Rotation Coppice Research Articles

Mycorrhizal inoculation effects on growth and the mycobiome of poplar on two phytomanaged sites after 7-year-short rotation coppicing.

Afforestation of trace-element contaminated soils, notably with fast growing trees, has been demonstrated to be an attractive option for bioremediation due to the lower costs and dispersion of contaminants than conventional cleanup methods. Mycorrhizal fungi form symbiotic associations with plants, contributing to their tolerance towards toxic elements and actively participating to the biorestoration processes. The aim of this study was to deepen our understanding on the effects of mycorrhizal inoculation on plant development and fungal community at two trace-element contaminated sites (Pierrelaye and Fresnes-sur-Escaut, France) planted with poplar (Populus trichocarpa x Populus maximowiczii). The 2 sites were divided into 4 replicated field blocks with a final plant density of 2200 tree h-1. Half of the trees were inoculated with a commercial inoculum made of a mix of mycorrhizal species. The sites presented different physico-chemical characteristics (e.g., texture: sandy soil versus silty-loam soil and organic matter: 5.7% versus 3.4% for Pierrelaye and Fresnes-sur-Escaut, respectively) and various trace element contamination levels. After 7 years of plantation, inoculation showed a significant positive effect on poplar biomass production at the two sites. Fungal composition study demonstrated a predominance of the phylum Ascomycota at both sites, with a dominance of Geopora Arenicola and Mortierella elongata, and a higher proportion of ectomycorrhizal and endophytic fungi (with the highest values observed in Fresnes-sur-Escaut: 45% and 28% for ECM and endophytic fungi, respectively), well known for their capacity to have positive effects on plant development in stressful conditions. Furthermore, Pierrelaye site showed higher frequency (%) of mycorrhizal tips for ectomycorrhizal fungi (ECM) and higher intensity (%) of mycorrhizal root cortex colonization for arbuscular mycorrhizal fungi (AMF) than Fresnes-sur-Escaut site, which translates in a higher level of diversity. Finally, this study demonstrated that this biofertilization approach could be recommended as an appropriate phytomanagement strategy, due to its capacity to significantly improve poplar productivity without any perturbations in soil mycobiomes.

Legacy of harvesting methods on coppice-rotation Eucalyptus at experimental and operational scales

Coppice-rotation stands comprise 20 to 30% of the Eucalyptus forests in Brazil and understanding the factors influencing the production ecology of the coppice-rotation is fundamental to improving silvicultural prescriptions. We investigated the effect of harvesting method, stump height and stump cleaning on survival, uniformity, growth, above-ground biomass and light use efficiency in a short rotation of a highly productive E. grandis x E. urophylla clone at two scales in Brazil. At the field experiment scale, treatments were composed of harvesting techniques (Chainsaw and Feller Buncher), stump height (High and Low) and stump cleaning (No harvesting residues over the stump or with residues). The treatments strongly affected growth in height and volume, with less effect on diameter. The largest response came from harvesting method, with mechanized harvesting with a 33% lower mean annual increment (MAI, 33 m³ ha−1 y−1) than harvesting with the chainsaw (50 m³ ha−1 y−1). Stump height did not influence growth in chainsaw clear-cut, but low stumps after Feller Buncher harvesting reduced growth by 23% (30 m³ ha−1 y−1) compared with high stumps (36 m³ ha−1 y−1). Stumps cleaning increased survival only in the semi-mechanized harvest but did not result in a difference in yield. Leaf area index and light use efficiency at the end of rotation were impacted by the clear-cut method, with an average of 3.3 and 2.1 m² m−2, and 0.7 and 0.57 g MJ−1 for chainsaw and Feller Buncher clear cut, respectively. The percentage of stumps that remained intact, the uniformity among individuals, the light capture and the light use efficiency, presented a r² of 67%, 55%, 60% and 86% (p-value < 0.001), respectively. At the operational scale of 12 plantations, we measured MAI, uniformity and survival of the two harvesting methods, all with high stump height and no stump cleaning (current operational prescription). The reduction in coppice-rotation MAI from Feller Buncher harvesting was consistent with the experimental scale, but the difference in MAI (age 4 years) was not as large: 37 m³ ha−1 y−1 for the Feller Buncher harvest and 44 m³ ha−1 y−1 for chainsaw harvest. Harvesting with the Feller Buncher, lowered survival (88%, compared with to 96% with chainsaw harvest) and stand uniformity. Overall, the impacts of harvesting treatment were large enough to those silvicultural systems that include a coppice rotation need to carefully account for the costs and efficiencies of operations for harvesting the planted rotation with subsequent impacts on coppice survival and production.

