Coppice Plantations Research Articles

The economic attractiveness of Short Rotation Coppice biomass plantations for bioenergy in Northern Ontario

With an apparent abundance of idled and under-utilized agricultural land in Northern Ontario, there is interest in the ability of short-rotation forests to supply bioenergy and other possible bioproducts. Once established, Short Rotation Coppice (SRC) plantations can be harvested on (roughly) three-year cutting cycles until about age 22. Purpose-grown plantations such as these could be used as stand-alone sources of fibre or used in conjunction with sources such as natural forests or woody residues. Using a recently developed land cover model we found that approximately 405 500 ha of agricultural-type land exists across Northern Ontario. Numerous scenarios were developed to calculate SRC profitability on these areas. The analyses are intended to reflect a broad range of expectations on physical yields and prices, including management costs. Although SRC involves a considerable up-front investment, our simulations suggest a significant amount of land could have a break-even biomass price of $85/oven-dried tonnes (ODT) (+/- $5/ODT) at farm gate. This farm gate biomass price represents roughly current traditional biomass prices paid. Thus SRC would need to produce biomass at a comparable cost to be a competitive option. A number of technological and price changes could increase the attractiveness of SRC systems in Northern Ontario, including decreases in establishment and management costs (while maintaining yield expectations) and improved cultivars offering increased yields.

Soil CO2 efflux in a bioenergy plantation with fast-growing Populus trees - influence of former land use, inter-row spacing and genotype.

AimsIn this study we quantified the annual soil CO2 efflux (annual SCE) of a short rotation coppice plantation in its establishment phase. We aimed to examine the effect of former (agricultural) land use type, inter-row spacing and genotype.MethodsAnnual SCE was quantified during the second growth year of the establishment rotation in a large scale poplar plantation in Flanders. Automated chambers were distributed over the two former land use types, the two different inter-row spacings and under two poplar genotypes. Additional measurements of C, N, P, K, Mg, Ca and Na concentrations of the soil, pH, bulk density, fine root biomass, microbial biomass C, soil mineralization rate, distance to trees and tree diameters were performed at the end of the second growth year.ResultsTotal carbon loss from soil CO2 efflux was valued at 589 g m−2 yr−1. Annual SCE was higher in former pasture as compared to cropland, higher in the narrow than in the wider inter-row spacings, but no effect of genotype was found.ConclusionsSpatial differences in site characteristics are of great importance for understanding the effect of ecosystem management and land use change on soil respiration processes and need to be taken into account in modeling efforts of the carbon balance.

Floristic diversity in Short Rotation Coppice (SRC)plantations: Comparison between soil seed bank and recent vegetation

In the near future an increase in Short Rotation Coppice (SRC) plantations is to be expected. The objective was to compare the recent vegetation and the soil seed bank in SRC plantations to reveal the functioning of the soil seed bank for phytodiversity and vegetation structure after reconversion of SRC plantations into arable land. For the analyses, above-ground vegetation surveys and soil seed bank samples of six German and four Swedish SRC plantations were used. Similarity in composition of soil seed banks and recent vegetation was low in terms of species, plant strategy types, species habitat preferences and seed longevity. On average, the proportion of common species of recent vegetation and soil seed bank was 8.4 % (± 6.7 % SD). The recent vegetation was dominated by competitive (c) plant species while in the soil seed banks highest proportions were detected for ruderals (r) and competitors (c). Species with long-term persistent seeds had the highest contribution to both the recent vegetation and the soil seed banks. Grassland species had highest species habitat preference proportion in the recent vegetation. The soil seed banks contained predominantly ruderal species and woodland species were almost absent. Due to the poor coherence of seed bank vs. recent vegetation, we conclude that the site history has only a minor influence on phytodiversity in SRC plantations, suggesting that recent vegetation composition is mainly due to the species pool of the adjacent vegetation and site conditions like below-canopy irradiance and site nutrition.

Assessment of variability in biomass yield and quality: what is an adequate size of sampling area for miscanthus?

