Special Issue "Short Rotation Woody Crop Production Systems for Ecosystem Services and Phytotechnologies"

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecology and Management".

Deadline for manuscript submissions: closed (15 May 2019) | Viewed by 31469

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Special Issue Editors

Dr. Ronald S. Zalesny, Jr.
E-Mail Website1 Website2
Guest Editor
USDA Forest Service, Northern Research Station Institute for Applied Ecosystem Studies, 5985 Highway K, Rhinelander, WI 54501, USA
Interests: bioenergy; biomass; ecophysiology; ecosystem services; forest genetics; intensive forestry; phytotechnologies; short rotation woody crops
Special Issues, Collections and Topics in MDPI journals
Dr. William L. Headlee
E-Mail Website
Guest Editor
1. School of Forestry & Natural Resources, University of Arkansas at Monticello, 110 University Court Monticello, AR 71656, USA
2. Arkansas Forest Resources Center, University of Arkansas Division of Agriculture, 110 University Court Monticello, AR 71656, USA
Interests: the effects of genotype, environment, and management on tree/forest growth, physical structure, and utilization by livestock and wildlife
Dr. Raju Y. Soolanayakanahally
E-Mail Website
Guest Editor
Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, SK S7N 0X2, Canada
Interests: poplar and willow genetic improvement, agroforestry, ecophysiology, production of bioenergy crops on marginal lands and phytoremediation
Mr. Jim Richardson
E-Mail Website
Guest Editor
Technical Director Poplar and Willow Council of Canada, 1876 Saunderson Drive, Ottawa, ON K1G 2C5, Canada
Interests: poplar and willow production, management and genetic improvement; agroforestry; bioenergy crops; ecosystem services; silviculture

Special Issue Information

Dear Colleagues,

Historically, international efforts in the development of short rotation woody crops (SRWCs) focused on the production of biomass for bioenergy, biofuels, and bioproducts, while research and deployment over the past decade has expanded to include broader objectives of achieving multiple ecosystem services. In particular, silvicultural prescriptions developed for SRWCs have been refined to include woody crop production systems for environmental benefits, such as carbon sequestration, water quality and quantity, and soil health. In addition, current systems have been expanded beyond traditional fiber production to other environmental technologies that incorporate SRWCs as vital components for phytotechnologies, urban afforestation, ecological restoration, and mine reclamation. In this Special Issue, we explore the broad range of current research dedicated to international “Short Rotation Woody Crop Production Systems for Ecosystem Services and Phytotechnologies”.

Dr. Ronald S. Zalesny, Jr.
Dr. William L. Headlee
Dr. Raju Y. Soolanayakanahally
Mr. Jim Richardson

Guest Editors

Keywords

  • biomass
  • carbon
  • forest restoration
  • mine reclamation
  • phytoremediation
  • soils
  • urban afforestation
  • water

Published Papers (18 papers)

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Article
Survival, Height Growth, and Phytoextraction Potential of Hybrid Poplar and Russian Olive (Elaeagnus Angustifolia L.) Established on Soils Varying in Salinity in North Dakota, USA
Forests 2019, 10(8), 672; https://doi.org/10.3390/f10080672 - 09 Aug 2019
Cited by 4 | Viewed by 1747
Abstract
Salt-affected soils in the Northern Great Plains, USA, can impact the long-term survival and growth of trees recommended for agroforestry systems, with Russian olive (Elaeagnus angustifolia L.) being one of few options that survives on these sites. Similarly, hybrid poplars have been [...] Read more.