The effects of cultivar and rotation length (5 vs. 10 years) on biomass production and sustainability of poplar (Populus spp.) bioenergy plantation

AbstractPoplars (Populus spp.) managed in short rotation woody crop (SRWC) systems are considered very promising in terms of biomass production for energy purposes in a temperate zone. In this study, several gaps in knowledge regarding the selection of the plant material, cultivar‐specific responses to coppicing and rotation length are addressed. Five‐ and 10‐year rotation lengths were considered, with a focus on the sustainability of the plantation and the quantification of the biomass production of 10 commercially available hybrid poplar cultivars during two consecutive 5‐year rotation cycles versus one 10‐year rotation in northern Poland. The biomass production varied considerably among cultivars, ranging from 1.6 (‘AF8’) to 7.5 (‘NE42’) Mg ha−1 year−1 at the end of the first 5‐year rotation, and 0.0 (‘AF8’)–5.4 (‘Degrosso’) Mg ha−1 year−1 in the second 5‐year rotation, while in a single 10‐year rotation, the mean annual increment (MAI) ranged from 1.0 (‘AF8’) to 15.1 (‘NE42’) Mg ha−1 yr−1. The 5‐year rotation cycles negatively influenced the sustainability of the plantation due to the high mortality of stems and sprouts in the second 5‐year coppice rotation. In the case of 5‐year and longer rotations, replanting (not resprouting) after harvest may be a more advantageous practice for maximizing the regeneration. The 10‐year rotation cycle allowed for enough development of the crown and root systems to produce sufficient basal area and height to achieve maximal MAI in the trees. The study revealed that an age ≥10 is a biologically optimal rotation age as the slope of MAI was equal/close to zero. This study further showed the crucial importance of testing cultivars before introducing them on a commercial scale and provided valuable information on poplar cultivars available to stakeholders in the biomass market.

Models for leaf area estimation of three forest species in a short coppice rotation

It was obtained statistical models to estimate the leaf area (LA) based in the length (L) and the width (W) of Bambusa vulgaris, two different eucalypt clones, AEC-144 (spontaneous hybrid of Eucalyptus urophylla) and LW07 (Eucalyptus urophylla x Eucalyptus grandis), and Salix nigra leaves. The trees or clumps were provbrided from a short rotation coppice (SRC) for bioenergy, mainly characterized by the high tree density, in Botucatu, Sao Paulo, Brazil. It was collected, by chance, more than 4000 leaves that represented a quarter of the coppices. The bamboo and AEC-144 clone were, at the time, 22 months old, while the willow and LW07 clone were 18 months old. Young, intermediate and old leaves were mixed and measured. The measured leaves were correlated to obtain the simple linear eqs. (LA in function of L and W) and multiple linear regression (LA in function of L × W), to each species. All the species shown a positive correlation coefficient (r) to L (r = 0.75 to 0.95), W (r = 0.70 to 0.82) e L × W (r = 0.87 to 0.95), significative to p ≤ .05. The multiple linear models, that used L × W, are the most appropriated once it had better adjustments with the determination coefficients (R2) between 0.76 and 0.91 with exception in the case of S. nigra (willow), the R2 of the simple linear regression using L was similar to the multiple linear regression, 0.90 and 0.91 respectively, showing that it is possible to estimate the LA in willow just using length.