To diversify energy crop production and improve its biodiversity and sustainability, there is currently a search for alternative energy crops. Many of the newly arising alternatives are perennial species such as the C4 grass miscanthus. The assessment of reliable data is a prerequisite for understanding the performance of these crops and developing corresponding management systems. However there is great uncertainty concerning research methodology for these crops. When data are collected from small plots of perennial crops, such as miscanthus or short rotation coppice plantations, a larger variability is expected than for cereals. A square meter cut, corresponding to harvest practice in cereals, is not sufficient for perennial C4 grasses and is not recommended for these species. The aim of this research was to identify an adequate size of sampling area for miscanthus to estimate the true biomass yield or quality. For this purpose, whole plots of 10- and 14-year old miscanthus stands were divided into smaller subplots. These were used to calculate variances for various sizes of simulated plots. The variances for all traits in the experiments were rather high when the sampling area was smaller than 2 m². A cutting regime of more than 5.6 m² would be advisable, but an area of 3 m² is sufficient to eliminate approximately 90% of the variances and is therefore an adequate size of sampling area.

Stand age characteristics and soil properties affect species composition of vascular plants in short rotation coppice plantations

Woody biomass plantations on agricultural sites are an attractive source of biomass for bioenergy, but their effects on local biodiversity are unclear. This study’s objective was to evaluate the influences of light availability, plantation age, and soil properties on phytodiversity in short rotation coppice (SRC) plantations. Ground vegetation mapping, irradiance measurement (PAR), and surface soil analyses were conducted in 15 willow and poplar SRC plantations in Central Sweden and Northern Germany. We performed different multivariate statistical methods like cluster analysis (CA), principal component analysis (PCA), and canonical correspondence analysis (CCA) in order to analyze species composition and the influence of irradiance, age, and soil properties on phytodiversity. CA revealed highest species composition similarities in SRC plantations in close proximity. PCA identified humus quality/essential plant nutrients, plantation age/irradiance effects, soil acidity and shoot age as the four principal components of the recorded parameters. The ground vegetation cover was negatively correlated with the plantation age component and positively with the nutrient component. With an increase in the plantation age component, a shift in species composition was proven towards more forest habitat species, more nutrient-demanding species, and increasing occurrence of indicator species for basic soils. Applying Ellenberg indicator values, basic soil indicator species corresponded in occurrence to increasing nutrient availability. However, species richness was not related to any of our studied site variables. Judged from CCA, species composition in SRC plantations was influenced by plantation age/irradiance, and nutrient availability; soil acidity and shoot age had no significant influence. Young poplar and willow SRC plantations showed greatest variation in photosynthetically active radiation (PAR). Our findings suggest that phytodiversity in SRC plantations depends mainly on plantation age and thus shifts over time.

Biomass Production with Willow and Poplar Short Rotation Coppices on Sensitive Areas—the Impact on Nitrate Leaching and Groundwater Recharge in a Drinking Water Catchment near Hanover, Germany

In a lowland drinking water catchment area, nitrate leaching as well as groundwater recharge (GWR) was investigated in willow and poplar short rotation coppice (SRC) plantations of different ages, soil preparation measures prior to planting and harvesting intervals. Significantly increased nitrate concentrations of 16.6 ± 1.6 mg NO3-N L−1 were measured in winter/spring 2010 on a poplar site, established in 2009 after deep plowing (90 cm) but then, subsequently decreased strongly to below 2 mg NO3-N L−1 in spring 2011. The fallow ground reference plot showed nitrate concentrations consistently below 1 mg L−1 and estimated annual seepage output loss was only 1.36 ± 1.1 kg ha−1 a−1. Leaching loss from a neighboring willow plot from 2005 was 14.3 ± 6.6 kg NO3-N ha−1 during spring 2010 but decreased to 2.0 ± 1.5 kg NO3-N ha−1 during the subsequent drainage period. A second willow plot, not harvested since its establishment in 1994, showed continuously higher nitrate concentrations (10.2 ± 1.7 NO3-N L−1), while a neighboring poplar plot, twice harvested since 1994 showed significantly reduced nitrate concentrations. Water balance simulations, referenced by soil water tension and throughfall measurements, showed that at 655 mm annual rainfall, GWR from the reference plot (300 mm a−1) was reduced by 40 % (to 180 mm a−1) on the 2005 willow stand, mainly due to doubled rainfall interception losses. However, transpiration was limited by low soil water storage capacities, which in turn led to a moderate impact on GWR. We conclude that well-managed SRC on sensitive areas can prevent nitrate leaching, while impacts on GWR may be mitigated by management options.

