Biomass Accumulation Rate Research Articles

Interactive effects of salinity, high light, and nitrogen starvation on fatty acid and carotenoid profiles in Nannochloropsis oceanica CCALA 804

Flexible responses of lipid metabolism to changes in cultivation conditions characteristic of oleaginous microalgae of the genus Nannochloropsis render them a promising source of triacylglycerols for biodiesel (under nutrient‐deprivation and high‐light stress) and eicosapentaenoic acid (EPA; C20:5, n‐3) (under nutrient sufficient conditions). We investigated the responses of fatty acid and pigment profile in the euryhaline Nannochloropsis oceanica CCALA 804 to the combined stresses of high light (HL), salinity (0, 27, and 40 g/L NaCl) and nitrogen deprivation. The growth in nitrogen‐replete medium under HL triggered a rapid acclimation of the microalgae to the HL stress in a salinity‐dependent manner associated with a moderate decrease of EPA proportion of total FA. Nitrogen starvation (i) slowed the biomass accumulation, (ii) enhanced the production of reserve lipids at the expense of chloroplast lipids, and (iii) triggered photoprotective responses of pigment apparatus in N. oceanica. Regardless of cultivation conditions, the stress‐induced changes in pigments and fatty acid profile were highly coordinated. Nitrogen‐starvation promoted total FA accumulation on the background of a marked decline in EPA and light‐harvesting Car as well as up‐regulation of violaxanthin cycle with concomitant rise in non‐photochemical quenching. Zero‐NaCl conditions appeared to be beneficial for biomass and EPA accumulation and alleviated, especially under nitrogen starvation, the effects of salinity stresses (the decline in biomass accumulation rate, content of light‐harvesting carotenoids and EPA, and photosynthetic efficiency). Strategies of N. oceanica acclimation to stresses of different nature and their possible implications for the biotechnology of this species are discussed.

Factors explaining variability in woody above-ground biomass accumulation in restored tropical forest

Secondary forests comprise an increasing area of the tropics and play an important role in global carbon cycling. We compare above-ground biomass accumulation of both planted and naturally regenerating trees, as well as C in the top soil layer, in three restoration treatments replicated at 14, six to eight year old restoration sites in southern Costa Rica. Restoration strategies include: control (no planting), planting tree islands, and conventional, mixed-species tree plantations. We evaluate the importance of past land-use, soil nutrients, understory cover, and surrounding forest cover in explaining variation in above-ground biomass accumulation (ABA) rate across sites. Total ABA and planted tree ABA rate were highest in plantations, intermediate in islands, and lowest in control treatments, whereas ABA rate of naturally regenerating trees did not differ across treatments. Most ABA in plantations (89%) and islands (70%) was due to growth of planted trees. Soil carbon did not change significantly over the time period of the study in any treatment. The majority of across-site variation in both total and planted tree ABA rate was explained by duration of prior pasture use. Tree growth in the first two years after planting explained approximately two-thirds of the variation in ABA rate after 6–8years. Soil nutrient concentrations explained relatively little of the variation in planted or naturally recruiting ABA rate. Our results show that planting trees substantially increases biomass accumulation during the first several years of forest recovery in former agricultural lands and that past-land use has a strong effect on the rate of biomass accumulation. Planting tree islands is a cost-effective strategy for increasing ABA and creating more heterogeneous habitat conditions than tree plantations. We recommend small scale planting trials to quickly assess potential biomass accumulation and prioritize sites for ecosystem service payments for carbon sequestration.

