Comparing hybrid Populus clones for SRF across northern Italy after two biennial rotations: Survival, growth and yield

Short rotation forest (SRF) plantations of hybrid poplars are attractive for Italian farmers due to the availability of public grants and the potential for producing wood chips for energy production. Growth and dendromass yield of new clones for SRF were evaluated after two biennial rotations within a network of experimental fields established in 2003 on three sites of low (Bigarello), medium (Vinovo) and high soil quality (Mira), across northern Italy. Soil preparation, planting density (5900 trees ha⁻¹), weed control, tree water status and mechanical harvesting were homogeneous across the sites. Nitrogen fertilization was applied only in Mira (300 kg N ha⁻¹).In all sites, survival was high for almost all clones, and stem density increased dramatically, with a decrease of stem dimensions, after the first coppicing. In Bigarello, with limiting soil conditions, there was no significant difference among clone biennial yields, which varied from 10.3 (first rotation) to 14.2 (second rotation) Mg ha⁻¹ in dry matter (dm). In the medium and high quality sites of Vinovo and Mira, there was a significant difference in clone yields, with the new clones performing better than control clones (I-214 and Lux). In Mira, mean biennial yield increased from 30.2 to 40.3 Mg dm ha⁻¹ from the first to second cycle.Preliminary results of new clones on medium and high soil quality need to be further confirmed throughout further coppicing cycles; on a marginal soil, even by using the new clones, poplar SRF is not an advisable option.     

Biomass production and nutrient cycling in Eucalyptus short rotation energy forests in New Zealand: II. Litter fall and nutrient return

Litter fall and nutrient return via the litter fall were measured during the first 3-yr rotation of three Eucalyptus short rotation forest species (E. botryoides, E. globulus and E. ovata) irrigated with meatworks effluent compared with no irrigation. Up to 13.4 oven dry t/ha/yr of annual litter fall was recorded with nutrient returns of up to 159 kg N/ha/yr, 9 kg P/ha/yr, 28 kg K/ha/yr, 125 kg Ca/ha/yr, 22 kg Mg/ha/yr, and 32 kg Mn/ha/yr. Effluent irrigation increased the litter fall and the return of some nutrients. More litter fall with higher nutrient return was found under E. globulus than under the other two species. However, the amounts of litter fall and nutrient return were highly dependent on the degree of biomass production and nutrient uptake. During the 3-yr period, up to 20% of the total above ground biomass produced was in the form of litter, and via the litter fall, up to 24% of the total N uptake was returned to the soil surface.     

Poplar diseases, consequences on growth and wood quality

Since 1948 Belgium has played a leading role in the selection and breeding of the genus Populus. In the late 1960s, this work resulted in the Unalclones, combining the most desired clonal properties. In this paper attention is given to the most important poplar diseases in Europe (i.e. poplar canker Xanthomonas populi, and rusts Melampsora species), how breeding and selection may result in broadly disease resistant clones, and the possible negative influence of these diseases on poplar growth and wood quality.     

Diseases and pests in energy crop plantations

The Pest and Disease Management Activity was established in response to an awareness of the potential importance of pests and diseases in woody biomass production systems. Annual surveys in Canada, Eire, England, N. Ireland, Scotland and Sweden from 1987–1991 confirmed that rust disease (Melampsora spp.) is currently the most serious problem in willow biomass production in Europe. Other pests and diseases cause problems only on a local scale, though they could become more generally severe. Increasing clonal susceptibility to rust and an an increasing association of premature defoliation with lower rust severity levels have occurred over the period. A high degree of intrinsic variability in pathogen populations is expressed as four formae speciales (f.spp.) and at least eight pathotypes of the most common rust species, M. epitea. The same f.spp. appear to occur among pathotypes in Sweden, New Zealand and the UK. A network of field experiments has been established, in collaboration with the Joint Trials Activity, to enable the rust pathotype composition to be compared between five countries. It also aims to identify an international set of standard willow clones to be utilized for characterizing rust pathotypes globally.     