Salt-affected soils in the Northern Great Plains, USA, can impact the long-term survival and growth of trees recommended for agroforestry systems, with Russian olive (Elaeagnus angustifolia L.) being one of few options that survives on these sites. Similarly, hybrid poplars have been used for phytotechnologies on high-salinity soils throughout the world. The objective of this study was to test the survival, height growth, and phytoextraction potential of eight hybrid poplar clones (Populus deltoides Bartr. ex Marsh. × P. nigra L. ‘Robusta’, ‘DN17’, ‘DN182’, ‘DN5’; P. deltoides × P. maximowiczii A. Henry ‘NC14104’, ‘NC14106’; P. nigra × P. maximowiczii ‘NM2’, ‘NM6’) versus Russian olive grown on soils categorized according to initial salinity levels: low (0.1 to 3.9 dS m−1), medium (4.0 to 5.9 dS m−1), and high (6.0 to 10.0 dS m−1). Seven trees per genotype were grown in each salinity treatment at a spacing of 3 × 3 m for four years in Burleigh County, North Dakota. Survival and height were determined following the first four growing seasons, and leaf phytoextraction potential of Al, Ca, Cd, Fe, K, Mg, Mn, Na, and Zn was measured for one-year-old trees. Soil salinity decreased over time, reflecting the phytoextraction potential of the trees. Russian olive did not survive as well as expected, having lower overall survival than three of the hybrid poplar clones (‘DN17’, ‘DN5’, ‘NM6’). At the end of three years when trees were removed per a landowner maintenance agreement, 86%, 71%, and 43% of the Russian olive trees were alive in the low-, medium-, and high-salinity soils, respectively. At this time, ‘NM2’ was the only hybrid poplar clone with similar survival to Russian olive in the high-salinity soils. Russian olive had greater Na, Cd, and Fe leaf concentrations than the hybrid poplar clones, but it also had the worst uptake of Ca and Mg of all genotypes. For hybrid poplar, the P. deltoides × P. nigra genomic group had the broadest clonal variability among all traits, with ‘Robusta’ and ‘DN182’ exhibiting great potential for establishment on high-salinity soils. ‘Robusta’ and ‘DN17’ are the same genotype but they came from different nursery sources (i.e., hence their different nomenclature), and they did not differ for height nor leaf phytoextraction. Populus deltoides × P. maximowiczii clones were not suitable for the soil conditions and silvicultural applications (e.g., tree shelters) of the current study, while P. nigra × P. maximowiczii clones exhibited the most stable performance across all years and salinity treatments. Both ‘NM2’ and ‘NM6’ had superior fourth-year survival and height, as well as average or above average phytoextraction of all elements tested. Full article
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Article
Tree Willow Root Growth in Sediments Varying in Texture
Forests 2019, 10(6), 517; https://doi.org/10.3390/f10060517 - 19 Jun 2019
Cited by 2 | Viewed by 1363
Abstract
We investigated the early root development of Salix nigra L. willow grown from cuttings in the different riverbank sediments; silt, sand and stones. Cuttings were grown for 10 weeks in layered sediment types in five large planter boxes, each box having three separate [...] Read more.
We investigated the early root development of Salix nigra L. willow grown from cuttings in the different riverbank sediments; silt, sand and stones. Cuttings were grown for 10 weeks in layered sediment types in five large planter boxes, each box having three separate compartments. The boxes differed in the proportion of silt, sand and stones. At 10 weeks, the roots were extracted and sorted into diameter classes (≥2 mm; 1 < 2 mm; <1 mm) according to sediment type and depth. Root length and dry mass were measured and root length density (RLD) and root mass density (RMD) calculated. Root development of S. nigra cuttings varied with the substrate, either silt, sand or stones. Roots initiated from the entire length of the cutting in the substrate but with a concentration of initials located at the bottom and close to the bottom of the cutting. There was substantial root extension into all three substrates and at all depths. Generally, RMD was higher in the stones, influenced by having the bottom of the cuttings in stones for four of the five treatments. RMD was highest for roots <1 mm diameter. RMD of roots <1 mm diameter was least for those roots growing in sand. Whereas RLD for roots >0.5 mm diameter was highest in the sand, RLD of roots with diameter <0.5 mm was lowest in sand. Roots of S. nigra cuttings were least effective in binding sand, primarily because of low RLD of roots <0.5 mm diameter. It is surmised that sand lacks water and nutrients sufficient to sustain growth of fine roots compared with silt and even stones. RLD for roots >0.5 mm diameter was lowest in silt likely due to the greater resistance of the substrate to root penetration, or possibly the greater investment into smaller roots with absorption capability. Full article
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Article
Productivity, Growth Patterns, and Cellulosic Pulp Properties of Hybrid Aspen Clones
Forests 2019, 10(5), 450; https://doi.org/10.3390/f10050450 - 24 May 2019
Cited by 9 | Viewed by 1387
Abstract
Research Highlights: This research provides a firm basis for understanding the improved aspen hybrid performance that aims at facilitating optimal clone selection for industrial application. Background and Objectives: Rapid growth and wood properties make aspen (Populus tremula L.) suitable for the production [...] Read more.
