A coffee agroecosystem model: I. Growth and development of the coffee plant

This paper is the first of three on the coffee production system consisting of (1) the coffee plant, (2) coffee berry borer (CBB) and (3) the role of CBB parasitoids. A previous simulation model of the coffee plant was developed using data from Brazil where coffee phenology is characterized by distinct seasonal flowering (Gutierrez et al., 1998). In contrast, flowering in Colombia is continuous with low seasonality. To capture the differences in coffee phenology and growth in the two climatic regions, the Gutierrez et al. (1998) model was modified using new data from Colombia.The modifications to the model include:

(1)

The effect of solar radiation on floral buds initiation;

(2)

An age structure population model to track the daily input and development of the floral buds;

(3)

The effect of leaf water potential on breaking dormancy in flower buds, and hence on the timing and intensity of flowering;

(4)

The incorporation of both the vegetative and the reproductive demands to predict the photosynthetic rate.

(5)

The effect of low temperature on photosynthesis and defoliation.

Other aspects of the model were re-interpreted and refinements made to generalize its structure for use across coffee varieties and geographic areas. The model, without modification, realistically simulates field data from Brazil and two Colombian locations having different varieties, patterns of rainfall and hence flowering phenology.The model will be used as the base trophic level for incorporating CBB and high tropic levels effects, and for the analysis of management options in the coffee production system.     

Towards a new physical theory of biotic evolution and development

Motivated by the postulates:

(a)

Matter has complementary properties: matter waves at high mass density and information oscillations at high information density.

(b)

Biological systems are information generating systems, i.e., genome capacity to generate developmental functional complexity (phenotype).

(c)

Biological information sustains the living state.

We discuss a definite model in which the life state of an organism, for successive generations, is a generalized Schrödinger's type of system which is non-conservative, nonlinear and irreversible. Vitality, the state variable, is the genome capacity to generate developmental functional complexity (phenotype). It is a function of the phenotypic variables of biological information, i.e., matter-energy growth function, life expectancy and natality.We also discuss evolution within this model. We find that the evolution of a unicellular organism, being a process through which the life function undertakes negative damping, leads to the increase of total vitality. Total vitality is a function of the system's lifespan, bio-complexity and total matter-energy metabolized or body mass. Total vitality is quantized. The derived quantization relationship provides plausible theoretical basis for punctuated equilibrium. Total bio-information (total vitality + total natality density) is conserved. The conserved quantity describes evolution and generates ecosystem, population and organism growth dynamics. Vitality has the dimension of flow-bits. Finally, a thought experiment is proposed to falsify the hypothesis.     

Modelling radiative balance in a row-crop canopy: Row-soil surface net radiation partition

Row crops like vineyards undergo various and significant manipulations of training system and cultural practices, which strongly influence the quality of products. Variations of water vapour fluxes from the soil surface and the leaves in the row volume are closely linked to the ratio of energy available to each compartment. A physically realistic model of available energy partition between the rows and the soil surface is therefore a key factor towards optimization of such systems, and must be included in canopy models. A number of available models were not directly validated. The purpose of the study was therefore to design a model of net radiation partition and check it directly.The model of net radiation partition between rows (Rnv), considered as a whole, and intervening soil surface (Rns) of a row-crop canopy was developed from physically realistic yet simple assumptions:

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global solar (short wave) radiation partition was calculated by a previously validated geometric model;

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long-wave radiative fluxes between the soil surface, the rows and the atmosphere were calculated from the corresponding view factors, which only depended on canopy geometry;

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atmospheric radiation was estimated by a simple empirical relation based on air temperature as the only input variable;

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air temperature in the vicinity of leaves replaced leaf surface temperatures as a more convenient input variable, with little loss of information.