Measurement of solar energy radiation at Nsukka and the determination of the regression coefficients

Solar radiation for Nsukka, latitude 6.8°N, longitude 7.35°E, located 488 m above sea level, was collected for 11 yr using a Gunn-Bellani instrument, and the data obtained were restandardized using an Eppley precision pyranometer. The sunshine data during this period were also obtained using a Campbell-Stokes sunshine recorder.

It is observed that the insolation level for the month of November during the period of measurement is the highest, with an average of 17.50 MJ/m². The level of insolation during this month varied sinusoidally with an amplitude of 3.84 MJ/m². The clearness index, k_T, is 0.53, and there is an indication that the atmosphere was persistently laden with dust. August has the least insolation level with an average of 11.86 MJ/m² and a k_T of 0.32. The atmosphere during this month was always covered with cloud. This work confirmed the assertion by Awachie and co-workers that dust and haze attenuate insolation less than cloud cover. The Nsukka weather is rated to be heavily overcast, and over 90% of the total solar radiation is diffuse, with an average k_T value of 0.43.

The average regression coefficients a and b for Nsukka are 0.21 and 0.51 respectively. These values do not agree with the general relations and values already quoted by some workers. The predicted insolation values for Nsukka using these coefficients in the Angstrom type of formula agree with the measured data with an error of 0.7%. This level of accuracy compares well with those obtained when the insolation values are predicted for each year using the values of a and b deduced for the respective year. Furthermore, there was an indication that the level of accuracy obtained using average values of a and b might increase if a longer period is considered. Thus, with reliable average values of a and b obtained over a reasonably long period, and knowledge of the bright sunshine hours, the measurement of solar radiation in a location, for design purposes, may not be necessary.     

Biomass system model estimates of short-rotation hardwood production in Hawaii

By coupling a short-rotation, intensive-culture (SRIC) biomass production model with a geographical information system and database, potential biomass supply (dry Mg) and delivered cost ($(dry Mg)⁻¹) of three promising tropical hardwoods, Eucalyptus grandis, E. saligna, and Leucaena leucocephala, were estimated at all locations identified as potentially available for tree plantations on the island of Maui. Analyses were performed at two scales-island-wide (10⁵ ha order of magnitude) for general land-use planning, and specific-site (10² ha order of magnitude) for field-level recommendations. The results are presented as yield and delivered cost maps and biomass supply curves for the entire island, and as management strategies depicted graphically as functions of growing space and rotation age that provide least-cost biomass feedstocks delivered from two specific field sites to a designated bioconversion facility on Maui. The methodology is a cost- and time-efficient means to provide useful information to land owners and other decision makers contemplating SRIC forestry as an alternative land use.     

Poplars as biological energy sources in Hungary

Ongoing trials with 12 poplar varieties on marginal and agricultural sites are reported. It is estimated that with a 4 year cutting cycle over 28 years average yields of 16.25 odt/ha/yr are possible.     

A new method for estimating solar radiation from bright sunshine data

Daily values of H/H₀, the ratio of total horizontal radiation to that outside the atmosphere has been correlated with s/S, bright sunshine as a fraction of daylength for 3 yr measurements in Adana and Ankara, Turkey. Using a maximum-likelihood quadratic fit, we show that monthly averages s/S and its standard deviation σ_s/S can be used to estimate the monthly average H/H₀ as

H/H₀ = 0.204 + 0.758s/S − 0.250[s/S² + σ²_s/S.

Comparison of the estimations of the above equation with measurements from different regions of Turkey indicate that less than 5 per cent relative error is possible. A further correlation σ²_s/S with s/S makes it possible to estimate H/H₀ with just the knowledge of s/S.     

Switchgrass production and establishment in the Southern Italy climatic conditions

Standard productivity trials on switchgrass (Panicum virgatum L.) have been performed at the ENEA Research Centre Trisaia in the framework of the FAIR Project (IV FWP). The main objective of the research work was to develop knowledge about the adaptability of this new crop in the South Italy climatic conditions. To achieve this goal, two sets of experiments with various genotypes were conducted to determine the switchgrass yields at the field level. In the nursery trial, 15 varieties were tested, while in the production experiment, only five varieties at different nitrogen fertiliser levels (0, 75, 150 kg N ha⁻¹) were tested for their yield. The experimental results obtained relating to biomass yield and genotype response to nitrogen fertilisation are discussed in the present communication. Though it seems that the N fertilisation did not directly influence the switchgrass productivity, most of the switchgrass varieties showed quite a good response for biomass production.     