Environmental Impacts of Short Rotation Coppice (SRC) Grown for Biomass on Agricultural Land

This issue of BioEnergy Research highlights the activitieswithin a European Union research project funded by ERA-NET Bioenergy, “Reducing environmental impact of SRCthrough evidence-based integrated decision support tools”(RATING-SRC). The project goal was to provide scientificevidence for evaluatingthe impacts —positiveandnegative—of short rotation coppice (SRC) plantations on soil, water,biodiversity, and landscape issues and also to propose waysto mitigate the negative and increase the positive impacts.Commercial SRC plantations are currently grown at limit-edscaleinsomecountries(e.g.,Sweden),buttheareaofSRCplantationshastoincreasedramaticallyinthefutureiftheyareto contribute significantly to the replacement of fossil energysources. Thus, a rapid increase of agricultural land dedicatedto SRC with willow (Salix spp.) or poplar (Populus spp.) forproduction of biomass for heat and/or electricity is projectedin the short-term in many regions of the world. A large-scaleshift from “conventional” arable crops to SRC will haveimplications on a range of environmental issues, and large-scale implementation of those crops for bio-energy purposemakes sense only if they prove to reduce negative effects onthe environment, especially when compared with other alter-natives for reduction of fossil energy sources. As a perennialcrop,SRCdiffersfrommostarablecropsinphysicaltraitsandmanagement practices. Results so far imply many positiveenvironmental benefits due to SRC implementation, but theeffects that SRC will have on the environment depend on theexisting or previous land use, the scale of planting and themanagement practices applied. In addition, SRC is a newproduction system for most regions in which it might begrown in future, and many uncertainties exist with respect tothe environmental impacts of those plantations on soil, water,biodiversity, and landscape issues.This special issue contains sevenpaperscoveringthetopicareasofSRCeffectsonissuesofwaterandsoil(twopapersbyDimitriou et al., Schmidt-Walter and Lamersdorf), biodiver-sity (Baum et al.), and the overall impact that these planta-tions may have on the environment and sustainability(Busch, Englund et al., Langeveld et al.). The paper on soilissues by Dimitriou et al. highlights the results for pH,organic carbon (C), and trace element concentrations in thesoil of 14 long-term (10–20 years) commercial willow SRCfields in Sweden when compared with those in adjacent,conventionally managed arable soils. The paper on waterissues by Dimitriou et al. reports the effects of SRC on waterquality by determining differences in leaching of nitrogenand phosphorus to groundwater of 16 commercial SRCstands in Sweden compared to adjacent arable fields grownwith “ordinary” crops. Schmidt-Walter and Lamersdorfdescribe effects on groundwater quality, specifically the po-tential effects of SRC grown under different managementregimes on groundwater recharge. Based on flora inventoriesin eight landscapes located in two European regions(Germany and Sweden), the paper by Baum et al. focus-es on the diversity of higher plants as an indicator ofbiodiversity in willow and poplar SRC, including variousscales ranging from habitat to landscape level diversity.The contribution by Busch is an attempt to assess theimpact of SRC on various landscape functions with thehelp of GIS-based tools. Englund et al. focus on thepotential effects of sustainability requirements within theEU Renewable Energy Directive (RED) on different stake-holders along SRC bioenergy supply chains, assessing theirusefulness in ensuring that SRC bioenergy is produced with

Changes in Organic Carbon and Trace Elements in the Soil of Willow Short-Rotation Coppice Plantations