Research Highlights: This research provides a firm basis for understanding the improved aspen hybrid performance that aims at facilitating optimal clone selection for industrial application. Background and Objectives: Rapid growth and wood properties make aspen (Populus tremula L.) suitable for the production of pulp and paper. We assessed the potential of tree improvement through hybridization to enhance aspen productivity in northern Poland, and investigated the effects of Populus tremula hybridization with Populus tremuloides Michaux and Populus alba L. on the growth and cellulosic pulp properties for papermaking purposes. Materials and Methods: A common garden trial was utilized that included 15 hybrid aspen clones of P. tremula × P. tremuloides, four of P. tremula × P. alba, and one, previously tested P. tremula clone. Clones of P. tremula, plus trees from wild populations, were used as a reference. Tree height and diameter at breast height (DBH) were measured after growing seasons four through seven. At seven years of age, the three clones representing all species combinations were harvested, and their cellulosic pulp properties and paper sheet characteristics were assessed. Results: The clones from wild populations exhibited the poorest growth. In contrast, the clone ‘Wä 13′ (P. tremula × P. tremuloides) demonstrated the highest DBH, height, volume production, and mean annual increment (MAI) (25.4 m3 ha−1 year−1). The MAI ratio calculated for interspecific crosses ranged from 1.35- to 1.42-fold, higher than that for the P. tremula. Chemical properties of pulp, fiber morphology, and the physical properties of paper sheets were more desirable for interspecific hybrid clones than those for the pure P. tremula clone. Conclusions: The results indicated that plantations of hybrid aspen may constitute an important additional source of wood for pulp and paper products in Poland. Our findings further suggested that the standard rotation of these trees may be reduced from 40 to 20 years, increasing overall biomass yield and enhancing atmospheric carbon sequestration. Full article
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Article
The Economics of Rapid Multiplication of Hybrid Poplar Biomass Varieties
Forests 2019, 10(5), 446; https://doi.org/10.3390/f10050446 - 23 May 2019
Cited by 6 | Viewed by 1249
Abstract
Background: Poplar (Populus spp.) hybridization is key to advancing biomass yields and conversion efficiency. Once superior varieties are selected, there is a lag in commercial use while they are multiplied to scale. Objective: The purpose of this study was to assess the [...] Read more.
Background: Poplar (Populus spp.) hybridization is key to advancing biomass yields and conversion efficiency. Once superior varieties are selected, there is a lag in commercial use while they are multiplied to scale. Objective: The purpose of this study was to assess the influence of gains in biomass yield and quality on investment in rapid propagation techniques that speed the time to commercial deployment. Material and Methods: A factorial experiment of propagation method and hybrid variety was conducted to quantify the scale-up rate of in vitro and greenhouse clonal multiplication. These data were used in modeling the internal rate of return (IRR) on investment into rapid propagation as a function of genetic gains in biomass yield and quality and compared to a base case that assumed the standard method of supplying operational varieties in commercial quantities from nurseries as hardwood cuttings, capable of yields of 16.5 Mg ha−1 year−1. Results: Analysis of variance in macro-cutting yield showed that propagation method and varietal effects as well as their interaction were highly significant, with hedge propagation exceeding serial propagation in macro-cutting productivity by a factor of nearly 1.8. The Populus deltoides × P. maximowiczii and the Populus trichocarpa × P. maximowiczii varieties greatly exceeded the multiplication rate of the P. × generosa varieties due to their exceptional response to repeated hedging required to initiate multiple tracks of serial propagation. Analyses of investment into rapid propagation to introduce new material into plantation establishment followed by a 20-year rotation of six coppice harvests showed that gains in biomass yield and quality are warranted for a commitment to rapid propagation systems. The base case analysis was generally favored at yields up to 18 Mg−1 year−1 dependent on pricing. The rapid multiplication analysis proved superior to the base case analysis at the two highest yield levels (27.0 and 31.5 Mg ha−1 year−1,) at all price levels and at yields of 22.5 Mg−1 year−1, dependent on price and farm location. Conclusion: Rapid multiplication is a reliable method to move improved plant material directly into operations when valued appropriately in the marketplace. Full article
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Article
Overhead Protection Increases Fuel Quality and Natural Drying of Leaf-On Woody Biomass Storage Piles
Forests 2019, 10(5), 390; https://doi.org/10.3390/f10050390 - 01 May 2019
Cited by 11 | Viewed by 1441
Abstract
Short-rotation woody crops (SRWC) have the potential to make substantial contributions to the supply of biomass feedstock for the production of biofuels and bioproducts. This study evaluated changes in the fuel quality (moisture, ash, and heating value) of stored spring harvested shrub willow [...] Read more.