The mycorrhizal status of selected poplar clones introduced in Alberta

Mycorrhizal associations are essential in the establishment and growth of plant species. The types of mycorrhizas were investigated in the roots of poplar clones introduced in Alberta. We sampled roots of 28 poplar clones from a 5-year old trial established at the Alberta-Pacific Forest Industries Inc. mill site located $\text{40}\text{km}$ North of Boyle, Alberta. The two most common types of mycorrhizas were quantified in plant roots. The poplar clones showed variable degrees of colonization by both ectomycorrhizal and arbuscular mycorrhizal fungi, suggesting differential host susceptibility. This highlights the potential use of selected strains of both ectomycorrhizal and arbuscular mycorrhizal fungi for inoculation trials in populiculture to improve the establishment of introduced poplars on to previously cleared agricultural or disturbed sites in the province of Alberta in particular and in the Canadian prairie provinces in general.     

Geneti|c diversity of superior Salix clones selected for intensive forestry plantations

A number of willow clones are today in use in short rotation intensive culture plantations. The clonal nature of this crop makes it an easy target for pests and pathogens when grown in monocultures. This is a major concern as plantations of coppice must remain viable for up to 20 years to be profitable. In this paper the genetic diversity of 114 selected willow clones was examined and the possible solution of growing willows in multiclonal plantations is discussed. Forty five Salix eriocephala clones, 53 S. exigua clones and 16 clones of their inter-specific hybrid (12 S. eriocephala×exigua clones and 4 S. exigua×eriocephala clones), were evaluated. Starch gel electrophoresis was employed and 12 enzyme systems were used for the assessment of the genetic variation in the clonal material. A total of 29 loci and 57 alleles were revealed. Three measures of genetic diversity were used in order to evaluate the genetic base of the clonal set: average number of alleles per locus, percentage of polymorphic loci and mean heterozygosity. Results indicated that the genetic diversity within a species, is generally lower than the genetic diversity observed in natural populations or full-sib families of the same species. These results, however, are within the limits obtained from natural populations of the Salicaceae family. Heterozygosity values were found to be greater than similar values from poplar clonal material. In contrast to the results within species, inter-specific hybrid clones presented relatively high amounts of genetic diversity. The significance of these results in the management of clonal plantations is discussed from both the operational and conservation points of view.     

Biomass production of Salix viminalis in southern Finland and the effect of soil properties and climate conditions on its production and survival

Ten Salix viminalis clones were cultivated in 35 experimental plantations situated on privately-owned farms in southern and central Finland. Management instructions were given to the farmers who established and tended the study plots. The biomass production and survival of the clones were recorded by inventory every year during the first rotation period, which consisted of the establishment year and three following growing seasons. The greatest amount of biomass production exceeded 30 above-ground tonne of dry matter/3 years, but amounts varied greatly between the experimental plantations. The main reasons causing this variation were the low frost hardiness of most of the S. viminalis clones and unsuccessful weed control during the year the plantations were established. Early autumn frost in particular caused severe damage. S. viminalis grew rather well on a wide variety of soil types. Sufficient amounts of nitrogen, potassium and organic matter seem to be the properties which most clearly have an effect on the biomass production and survival of S. viminalis in mineral soils. A relatively small amount of manganese in wet and low oxygenic soils is recommended, because a high content may cause toxic effects. In this study S. viminalis clones only succeeded well in southernmost Finland, where properly managed plantations produced rather high biomass yields. In other parts of southern and central Finland more research work on frost resistance and the breeding of new clones is needed. To conclude, in the climatic conditions of Finland energy willow husbandry is a compromise between high biomass yield and frost hardiness.     