不同倍性冬小麦种内竞争能力的比较研究

In order to illustrate the competitiveness of three different ploidy wheats( the diploid Triticum monococcum,the tetraploid Triticum dicoccum,and the hexaploid Triticum aestivum Changwu 134),field experiment was conducted in Yangling with three planting densities( low,medium and high density,exactly 1,2. 5 and 4 million plants per hectare),two kinds of water conditions were taken as well respectively one with normal rainfall and irrigation while the other with none. The response of plant height,above-ground biomass,the tiller number per plant,grain yield and yield components to the density and water conditions among three wheat varieties was investigated. The result indicates that: 1) As wheat population density increased,the competition between individuals turned more intensive,biomass and tiller was obvious reduced,biomass accumulation rate declined. On the other side,the ample supply of moisture promoted the individual growth,difference between populations increased significantly along with individuals competition decreased. The diploid and tetraploid got the greatest height under medium density at harvest time,comparing with hexaploid what; 2) With the increase of population,the competition was strengthened and individual fecundity decreased gradually. Although spike density increased significantly,the strengthening of individual competition for resources limited the dry matter accumulation in post flowering,ultimately resulting in a significant declined in individual reproductivty,the final induced that the grain yeild did not increase with the population increased,especially under water deficit. The results showed that there is not a determined positive linear relationship between population size and yield. Under normal water supply both tetraploid and hexaploid got the highest yield under low density,which proved that high yield could be obtained under appropriate density in the premise of water saving with reasonable water strategy,improved population photosynthetic capacity,increased dry matter accumulation and proportion in post flowering; 3) Tiller number and plant height of Changwu 134 was lower thandiploid and tetraploid,the individual ability to compete for resources was lower,while the biomass accumulation rate had obvious superiority. Tetraploid showed the strongest ability in individual competition among the three ploidy wheats.Chagnwu 134 abtained the highest population yield under both drought and irrigation treatments,the two primitive species showed no significant difference meanwhile. Chagnwu 134 put up no obvious superiority on grain number per spike and spike density,but seed weight reached around 50 g /per 1000,and harvest index was close to 50%. Modern variety Chagnwu134 proved the the most significant yield reduction under drought condition,and showed up the strongest response to density under drought stress,which confirmed that drought influenced it most and it had a lowest drought resistance ability. The low competitive ability is the foundation in high population production. Modern wheat varieties put up more reasonable dry matter allocation ability,and they are more close to ideal plant type,which means that modern wheat variety receive high yield from the decrease of individual competiveness. All above-mentioned results provides the theory basis and good understand for water saving and high yield cultivation and the breeding in the arid and semi-arid area.

Nutrient Uptake Efficiency and Growth of Two Aquatic Macrophyte Species under Constructed Wetlands, Ethiopia

This study was carried out to investigate the growth and nutrient uptake of two wetland plants from Lake Tana. Rhizomes of Cyperus papyrus and Phragmites karaka were grown outdoors in four parallel-aligned horizontal sub-surface flow constructed wetland (hssfcw) treatment beds. The treatment beds were irrigated with wastewater sourced from students’ residence from January 21 to March 20, 2011. The results of the study showed that Cyperus papyrus had higher rate of biomass accumulation as evidenced by increase in shoot and root weights (83.93 gm) compared to Phragmites karka . It had also significantly (p < 0.05) higher root total phosphorus and leaf total nitrogen content than that of Phragmites karka . The mean removal efficiency of the papyrus -planted treatment bed was 56.37% (NO 3 -N), 84.04% (PO 4 3- ); the phragmites- planted treatment bed was 58.37% (NO 3 -N), 65.18% (PO 4 3- ) and the unplanted (control) treatment bed was 36.13% (NO 3 -N) and 50.21% (PO 4 3- ). Pollutant removal efficiency differences were statistically significant (p < 0.05) between planted and unplanted treatment beds for PO4 3- but not for NO 3 -N. The study also showed that the progressive increase in the plant density, shoot length and stem diameter was positively correlated with the nutrient removal efficiency of the treatment beds. The average removal efficiency of the two planted treatment beds was higher than unplanted bed. The study proved that these macrophytes had the ability to accumulate high biomass and remove nutrients and therefore have high potential in biological nutrient removal processes.

A METHOD FOR PROCESSING OF KERATIN-CONTAINING RAW MATERIAL USING A KERATINASE-PRODUCING MICROORGANISM STREPTOMYCES ORNATUS S 1220