Short rotation coppice (SRC) is a biomass production system for energy usually grown on former agricultural land with fast-growing tree species. In Sweden, willow SRC has been grown since the late 1980s. SRC on arable soils may induce changes in some soil quality parameters due to differences in crop characteristics and management practices. In this study, pH, organic carbon (C), and trace element concentrations in the soil of 14 long-term (10–20 years) commercial willow SRC fields in Sweden were compared with those in adjacent, conventionally managed arable soils. The results showed that organic C concentrations in the topsoil and subsoil of SRC fields were, on average, significantly higher (9 % in topsoil, 27 % in subsoil) than in the reference fields. When comparisons were made only for the ten sites where the reference field had a crop rotation dominated by cereal crops, the corresponding figures were 10 % and 22 %. The average concentration of cadmium (Cd), which is considered the most hazardous trace element for human health in the food chain, was 12 % lower in the topsoil of SRC fields than in the reference fields. In the corresponding comparison of subsoils, no such difference was found. For chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn), there were no significant differences in concentrations between SRC fields and the reference fields in either topsoil or subsoil. Negligible differences in pH in the same comparisons were found.

Short Rotation Coppice (SRC) Plantations Provide Additional Habitats for Vascular Plant Species in Agricultural Mosaic Landscapes

Increasing loss of biodiversity in agricultural landscapes is often debated in the bioenergy context, especially with respect to non-traditional crops that can be grown for energy production in the future. As promising renewable energy source and additional landscape element, the potential role of short rotation coppice (SRC) plantations to biodiversity is of great interest. We studied plant species richness in eight landscapes (225 km2) containing willow and poplar SRC plantations (1,600 m2) in Sweden and Germany, and the related SRC α-diversity to species richness in the landscapes (γ-diversity). Using matrix variables, spatial analyses of SRC plantations and landscapes were performed to explain the contribution of SRC α-diversity to γ-diversity. In accordance with the mosaic concept, multiple regression analyses revealed number of habitat types as a significant predictor for species richness: the higher the habitat type number, the higher the γ-diversity and the lower the proportion of SRC plantation α-diversity to γ-diversity. SRC plantation α-diversity was 6.9 % (±1.7 % SD) of species richness on the landscape scale. The contribution of SRC plantations increased with decreasing γ-diversity. SRC plantations were dominated more by species adapted to frequent disturbances and anthropo-zoogenic impacts than surrounding landscapes. We conclude that by providing habitats for plants with different requirements, SRC α-diversity has a significant share on γ-diversity in rural areas and can promote diversity in landscapes with low habitat heterogeneity and low species pools. However, plant diversity enrichment is mainly due to additional species typically present in disturbed and anthropogenic environments.

Establishment and two-year growth of a bio-energy plantation with fast-growing Populus trees in Flanders (Belgium): Effects of genotype and former land use

Abstract In April 2010, a large-scale Short Rotation Coppice (SRC) plantation was established with mainly poplar ( Populus spp.) on a former agricultural site (cropland and pasture) in Flanders. The 12 selected genotypes planted were assessed on establishment and production characteristics during the first two years of growth and were found highly productive, with a volume index ranging between 1.00 (±0.68) and 1.93 (±0.97) dm³ in growing season 1 (GS1) and between 2.75 (±1.70) and 11.91 (±6.33) dm³ in growing season 2 (GS2). Despite high survival rates of the cuttings after planting, competitive weeds and management operations increased tree mortality during the growing season from 3.4 % up to 18.2 % averaged over the entire plantation. Weed control therefore turned out to be the key factor in the establishment success. Only a minor influence of former land use was observed during GS1, which is explained by the non-limiting nutrient conditions on both former cropland and pasture, and which disappeared during GS2. These productive soils also explained the high growth rates, with an average tree height of 247 cm and 445 cm and stem diameter (at 22 cm height) of 25.21 mm and 40.73 mm after GS1 and GS2, respectively. Genotypic and parentage variations were found to be less pronounced during GS1, and increased during GS2 as expected. The maximum leaf area index and total leaf area duration were shown to be good indicators of production and growth performance. The results of this paper confirm the high potential of SRC with poplar on agricultural land for bio-energy purposes.