The input variables were incoming direct and diffuse solar radiation, soil surface mean temperature and air temperature near the leaves. The main parameters were soil and leaf albedos, row porosity and dimensions.A direct validation of the model was attempted by measuring net radiation above the canopy and at five positions above the soil surface in a vineyard of the Bordeaux area. The reliability of soil surface net radiation measurements was estimated by thorough error propagation analysis. When found significant, errors were corrected and finally soil surface net radiation data were corrected only for delay in direct downward solar radiation striking net radiometers, because canopy was discontinuous and height of net radiometers was not negligible compared to canopy height.In these conditions, model calculations were in agreement with measurements, although the model slightly underestimated Rns and therefore overestimated Rnv. As the mean error was about 20 W m⁻², and therefore compatible with instrument accuracy, the results were considered satisfactory.This available energy partition model is able to estimate radiative balance in various canopy systems and in various thermal environment conditions, leading to easier simulations of energy balance and water fluxes. It could therefore be a useful tool for optimizing row-crop canopies, taking fully into account any kind of present or future thermal environment.     

Dynamic model of Lake Chozas (León, NW Spain)—Decrease in eco-exergy from clear to turbid phase due to introduction of exotic crayfish

We developed a dynamic model of the phosphorus cycle in Lake Chozas, a small shallow water body in León (NW Spain). The calibrated model simulated seasonal dynamics of phosphorus concentrations in major components of the lake's ecological network before and after 1997, the year when an invasive allochthonous crustacean, the Louisiana red swamp crayfish (Procambarus clarkii), was introduced into the lake. The shift from clean to turbid phase, due to grazing by crayfish on submerged vegetation, caused a gradual decrease in eco-exergy, reflecting an increase in entropy, related to breakdown of ecosystem internal equilibria. This case study verifies the hypothesis of Marchi et al. (2010) that, after an initial relatively stable state, the allochthonous species may cause an increase in entropy indicating perturbation of the ecosystem.     

Definition and calculation of uncertainty in ecological process models

We present a method of multi-criteria assessment for the analysis of process model uncertainty that combines analysis of model structure, parameters and data requirements. There are three components in calculation and definition of uncertainty.

(1)

Assessment criteria: Uncertainty in a process model is reduced as the model can simultaneously simulate an increased number of assessment criteria selected to test specific aspects of the theory being investigated, and within acceptable limits set for those criteria. This reduces incomplete specification of the model—the characteristic that a model may explain some, but not all, of the observed features of a phenomenon. The calculation required is computation of the Pareto set which provides the list of simultaneously achieved criteria within specified ranges.     

The free energy and information embodied in the amino acid chains of organisms

It is generally accepted as a useful and workable hypothesis that when an ecosystem receives an inflow of exergy (energy that can do work) it will utilize this flow of exergy to move as far away from thermodynamic equilibrium as possible after the exergy (energy) for maintenance has been covered. If more combinations of system components including organisms are offered, the combination of components and processes that will bring the system most away from thermodynamic equilibrium will win.The amino acid sequences of the proteins e.g. enzymes determine and control the life processes of the organisms and may be viewed as information sensu lato. The free energy of oxidation of the amino acids and the peptide bonds of the cell enzymes expresses therefore the exergy content, eco-exergy or work capacity that the information contributes to “moving further away from thermodynamic equilibrium”. In this paper eco-exergy is calculated and plotted versus the β-values (a measure of the information contained in the genome) for different organisms. The eco-exergy density was previously (see [J?rgensen et al., 1995] and [J?rgensen et al., 2005]) proposed to be calculated as the summation of the product of the β-values representing the information of the genome multiplied by the concentrations of the respective ecosystem components. This analysis shows a strong correlation between the β-values and free energy released when oxidizing the enzymes. The β-values can therefore be assumed to represent the free energy that the organisms have invested in genetic information.     