Agronomic performance of 27 Populus clones evaluated after two 3‐year coppice rotations in Henan, China

AbstractSelecting superior clones is the first step for commercial short‐rotation coppice cultures to provide biomass and bioenergy. Till date, such selection for hybrid Populus clones in middle China is absent. Here we describe the growth, aboveground biomass production and cell wall composition of 27 hybrid poplar clones in Henan, China for two 3‐year rotations. Significant variation in these three characteristics over two triennial rotation coppices among the 27 poplar clones was observed. During two 3‐year rotation coppices, clones ‘276’, ‘02‐17’, and ‘599’ showed relatively higher tree heights and larger basal diameters than those of the other clones. However, the most productive clones were ‘36’ and ‘01‐30’. At the end of the second triennial rotation, the aboveground biomass production reached 18 Mg ha−1 year−1. For the cell wall composition analysis, the cellulose contents of clones ‘01‐243’ and ‘2001’ were relatively high, while the xylose contents of clones ‘01‐30’ and ‘65’ were relatively high. Cluster analysis based on height, basal diameter, biomass, heat value, cellulose content, and survival rate revealed five growth potential classes. Accordingly, clones ‘03‐332’, ‘36’, and ‘599’ exhibited high biomass and growth and had the greatest potential to serve as excellent biomass producers in Henan, China. In addition, the expression patterns of 20 key regulatory genes were analyzed, and an integrated coexpression network was constructed. This field trial provides a comprehensive quantification and evaluation of the agronomic performance of 27 poplar clones in Henan, China. The results of this study and the analytical strategies provide an efficient mechanism for selecting clones that will perform well agronomically in local environments. The expression of key genes and the integrated coexpression network provide the molecular mechanisms of poplar biomass performance.

Changes in vascular plant species composition, top-soil and seed-bank along coppice rotation in an Ostrya carpinifolia forest

Ostrya carpinifolia forests are formations traditionally managed as coppice, with a high biodiversity that characterizes much of the Italian and Balkan low mountain and hill landscapes. Here, we analyze changes in vegetation, seed-bank, soil and litter at six different stages during the coppicing rotation and after 10 years of abandonment of an Ostrya carpinifolia forest located in the central Apennines. Data show that the dynamism characterizing this coenose during traditional coppice rotation alters after cessation of the management practices. Although from the phytosociological point of view all the forest stands belonged to the same association, the highest biodiversity was achieved in the early stages after cutting. This was ascribed to the canopy removal, which creates favourable conditions for the germination of pre-mantels and mantels species stored in the soil seed-bank, while suitable conditions for the nemoral flora are maintained around the tree stumps. In later years, a reduction of non-strictly forest species and an increase in the relative thicknesses of the more superficial top-soil horizons occurred, reaching the maximum around 18 years after cutting. With the abandonment, simplification of the top-soil morphology, total loss of seed bank viability and increase of open-environments species were observed.

Effect of planting density and harvest protocol on field-scale phytoremediation efficiency by Eucalyptus globulus

The phytoremediation efficiency of multi-metal-polluted sites in an electronic waste recycling town by Eucalyptus globulus was evaluated through a series of 2-year field experiments. Different initial planting densities (2500, 5000, and 10,000 plants per ha), coppice rotations, and harvesting position (5 or 30cm above the ground) protocols were designed to improve the remediation potential of the species. There were unnoticeable variations in metal concentrations and distribution characteristics in plant tissues in a low and medium planting-density field during the experimental period. At the end of the experiment, total biomass production per hectare in different protocols displayed a wide range with maximum yield produced in high density, moderate harvesting, and coppice rotation protocol being 2.9 times higher than the minimum yield. The moderate harvest protocol performed with medium planting density was the optimal Cd and Cu decontamination technique. Although the high planting-density field without coppice rotation had the strongest potential for Pb decontamination, it would take more time to remove other metals for the multi-metal-polluted soil decontamination. Considering the remediation efficiency and maintainability of the cultivation system, the moderate harvest protocol performed with the medium planting density was commended for phytoremediation of e-waste recycling impacted area.

