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The East China Sea (ECS) is a marginal sea with high productivity, especially in summer. In the Zhejiang coastal region of ECS, the large phytoplankton biomass in summer is attributed to the nutrients pumped up by Zhejiang coastal upwelling (ZCU), and oceanic nutrients supplied by the Kuroshio intrusion (KI) onto continental ECS. However, the yearly variations in these two processes are not consistent, which complicates coastal nutrient supplies. In this study, to understand the contributions of ZCU and KI to the nutrient supplies, nutrient concentrations, and phytoplankton biomass in ECS as well as their yearly variations, a physical‐biochemical coupled model was applied. According to model results and observations, the years 2013 and 2018 were identified as strong and weak ZCU years during 2010–2018 period, respectively. In 2013, nutrient and chlorophyll‐a concentrations were higher than 2018 in nearshore areas, but nutrient concentrations were lower than 2018 at the bottom of wide offshore areas. Strong wind stress in 2013 induced strong ZCU and shoreward net nutrient flux along the 60‐m isobath, which was seaward in 2018. The fewer nutrient supplies from KI in the spring of 2013 decreased the nutrient concentrations at the bottom of offshore areas, but its influence on nearshore nutrient concentrations was not as obvious as that caused by ZCU. Phytoplankton biomass in the nearshore and offshore areas reflected different mechanisms of nutrient supplies. In conclusion, the intensity of ZCU, rather than KI, is the principal factor influencing the coastal primary productivity of ECS in summer. Plain Language Summary: The Zhejiang coastal region in the East China Sea is one of the most important fishing grounds in China. The highest productivity in this region appears in summer. It is reported that the coastal productivity benefit from the nutrients transported by local upwelling in summer and Kuroshio intrusion (KI) from the open sea in spring. To reveal the contributions of the two processes, we used a numerical model to investigate the nutrient supply and phytoplankton biomass influenced by the upwelling and KI. The results showed that the more intense alongshore wind in summer induced stronger upwelling, and significantly increased nutrient supply in nearshore areas. The KI mainly influenced the nutrient supply from the open sea and the nutrient concentrations in offshore areas at the sea bottom. The nearshore nutrient supply and phytoplankton biomass are primarily determined by the intensity of upwelling and secondarily influenced by that of KI. This study distinguished the effects of local and remote processes, and highlighted the influences of their match and mismatch to the yearly variations in the nutrient supply to the nearshore area of East China Sea. Key Points: A strong upwelling year and a weak upwelling year are identified from 2010 to 2018 based on model results and observationsCoastal upwelling and Kuroshio intrusion mainly control the nutrient supply in nearshore and offshore areas, respectivelyNearshore chlorophyll‐a and offshore subsurface chlorophyll maximum are accordingly determined by Zhejiang coastal upwelling and Kuroshio intrusion intensities, respectively [ABSTRACT FROM AUTHOR]

Metasequoia glyptostroboides (M. glyptostroboides) is a unique plant species related to relic flora in China. It plays a positive role in afforestation and its long-term protection with high paleoclimate research value. However, due to the nutrients-supply deficiency, it is a big challenge to cultivate the high-quality seedlings of M. glyptostroboides. In this study, a pot experiment in a greenhouse environment was carried out to identify the effect of N-exponential fertilization on the growth and nutrient distribution of M. glyptostroboides seedling. The M. glyptostroboides rooted seedlings with 12-month growth were chosen. Different N fertilizer levels with conventional fertilization (CF: 5.0 g seedling-1), exponential fertilization including EF1, EF2, EF3 and EF4 were determined. The relevant growth indexes were measured after 210-day growth. The results indicated that non-significant differences in seedlings' height and ground diameter were found among the above treatments (P > 0.05); At the same time, N-exponential fertilization promoted the M. glyptostroboides's biomass in different organs (P < 0.05), with the maximum total biomass under EF3 treatment. The N accumulation in root and stem of the N-exponential fertilization treatments were increased in to some extent (P < 0.05). The maximum N accumulation was also found under EF3 treatment. Therefore, steady-state nutrition and superior growth performance of M. glyptostroboides could be obtained by N-exponential fertilization of 5.0 g cutting-1. [ABSTRACT FROM AUTHOR]