Short-rotation woody crops (SRWC) have the potential to make substantial contributions to the supply of biomass feedstock for the production of biofuels and bioproducts. This study evaluated changes in the fuel quality (moisture, ash, and heating value) of stored spring harvested shrub willow (Salix spp.) and hybrid poplar (Populus spp.) chips with respect to pile protection treatments, location within the storage piles, and length of storage. Leaf-on willow and poplar were harvested in the spring, and wood chips and foliage with moisture content in the range of 42.1% to 49.9% (w.b.) were stored in piles for five months, from May to October 2016. Three protection treatments were randomly assigned to the piles. The control treatment had no cover (NC), so piles were exposed to direct solar radiation and rainfall. The second treatment had a canopy (C) installed above the piles to limit direct rainfall. The final treatment had a canopy plus a dome aeration system (CD) installed over the piles. Covering piles reduced and maintained the low moisture content in wood chip piles. Within 30 days of establishment, the moisture content in the core of the C pile decreased to less than 30%, and was maintained between 24%–26% until the end of the storage period. Conversely, the moisture content in the NC piles decreased in the first two months, but then increased to the original moisture content in the core (>45 cm deep) and up to 70% of the original moisture content in the shell (<45 cm deep). For all the treatments in the tested conditions, the core material dried faster than the shell material. The higher heating value (HHV) across all the treatments increased slightly from 18.31 ± 0.06 MJ/kg at harvest to 18.76 ± 0.21 MJ/kg at the end of the storage period. The lower heating value (LHV) increased by about 50% in the C and CD piles by the end of the storage period. However, in the NC piles, the LHV decreased by 3% in the core and 52% in the shell. Leaf-on SRWC biomass stored in piles created in late spring under climatic conditions in central and northern New York showed differing moisture contents when stored for over 60–90 days. Overhead protection could be used to preserve or improve the fuel quality in terms of the moisture content and heating value if more than two months of storage are required. However, the implementation of such management practice will depend on whether the end users are willing to pay a higher price for dryer biomass and biomass with a higher LHV. Full article
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Article
Short Rotation Eucalypts: Opportunities for Biochar
Forests 2019, 10(4), 314; https://doi.org/10.3390/f10040314 - 05 Apr 2019
Cited by 5 | Viewed by 1247
Abstract
Eucalypts can be very productive when intensively grown as short rotation woody crops (SRWC) for bioproducts. In Florida, USA, a fertilized, herbicided, and irrigated cultivar planted at 2471 trees/ha could produce over 58 green mt/ha/year in 3.7 years, and at 2071 trees/ha, its [...] Read more.
Eucalypts can be very productive when intensively grown as short rotation woody crops (SRWC) for bioproducts. In Florida, USA, a fertilized, herbicided, and irrigated cultivar planted at 2471 trees/ha could produce over 58 green mt/ha/year in 3.7 years, and at 2071 trees/ha, its net present value (NPV) exceeded $750/ha at a 6% discount rate and stumpage price of $11.02/green mt. The same cultivar grown less intensively at three planting densities had the highest stand basal area at the highest density through 41 months, although individual tree diameter at breast height (DBH) was the smallest. In combination with an organic fertilizer, biochar improved soil properties, tree leaf nutrients, and tree growth within 11 months of application. Biochar produced from Eucalyptus and other species is a useful soil amendment that, especially in combination with an organic fertilizer, could improve soil physical and chemical properties and increase nutrient availability to enhance Eucalyptus tree nutrition and growth on sandy soils. Eucalypts produce numerous naturally occurring bioproducts and are suitable feedstocks for many other biochemically or thermochemically derived bioproducts that could enhance the value of SRWCs. Full article
Article
Hormones and Heterosis in Hybrid Balsam Poplar (Populus balsamifera L.)
Forests 2019, 10(2), 143; https://doi.org/10.3390/f10020143 - 10 Feb 2019
Cited by 5 | Viewed by 1485
Abstract
Balsam poplar (Populus balsamifera L.) is a transcontinental tree species in North America, making it an ideal species to study intra-specific hybrid vigour as a tool for increasing genetic gain in growth. We tested the hypothesis that intra-specific breeding of disparate populations [...] Read more.
Balsam poplar (Populus balsamifera L.) is a transcontinental tree species in North America, making it an ideal species to study intra-specific hybrid vigour as a tool for increasing genetic gain in growth. We tested the hypothesis that intra-specific breeding of disparate populations of balsam poplar would lead to the expression of hybrid vigour and we determined the role of endogenous hormones linked to ecophysiological and growth performance. In September 2009, three field trials were established in Canada (two in Alberta (AB), i.e., Fields AB1 and AB2, and one in Quebec (QC), i.e., Field QC1) in conjunction with Alberta-Pacific Forest Industries Inc. and the Ministry of Forests, Wildlife and Parks, Quebec. Five male parents from each province as well as five female parents from QC and four female parents from AB were used for breeding intra-regional and inter-regional crosses. Based on a significant difference at year six for height and diameter, from the AB1 and AB2 field trials, the AB × QC cross-type was selected for further study. Cuttings from the AB × QC cross-type were grown in a randomized complete block design under near-optimal greenhouse conditions. Families were identified as slow- or fast-growing, and the relationship between hormone levels and growth performance of the genotypes within the families were examined. In late June, after 34 days of growth, internode tissue samples collected from each progeny were analyzed for gibberellic acids, indole-3-acetic acid, and abscisic acid content. Stem volume of two-month-old rooted cuttings, grown under optimal greenhouse conditions, was positively and significantly correlated with the photosynthetic rate, greenhouse growth, and stem volume of 8-year-old field-grown trees (Fields AB1 values: r = 0.629 and p = 0.012; AB2 values: r = 0.619 and p = 0.014, and QC1 values: r = 0.588 and p = 0.021, respectively). We determined that disparate and native populations of balsam poplar can be bred to produce superior progeny with enhanced stem growth traits. Full article
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Article
Adaptability of Populus to Physiography and Growing Conditions in the Southeastern USA
Forests 2019, 10(2), 118; https://doi.org/10.3390/f10020118 - 02 Feb 2019
Cited by 15 | Viewed by 1281
Abstract
Populus species have a high productivity potential as short-rotation woody crops, provided that site-suitable varieties are planted. The Coastal Plain, the Piedmont, and the Blue Ridge Mountains make up a significant part of the eastern and southeastern USA, and an insight into poplar [...] Read more.