Near-infrared spectroscopy enables the genetic analysis of chemical properties in a large set of wood samples from Populus nigra (L.) natural populations

High-throughput techniques for the compositional analysis of lignocellulosic biomass are essential to allow the genetic analysis and genetic improvement of bioenergy feedstocks. In this study, we investigated the feasibility of using near-infrared (NIR) spectroscopy for rapid assessment of wood chemical traits in a large sample of Populus nigra L. individuals evaluated in clonal trials at two contrasting sites. Spectra were acquired from 5799 wood samples collected in 3 harvests corresponding to two coppice rotations at one site and one coppice rotation at the second. Calibrations were developed and validated using 120 reference samples, representing spectral and chemical variations in the samples. The resulting global and site specific calibrations for most of the traits were at least good enough for ranking of genotypes, demonstrating the usefulness of NIR analysis for phenotyping the studied population. Clonal repeatability (Hc2) estimates of the studied traits based on all samples were moderate to high (Hc2 ranging from 0.57 to 0.89 in the 3 harvests). When data were pooled over coppice rotations or sites, the genotype×environment interaction was more evident across sites than across rotations. However, the interaction was smaller than the genotype main effect for all traits, except for glucose and extractives contents. Importantly, the interaction resulted mainly from re-ranking of a few genotypes leaving a substantial amount of stable and performant genetic material, which may encourage breeding for improved main wood components. Optimization of the NIR analysis for assessing clonal trials would facilitate the exploitation of standing genetic variation of energy or chemical related traits in tree breeding program.

Approaches to quantitative reconstruction of woody vegetation in managed woodlands from pollen records

There has been increasing interest in developing quantitative methods for reconstructing the dynamics of cultural landscapes over the last 15years. This paper adds to this literature by using various approaches to reconstruct the vegetation of two woodlands subject to rotational coppicing (the periodic cutting of broadleaved trees and shrubs for wood products). Pollen deposition at ground level was determined at both sites using ‘Tauber’ traps placed near to the centre of 14 compartments of differing age in the coppice rotation. For the main woody taxa, Relative Pollen Productivity (RPP) estimates were derived using linear regression for pollen influx data and Extended R-value analysis for percentage data. The vegetation around three ponds was reconstructed by applying four methods (inverting the two RPP estimate approaches, the modern analogue technique and correction for pollen productivity using the linear regression estimated RPP values) to pollen data obtained from the uppermost sample of sediment from the ponds. To determine whether these methods gave better estimates of the vegetation composition than the original pollen proportions, the results were compared with the surveyed vegetation around each pond using the Bray–Curtis Index. Linear regression of pollen influx produced RPP values which are comparable with previous European studies, whilst for some taxa the Extended R-value analysis produced estimates which are orders of magnitude different both from values derived from the linear regression and previous work. No single approach performed equally well at reconstructing the vegetation around the ponds, and at two of the three locations the uncorrected pollen proportions were most similar to the surveyed vegetation. We conclude that applying quantitative reconstruction methods to individual small sites is, currently, not likely to be useful in complex cultural landscapes. In the context of coppiced woodland, deficiencies in our understanding of pollen taphonomy and the impact of the practice on pollen production first need to be rectified, and we identify strategies to address this situation.