Various types of flat rhizoboxes aid in root visualization and tracking in experiments where the focus is upon root system growth and development. While size of the pot is known to affect experiments, nothing is known about the impact of rhizoboxes—not only their volume, but also their shape might affect root and shoot growth. Therefore, we investigated how rhizoboxes change plant biomass and root:shoot biomass partitioning. We compared biomass and root:shoot ratio of plants growing in the pots with different geometry—usual three-dimensional, cuboid plant pots and flat two-dimensional rhizoboxes about the same volume. We used two different nutritional treatments (deionized water and additional nutrients) for investigating whether the nutrient availability in the substrate changed the impact of rhizoboxes on plant growth. We used 15 species for the generalizability of our results across the phylogenetic tree. Proportional investment of plants into roots was similar in usual pots and in rhizoboxes. This pattern was stable across nutrition treatments and across species. Further, we found no differences in total biomass of plants between pot type within nutrient treatments. With added nutrients, the plants had a higher biomass and lower root:shoot ratio compared to treatments without nutrient addition. Thus, species can be safely compared when grown in the rhizoboxes; rhizoboxes did not affect root system growth comparisons among species and nutrient levels. Also, they did not affect plant growth in terms of total biomass. [ABSTRACT FROM AUTHOR]

Three cruises were conducted to investigate the distributions of nutrients, chlorophyll a (Chl-a), new and regenerated primary production, bacterial abundance and production, and microzooplankton grazing rates in the Yellow Sea (YS) and the South China Sea (SCS) during March and May. As the water column moved from low to high temperature, weak to strong stratification and high to low nutrients from the YS to the SCS, Chl-a, primary production and bacterial biomass decreased. In contrast, bacterial production, microzooplankton grazing and size preference increased from the YS to the SCS. The increasing grazing activity and decreasing f-ratio from the YS to the SCS suggest roles of regenerated nutrients in the supporting the community increased and more bacteria played important roles in the carbon flow in the oligotrophic SCS than in the eutrophic YS. These variabilities force the classical food chain dominated community in the eutrophic waters into the microbial loop, which is dominant in oligotrophic waters. As nutrients decrease, temperature and grazing activity increase from the YS to the SCS. The increasing ratio of integrated bacterial production to integrated primary production indicates that communities change from autotrophy to heterotrophy and waters change from a carbon sink to a carbon source. [ABSTRACT FROM AUTHOR]

Large areas of peatlands have worldwide been drained to facilitate agriculture, which has adverse effects on the environment and the global climate. Agriculture on rewetted peatlands (paludiculture) provides a sustainable alternative to drainage-based agriculture. One form of paludiculture is the cultivation of Sphagnum moss, which can be used as a raw material for horticultural growing media. Under natural conditions, most Sphagnum mosses eligible for paludiculture typically predominate only in nutrient-poor wetland habitats. It is unknown, however, how the prevailing high nutrient levels in rewetted agricultural peatlands interfere with optimal Sphagnum production. We therefore studied the effect of enriched nutrient conditions remaining even after top soil removal and further caused by external supply of nutrient-rich irrigation water and (generally) high inputs of atmospheric nitrogen (N) to habitat biogeochemistry, biomass production and nutrient stoichiometry of introduced Sphagnum palustre and S. papillosum in a rewetted peatland, which was formerly in intensive agricultural use. Airborne N was responsible for the major supply of N. Phosphorus (P) and potassium (K) were mainly supplied by irrigation water. The prevailing high nutrient levels (P and K) are a result of nutrient-rich irrigation water from the surroundings. Peat porewater (10 cm below peatmoss surface) CO 2 concentrations were high, bicarbonate concentrations low, and the pH was around 4.2. Provided that moisture supply is sufficient and dominance of fast-growing, larger graminoids suppressed (in order to avoid outshading of Sphagnum mosses), strikingly very high biomass yields of 6.7 and 6.5 t DW ha −1 yr −1 ( S. palustre and S. papillosum [including S. fallax biomass], respectively) were obtained despite high N supply and biomass N concentrations. Despite high P and K supply and uptake, N:P and N:K ratios in the Sphagnum capitula were still low. Sphagnum mosses achieved high nutrient sequestration rates of 34 kg N, 17 kg K and 4 kg P ha −1 yr −1 from May 2013 to May 2014, which shows that the site acted as an active nutrient sink. Nutrient management still needs further improvement to reduce the competitive advantage of fast growing peatmoss species (cf. S. fallax ) at the expense of slower growing but preferred peatmosses as horticultural substrate ( S. palustre and S. papillosum ) to optimize the quality of biomass yields. In conclusion, Sphagnum farming is well able to thrive under high N input provided that there is a simultaneous high input of P and K from irrigation water, which facilitates high production rates. Due to the lack of suitable, nutrient poor sites, it seems to be useful to remove the topsoil (mainly P removal) prior to start growing Sphagnum mosses. In addition, bicarbonate concentrations have to stay sufficiently low to ensure a low pH, CO 2 supply from the peat soil should be sufficiently high to prevent C limitation, and graminoids should be mown regularly. [ABSTRACT FROM AUTHOR]