Populus species have a high productivity potential as short-rotation woody crops, provided that site-suitable varieties are planted. The Coastal Plain, the Piedmont, and the Blue Ridge Mountains make up a significant part of the eastern and southeastern USA, and an insight into poplar productivity and adaptability will be valuable for the successful implementation of large-scale poplar stands in these regions. The objectives of this study were to examine the green wood biomass (hereafter biomass), biomass allocation, and wood properties of poplars in relation to growing conditions, physiography, and topography. The biomass of 4-year-old poplars was estimated using an equation derived through destructive sampling. Biomass-based clonal rankings were compared across the various site conditions (fertility, irrigation, land marginality, soil preparation, and topography) and the three physiographic provinces. Although not all clonal differences in biomass were significant, growing conditions, physiography, and soil preparation affected the clonal rankings and the significance of the clonal differences. Biomass changes due to physiography and land conditions were more structured at the genomic-group level. A higher-altitude physiography led to greater biomass increases in Populus trichocarpa × Populus deltoids (TD) clones than in P. deltoids × P. deltoids (DD) clones and vice versa. Favorable soil quality or management generally led to greater biomass of DD clones than of TD and P. deltoids × Populus maximowiczii (DM) clones. Weather-related variables were not clearly correlated with biomass, while land aspect was a significant influence on the biomass of genomic groups and clones. The site significantly affected wood density, moisture content, and carbon and nitrogen concentrations, while the clonal effects on wood composition and the clonal and site effects on biomass allocation were insignificant. Although clones showing greater biomass responses to growing conditions generally belonged to the same genomic group, clone-level selection could produce greater biomass gains than selection at the genomic-group level. Full article
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Article
Relationships among Root–Shoot Ratio, Early Growth, and Health of Hybrid Poplar and Willow Clones Grown in Different Landfill Soils
Forests 2019, 10(1), 49; https://doi.org/10.3390/f10010049 - 10 Jan 2019
Cited by 15 | Viewed by 2002
Abstract
Root–shoot allocation of biomass is an underrepresented criterion that could be used for tree selection in phytoremediation. We evaluated how root–shoot allocations relate to biomass production and overall health of poplar and willow clones grown in landfill soil treatments. Fifteen poplar clones and [...] Read more.
Root–shoot allocation of biomass is an underrepresented criterion that could be used for tree selection in phytoremediation. We evaluated how root–shoot allocations relate to biomass production and overall health of poplar and willow clones grown in landfill soil treatments. Fifteen poplar clones and nine willows were grown in a greenhouse for 65 days in soils from five Wisconsin landfills and one greenhouse control. We tested for treatment, clone, and interaction differences in root–shoot ratio (RSR), health, and growth index, along with relationships between RSR with diameter, health, height, total biomass, and growth index. Treatments, clones, and their interactions were not significantly different for poplar RSR, but willow clones differed (p = 0.0049). Health significantly varied among willow clones (p < 0.0001) and among the clone × treatment interaction for poplars (p = 0.0196). Analysis of means showed that willow clones ‘Allegany’ and ‘S365’ exhibited 28% and 21% significantly greater health scores than the overall mean, respectively. Root–shoot ratio was not significantly correlated with health in either genus but was positively correlated with growth index for poplars, which was corroborated via regression analyses. Selecting clones based on a combination of biomass allocation, health, and growth indices may be useful for using phyto-recurrent selection to satisfy site-specific ecosystem services objectives. Full article
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Article
Stakeholder Assessment of the Feasibility of Poplar as a Biomass Feedstock and Ecosystem Services Provider in Southwestern Washington, USA
Forests 2018, 9(10), 655; https://doi.org/10.3390/f9100655 - 20 Oct 2018
Cited by 4 | Viewed by 2665
Abstract
Advanced Hardwood Biofuels Northwest (AHB), a USDA NIFA-funded consortium of university and industry partners, identified southwestern Washington as a potential location for a regional bioproducts industry using poplar trees (Populus spp.) as the feedstock. In this qualitative case study, we present the [...] Read more.