Abstract: The effect of substrate on mycelium growth, the optimal composition of the culture medium, and the optimal cultivation conditions for Streptomyces ornatus S 1220 have been investigated in the present work. The specific activity of keratinase has been monitored during cultivation and activity variation caused by addition of various salts to the cul-tivation medium has been analyzed. The results of the optimization study are reported and successful use of the culture studied in the present work in processes performed on an industrial scale is anticipated. Key words: keratin, secondary raw materials, processing, keratinase-producing microorganism, enzyme, protein, culti-vation, keratinase activity, bioconversion UDC 577.151.35:547.962.9 DOI 10.12737/2051 INTRODUCTION The amount of secondary raw material obtained dur-ing slaughter and processing of poultry can be as high as 45% of the live weight of the birds. Most of this materi-al is constituted by down and feathers, which have a high biological value, since they contain about 85% keratin. Keratins are abundant proteins found in epithelial cells. They are major structural components of skin, nails, hair, feathers, and wool. Analysis of the amino acid composition of keratins shows that these proteins are a rich source of essential amino acids. However, the transformation of natural keratin into a digestible form is problematic, since keratins are fibrillar proteins and their mechanical stability is higher than that of all other materials of biological origin except chitin. The conven-tional techniques used for the processing of keratin-containing raw materials are neither efficient nor ration-al. The use of physical and chemical processing meth-ods can result in formation of various toxic substances, as well as in loss of up to 75% of protein. Consequently, novel procedures for the processing and efficient use of the secondary raw material are needed. Enzymatic methods for the processing of protein-containing raw materials, which became available due to the development of biotechnology, allow for the preser-vation of all essential amino acids. The use of ready-made enzyme preparations on an industrial scale can lead to a significant increase in costs and expenses, and there-fore it is necessary to find solutions which enable the minimization of processing costs for the keratin-containing raw material. The use of live microorganism cultures in the processing of keratin-containing raw material allows for a reduction of the processing costs. The bioconversion method involves cultivation of the enzyme-producing strains on a substrate formed by the raw material to be processed. High efficiency of the sub-sequent decomposition of the substrate can be attained if this method is used. Selection of the optimal enzyme-producing microorganism and the optimal cultivation conditions is necessary in order to increase the rate and efficiency of bioconversion employing this method. With the requirements concerning the strain and its functional efficiency taken into account, we chose the keratinase-producing strain Streptomyces ornatus S 1220. Simple composition and low cost of cultivation media, high levels of keratinase production, short culti-vation time, and high enzyme yield [4] were the primary reasons for the choice of this strain. The aim of the present work, formulated with the current problems taken into account, was to define the optimal composition of the cultivation medium provid-ing for a high biomass yield of Streptomyces ornatus S 1220, to determine the most appropriate cultivation temperature and the period during which the rate of bi-omass accumulation is the highest, and to assess the effect of chemical additives on the specific enzyme ac-tivity. The tasks to be fulfilled in order to achieve the aim included analysis of the chemical composition of feathers, characterization of the effect of complex culti-vation media on the yield of keratinase produced by the microorganism, analysis of environmental effects on the growth and productivity of the microorganism under investigation, and optimization of the cultivation pa-rameters established.

PHOTOSYNTHESIS, RESPIRATION AND GROWTH RATE OF СHLAMYDOMONAS REINHARDTII ON EXOGENIC ETHANOL APPLICATION

Aim. The aim of the present work was studying the effect of ethanol on the rate of photosynthesis, respiration and productivity of Chlamydomonas reinhartdii. Methods. The amount of chlorophyll (Chl) was estimated photometrically. The rate of biomass accumulation was estimated by changes in packed cell volume. The rate of photosynthesis, maximum intensity of respiration and dark respiration was determined by infrared gas analysis. Results. In the presence of ethanol growth of culture in the terms of packed cell volume is inhibited, also the accumulation of Chl in cell culture is reduced and cell death is observed both in the light and in the dark. This is accompanied by decreasing pH of the culture medium from 7.2 to 3.5. The intensity of dark respiration is doubled after the addition of 50 mM ethanol to the culture medium. The rate of photosynthesis is reduced in the presence of 50 mM ethanol on 25% compared with the control. Conclusions. There were made a conclusion that the cause of growth inhibition of C. reinhartdii was incomplete oxidation of ethanol, resulting reduction of pH in the medium by a few units.

Comment on “Annual cycles of ecological disturbance and recovery underlying the subarctic Atlantic spring plankton bloom”

Key Points The Dilution‐Recoupling Theory (DRT) computes biomass accumulation rates from depth‐integrated biomass in autumn and winter but from surface concentration in spring This formulation is valid during autumn and winter. Hence the DRT provides a useful explanation of winter ecosystem functioning This formulation is invalid during spring. As a consequence, the DRT does not provide an explanation for the evolution of the spring bloom.