Thermodynamical properties of La–Ni–T (T = Mg, Bi and Sb) hydrogen storage systems

The hydrogen absorption properties of LaNi_4.8T_0.2 (T = Mg, Bi and Sb) alloys are reported. The effects of the substitution of Ni in the LaNi₅ compound with Mg, Bi and Sb are investigated. The ability of alloys to absorb hydrogen is characterized by the pressure–composition (p–c) isotherms. The p–c isotherms allow the determining thermodynamic parameters enthalpy (ΔH^des) and entropy (ΔS^des) of the dehydrogenation processes. The calculated ΔH^des and ΔS^des data helps to explain the decrease of hydrogen equilibrium pressure in alloys doped with Al, Mg and Bi and its increase in the Sb-doped LaNi₅ compound. Generally, partial substitution of Ni in LaNi₅ compound with Mg, Bi and Sb cause insignificant changes of hydrogen storage capacity compared to the hydrogen content in the initial LaNi₅H₆ hydride phase. However, it is worth to stress that, in the case of LaNi_4.8Bi_0.2, a small increase of H/f.u. up to 6.8 is observed. The obtained results in these investigations indicate that the LaNi_4.8T_0.2 (T = Al, Mg and Bi) alloys can be very attractive materials dedicated for negative electrodes in Ni/MH batteries.     

Long-term biomass productivity of willow bioenergy plantations maintained in southern Quebec,Canada

Maintaining the long-term productivity of short-rotation coppice plantations is very important to ensure the large-scale deployment of biomass as a renewable energy source. In Quebec (Canada), willow short rotation coppice has been studied since the early ‘90s, thereby allowing long-term analysis of the dynamic performance of several species and hybrids as well as management practices. In this study, we report on the long-term productivity of two trials maintained in southern Quebec and carried out to compare a) growth and biomass yield of willow Salix viminalis (cultivar 5027) grown for 15 years under fertilized and unfertilized conditions and b) growth of different willow cultivars over three successive rotations (10 years). The first trial showed that after four rotations, sludge-fertilized S. viminalis 5027 produced significantly more biomass, 19.2 odt ha⁻¹ yr⁻¹, whereas unfertilized plots yielded 13.8 odt ha⁻¹ yr⁻¹. The second trial showed that among the wide variety of commercial willow cultivars available, SX64 and SX61 along with some indigenous species (i.e. S25, S365, S546) were the most suitable for short-rotation forestry in southern Quebec.     

Keeping warming within the 2 °C limit after Copenhagen

The object of the United Nations Climate Change Conference in Copenhagen in December 2009 was to reach an agreement on a new international legal architecture for addressing anthropogenic climate change post-2012. It failed in this endeavour, producing a political agreement in the form of the Copenhagen Accord. The Accord sets an ambitious goal of holding the increase in the global average surface temperature to below 2 °C. This paper describes 45 CO₂-only mitigation scenarios that provide an indication of what would need to be done to stay within the 2 °C limit if the international climate negotiations stay on their current path. The results suggest that if developed countries adopt a combined target for 2020 of ≤20% below 1990 levels, global CO₂ emissions would probably have to be reduced by ≥5%/yr, and possibly ≥10%/yr, post-2030 (after a decade transitional period) in order to keep warming to 2 °C. If aggressive abatement commitments for 2020 are not forthcoming from all the major emitting countries, the likelihood of warming being kept within the 2 °C limit is diminutive.     

The carbon sequestration potential of unmanaged forest stands in Finland under changing climatic conditions

Changes in stand-level carbon (C) storage and C flows in biomass, litter and soil organic matter in the humus layer were studied under current and changing climatic conditions in Finland with the help of a gan-type simulation model. The changing climate scenario assumed increases in mean annual temperature of 0.4°C per decade for the first one hundred years and 0.2°C per decade for the second hundred years. Warming was assumed to be larger during the winter than during the other seasons.

In southern Finland, the long term average (over 200 years) net forest ecosystem production (NEP) at the stand level was 0.4–1.0 Mg C/ha/a under the current climatic conditions, and 0.1–0.9 Mg C/ha/a under changing conditions, depending on the tree species. Under the climate change scenario, NEP decreased in Scots pine, Norway spruce and Pubescent birch stands, but increased in Pendula birch stands. During the first 25–50 years, however, NEP was found to be larger both in Scots pine and Pubescent birch stands. In northern Finland, the long term average NEP increaed, regardless of tree species, from 0.3–0.8 Mg C/ha/a to 0.4–1.0 Mg C/ha/a. The biggest changes took place in Norway spruce and Pendula birch stands.