Advanced Hardwood Biofuels Northwest (AHB), a USDA NIFA-funded consortium of university and industry partners, identified southwestern Washington as a potential location for a regional bioproducts industry using poplar trees (Populus spp.) as the feedstock. In this qualitative case study, we present the results of an exploratory feasibility investigation based on conversations with agricultural and natural resources stakeholders. This research complements a techno-economic modelling of a hypothetical biorefinery near Centralia, WA, USA. Interviews and group discussions explored the feasibility of a poplar-based bioproducts industry in southwestern WA, especially as it relates to converting land to poplar farms and the potential for poplar to provide ecosystem services. Stakeholders revealed challenges to local agriculture, past failures to profit from poplar (for pulp/sawlogs), land-use planning efforts for flood mitigation and salmon conservation, questions about biorefinery operations, and a need for a new economic opportunity that “pencils out”. Overall, if the business model is convincing, participants see chances for win-win situations where landowners could profit growing poplar on otherwise low-value acreage and achieve ecosystem services for wastewater or floodplain management. Full article
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Article
Quality Testing of Short Rotation Coppice Willow Cuttings
Forests 2018, 9(7), 378; https://doi.org/10.3390/f9070378 - 23 Jun 2018
Cited by 2 | Viewed by 1666
Abstract
The production and feasibility of Short Rotation Coppice depend on cutting early performance. The shoot and root biomass production of Salix cuttings in hydroponic conditions was studied. The amount of sprouted biomass after four weeks of growth depended on cutting the diameter, but [...] Read more.
The production and feasibility of Short Rotation Coppice depend on cutting early performance. The shoot and root biomass production of Salix cuttings in hydroponic conditions was studied. The amount of sprouted biomass after four weeks of growth depended on cutting the diameter, but the original position of the cutting along the rod or number of visible buds was not in correlation with biomass produced. Application of mineral fertilizer or soil originating from the willow plantation did not increase the total production. On the contrary, the addition of soil tended to decrease biomass production and we assumed this was a result of a shortage of light. Under the influence of fertilization, plants allocated greater biomass to roots. Comparison of different clones revealed that those with S. dasyclados genes tended to allocate less biomass to roots and the poorest-performing clone in our experiment, also had the lowest wood production in the plantation. The number of visible buds on the cutting was also clone-specific. Full article
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Article
The Performance of Five Willow Cultivars under Different Pedoclimatic Conditions and Rotation Cycles
Forests 2018, 9(6), 349; https://doi.org/10.3390/f9060349 - 13 Jun 2018
Cited by 4 | Viewed by 1894
Abstract
A plant’s genotype, their environment, and the interaction between them influence its growth and development. In this study, we investigated the effect of these factors on the growth and biomass yield of willows in short-rotation coppice (SRC) under different harvesting cycles (i.e., two- [...] Read more.
A plant’s genotype, their environment, and the interaction between them influence its growth and development. In this study, we investigated the effect of these factors on the growth and biomass yield of willows in short-rotation coppice (SRC) under different harvesting cycles (i.e., two- vs. three-year rotations) in Quebec (Canada). Five of the commercial willow cultivars most common in Quebec, (i.e., Salix × dasyclados Wimm. ‘SV1’, Salix viminalis L. ‘5027’, Salix miyabeana Seeman ‘SX61’, ‘SX64’ and ‘SX67’) were grown in five sites with different pedoclimatic conditions. Yield not only varied significantly according to site and cultivar, but a significant interaction between rotation and site was also detected. Cultivar ‘5027’ showed significantly lower annual biomass yield in both two-year (average 10.8 t ha−1 year−1) and three-year rotation (average 11.2 t ha−1 year−1) compared to other cultivars (15.2 t ha−1 year−1 and 14.6 t ha−1 year−1 in two- and three-year rotation, respectively). Biomass yield also varied significantly with rotation cycle, but the extent of the response depended upon the site. While in some sites the average productivity of all cultivars remained fairly constant under different rotations (i.e., 17.4 vs. 16 t ha−1 year−1 in two- and three-year rotation, respectively), in other cases, biomass yield was higher in the two- than in the three-year rotation or vice versa. Evidence suggests that soil physico-chemical properties are better predictors of willow SRC plantation performance than climate variables. Full article
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Article
Planting Density and Site Effects on Stem Dimensions, Stand Productivity, Biomass Partitioning, Carbon Stocks and Soil Nutrient Supply in Hybrid Poplar Plantations
Forests 2018, 9(6), 293; https://doi.org/10.3390/f9060293 - 25 May 2018
Cited by 20 | Viewed by 2336
Abstract
In this study, planting density and site effects on hybrid poplar productivity and stem dimensions were evaluated on the mid-term and longer term (8 and 14 years) in southern Québec (Canada). We also evaluated the effects of planting density and site on biomass [...] Read more.