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The article focuses on a study regarding the impact of faunal diversity on benthic microalgae, net ecosystem metabolism, sediment nutrient fluxes and macroalgal biomass and productivity in shallow estuaries. The site chosen for the study is West Falmouth Harbor in Cape Cod, Massachusetts which has an average depth of 0.6 meters (m) at mean low water. Macroalgae considered in the study are given which are the rhodophyte Gracilaria, the chlorophyte Ulva and the phaeophyte Fucus vesiculosus while the macroinvertebrate species observed are the eastern mudsnail Ilyanassa obsoleta Say, the soft-shelled clam Mya arenaria and the king ragworm Alitta virens Sars. Findings of the study are discussed, one is the decline of Gracilaria biomass over time in all treatments under experiment II.

Abstract: This paper reviews about 190 publications related to the anatomy, morphology and growth of aboveground and belowground parts of common reed (Phragmites australis). In addition to the general description of plant structure, observations on germination, growth dynamics, biomass, effects of habitat conditions such as temperature, salinity, nutrient supply and water depth are evaluated. The impact of animal, fungal and algal attacks, and human intervention (burning and harvesting) on reed growth, and the potential genetic determinacy behind the response of reed to environmental changes are also discussed. [Copyright &y& Elsevier]

Abstract: In Canada''s eastern boreal forest, the stagnant growth of black spruce (Picea mariana (Mill.) BSP) seedlings is often observed in the presence of ericaceous shrubs such as Kalmia angustifolia L. Many mechanisms, including allelopathic interference, reduced soil N mineralization, soil enzymes inhibition, and direct resource competition have been proposed to explain poor spruce growth in the presence of Kalmia. However, the relative importance of direct competition versus indirect interference remains unclear. Our objective was thus to adequately isolate the “Kalmia effect” from other growth-limiting factors and to determine if removal of Kalmia also resulted in fundamental changes in the biochemical properties of the forest floor. By sampling plots established in 2000, we evaluated how Kalmia eradication and spot fertilization influenced soil nutrient availability, N mineralization rates, microbial basal respiration and biomass, as well as planted black spruce seedling growth, dimensions, and foliar nutrient concentrations 6 years later. We measured higher extractable-P, mineralizable-N, seedling dimensions and growth rates, as well as lower extractable-K, total-K, basal respiration and microbial biomass, in plots without Kalmia than in those where Kalmia had been maintained from 2000 to 2006. Our results thus confirmed that Kalmia eradication over 6 years not only improved the growth and nutrition of black spruce seedlings, but also resulted in fundamental changes in the biochemical properties of the forest floor. We demonstrated that along with direct competition for resources, Kalmia interferes indirectly with black spruce by modifying nutrient cycling and energy fluxes in soil. Higher indices of available C in plots with Kalmia corroborates that Kalmia tannins or rhizodeposition may reduce N mineralization by stimulating microbial immobilization, a relation that however needs to be confirmed with longer term laboratory incubations. Our results indicated that although it had a positive influence on seedling growth, the fertilization effect was confined to the first few years following treatment application, and failed to influence soil processes as did Kalmia eradication. Further monitoring will indicate if the increased litterfall in fertilized plots will eventually initiate a second wave of fertilizer-induced changes to soil processes, as observed in other ecosystems. [Copyright &y& Elsevier]

