wood or fungi, implying potential habitat specificity. The yeasts have not yet been localized, and potential function is not known, but they may contribute to rapid nutrient cycling or serve as the first line of defense against plant toxins.

The potential bioavailability of organic C, N, and P through enzyme hydrolysis in soils of the Mojave Desert

Increases in the growth rate of plants and microbes in the Mojave Desert in response to predicted increases in precipitation and CO2 due to global climate change may induce nutrient limitations. This study was designed to measure the pool of potentially bioavailable nutrients in soils of the Mojave Desert. Soils were collected from shrub and interspace microsites and then subjected to amendment with buffered solutions of an excess of various enzymes. The products of each enzyme reaction were then measured and the maximum quantity of hydrolyzable substrates was calculated. In interspace and shrub microsite soils, respectively, 14.5 and 9.7% of the organic C in the form cellulose, 60.0-97.8% and 61.2- 100.0% of the organic N in the form protein, and 44.0 and 57.5% of the organic P was hydrolyzable. There were significant differences between microsites for hydrolyzable substrate using all enzyme amendments, except protease. We propose that accumulations of hydrolyzable organic C, N, and P in the Mojave Desert could be a result of the persistently dry soil conditions often found in desert ecosystems and the immo- bilization of enzymes, which may result in low diffusivity of soil substrates and enzymes and, accordingly, little degradation of organic C, N, and P. Alternatively, rapid nutrient cycling and immobilization by soil microorganisms could account for accumulations of organic C, N, and P. Further refinement of the methods used in this study could lead to a valuable tool for the assessment of potential bioavailability of nutri- ents in a variety of soils.

Wildfire mitigation strategies affect soil enzyme activity and soil organic carbon in loblolly pine (Pinus taeda) forests

We quantified the effects of three wildfire hazard reduction treatments (prescribed fire, thinning from below, and the combination of fire and thinning), and passive management (control) on mineral soil organic C, and enzyme activity in loblolly pine (Pinus taeda L.) forests on the Piedmont of South Carolina. Soil organic C was reduced by thinning, either alone or with prescribed fire, and this effect persisted through the fourth post-treatment year. Fire also resulted in reduced soil organic C, but not until several years after treatment. Soil C/N ratio initially increased after fire, either alone or with thinning, but this difference did not persist. The activities of three soil enzymes (acid phosphatase, chitinase, and phenol oxidase) in the upper mineral soil were quantified as measures of microbial activity. During the fourth post-treatment year we observed significant stimulation of all three enzyme systems as a result of thinning or thinning and burning. Although the patterns of variation in acid phosphatase and chitinase activity among treatments were similar during the first and fourth post-treatment years, the first-year treatment effects were not statistically significant. Given the management objective of utilizing these stands for timber production, the increased potential for rapid nutrient turnover offered by thinning gives this approach advantages over prescribed fire; however, management for maximum long-term storage of soil C may be better facilitated by prescribed fire.

Estimation of a stock–recruitment relationship for Black Sea anchovy ( Engraulis encrasicolus) under the influence of nutrient enrichment and the invasive comb-jelly, Mnemiopsis leidyi

The Black Sea is typical of a highly degraded marine ecosystem. Nutrient loads increased dramatically in the 1970s, which appeared to benefit the Black Sea anchovy ( Engraulis encrasicolus). However, the accidental introduction of the comb-jelly Mnemiopsis leidyi, which preys on young anchovy and competes with adults, contributed to a collapse in the anchovy fishery in the late 1980s. Recent efforts to model Black Sea anchovy population dynamics emphasize general environmental influences and do not take these ecosystem shocks explicitly into account. In this paper, I estimate anchovy recruitment using the traditional Ricker model and under rapid nutrient enrichment. Mnemiopsis’ influence on anchovy is captured as a shift in the parameters of the recruitment function. By incorporating these environmental disturbances, the seemingly monotonic relationship between parent stock and recruitment for anchovy disappears and is replaced by a dome-shaped stock–recruitment relationship subject to regime shifts.