High value of short rotation coppice plantations for phytodiversity in rural landscapes

AbstractThe demand for wood from short rotation coppice (SRC) plantations as a renewable energy source is currently increasing and could affect biodiversity in agricultural areas. The objective was to evaluate the contribution of SRC plantations to phytodiversity in agricultural landscapes assessed as species richness, species–area relationships, Shannon indices, detrended correspondence analysis on species composition, Sørensen similarities, habitat preference proportions, and species proportions found in only one land use. Vegetation surveys were conducted on 12 willow (Salix spp.) and three poplar (Populus spp.) coppice sites as well as on surrounding arable lands, grasslands and forests in central Sweden and northern Germany. SRC plantations were richer in plant species (mean: 30 species per 100 m²) than arable land (10), coniferous forests (13) and mixed forests in Germany (12). Comparing SRC plantations with other land uses, we found lowest similarities in species composition with arable lands, coniferous forests and German mixed forests and highest similarities with marginal grassland strips, grasslands and Swedish mixed forests. Similarity depended on the SRC tree cover: at increased tree cover, SRC plantations became less similar to grasslands but more similar to forests. The SRC plantations were composed of a mixture of grassland (33%), ruderal (24%) and woodland (15%) species. Species abundance in SRC plantations was more heterogeneous than in arable lands. We conclude that SRC plantations form novel habitats leading to different plant species composition compared to conventional land uses. Their landscape‐scale value for phytodiversity changes depending on harvest cycles and over time. As a structural landscape element, SRC plantations contribute positively to phytodiversity in rural areas, especially in land use mosaics where these plantations are admixed to other land uses with dissimilar plant species composition such as arable land, coniferous forest and, at the German sites, also mixed forest.

Below-ground biomass production and allometric relationships of eucalyptus coppice plantation in the central highlands of Madagascar

Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood production in Madagascar. Nevertheless, little is known about their biomass production and partitioning and their potential in terms of carbon sequestration. If above-ground biomass (AGB) can be estimated based on established allometric relations, below-ground (BGB) estimates are much less common. The aim of this work was to develop allometric equations to estimate biomass of these plantations, mainly for the root components. Data from 9 Eucalyptus robusta stands (47–87 years of plantation age, 3–5 years of coppice-shoot age) were collected and analyzed. Biomass of 3 sampled trees per stand was determined destructively. Dry weight of AGB components (leaves, branches and stems) were estimated as a function of basal area of all shoots per stump and dry weight for BGB components (mainly stump, coarse root (CR) and medium root (MR)) were estimated as a function of stump circumference. Biomass was then computed using allometric equations from stand inventory data. Stand biomass ranged from 102 to 130 Mg ha−1 with more than 77% contained in the BGB components. The highest dry weight was allocated in the stump and in the CR (51% and 42% respectively) for BGB parts and in the stem (69%) for AGB part. Allometric relationships developed herein could be applied to other Eucalyptus plantations which present similar stand density and growing conditions; anyhow, more is needed to be investigated in understanding biomass production and partitioning over time for this kind of forest ecosystem.

Hydraulic efficiency and coordination with xylem resistance to cavitation, leaf function, and growth performance among eight unrelated Populus deltoides×Populus nigra hybrids