Nitrogen removal and its determinants in hybrid Populus clones for bioenergy plantations after two biennial rotations in two temperate sites in northern Italy

Abstract: The sustainability of bioenergy coppice plantations is strongly affected by the Nitrogen (N) balance, whose removal is very high due to the frequent harvest of large quantities of biomass composed of small-sized shoots. Poplar bioenergy coppice plantations could have a Nitrogen removal comparable to herbaceous crops. In this study, five hybrid poplar genotypes (“AF2”, “AF6”, “Monviso”, “83.148.041”, “I214”) were compared for tree morphological traits related to yield, N removal in the harvested biomass and Nitrogen wood concentration (N%) after two biennial coppice rotations in two experimental plantations located in northern Italy. N removal was primarily influenced by biomass production, and linear positive relationships between biomass yield and N removal were established. N removal also varied greatly among genotypes due to clonal differences in yield and in N%, in relation to significant differences among clones for their branching and sprouting habits. In the first rotation, branchiness was positively correlated to N% with a significant coefficient of determination (R2=0.813), while at the end of the second rotation it was also significantly correlated to the shoots per stool ratio (R2=0.804). “Monviso” and “83.148.041” were the clones showing the highest yield, but also a high N% associated to an high level of branchiness and shoots per stool ratio. Our results highlight that poplar genotype selection for sustainable N management should be aimed at genotypes with low wood N concentration, coupling high yield with low branching and sprouting habits as in the case of the clone “AF2”.

Growth of intact plants and coppice in short rotation eucalypt plantations

The growth of intact plants and coppice of juvenile plants of eight eucalypt clones (3 × 3 m spacing) was evaluated in the savanna region, Brazil (17°36′09″S and 46°42′02″W), aiming for biomass production for energy in short rotations. The treatments included intact plants and juvenile plant coppice (cut at 13 months of age). Coppice was managed either with thinning to two sprouts/stump at 9 months after harvesting or without sprout thinning. The diameter of the intact plants was greater than that of coppice for clones 58, GG100, 26 and 8B, and no differences were noted between treatments for the other clones. Yield did not differ between the thinned and unthinned sprouts for most clones. At younger ages, the coppice yield was greater than that of the intact plants for most clones. Later, there was a decline in the coppice yield, and intact plants surpassed coppice. Then, the maximum coppice mean annual increment was achieved at younger ages than for the intact plants, which resulted in coppice rotation age shortening. The greatest differences between the coppice and intact plants yield was between 38 and 40 months, when the coppice yield was 59, 56, 127, 149 and 75 % greater than that of the intact plants, for the clones 58, GG100, 1000, 36 and 910, respectively. Clone GG100 revealed the highest yield estimation among the intact and coppice plants. The results indicate that by coppicing juvenile eucalypt clone plants, in dense stands, it is possible to produce biomass for energy, without sprout thinning, if rotation age is shortened.

Evaluation of biomass production potential and heating value of hybrid poplar genotypes in a short-rotation culture in Italy

Ensuring increased and sustainable biomass production is critical for European countries. Short-rotation coppice (SRC) plantations on agricultural lands have a great potential to increase biomass supply for biofuels, bioenergy, and bioproducts. In Italy, SRC is based on the use of fast growing species, high planting density, and short harvesting cycles. In this study, the performance of new genotypes to be used in SRC plantations for biomass production was evaluated after three biennial rotations. At the trial plantation in Mira (Northern Italy), six different poplar (Populus) genotypes, belonging to different interspecific hybrids were studied. This plantation provided the opportunity to study the relationships between survival, biomass production and other growth parameters over multiple rotations and for a wide genotypic range. Biomass production differed significantly among rotations starting from 16Mgha−1year−1 in the first, peaking at 20Mgha−1year−1 in the second, and decreasing to 17Mgha−1year−1 in the third rotation. At the end of each rotation, significant differences among genotypes were observed in number of shoots per stool and per ha, stem diameter, tree height, and biomass production. Mean survival rates became significantly different from the other rotations only in the third rotation during which survival rate ranged from 95% for (P.×generosa)×P. nigra ‘Monviso’ to 75% for (P.×generosa)×P. nigra ‘AF6’, but non-significant difference was observed among genotypes. Skewness and inequality of shoot size distributions were genotype-dependent and increased with rotations. Highest biomass production was found for genotypes P.×canadensis ‘83.148.041’, ‘Monviso’ and (P.×generosa)×P. trichocarpa ‘AF8’ with mean annual dry mass production of 21.7, 19.5 and 19.3Mgha−1year−1, respectively. Genotype×rotation interactions were significant on shoot size, diameter and number, but not on survival and biomass production highlighting that genotypes behaved differently over rotations. Moisture and ash content, wood specific gravity, and higher heating value were determined at the end of the third biennial rotation, and significant differences among genotypes were found. This study is critical for investigating the behavior of novel poplar genotypes with potential for commercial biomass production over multiple coppice rotations.