Impacts of invasive riparian knotweed on litter decomposition, aquatic fungi, and macroinvertebrates

Bohemian knotweed (Polygonum × bohemicum), the hybrid between Japanese and giant knotweed, is the most common invasive knotweed species in western North America and the most difficult to control. Invasive knotweed congeners spread aggressively along streams and establish dense monotypic stands, reducing riparian plant species diversity. Allochthonous organic matter inputs from riparian plants are an important source of energy and nutrients for organisms in small streams. However, little information exists concerning the influence of knotweed on stream processes. This study examines the quality of Bohemian knotweed leaves compared to native red alder and black cottonwood leaves, along with leaf-associated fungal biomass accumulation, macroinvertebrate communities, and decay rates from three forested streams in western Washington State. Senesced knotweed leaves were lower in nitrogen and phosphorus, and higher in cellulose, fiber, and lignin content than alder leaves, but were more similar to cottonwood leaves. Fungal biomass differed among species and changed over time. Macroinvertebrate shredders collected from leaf packs after 31 days were proportionately more abundant on alder leaves than knotweed and cottonwood. Decay rates were not significantly different among leaf species, but during the first 31 days alder broke down faster than knotweed. After 56 days, all of the leaf packs were mostly decomposed. Overall, these findings do not show major discrepancies between leaf species except those related to initial litter structural and chemical quality. However, changes in the timing and quantity of litter inputs are also important factors to be considered in understanding the impact of invasive knotweed on stream ecosystem processes.

Carbon Sequestration Potential of Chir Pine (&lt;i&gt;Pinus&lt;/i&gt;&lt;i&gt; &lt;/i&gt;&lt;i&gt;roxburghii&lt;/i&gt;. Sarg) Forest on Two Contrasting Aspects in Kumaun Central Himalaya between 1650-1860 m Elevation

The tree density for Chir Pine forests on the southern aspect was 1676.66 indi. /ha and on northern aspect 1026.66 indi. /ha. The tree biomass on southern aspect was 252.65 t ha<SUP>-1</SUP> and on northern aspect it was 453.58 t ha<SUP>-1</SUP>. The tree biomass accumulation rate on the southern aspect was lower than the northern aspect. The forest carbon stock on the southern aspect was 120.0 t ha<SUP>-1</SUP> compared to 215.45 t ha<SUP>-1</SUP> on the northern aspect. The carbon sequestration rate on the northern aspect was also lower than southern aspect.

Resurrecting the Ecological Underpinnings of Ocean Plankton Blooms

Nutrient and light conditions control phytoplankton division rates in the surface ocean and, it is commonly believed, dictate when and where high concentrations, or blooms, of plankton occur. Yet after a century of investigation, rates of phytoplankton biomass accumulation show no correlation with cell division rates. Consequently, factors controlling plankton blooms remain highly controversial. In this review, we endorse the view that blooms are not governed by abiotic factors controlling cell division, but rather reflect subtle ecosystem imbalances instigated by climate forcings or food-web shifts. The annual global procession of ocean plankton blooms thus represents a report on the recent history of predator-prey interactions modulated by physical processes that, almost coincidentally, also control surface nutrient inputs.

Hydrothermal upgrading of algae paste: Application of 31P‐NMR

Although already proposed in the 1940s, hydrothermal upgrading of biomass, and specifically algae, to produce biocrude has only recently become a much researched topic. Algae are of special interest as they are capable of much higher biomass accumulation rates than terrestrial plants. To understand the transformation of algal biomass into biocrude, this process needs to be scrutinized in as much detail as possible to identify the most appropriate reaction conditions. It is usually not possible to identify individual transformation steps; however, in this article we demonstrate the use of 31P‐NMR to follow the fate of derivatized (2‐chloro‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaphospholane) hydroxyl groups to start understand, which chemical species are involved in the initial degradation steps.Our data show the occurrence of a very fast degradation of acidic OH groups (derived from the hydrolysis of lipids) and aliphatic OH groups (derived from the fast hydrolysis of carbohydrates). The degradation of proteins leads to polyphenols, which appear to be rather stable even over prolonged treatment periods. Small quantities of aromatic compounds are also formed as secondary degradation products through sugar dehydration and cyclization as well as peptide transformation. It appears that additional deoxygenation routes exist as the deoxygenation rate using 31P‐NMR and that determined by elemental analysis differ. The formed oil (biocrude) is compared with typical North Sea oils using simulated distillation and was found to contain a significant high boiling faction, which would require further treatment (e.g., hydrocracking) to shift the boiling range to a more valuable oil composition. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 1002–1012, 2013