Identifying demand parameters in the presence of unobservables: A combined revealed and stated preference approach

• ALTHOUGH MOST ACADEMIC programs use hospital-based sites for perioperative clinical experiences, the exponential growth in the number of ambulatory surgery centers (ASCs) and the increased variety of procedures performed in these settings make ASCs excellent venues for student learning experiences.• NURSING STUDENTS in one program in Florida have the opportunity to take a perioperative practicum designed to allow them to learn about all aspects of patient care and administrative functions in ASCs.• THE ASC PRACTICUM EXPERIENCE is popular with students and staff members alike, and ASC administrators are seeking ways to increase the number of students in the program in an effort to attract new graduates to ASCs. AORN J 84 (August 2006) 219–232. © AORN, Inc, 2006.

Effect of inorganic phosphorus on the growth rate of diatoms

The effect is studied of different inorganic phosphorus concentrations on changes in growth rates of 7 diatom species isolated from the plankton of the Black Sea. All species examined increase their cell-division rate with increasing phosphorus concentration in the medium. The phosphorus concentrations have been determined above which division rate is not limited by phosphorus content in the medium. The non-limiting concentration amounts to V/V _m =0.9. In the species studied, non-limiting concentrations ranged from 1 to 30 g P/1. The highest values were obtained for relatively large-sized species. The ratio of cell surface to volume tended to be inversely related to the growth-rate-limiting concentration. Minimal values of phosphorus content in cells have been calculated to range from 0.6 to 4.0·10^–17 g.at–P/^–3. Based on a comparison of phosphate levels in the Black Sea with experimentally-derived rate-limiting concentrations, it is concluded that phosphorus does not limit the reproduction rate of phytoplankton in the more productive regions of the Black Sea or in the lower strata of the euphotic zone.     

Effect of different carbon sources on performance of an A<Subscript>2</Subscript>N-MBR process and its microbial community structure

Effect of different carbon sources on purification performance and change of microbial community structure in a novel A₂N-MBR process were investigated. The results showed that when fed with acetate, propionate or acetate and propionate mixed (1:1) as carbon sources, the effluent COD, NH₄ ⁺-N, TN and TP were lower than 30, 5, 15 and 0.5 mg?L^–1, respectively. However, taken glucose as carbon source, the TP concentration of effluent reached 2.6 mg?L^–1. Process analysis found that the amount of anaerobic phosphorus release would be the key factor to determine the above effectiveness. The acetate was beneficial to the growth of Candidatus Accumulibacter associated with biological phosphorus removal, which was the main cause of high efficiency phosphorus removal in this system. In addition, it could eliminate the Candidatus Competibacter associated with glycogen-accumulating organisms and guarantee high efficiency phosphorus uptake of phosphorus accumulating organisms in the system with acetate as carbon source.

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Respiration and excretion by the ctenophore Mnepiopsis leidyi

Respiration (dissolved oxygen and carbon dioxide) and excretion (dissolved organic carbon, inorganic and organic nitrogen and phosphorus) rates were measured for a variety of sizes of Mnemiopsis leidyi over a temperature range of 10.3° to 24.5°C. Both respiration and excretion rates were a direct linear function of animal weight and very temperature sensitive (Q₁₀4). Oxygen uptake ranged from 155 to 489 g at O/(g dry weight) day^-1 and carbon dioxide release from 43 to 166 M. Organic carbon made up about 38% of the total carbon released. Inorganic nitrogen excretion, exclusively in the form of ammonium, comprised 54% of the total nitrogen release and ranged from 10 to 36 M NH₄/(g dry weight) day^-1. Average release of dissolved primary amines (expressed as glycine equivalents) equaled 43% of the organic nitrogen fraction. Inorganic phosphorus release ranged from 2.0 to 4.9 M/(g dry weight) day^-1 and made up about 72% of the total phosphorus loss. The turnover of elements in the body was calculated as 5 to 19% per day for carbon and nitrogen, depending on the temperature, and an even higher 20 to 48% per day for phosphorus. These values are comparable to rates observed for small, active zooplankton.     