Perspektiven und Herausforderungen im Überblick - Hoffnungsträger Kurzumtriebsplantagen?Pinning Hopes on Short Rotation Coppice? Reviewing Perspectives and Challenges

Over the coming years a rising demand for woody biomass fuels is to be expected. Parts of this demand could be met by short rota tion coppice. If compared with intensive farming practices for annual energy crops, short rotation coppice has lower environmen tal impacts and lower requirements concerning climate and soil quality. High yields in terms of energy content per hectare can be achieved. This article reviews the prospects for short rotation coppice considering land availability as well as site-specific, economic and environmental requirements. Against the backdrop of a changing political framework in the areas of agriculture and energy, the issue of competing land use requirements of energy crops, food production, and nature conser vation will be discussed.

Modern pollen studies from coppiced woodlands and their implications for the detection of woodland management in Holocene pollen records

Investigations of pollen production, modern pollen–vegetation relationships and pollen‐stratigraphic changes have been undertaken from three woodlands under coppice management to establish the impact that woodland management techniques (the periodic cutting of broadleaved trees and shrubs for wood and fodder) have on pollen representation. The number of inflorescences (catkins/flowers) produced over the length of a coppice rotation has been quantified for three species; Corylus avellana, Alnus glutinosa and Tilia cordata. For C. avellana the number inflorescences produced is significantly higher in the early years after coppicing. For A. glutinosa and particularly T. cordata flowering is suppressed after coppicing and only recovers slowly. In the later years the number of inflorescences produced by all three species is related to the height of the regrowths and therefore competition for light. However, the number of pollen grains produced per inflorescence appears not to be related to age in the coppice rotation. The modern pollen rain within the coppiced woodlands largely reflects differences in the vegetation of the coppiced areas rather than variations resulting from their age in the coppice rotation. High resolution pollen-stratigraphic records from small ponds record long-term vegetation trends, while the coppicing of adjacent areas is difficult to detect. Nevertheless, the results from these studies are broadly consistent with the pollen production investigations and together show that coppicing results in a shift in pollen production from canopy to under-storey species and may render some taxa (notably T. cordata) palynologically invisible. Model simulations, with corrections for differences in pollen production through the coppice rotation, have been produced for three types of basin; small ponds/hollows, small lakes and wet woodlands with A. glutinosa. These explore the impact of changes in the intensity and scale of coppicing on pollen assemblages from mixed deciduous woodland. The simulated assemblages are compared with mid–late Holocene pollen records from temperate regions of north-west Europe where archaeological/historical evidence suggests that woodland management is likely to have been practiced. Some changes in the representation of trees and shrubs recorded in pollen diagrams from small hollows within wooded landscapes in southern Scandinavia and from A. glutinosa woodland in southern England are consistent with woodlands being managed. Notably pollen diagrams from the northern Alpine Forelands and East Anglia are compatible with long-standing ideas that woodland was managed on a landscape scale during the Neolithic. Further studies are required to determine whether a number of related woodland management practices produce distinct pollen signatures and the impact of these processes on a wider range of species.