Tests were carried out to determine whether variations in the hydraulic architecture of eight Populus deltoides×Populus nigra genotypes could be related to variations in leaf function and growth performance. Measurements were performed in a coppice plantation on 1-year-old shoots under optimal irrigation. Hydraulic architecture was characterized through estimates of hydraulic efficiency (the ratio of conducting sapwood area to leaf area, A(X):A(L); leaf- and xylem-specific hydraulic conductance of defoliated shoots, k(SL) and k(SS), respectively; apparent whole-plant leaf-specific hydraulic conductance, k(plant)) and xylem safety (water potential inducing 50% loss in hydraulic conductance). The eight genotypes spanned a significant range of k(SL) from 2.63 kg s(-1) m(-2) MPa(-1) to 4.18 kg s(-1) m(-2) MPa(-1), variations being mostly driven by k(SS) rather than A(X):A(L). There was a strong trade-off between hydraulic efficiency and xylem safety. Values of k(SL) correlated positively with k(plant), indicating that high-pressure flowmeter (HPFM) measurements of stem hydraulic efficiency accurately reflected whole-plant water transport efficiency of field-grown plants at maximum transpiration rate. No clear relationship could be found between hydraulic efficiency and either net CO(2) assimilation rates, water-use efficiency estimates (intrinsic water-use efficiency and carbon isotope discrimination against (13)C), or stomatal characteristics (stomatal density and stomatal pore area index). Estimates of hydraulic efficiency were negatively associated with relative growth rate. This unusual pattern, combined with the trade-off observed between hydraulic efficiency and xylem safety, provides the rationale for the positive link already reported between relative growth rate and xylem safety among the same eight P. deltoides×P. nigra genotypes.

Relation between leaf rust (Melampsora epitea) severity and the specific leaf area in short rotation coppice willows

Willow leaf rust (Melampsora epitea) is an important leaf pathogen in short rotation coppice plantations. Although ecological factors influencing rust severity are rather well known, to date, the connections between leaf morphological traits and rust infections are poorly studied. The aim of this study was to examine the relation between rust severity and specific leaf area (SLA). Willow leaves of three different clones from waste-water-irrigated and non-irrigated plantation areas were used. The results revealed a significant positive correlation between SLA and rust severity. There were clone specific differences whereas more rust pustules were always accompanied with higher SLA. Waste-water-irrigated plants had higher SLA and always more rust damages. These results suggest that leaves with low SLA are less susceptible to leaf rust in various conditions.

Potentials and impacts of short-rotation coppice plantation with aspen in Eastern Germany under conditions of climate change

Woody biomass generated in short-rotation coppice (SRC) plantations with aspen (Populus tremula L.) has good properties for bioenergy crop production: annual yields are high, labour input per year is low, and it is ecologically valuable because of the multi-year rotation periods. Eastern Germany has a special advantage in producing bioenergy crops: the former “agricultural cooperatives” built up quite large farms with, compared to Western Germany, comparatively large fields. Therefore, a modelling study of the potential and the impacts of aspen SRC plantations in the five eastern federal states of Germany under the recent climate and future climate projections was conducted. The ecophysiological forest growth model 4C was used to simulate the growth of aspen SRC plantations and their impacts on carbon in soils, and groundwater recharge, on selected suitable areas currently under crops but with marginal site conditions for cropping. A clear signal to enhanced growth condition over the whole area can be seen in the simulation of the mean annual woody biomass yield under conditions of climate change, which increased from 7.47 t DW ha−1 a−1 under the recent climate to 9.26 t DW ha−1 a−1 at the end of the considered future period 2034–2055 under climate change. The mean soil carbon sequestration rate was 0.81 t C ha−1 a−1 under the recent climate and could rise up to 0.93 t C ha−1 a−1 under the assumption of climate change. On the other hand, the mean annual percolation rate, used as an indicator of impacts on the regional water budget, will diminish under future climatic conditions. The results suggest that aspen SRC plantations are a suitable contribution to regional CO2 mitigation and carbon sequestration under possible change of climate, but that negative impacts on the regional water budget are possible.

Above-ground biomass production and allometric relations of Eucalyptus globulus Labill. coppice plantations along a chronosequence in the central highlands of Ethiopia

Abstract Eucalyptus plantations are extensively managed for wood production in the central highlands of Ethiopia. Nevertheless, little is known about their biomass (dry matter) production, partitioning and dynamics over time. Data from 10 different Eucalyptus globulus stands, with a plantation age ranging from 11 to 60 years and with a coppice-shoot age ranging from 1 to 9 years were collected and analyzed. Above-ground tree biomass of 7–10 sampled trees per stand was determined destructively. Dry weights of tree components ( W c ; leaves, twigs, branches, stembark, and stemwood) and total above-ground biomass ( W a ) were estimated as a function of diameter above stump ( D ), tree height ( H ) and a combination of these. The best fits were obtained, using combinations of D and H . When only one explanatory variable was used, D performed better than H . Total above-ground biomass was linearly related to coppice-shoot age. In contrast a negative relation was observed between the above-ground biomass production and total plantation age (number of cutting cycles). Total above-ground biomass increased from 11 t ha −1 at a stand age of 1 year to 153 t ha −1 at 9 years. The highest dry weight was allocated to stemwood and decreased in the following order: stemwood > leaves > stembark > twigs > branches. The equations developed in this study to estimate biomass components can be applied to other Eucalyptus plantations under the assumption that the populations being studied are similar with regard to density and tree size to those for which the relationships were developed.