DIATOM ECOLOGY AND MICROBIAL MAT STRUCTURE AND FUNCTION IN ANTARCTIC DRY VALLEYS

Streams in the McMurdo Dry Valleys of Antarctica (MDV) are harsh habitats for life. Months of perpetual darkness and subzero temperatures are punctuated by months of perpetual sunlight, intense UV radiation, and temperatures that hover around freezing. The availability of liquid water regulates biological activity and limits the growing season to 6–10 weeks each year. These harsh conditions likely allow perennial microbial mats to persist in this freshwater environment (Fig. 1), as the rates of biomass accumulation exceed losses due to grazing metazoans and scouring (McKnight and Tate, 1997). FIGURE 1— Harnish Creek Tributary in the McMurdo Dry Valleys of Antarctica. A) Glacial meltwater flows into stream channels that drain into closed-basin lakes on the valley floors. The unconsolidated sediments in this image represent much of the ground surface, while a stable stone pavement is found in numerous stream channels, which results from freeze-thaw action over many years. Large seepage areas and a wide hyporheic zone develop as meltwater infiltrates the unconsolidated sediment. B) Close-up of area. C) Vibrant black and orange colors are UV-protective pigments produced by filamentous cyanobacteria, which form the matrix. Gas bubbles within the microbial mat demonstrate the high photosynthetic rates that can be achieved. Photo credit: Breana Simmons. Despite the extreme selective conditions, MDV microbial mats harbor a diverse diatom flora. Diatoms comprise a large lineage of eukaryotic algae that are broadly distributed in aquatic habitats and contribute significantly to global primary productivity (Treguer et al., 1995; Field et al., 1998). Their cell walls, or frustules, are constructed out of biogenic silica (SiO2), which can persist as a biosignature in sediments and the rock record for millions of years (Kooistra et al., 2007). The morphology of the frustule is generally species specific and is, therefore, relied upon for taxonomic identification, although cryptic species do exist (Beszteri …

Annual cycles of ecological disturbance and recovery underlying the subarctic Atlantic spring plankton bloom

Satellite measurements allow global assessments of phytoplankton concentrations and, from observed temporal changes in biomass, direct access to net biomass accumulation rates (r). For the subarctic Atlantic basin, analysis of annual cycles in r reveals that initiation of the annual blooming phase does not occur in spring after stratification surpasses a critical threshold but rather occurs in early winter when growth conditions for phytoplankton are deteriorating. This finding has been confirmed with in situ profiling float data. The objective of the current study was to test whether satellite‐based annual cycles in r are reproduced by the Biogeochemical Element Cycling–Community Climate System Model and, if so, to use the additional ecosystem properties resolved by the model to better understand factors controlling phytoplankton blooms. We find that the model gives a similar early onset time for the blooming phase, that this initiation is largely due to the physical disruption of phytoplankton‐grazer interactions during mixed layer deepening, and that parallel increases in phytoplankton‐specific division and loss rates during spring maintain the subtle disruption in food web equilibrium that ultimately yields the spring bloom climax. The link between winter mixing and bloom dynamics is illustrated by contrasting annual plankton cycles between regions with deeper and shallower mixing. We show that maximum water column inventories of phytoplankton vary in proportion to maximum winter mixing depth, implying that future reductions in winter mixing may dampen plankton cycles in the subarctic Atlantic. We propose that ecosystem disturbance‐recovery sequences are a unifying property of global ocean plankton blooms.