Abstract: According to ocean-color remote sensing data, a low phytoplankton biomass exists in the central parts of the Sulu and Celebes seas, whereas higher concentrations of chlorophyll a are observed in the waters near the Sulu Archipelago, which separates these water bodies. These high-chlorophyll a waters have lower temperatures than those of surrounding waters, indicating vertical mixing of nutrient-rich subsurface water that is attributable to the topographical features of the Sulu Ridge. Differences in photosynthetic parameters, primary productivity and the phytoplankton community structure between the high-chlorophyll area near the Sulu Archipelago and the oligotrophic basin area in the Philippine, Sulu and Celebes seas were investigated in November 2002 during the R.V. Hakuho-Maru KH-02-4 cruise. Entrainment of subsurface water and vertical mixing by intense tidal flow from the Sulu Archipelago to the Celebes Sea created a low-temperature, high-nutrient condition at the southeastern edge of the Sulu Ridge. Chlorophyll a concentrations greater than 2μgl−1 were observed at stations 5–15km offshore at the edge of the Sulu Ridge. This high-chlorophyll tongue in the Celebes Sea showed high primary productivity: it was 1.6–18 times higher than those measured in oligotrophic central basin regions of the Philippine, Sulu, and Celebes seas. Microscopic observation of these high-chlorophyll waters showed the dominance of chain-forming large centric diatoms. Extension of high-chlorophyll waters was not observed at the Sulu Sea side, where the surface water salinity was lower than in the Celebes Sea and consequently prevented intrusion of the Celebes Sea water into the surface layer. Occasional extensions of productive, chlorophyll-rich surface water from the archipelagic zone to the surrounding basin area seems to be an important factor causing spatiotemporal variability in the phytoplankton biomass in the southern Sulu Sea and the western Celebes Sea. [Copyright &y& Elsevier]

The taxonomic composition and biomass of phytoplankton in the San Joaquin River, California, were examined in relation to water depth, flow regime, and water chemistry. Without substantial tributary inflow, maintenance demands exceeded algal production during summer and autumn in this eutrophic, `lowland type' river due to light-limiting conditions for algal growth. Streamflow from tributaries that drain the Sierra Nevada contributed to a substantial net gain in algal production during the spring and summer by increasing water transparency and the extent of turbulence. Abundances of the major taxa (centric diatoms, pennate diatoms and chlorophytes) indicated differing responses to the longitudinal variation in water depth and flow regime, with the areal extent of pools and other geomorphic features that influence time-for-development being a major contributing factor to the selection of species. Tychoplanktonic species were most abundant upstream and in tributaries that drain the San Joaquin Valley. Seasonally-varying factors such as water temperature that influence algal growth rates also contributed significantly to the selection of species. Nutrient limitation appears not to be a primary constraint on species selection in the phytoplankton of this river. [ABSTRACT FROM AUTHOR]

The effects of cropping, nutrition and water supply on accumulation and distribution of biomass and nutrients for apple trees on `M9' root systems were examined using trees growing in lysimeters. For 3-year-old `Golden Delicious' trees, cropping significantly increased total biomass, although leaf and root biomass were reduced. For 3-year-old `Golden Delicious', `Con Orange' and `Gloster' trees, cropping only in the third year reduced root biomass by 39 to 45%. Cropping did not affect water use by trees of any cultivar early in the season, but increased water use later in the season for `Gloster' trees. For trees with fruit, total non-structural carbohydrate (TNC) contents at the end of the season were highest in fruit (up to 1400 g plant-). For trees without fruit, TNC contents were generally highest in the roots (up to 110 g plant-1). Supplying trees with nutrient solution diluted to 10% of the standard composition increased the root biomass for `Golden Delicious' trees only, but decreased biomass of above-ground tissues for all cultivars. Reducing the nutrient supply decreased water and nutrient uptake, and reduced nutrient contents within vegetative parts of the tree more than within roots. For `Golden Delicious' trees., restricting the water supply to 50% or 25% of that consumed by control trees significantly reduced above-ground biomass, but root biomass was not significantly affected. The N, P and K contents for the trees were also reduced by water stress, due to reduced contents within above-ground organs. Water stress reduced the TNC and starch contents of all tissues, except the roots. These results are discussed in relation to the efficiency of root systems for water and nutrient uptake. [ABSTRACT FROM AUTHOR]