First Report of Phoma exigua var. populi Causing Canker of Twigs and Shoots of Poplar in the Czech Republic.

During 2007 and the spring of 2008, a disease of poplars (Populus spp.) resembling the Dothichiza canker was found in plantations of fast-growing trees in central Bohemia and in southern Moravia where it was more abundant. The yellowish brown-to-brown, round or elongated cankers occurred on damaged shoots and twigs. Tissues directly under the bark were discolored and turned black. As the cankers enlarged, infected shoots and twigs died after several months. Small, black, gregarious pycnidia were observed under the bark or in lenticels after several weeks. The disease occurred on Populus nigra, P. × euroamericana cvs. Regenerata, Robusta, Brabantica, Spreewald, CZ-425/58, Blanc du Poitou, and Flaschlanden, and other Populus spp. Isolates of a species of Phoma were acquired by culturing damaged tissues on agar plates containing 3% oatmeal agar (OA) and 2% malt agar. Initial identification of the isolates was done by cultural and morphological characteristics (1). Colonies were floccose, aerial mycelium was olivaceous gray to gray, reverse olivaceous gray sometimes with darker tones at the margins or in the colony center, and NaOH reaction was negative. The growth rate was 42 to 56 in diameter after 7 days at 20°C on OA (optimum temperature for growth was 22°C with a minimum of 1°C and a maximum of 28 to 29°C). Pycnidia in culture scattered, were globose or subglobose, obviously with one nonpapillate ostiolum, olivaceous black or black, 120 to 370 μm in diameter, and conidial exudate was whitish. Phialides were globose to ampulliform and 3 to 7 × 3 to 6 μm. Conidia were hyaline, ellipsoidal, often guttulate, 3.1 to 7.8 × 1.9 to 3.1 μm, and L/B ratio 1.4:3.1. Septate conidia occurred only on natural substrate up to 10.6 × 3.9 μm. Morphological and cultural characteristics resembled those of P. exiqua var. populi Gruyter & P. Scheer (1). The internal transcribed spacer (ITS) sequence (GenBank Accession No EU562206) for the representative isolate (CCF No 3759) confirmed 100% identity to P. exigua. Pathogenicity was confirmed with 1-year-old P. nigra plants during a 2-month greenhouse experiment at 15 to 20°C. Fifteen replicate plants were wounded (5-mm diameter), inoculated with 5-mm OA plugs from actively growing colonies (isolate CCF No 3759), and sealed by Parafilming. An additional 15 control plants following wounding were inoculated with a sterile agar plug. After 3 to 4 weeks, yellowish or brownish necrotic lesions ranging from 1 to 1.5 cm long developed on all inoculated plants. The pathogen was successfully reisolated from lesions and the control plants were asymptomatic. P. exigua var. populi is considered an opportunistic poplar and willow pathogen (2) that becomes more important in winter (1). The pathogen potentially invades host tissues damaged by frost, sun scald, or weakened by excessive transpiration during sunny winter days. To our knowledge, this is the first record of the pathogen on poplars in the Czech Republic, which may have an economic impact on short-rotation coppice plantations.