Optimal nitrogen application rates for three intensively-managed hardwood tree species in the southeastern USA

Forest production can be limited by nutrient and water availability, and tree species are expected to respond differently to fertilization and irrigation. Despite these common expectations, multi-species comparisons are rare, especially ones implementing a range of fertilization rates crossed with irrigation. This study compares the response of three forest hardwood species to numerous nitrogen (N) fertilization levels and water availability using a novel non-replicated technique. A range of N levels was included to determine how N affected the growth response curve, and statistical procedures for comparing these non-linear response functions are presented. We used growth and yield data to calculate the Land Expectation Value (LEV) for these intensive management treatments, and to determine the optimal growing conditions (accounting for tree productivity and grower expenses). To accomplish these objectives, we used a series of cottonwood, sycamore, and sweetgum plots that received a range of N fertilization with or without irrigation. Regression is an economical approach to define treatment responses in large-scale experiments, and we recommend >3 treatment levels so the response of any single plot does not disproportionally influence the line. The non-replicated plots showed a strong positive N response below 150kgNha−1yr−1, beyond which little response was observed. However, different amounts of fertilization were required for the greatest biomass accumulation rate in each tree species. Cottonwood and sycamore growth was optimized with less than 150kgNha−1yr−1 while sweetgum growth was optimized with less than 100kgNha−1yr−1. Results from this experiment should be representative of many of the nutrient-poor soils in the Coastal Plain in the southeastern USA. The LEVs were not positive for any treatment×genotype combination tested when using irrigation or liquid fertilizer, but our analysis showed that several non-irrigated treatments in sycamore and sweetgum did result in positive LEVs when fertilized with granular urea.

Patterns of stocks of aboveground tree biomass, dynamics, and their determinants in secondary Andean forests

In this study, we aimed to identify the main factors that affect the dynamics and rates of aboveground biomass (AGB) accumulation in secondary forests located in the interandean valleys of Colombia. We used two censuses performed on trees with a diameter at breast height of⩾10cm in 10 1-ha plots to answer the following questions: (1) Does prior use of the land for raising crops (instead of pastureland for cattle ranching) promote an increase in the rate of AGB accumulation? (2) To what extent did climate, soil characteristics, the functional traits of resident species, and/or stand age affect the stocks and dynamics of the AGB in these secondary forests? We did not find any evidence that prior land use for cattle ranching had a negative effect on the tree AGB-accumulation rate, when compared with land previously used for raising crops. Greater AGB stocks at an intermediate fertility point may be associated with a higher abundance of tall, short-lived, fast-growth pioneer species. Tree mortality rates in secondary forests were primarily determined by the forest’s composition and the variation in the amount of rainfall between sites. Soil fertility, which is known to accelerate the growth rate of plant species, was significantly and positively associated with the rate of AGB recruitment. We did not find any evidence for a negative correlation between wood density and growth, as has been reported for primary tropical forests. The net AGB change (%) was primarily associated with the low soil-fertility characteristics of sandy well-drained soils that could, in the presence of steep slopes, increase forest dynamics. Land restoration that restores the natural cycle of secondary forests could assist in the mitigation of global warming by promoting key environmental functions, such as carbon sequestration.

Increased lipid productivity and TAG content in Nannochloropsis by heavy-ion irradiation mutagenesis

One mutant (HP-1) with higher growth rate was obtained from Nannochloropsis oceanica IMET1 by heavy-ion irradiation mutagenesis. Compared to the wild type, the biomass accumulation and maximum growth rate of HP-1 were individually increased by 19% and 6%, and its lipid productivity was increased by 28% from 211 to 271mgL−1d−1. Subsequently analysis indicated photosynthetic efficiency of HP-1 was higher than that of wild type during cultivation. Further, lipid composition analysis indicated TAG content of HP-1 was 14% higher, while polar lipid content was 15% lower than that of wild type. Moreover, fatty acid profiles analysis revealed no significant variation was found between the two strains. The mutant is discussed in terms of its comparative advantage over the wild type with respect to its potential utilization for biodiesel production. Owing to its higher lipid productivity and TAG content, HP-1 could be considered as a valuable candidate for microalgal biodiesel production.

Consequences of defaunation for a tropical tree community

Hunting affects a considerably greater area of the tropical forest biome than deforestation and logging combined. Often even large remote protected areas are depleted of a substantial proportion of their vertebrate fauna. However, understanding of the long-term ecological consequences of defaunation in tropical forests remains poor. Using tree census data from a large-scale plot monitored over a 15-year period since the approximate onset of intense hunting, we provide a comprehensive assessment of the immediate consequences of defaunation for a tropical tree community. Our data strongly suggest that over-hunting has engendered pervasive changes in tree population spatial structure and dynamics, leading to a consistent decline in local tree diversity over time. However, we do not find any support for suggestions that over-hunting reduces above-ground biomass or biomass accumulation rate in this forest. To maintain critical ecosystem processes in tropical forests increased efforts are required to protect and restore wildlife populations.