Effects of the Interactions Between Selenium and Phosphorus on the Growth and Selenium Accumulation in Rice (Oryza Sativa)

The solution culture, paddy soil culture and the simulation experiments in the laboratory were conducted to clarify the interactions between selenium and phosphorus, and its effects on the growth and selenium accumulation in rice. Results revealed that a suitable supply of selenium could promote rice growth and excessive selenium could injure rice plant, causing lower biomass, especially in the roots. The supply of selenite could enhance the selenium contents of rice shoots and roots in solution culture and in soil culture. The selenium concentrations in roots were much higher than those in shoots supplied with the same rates of selenium and phosphorus. The interaction between selenium and phosphorus was evident. When the phosphorus supply increased to meet the needs of plant growth, phosphorus could promote absorption and accumulation of selenium in the shoots. If the phosphorus supply was excessive, phosphorus could inhibit the accumulation of selenium in the shoots at the lower selenite level (2 mol l^–1), but could not at the higher selenite level (10 mol l^–1). With the supply of phosphate increased, the selenium concentrations in the roots decreased significantly at both selenite levels. The presence of phosphate could decrease Se sorption on the soil surface and increase the selenium concentration in the soil solution. The concentrations of selenium in shoots and roots supplied with 0.08 g kg^–1 phosphorus were lower than those with no phosphorus supplied. With the increase of phosphorus added to 0.4 g kg^–1, the selenium concentration in shoots and roots increased. The effect of phosphorus on the concentration was statistically significant at all three selenium levels.     

Spatial mesoscale patterns of West Pacific picophytoplankton as analyzed by flow cytometry: their contribution to subsurface chlorophyll maxima

Vertical distributions of picophytoplankton (ppp) (<2 m) were studied by ship-board flow cytometry during two cruises in Western Pacific waters to Palau and to Australia in 1990. Weak red-fluorescing small ppp, supposed to be free-living prochlorophytes (Chisholm et al. 1988), were abundant in the area surveyed. These ppp, designated the prochlorophytes, were abundant in the surface waters (>10⁴ cells ml^-1) at the northern region (27°03N; 7°11N) in November, whereas in December at the southern tropical stations (0°23.54S; 9°20.30S; 13°50.6S), they formed subsurface maximum layers (>10⁵ cells ml^-1) on a nitracline at a depth of 3.5 to 5.4% surface irradiation. Their fluorescence intensity increased with depth below 10% surface irradiation. The prochlorophytes at a depth of 1% surface irradiation had ten times higher fluorescence than those at the surface layer. The total fluorescence intensity of the prochlorophytes accounted for 32 to 63% of the sum of the total fluorescence intensity of all fluorescing phytoplankton detected at subsurface chlorophyll maxima in the tropical area. These results suggest that distribution of the prochlorophytes is greatly affected by nitracline and by light intensity and that their chlorophyll is a major contributor to the subsurface chlorophyll maximum in the pelagic West Pacific Ocean.     

Writing it down: suggestions for a new approach towards understanding pro-environmental behaviour

A fashionable field of enquiry – the relationship between expressed attitudes and actual behaviour in the context of sustainable development – is complex (Staats et al. 2004 Staats, H, Harland, P and Wilke, H. 2004. Effecting durable change: a team approach to improve environmental behaviour in the household. Environ Behav., 36(3): 341–367. [Crossref], [Web of Science ®] , [Google Scholar]) and difficult to apply in a policy-relevant manner (Aall and Norland 2005 Aall, C and Norland, I. 2005. The use of the ecological footprint in local politics and administration: results and implications from Norway. Local Environ., 10(2): 159–172. [Taylor & Francis Online] , [Google Scholar]). However, recent research indicates that the use of a household diary can be beneficial in helping to quantify household environmental impact, in educating householders about their impact, and in identifying major ‘behavioural turning points’, where householders may focus efforts to reduce their environmental impact (Hunter et al. 2006 Hunter, C, Carmichael, K and Pangbourne, K. 2006. Household ecological footprinting using a new diary-based data-gathering approach. Local Environ, 11(3): 307–327. [Taylor & Francis Online] , [Google Scholar]). In other words, the use of a diary by householders is a potentially powerful tool in encouraging and facilitating desired behavioural change. This paper reports on the initial findings of an innovative study that assessed the use of a household diary approach as a means of framing and collecting household environmental data and, critically, as an educational vehicle for bringing about behavioural change. Based on the initial findings, it is clear that there is some potential to develop practical policy measures that empower householders by allowing them to better grasp their environmental impact and, consequently, recoup positive implications in terms of financial savings (e.g. reducing the amount of food thrown out) and health benefits (e.g. more walking/cycling).     