In this study, planting density and site effects on hybrid poplar productivity and stem dimensions were evaluated on the mid-term and longer term (8 and 14 years) in southern Québec (Canada). We also evaluated the effects of planting density and site on biomass accumulation and carbon stocks in different plantation compartments, on biomass partitioning at the stand-level, on soil carbon stocks and on soil nutrient supply rate after 14 years. The experimental design consisted of three replicate poplar stands located along a site fertility gradient. Each stand contained six planting densities (ranging from 494 to 1975 trees/ha) and a single genotype (Populus canadensis × P. maximowiczii hybrid). Planting density had a large effect on stem dimensions, but a minor effect on stand volume, aboveground woody biomass production, and aboveground biomass carbon stocks. Site selection and tree survival were more important factors affecting these variables. At all sites, and independent of planting density, mean annual volume increments were also higher after 14 vs. 8 years. On fertile sites, strong correlations between area per tree at planting and biomass partitioning, carbon allocation belowground, soil nutrient supply rate and soil carbon stocks were observed. Aboveground, higher competition for light with increasing planting density resulted in an increase in the stem to branch ratio. Belowground, higher competition for soil resources with increasing planting density reduced soil macronutrient availability (except for potassium), which likely stimulated carbon allocation belowground and carbon accumulation in the soil. Over the longer-term, higher density plantations of poplars could provide greater benefits in terms of carbon storage belowground (soil and roots). Full article
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Article
Investigating the Effect of a Mixed Mycorrhizal Inoculum on the Productivity of Biomass Plantation Willows Grown on Marginal Farm Land
Forests 2018, 9(4), 185; https://doi.org/10.3390/f9040185 - 04 Apr 2018
Cited by 5 | Viewed by 1828
Abstract
Inoculation with mycorrhizal fungi, proven mediators of soil fertility, has great potential in agricultural and silvicultural systems. This is particularly true in short-rotation coppices (SRCs), where questions of food displacement and fertilization are causes of concern for researchers and policy makers. We set [...] Read more.
Inoculation with mycorrhizal fungi, proven mediators of soil fertility, has great potential in agricultural and silvicultural systems. This is particularly true in short-rotation coppices (SRCs), where questions of food displacement and fertilization are causes of concern for researchers and policy makers. We set out to thoroughly test if current inoculation methods, coupled with reduced fertilization, can demonstrate a growth benefit in SRC willows on marginal lands. Roughly 21,600 Salix miyabeana Seeman (‘SX61’ and ‘SX64’) were planted in a hierarchical design with inoculation treatments randomized first, cultivars randomized second, and fertilization treatments randomized third. This process was repeated across three fields of different marginal soil type (which, in our experiment, were given the descriptive names Sandy, Rocky, and Dry). The inoculum species, Rhizoglomus irregulare Błaszk., Wubet, Renker & Buscot Sieverd., G.A. Silva & Oehl and Hebeloma longicaudum (Pers.) P. Kumm., were chosen as they are most likely to be commercially available, and because they represent both arbuscular and ectomycorrhizal inoculum types. Growth was measured over 2.5 years, or three growing seasons. Fertilization treatment (75 kg/ha Nitrogen), however, was only applied during the second growing season. Our results conclusively showed no benefit from mycorrhizal inoculation across fields that exhibited significantly different growth rates, as well as significant differentiation from fertilization. Full article
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Article
The Evaluation of Radiation Use Efficiency and Leaf Area Index Development for the Estimation of Biomass Accumulation in Short Rotation Poplar and Annual Field Crops
Forests 2018, 9(4), 168; https://doi.org/10.3390/f9040168 - 27 Mar 2018
Cited by 11 | Viewed by 2419
Abstract
We evaluated the long-term pattern of leaf area index (LAI) dynamics and radiation use efficiency (RUE) in short rotation poplar in uncoppice (single stem) and coppice (multi-stem) plantations, and compared them to annual field crops (AFCs) as an alternative for bioenergy production while [...] Read more.
We evaluated the long-term pattern of leaf area index (LAI) dynamics and radiation use efficiency (RUE) in short rotation poplar in uncoppice (single stem) and coppice (multi-stem) plantations, and compared them to annual field crops (AFCs) as an alternative for bioenergy production while being more sensitive to weather fluctuation and climate change. The aim of this study was to evaluate the potential of LAI and RUE as indicators for bioenergy production and indicators of response to changing environmental conditions. For this study, we selected poplar clone J-105 (Populus nigra L. × P. maximowiczii A. Henry) and AFCs such as barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), maize (Zea mays L.), and oilseed rape (Brassica napus L.), and compared their aboveground dry mass (AGDM) production in relation to their LAI development and RUE. The results of the study showed the long-term maximum LAI (LAImax) to be 9.5 in coppice poplar when compared to AFCs, where LAImax did not exceed the value 6. The RUE varied between 1.02 and 1.48 g MJ−1 in short rotation poplar and between 0.72 and 2.06 g MJ−1 in AFCs. We found both LAI and RUE contributed to AGDM production in short rotation poplar and RUE only contributed in AFCs. The study confirms that RUE may be considered an AGDM predictor of short rotation poplar and AFCs. This may be utilized for empirical estimates of yields and also contribute to improve the models of short rotation poplar and AFCs for the precise prediction of biomass accumulation in different environmental conditions. Full article
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Article
Phytoremediation Efficacy of Salix discolor and S. eriocephela on Adjacent Acidic Clay and Shale Overburden on a Former Mine Site: Growth, Soil, and Foliage Traits
Forests 2017, 8(12), 475; https://doi.org/10.3390/f8120475 - 02 Dec 2017
Cited by 7 | Viewed by 2343
Abstract
Plants regularly experience suboptimal environments, but this can be particularly acute on highly-disturbed mine sites. Two North American willows—Salix discolor Muhl. (DIS) and S. eriocephala Michx. (ERI)—were established in common-garden field tests on two adjacent coal mine spoil sites: one with high [...] Read more.