Dynamic remediation test of polluted river water by Eco-tank system

Dynamic remediation of river water polluted by domestic sewage using an aquatic plants bed-based Eco-tank system was investigated. Over a period of 18 days, the test demonstrated that average effluent concentrations of chemical oxygen demand (COD), ammonium nitrogen () and total phosphorus (TP) were as low as 17.28, 0.23 and 0.03 mg/L, respectively, under the hydraulic retention time (HRT) of 8.7 d. The average removal efficiencies in terms of COD, and TP could reach 71.95, 97.96 and 97.84%, respectively. The loss of both and TP was mainly ascribed to the uptake by plants. Hydrocotyle leucocephala was effective in promoting the dissolved oxygen (DO) level, while Pistia stratiotes with numerous fibrous roots was significantly effective for the removal of organic compounds. The net photosynthetic rate, stomatal conductance, transpiration rate and biomass accumulation rate of Myriophyllum aquaticum were the highest among all tested plants. Thus, the Eco-tank system could be considered as an alternative approach for the in situ remediation of polluted river water, especially nutrient-laden river water.

Forest degradation and recovery in a miombo woodland landscape in Zambia: 22 years of observations on permanent sample plots

Because dry tropical forests cover 40% of tropical forest area and contain considerable biomass and carbon stocks, deforestation and forest degradation of these forests have global significance. However, in most developing countries with dry forests there is no quantitative information on past trends of forest degradation so that the development of historical reference levels is virtually impossible. This study assessed impacts of forest practices on forest degradation from 1990 to 2012 using data from destructive tree sampling and permanent sample plots in a miombo woodland landscape in central Zambia. Aboveground live wood biomass was estimated using allometric equations developed from 113 felled trees. Resprouting was a major source of regeneration on clear-cut subplots and the rate of aboveground wood biomass accumulation was much higher on re-growth sites than on old-growth sites. Changes in aboveground live wood biomass on uncut subplots were linked to biomass loss due to fire, harvesting and conversion to crop cultivation on the one hand and biomass increment due to growth of remaining trees on the other hand. Forest degradation was estimated to cause aboveground wood biomass loss of 0.3tha−1year−1 on the least impacted site to 4.0tha−1year−1 on the most impacted site. Control of fire and harvesting for charcoal production is recommended if miombo woodland is to be managed for biomass and carbon storage and sequestration. The study also found that negative trends in woody biomass accumulation rate and standing stocks are good indicators of forest degradation while positive trends in species diversity indices and standing wood biomass are useful indicators of forest recovery. However, the application of these indicators requires repeated inventories at permanent sample plots to establish reference levels against which changes in these indicator variables can be compared.

Effect of Potassium Application Rate on Cotton (Gossypium hirsutum L.) Biomass and Yield

Cotton production in China is recently confronted with either yield loss by plant early senescence resulted from potassium (K) deficit, or cost rise and nutrients leaching by K excess use. However, the optimal K rate in term of cotton biomass production and yield remains uncertain to make a recommendation for the farmers. Both field with random block design and outdoor pot trials were carried out to determine how cotton (Gossypium hirsutum L. vs. Huazamian H318) biomass and yield were affected by K rates. The result showed that K2 (225 kg ha–1) harvested the highest yield (1 341 kg ha–1) and bore the most bolls (74 bolls per square meter) in the field trial, with a similar trend for the pot trial. As expected, cotton biomass of K2 was the highest at each of the sampling stages, especially for reproductive organs. Cotton biomass initiated simultaneously the fast accumulation period (FAP), but terminated the period differently among five K rates (0–450 kg ha–1). During the period, K2 had the highest biomass accumulation rate both on an average and in the maximum, and for vegetative and reproductive organs. It suggests that K rate of 225 kg ha–1 be optimal to produce a favorable yield in the field of medium fertility when N 300 kg ha–1 and P2O5 90 kg ha–1 are applied in the Middle Reaches of Yangtze River, in which condition cotton plants accumulate greater amount of biomass with a higher accumulating rate.