Field drains as a route of rapid nutrient export from agricultural land receiving biosolids

We report research on the environmental risk of incidental nutrient transfers from land to water for biosolids amended soils. We show that subsurface (drainflow) pathways of P transport may result in significant concentrations, up to 10 mg total P l − 1 , in the drainage network of an arable catchment when a P source (recent biosolids application) coincides with a significant and active transport pathway (rainfall event). However, the high P concentrations were short-lived, with drainage ditch total P concentrations returning to pre-storm concentrations within a few days of the storm event. In the case of the drainflow concentrations reported here, the results are unusual in that they describe an ‘incidental event’ for a groundwater catchment where such events might normally be expected to be rare owing to the capacity of the hydrological system to attenuate nutrient fluxes for highly adsorbed elements such as P. Consequently, there is a potential risk of P transfers to shallow groundwater systems. We suggest that the findings are not specific to biosolids-alone, which is a highly regulated industry, but that similar results may be anticipated had livestock waste or mineral fertilizer been applied, although the magnitude of losses may differ. The risk appears to be more one of timing and the availability of a rapid transport pathway than of P source.

PH BUFFER SELECTION AND ITS EFFECT ON GROWTH OF &amp;lt;EM&amp;gt;GRACILARIA LEMANEIFORMIS&amp;lt;/EM&amp;gt;

Background and Aims We examined the effect of acid-alkaline concentrations in media on growth rate and nutrient uptake of a red macroalga, Gracilaria lemaneiformis, which has a rapid growth rate, rapid nutrient uptake rate, and high agar content. We address the following questions: 1) can the culture media be kept relatively stabilized, 2) what organic compound best buffers pH, and 3) how does the compound buffer the media and affect growth of the alga? Methods Utilizing the dark-light bottles method, we selected a suitable zwitterionic organic compound from seven reagents (barbitone, borate, HEPES, TRIS, MOPS, TAPS, POPSO) that did not inhibit photosynthetic production of dissolved oxygen (DO), did not increase depletion of DO in respiration, and adjusted acid-alkaline balance in the culture media. We examined the effects of each buffer on growth rate (SGR) of G. lemaneiformis, measured diurnal and weekly variations of pH and dissolved inorganic carbon (DIC), and determined CO2 concentrations according to pH and DIC. We integrated these with the growth rate of G. lemaneiformis, to investigate the mechanisms of growth and carbon uptake. Key Results POPSO was the zwitterionic organic compound that best met our objectives. During the diurnal experiment of POPSO's effect on algal growth, pH rose continuously during the light cycle, contrary to DIC; however, high concentration of POPSO can buffer this fluctuation. During the one-week experiment, according to results of the diurnal experiment, pH values and DIC at the beginning and end of the light cycle indicated that lower concentrations of POPSO (0 and 5 mmol·L -1 ) did not buffer pH fluctuations, but higher concentrations (15 mmol·L -1 ) suitably stabilized pH values and leveled off DIC content in the media. Ambient CO2 concentration determined algal growth rates, with the relationship between SGR of G. lemaneiformis and ambient CO2 concentration similar to a Michaelis-Menton kinetics equation. The saturated concentration of CO2 was 5.25 μmol·L -1 , and the maximum growth rate of the alga was 10.11%·d -1 . Conclusions This study determined that POPSO is a suitable organic compound to buffer G. lemaneiformis culture media. A possible mechanism is that, under relative stabilization of acid-alkaline media, HCO3-and CO3 2- (components of DIC), transformed into CO2 and accelerated growth rate of the alga.

TRACING RIVER INFLUENCES ON PHYTOPLANKTON DYNAMICS IN TWO LOUISIANA ESTUARIES

To evaluate effects of river inputs on estuarine phytoplankton, we compared particulate organic matter (POM) dynamics in two neighboring estuaries from the Missis- sippi River delta. The two estuaries, Barataria Basin and Breton Sound, have been isolated from the Mississippi River at their upstream ends for most of the last century due to levee construction, but for the last 13 years, Breton Sound has been reconnected to the Mississippi River via a gated diversion at Caernarvon, Louisiana. Thus, Barataria Basin was the ref- erence estuary and Breton Sound was the river-impacted estuary. We focused on POM because it was relatively easy to collect and analyze, and because POM dynamics gave a good ecosystem-level overview of phytoplankton responses to riverine nutrient forcing and hydrologic forcing. A combination of C:N and PO13C analyses indicated that most POM was phytoplankton with smaller contributions of sediment. Estuarine concentrations of particulate organic carbon (POC) and nitrogen (PON) were typically higher than end- member freshwater or marine inputs, indicating the importance of within-system phyto- plankton growth likely fueled by rapid nutrient regeneration in these warm, shallow and well-mixed estuarine systems. Isotopic analyses generally showed typical estuarine gra- dients in the reference Barataria Basin estuary, but the river-influenced upper Breton Sound had elevated PO'3C and PO'5N values useful for following the spatial extent of river impacts. Rapid river-assisted flushing in Breton Sound probably prevented widespread development of algal blooms in response to introductions of the nutrient-rich river water, but study of some isolated lakes suggested that when longer residence times apply, introduction of river water to coastal estuaries can lead to eutrophic conditions and in some cases, harmful algal blooms. Overall, routinely monitoring amounts and isotopic compositions of POM proved an effective way to trace linkages between river inputs and downstream estuarine phyto- plankton dynamics.