Plants regularly experience suboptimal environments, but this can be particularly acute on highly-disturbed mine sites. Two North American willows—Salix discolor Muhl. (DIS) and S. eriocephala Michx. (ERI)—were established in common-garden field tests on two adjacent coal mine spoil sites: one with high clay content, the other with shale overburden. The high clay content site had 44% less productivity, a pH of 3.6, 42% clay content, high water holding capacity at saturation (64%), and high soil electrical conductivity (EC) of 3.9 mS cm−1. The adjacent shale overburden site had a pH of 6.8, and after removing 56.5% stone content, a high sand content (67.2%), low water holding capacity at saturation (23%), and an EC of 0.9 mS cm−1. The acidic clay soil had significantly greater Na (20×), Ca (2×), Mg (4.4×), S (10×), C (12×) and N (2×) than the shale overburden. Foliar concentrations from the acidic clay site had significantly greater Mg (1.5×), Mn (3.3×), Fe (5.6×), Al (4.6×), and S (2×) than the shale overburden, indicating that these elements are more soluble under acidic conditions. There was no overall species difference in growth; however, survival was greater for ERI than DIS on both sites, thus overall biomass yield was greater for ERI than DIS. Foliar concentrations of ERI were significantly greater than those of DIS for N (1.3×), Ca (1.5×), Mg (1.2×), Fe (2×), Al (1.5×), and S (1.5×). There were no significant negative relationships between metal concentrations and growth or biomass yield. Both willows showed large variation among genotypes within each species in foliar concentrations, and some clones of DIS and ERI had up to 16× the Fe and Al uptake on the acidic site versus the adjacent overburden. Genetic selection among species and genotypes may be useful for reclamation activities aimed at reducing specific metal concentrations on abandoned mine sites. Results show that, despite having a greater water holding capacity, the greater acidity of the clay site resulted in greater metal mobility—in particular Na—and thus a greater EC. It appears that the decline in productivity was not due to toxicity effects from the increased mobility of metals, but rather to low pH and moisture stress from very high soil Na/EC. Full article
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Erratum
Erratum: Hart, N.M., et al. Stakeholder Assessment of the Feasibility of Poplar as a Biomass Feedstock and Ecosystem Services Provider in Southwestern Washington, USA. Forests 2018, 9, 655
Forests 2018, 9(12), 741; https://doi.org/10.3390/f9120741 - 27 Nov 2018
Viewed by 1070
Abstract
The authors have requested that the following changes be made to their paper [...] Full article
Conference Report
The 2018 Woody Crops International Conference, Rhinelander, Wisconsin, USA, 22–27 July 2018
Forests 2018, 9(11), 693; https://doi.org/10.3390/f9110693 - 07 Nov 2018
Cited by 5 | Viewed by 1530
Abstract
The 2018 Woody Crops International Conference was held from 22 to 27 July 2018 throughout Minnesota and Wisconsin, USA to unite world-leading short rotation woody crop (SRWC) organizations at a forum designed to enhance information exchange while also building a platform for developing [...] Read more.
The 2018 Woody Crops International Conference was held from 22 to 27 July 2018 throughout Minnesota and Wisconsin, USA to unite world-leading short rotation woody crop (SRWC) organizations at a forum designed to enhance information exchange while also building a platform for developing future collaboration around SRWC production systems. The meeting included pre-conference and post-conference tours in Minnesota and Wisconsin and technical sessions in Rhinelander, Wisconsin. Technical sessions were framed under the topics: Genetics and Physiology, Phytotechnologies, Stakeholders, Bioproducts, Harvesting and Logistics, Biomass Production, and Ecosystem Services. This Conference Report provides a compilation of abstracts from each of the 38 oral and poster presentations delivered during the technical program. It should serve to enhance future discussions among scientists, academicians, regulators, and the general public relative to sustainable application of SRWC technologies for a multitude of current objectives. Full article
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