Energy crop production costs in the EU

The objective of this study was to calculate indicative ranges of production costs and assess the main sources of cost for a number of energy crops, both annual and perennial, on a regional level in Europe. The production costs were calculated in terms of the economic compensation required by the farmer in order to grow the crop, and therefore include not only the cost of cultivation, but also the costs of land and risk, which are often omitted in production cost calculations. The cost of land was calculated as the opportunity cost based on the production of cereals. Thus, higher food prices lead to higher land costs, which in turn lead to higher energy crop production costs. The analysis was performed for three cases with different assumptions concerning yields and production cost reductions resulting from scale (total cultivation area in the region), and learning effects. The calculated energy crop production costs were found to be consistently lowest for short- rotation coppice (SRC) crops and highest for annual straw crops. The production costs of SRC crops were calculated to be about 4-5 € GJ -1 under present conditions and 3-4 € GJ -1 under improved future conditions. The production costs for perennial grasses were calculated to be about 6-7 € GJ -1 and 5-6 € GJ -1 under present and improved future conditions, respectively. The production costs for annual straw crops were estimated to be 6-8 € GJ -1 under present conditions with small potential for cost reductions in the future.

Dynamics of biomass production in a poplar coppice culture over three rotations (11 years)

Short rotation coppice culture systems are characterized by a high stool and shoot density, and by rotation durations between 2 and 3 years for species showing an extremely fast growth such as poplar. With the objective to study the long-term biomass production evolution and dynamic of such systems, a high-density plantation with 17 poplar ( Populus) clones belonging to six parentages was established in April 1996 and coppiced in December 1996, January 2001, and February 2004. At the end of each growing season, stool survival, shoot diameter, and the number of shoots per stool were measured. Biomass production was estimated directly by harvesting a number of shoots or indirectly via allometric power equations. Stool survival rates differed among parentages and from year to year irrespective of number of rotations; the highest rates were for P. nigra and the lowest rates were for P. deltoides × P. nigra and P. deltoides × P. trichocarpa parentages. In the second and third rotations, the P. trichocarpa × P. deltoides hybrids showed very high mortality rates. The number of shoots per stool varied among rotations and parentages, and shoot elimination was parentage specific. The number of shoots per stool increased with increasing rotation number, while they decreased from year to year within each rotation. A single general allometric equation linking shoot diameter to shoot biomass could be used to estimate biomass production for most years and most clones. Exceptions were found for the year 2001 and for clone Hazendans. Biomass production differed among parentages and among rotations. The different parentages also differed in their strategy of biomass accumulation. Although P. nigra had the highest biomass production over 11 years, the parentage ranking of biomass production shifted over rotations. The P. trichocarpa × P. deltoides hybrids showed high biomass production in the first rotation, but low in the second and third rotations. Biomass production increased from year to year within one rotation, while it decreased with rotation number. Among the parentages examined, P. nigra and P. trichocarpa were the best performing ones and the best adapted to the multiple coppice rotations.

Optimal rotations on Eucalyptus plantations including carbon sequestration—A comparison of results in Brazil and Spain

Economically optimal rotations are not frequently employed in Eucalyptus plantations management despite eucalypts’ economic importance to the pulp industry. The coppice regeneration method used to manage eucalypts leads to a simultaneous optimization problem. In such cases, the manager has to simultaneously define the optimal age in each coppice rotation and the optimal number of coppice rotations for each plantation full cycle. The dynamic nature of the problem of looking for the optimal set of coppice rotations for Eucalyptus plantations obliges managers to use the dynamic programming technique. In order to evaluate the economic loss occasioned when optimal rotations are not considered, two plantations are shown, one with Eucalyptus urophylla S.T. Blake in Brazil and another with Eucalyptus globulus Labill in Spain. Different clearcut ages are established in each country, 5–9 years in Brazil, and 13–18 years in Spain. A multiple products context (wood and carbon) is considered in this paper. The results show different rotations and optimal number of coppice rotations for each site index and case considered. To repeat the seedling rotation in the following coppice rotations usually is not the best option. Besides, the optimal cycle and the land expectation value vary when carbon sequestration is evaluated for the two plantations considered. Finally, on some occasions the results are very sensitive to changes in parameters like the carbon price and discount rate.