Growth and nutritional response of hardwood seedlings to controlled-release fertilization at outplanting

Hardwood bareroot seedlings typically undergo transplant shock immediately following afforestation planting associated with moisture or nutrient stress. Broadcast field fertilization at outplanting with readily available nutrients has shown limited capacity to reduce nutrient stresses. Furthermore, the rapid nutrient release characteristic of broadcast fertilization leads to high levels of nutrient leaching and may stimulate growth of competing vegetation more than target trees. Application of controlled-release fertilizer (CRF) in the outplanting hole could be a useful alternative to help improve fertilizer use efficiency and alleviate competition problems associated with broadcast fertilization, thereby promoting early regeneration success of outplanted seedlings. We tested growth and nutritional response of black walnut ( Juglans nigra L.), white ash ( Fraxinus americana L.), and yellow-poplar ( Liriodendron tulipifera L.) to 6 rates (0, 15, 30, 45, 60, and 75 g plant −1) of polymer-coated CRF applied to the root zone at outplanting in southern Indiana, USA. Fertilizer release was evenly distributed between years 1 and 2. Seedling survival was above 85% for all treatments. Compared to non-fertilized seedlings, the 60 g seedling −1 rate accelerated mean height and root-collar diameter (RCD) growth by 52 and 33% in year 1 and 17 and 21% in year 2. Nitrogen (N) and potassium (K) uptake were increased 40 and 30% at the 60 g rate compared with controls. Height and RCD growth were greater by 543 and 200% in white ash and 300 and 233% in yellow-poplar, relative to black walnut. Uptake of N and K was increased by 79 and 22% in yellow-poplar and 93 and 56% in white ash, compared to black walnut. Results suggest CRF has potential to improve early establishment success of hardwood afforestation plantings.

Effect of forest tree species on the humus form state at lower altitudes

&amp;nbsp; The paper documents the effects of forest stands of different species composition on the humus form state and soil profile chemistry. It compares the situation in mixed broadleaved (ash, oak, hornbeam), basswood and spruce stands. Spruce demonstrates the site degradation effects: raw humus accumulation, soil acidification, negative effects on nutrient dynamics. Both broadleaved stands were similar as for site effects, lower litter accumulation, more rapid organic matter mineralization and more rapid nutrient cycling and intense uptake were documented in the basswood stand. &amp;nbsp;

Nutrient sensing through the plasma membrane of eukaryotic cells, Cirencester, UK, 25?29 September, 2004

Yeast has been at the forefront of research on nutrient signaling for many years. Also in many other eukaryotic cell types, nutrients exert a wide variety of regulatory effects. Up till recently, however, the literature on nutrient-induced regulatory phenomena was very diverse. The discovery of several types of plasma membrane-based nutrient sensors in yeast has dramatically changed this situation. Non-transporting nutrient carrier homologues, G-protein-coupled receptors and actively-transporting nutrient carriers have all been identified as nutrient sensors in the yeast plasma membrane and in several cases this has rapidly been extended to other yeast species. These striking discoveries have resulted in an intensive search in other eukaryotic systems, fungal, plant as well as mammalian types, for similar nutrient sensors and several examples have recently been identified (for a review see: Holsbeeks et al., 2004, Trends Biochem. Sci. 29, 556–564). The conference in Cirencester, organized by Soraya Shirazi-Beechey, Johan Thevelein and Frank Stolz and managed by the UK. Biochemical Society as a focused meeting, concentrated on these novel types of nutrient-sensing systems present in or functionally closely linked to the eukaryotic plasma membrane. The meeting was divided in three sections with basically one day each devoted to nutrient sensing in yeasts, plants and mammalian cells. The first day had lectures by Mark Johnston explaining the rationale of glucose sensing in yeast with respect to its fermentative lifestyle and further concentrating on the Snf3-Rgt2 signaling pathway which controls the induction of the glucose carrier genes by glucose. It was the first example discovered in eukaryotic cells of a nutrient sensing system employing non-transporting nutrient carrier homologues as nutrient sensors. The next talk was given by Johan Thevelein who concentrated on the remarkable variety of nutrient sensors involved in rapid nutrient activation of the protein kinase A (PKA) pathway. Glucose activation of cAMP synthesis …