Genetic structure and spatial distribution of the mycoparasite Sphaerellopsis filum on Melampsora larici‐epitea in a short‐rotation coppice willow planting

AFLP analysis was used to examine the genetic structure of the mycoparasite Sphaerellopsis filum on willow rust Melampsora larici‐epitea using two sets of samples of a willow clone in a short‐rotation coppice planting. The first set was collected from a plot (short strip) in 1998, 1999 and 2000 and the second from another plot (long strip) in 2000. In all, 228 S. filum isolates were typed, 139 AFLP loci scored and 54 AFLP genotypes identified. In the short strip, genotypes sampled in 1998 were no longer detected in subsequent years and genotype diversity fluctuated (0·25–0·68) over the years, indicating that migration had a major impact on the genotype structure. Two distinct groups (average Nei and Li's similarity coefficient between the groups = 0·047) were identified. The group B genotypes were sampled only in 2000. Within the groups, the average similarities were > 0·96. Both the index of association test and the parsimony tree length permutation test suggest that there was a significant clonality in group A while recombination cannot be ruled out in group B. Localized clusters of AFLP genotypes were detected using the software SaTScan that is based on the spatial scan statistic. Possible mechanisms involved in the spread of S. filum in willow coppice plantations are discussed.

Woody biomass production during the second rotation of a bio‐energy Populus plantation increases in a future high CO2 world

AbstractThe quickly rising atmospheric carbon dioxide (CO2)‐levels, justify the need to explore all carbon (C) sequestration possibilities that might mitigate the current CO2 increase. Here, we report the likely impact of future increases in atmospheric CO2 on woody biomass production of three poplar species (Populus alba L. clone 2AS‐11, Populus nigra L. clone Jean Pourtet and Populus×euramericana clone I‐214). Trees were growing in a high‐density coppice plantation during the second rotation (i.e., regrowth after coppice; 2002–2004; POPFACE/EUROFACE). Six plots were studied, half of which were continuously fumigated with CO2 (FACE; free air carbon dioxide enrichment of 550 ppm). Half of each plot was fertilized to study the interaction between CO2 and nutrient fertilization. At the end of the second rotation, selective above‐ and belowground harvests were performed to estimate the productivity of this bio‐energy plantation. Fertilization did not affect growth of the poplar trees, which was likely because of the high rates of fertilization during the previous agricultural land use. In contrast, elevated CO2 enhanced biomass production by up to 29%, and this stimulation did not differ between above‐ and belowground parts. The increased initial stump size resulting from elevated CO2 during the first rotation (1999–2001) could not solely explain the observed final biomass increase. The larger leaf area index after canopy closure and the absence of any major photosynthetic acclimation after 6 years of fumigation caused the sustained CO2‐induced biomass increase after coppice. These results suggest that, under future CO2 concentrations, managed poplar coppice systems may exhibit higher potential for C sequestration and, thus, help mitigate climate change when used as a source of C‐neutral energy.

A new independent validation of the 70-gene signature in node-negative breast cancer

To assess non-destructive above-ground biomass measurements in comparison to destructive measurements in willow (Salix sp.) coppice plantations, individual plant weights of twelve 4-year old willow clones (Salix viminalis L., S. dasyclados Wimm.) were estimated by constructing allometric relationships between stem diameter and shoot dry weight. The plants were also measured with a destructive method, i.e. harvest, weighing, and determination of wood dry matter content. The allometric relationships between shoot dry weight and stem diameter at 55, 85 and 105cm from the shoot base, were compared. Mean differences between the destructively and non-destructively measured plant weights were small and only significant for two of the clones. For nine of the clones, the non-destructive assessments deviated less than 3% from destructively measured weights. The maximum deviation was a 7% underestimation of the mean plant weight. However, the resulting differences between methods increased with increasing plant weight for six of the clones. For most clones, the best fit of the model relating shoot dry weight and stem diameter was found at 105cm above shoot base (r2-adj⩾0.987) but high model fits also were found at 55cm(r2-adj⩾0.973) and 85cm(r2-adj⩾0.961) above shoot base. Plant survival was determined to obtain production assessments per unit area. Standing woody biomass after 4 years ranged from 24.6 to 38.1t dry matter ha−1 and plant survival from 71% to 98%. We conclude that non-destructive methods are reliable for a range of clones in commercial practice, while improvement is needed for purposes in which detection of small growth differences is crucial.