05/02161 The effect of moisture content on retention of fluorocarbon tracers on sand

Various cultural factors influence the biological and economic potentials of Eucalyptus grandis and slash pine as biomass energy crops for southern and northern Florida, respectively. On muck soil, superior E. grandis progenies may produce up to 70 dry Mg ha−1 in 24 months. However, coppicing success on muck soil has been inconsistent. Clones superior in frost-resilience and vigor and propagated as rooted cuttings have increased productivity potential on sandy soils. Break-even costs GJ−1 range from just under US$2 for E. grandis short-rotation intensive culture (SRIC) on muck soils (10 000 trees ha−1 with a 6-year rotation, i.e. seedling/coppice/coppice cycles of 2 years each) to US$4.00 GJ−1 on sandy soils. Planting density, but not coppice rotation, is sensitive to the discount factor. Through 8 years, slash pine yields responded well to soil amendments on typical sites and to high planting densities. Fertilization and vegetation control increased productivity some seven times over conventional culture through 5 years. For slash pine SRIC, higher discount rates increased initial stocking levels and shortened rotations. Break-even costs for slash pine are within the range of values estimated for E. grandis.

Morphological and physiological traits influencing biomass productivity in short-rotation coppice poplar

Fast-growing hybrid poplar (Populus spp.) have potential as a short-rotation coppice crop grown for biomass energy. This work identifies traits for fast growth studied in an American interspecific pedigree derived from Populus trichocarpa Torr. &amp; A. Gray × Populus deltoides Marsh. grown in the United Kingdom for the first time. The biomass yield after the first coppice rotation was estimated to range from 0.04 to 23.68 oven-dried t·ha–1·year–1. This great range suggests that genotypes from this pedigree may be used to understand the genetic basis of high yield in short-rotation coppice, which would be advantageous for informing breeding programs for biomass crops. Relationships between stem, leaf, cell traits, and biomass yield were investigated. Partial least-squares analysis was used to order the traits by importance. The traits most influential on biomass were maximum stem height throughout the growing season, basal diameter, number of stems, and number of sylleptic branches, which showed high heritability, indicating excellent potential for breeding programs. The leaf traits, leaf area, number of leaves on the leading stem, and plastochron index were also associated with an increase in biomass, leading to a better understanding of this trait.

Regeneration by coppicing (resprouting) of miombo (African savanna) trees in relation to land use

This study compared and contrasted natural regeneration by coppicing of tree species in a forest reserve and more disturbed adjacent public lands in eastern Tanzanian miombo woodlands. Data were collected between August and October 1997 using sixty-four 20 m×50 m plots. Eighty-three percent of the 30 harvested woody species in the forest reserve resprouted after harvesting compared with 90% of the 39 species in the public lands. Coppicing effectiveness (mean number of shoots per stump) varied among species and depended on plant size at the time of cutting, stump height and percentage of the stand removed. Comparing the 16 species effectively sampled in both sites, coppicing effectiveness was 4.9±1.6 (S.E.) shoots per stump in public lands, which is greater than the 3.1±1.4 shoots per stump in the reserve (paired t 15=2.433, P=0.014). However, the percentage of resprouting stumps did not differ (paired t 15=1.440, P=0.085), but tended to be higher in public lands. The percentages of stumps sprouting per species varied from 0 to 100%, with means of 59 (reserve) and 74% (public lands). Coppicing effectiveness for the most utilised species, Combretum molle (fuelwood; 4.0 shoots per stump in the reserve, 6.1 shoots per stump in public lands), Julbernardia globiflora (fuelwood; 5.6 vs. 5.3 shoots per stump), Pterocarpus angolensis (carpentry; absent vs. 7.3 shoots per stump) and Spirostachys africana (building poles; 1.0 vs. 0.4 shoots per stump) showed typical variation. The greater levels of resprouting in public lands is interpreted as release from self-thinning dynamics, as the reserve has a much higher tree biomass. Despite high levels of harvesting in public lands, tree densities are virtually identical between land uses as a result of the high levels of resprouting. Due to the prolific coppicing of trees in public lands, it is recommended that the woodland should be managed using coppice rotation as a silvicultural system.