During the early and late phases of stand development, the stands were C sources, since emissions from decaying litter and soil organic matter in the humus layer exceeded the growth of vegetation. Stands became C sources earlier under the changing climatic conditions than under the current conditions. In southern Finland, the long term average C storage was 107–201 Mg C/ha under the current climatic conditions, and 88–142 Mg C/ha under the changing conditions, depending on tree species. In northern Finland, the long term average C storage was 77–151 Mg C/ha under the current climatic conditions and 89–177 Mg C/ha under the changing conditions.     

Electrochemical behavior of CO, CO2 and methanol adsorption products formed on Pt–Rh alloys of various surface compositions

CO, CO₂ and methanol adsorption/electro-desorption processes have been studied on Pt–Rh alloy electrodes with various surface compositions and on the pure Pt and Rh electrodes. Pt–Rh alloys are slightly more tolerant to poisons from these molecules’ adsorption compared to pure Pt and Rh.

The values of electrode coverage by the adsorption products and the values of the average electron-per-site (eps) parameter obtained from stripping voltammetry suggest some differences exist between the adsorption layers formed depending on the adsorbing molecule, the electrode's surface composition and the adsorption conditions. The observations could be rationalized by considering the differences in adsorption mechanisms of CO, CO₂ and methanol and by taking the adsorption products to be uniquely bridge-bonded and on-top-bonded CO.

There is no direct correlation between the average eps parameter and the stability of the adsorption layer. Adsorption layers formed on an electrode with a given surface composition and characterized by the same value of the average eps parameter can have different potential stability, if they were formed by different molecules or under different conditions.     

Natural convection in a cavity with undulated walls filled with water-based non-Newtonian power-law CuO–water nanofluid under the influence of the external magnetic field

Natural convection heat transfer in a square cavity (with wavy or plane wall) filled with non-Newtonian power-law nanofluid has been elucidated for several input parameters like Ra spanning from 10⁵ to 10⁶, power-law index (n) from 0.6 to 1.4, and volume fraction of CuO nanoparticles (?) from to 0 to 0.12. Effect of external magnetic field on heat transfer has been illustrated by varying the Ha from 0 to 90. In the present study, our main objective is to explore the effect of nanoparticles on heat transfer enhancement in non-Newtonian power-law fluid. It is found that the addition of nanoparticles (?) to shear thinning fluid enhances the heat transfer approximately 15% when ? increases from 0 to 0.12 for Ha less than 60 at all Ra. For a shear thickening fluid, the same thing happens for all Ha at any Ra. The average surface Nusselt number for a cavity with wavy wall is less than that of a plane wall for all cases which is not true for the case of local Nusselt number.     

Effect of Titanium additive element on the discharging behavior of MgNi Alloy electrode

Mg_0.90Ti_0.10Ni, Mg_0.85Ti_0.15Ni, Mg_0.80Ti_0.20Ni, Mg_0.90Ti_0.15Ni_0.95, Mg_0.90Ti_0.20Ni_0.90 and Mg_0.95Ti_0.15Ni_0.90 ternary alloys were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. Among the Mg-Ti-Ni ternary alloys Mg_0.90Ti_0.20Ni_0.90 alloy showed the best discharge performance. The initial discharge capacity was observed to depend on Mg/Ni atomic ratio rather than Ti/Mg atomic ratio in alloys. As the Ti/Mg atomic ratio increased the alloy charge transfer resistances decreased probably due to the partial selective dissolution of the surface Ti/Ti-oxides and thus the limited enrichment of the surface by the electro-catalytic Ni. The average hydrogen diffusion coefficients in all the Ti-including alloys were higher than that in MgNi alloy. The increase in Ti/Mg atomic ratio, however, did not cause any further increase in the average hydrogen diffusion coefficient.