Stable isotope ratio variations in non-scleractinian coelenterate carbonates as a function of temperature

Some coelenterates of the class Hydrozoa and some anthozoan coelenterates from the subclass Octocorallia secrete skeletons of calcium carbonate. Skeletal carbonates of three hydrozoans and of two octocorals were analyzed for the stable isotopes of carbon and oxygen. The results suggest that each of these coelenterates deposits CaCO₃ in oxygen isotopic equilibrium with seawater, and that at least one octocoral, Heliopora, has skeletal carbon in apparent isotopic equilibrium with atmospheric CO₂. Two of these coelenterates, Millepora and Helipora, are significant contributors to the construction of coral reefs. Whereas ¹⁸O of these corals is temperature dependent, ¹³C is not obviously related to temperature. The ¹⁸O-temperature relationship is not significantly different from the oxygen isotope paleotemperature scale developed by Epstein et al. (1953). These findings contrast with numerous analyses of the carbonate in scleractinian coelenterates, which have long been reported to deposit CaCO₃ skeletons whose carbon and oxygen isotopic compositions are not in equilibrium with the external sea-water environment.     

Comparison of three techniques for administering radiolabeled substrates to sediments for trophic studies: uptake of label by harpacticoid copepods

Microbial grazing by two species of meiofaunal harpacticoid copepods (Heteropsyllus nunni and Thompsonula hyaenae) was determined by uptake of radioactive labels following their introduction into natural sediments from a low-energy intertidal site in Florida (29°5440N; 84°3130W) in May 1986. Grazing was related to three methods of radioactive-label introduction: injection, porewater replacement, and slurry. Uptake of label by harpacticoids was examined using two dual-label combinations, ³H-thymidine/¹⁴C-bicarbonate and ³H-thymidine/¹⁴C-acetate. The injection and porewater-replacement methods yielded statistically indistinguishable results. Results obtained by the slurry method differed significantly from the other two methods. We suggest that the unique results obtained in the slurry method were a consequence of the disruption of microbial-meiofaunal spatial relationships.     

Alkaline phosphatase activity in marine macrophytes: histochemical localization in some widespread species in southern Spain

Alkaline phosphatase activity (APA) was determined in 44 species of marine macrophytes collected throughout 1991 and 1992 along the southern coast of Spain. Activity varied between 0.83 mol paranitrophenol (pNP) released g^-1 dry wt h^-1 in Ulva rigida var. gigantea and 238.8 mol pNP g^-1 dry wt h^-1 in Bangia fuscopurpurea. Using a histochemical method, APA sites were located in five of these species: Corallina elongata Ellis et Soland, Gelidium latifolium (Grev.) Thur. et Born., G. sesquipedale (Clem.) Born. et Thur., Porphyra umbilicalis (L.) Kützing and Zostera noltii Hornem. Enzymatic activity was found in the outer part of the thallus, either on the cell wall or in the cortical cells. In the marine phanerogam Z. noltii activity was also located in the vascular bundle. The results suggest that APA is present in many, if not all, marine macrophytes from southern Spain, and plays a relevant role in the utilization of dissolved organic phosphorus compounds.