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Truax B.,Eastern Townships Forest Research Trust | Gagnon D.,Eastern Townships Forest Research Trust | Gagnon D.,University of Regina | Fortier J.,Eastern Townships Forest Research Trust | And 2 more authors.
Forests | Year: 2014

In this study, we developed clone-specific allometric relationships, with the objective of calculating volume and biomass production after 13 years in 8 poplar plantations, located across an environmental gradient, and composed of 5 unrelated hybrid poplar clones. Allometry was found to be very similar for clones MxB-915311, NxM-3729 and DNxM-915508, all having P. maximoviczii parentage. Clones DxN-3570 and TxD-3230 also had a similar allometry; for a given DBH they have a lower stem volume, stem biomass and branch biomass than P. maximoviczii hybrids. Strong Site × Clone interactions were observed for volume and woody biomass growth, with DxN and TxD hybrids only productive on low elevation fertile sites, whereas P. maximovizcii hybrids were also very productive on higher elevation sites with moderate to high soil fertility. At the site level (5 clones mean), yield reached 27.5 and 22.7 m3/ha/yr. on the two best sites (high fertility and low elevation), confirming the great potential of southern Québec (Canada) for poplar culture. The productivity gap between the most and least productive sites has widened from year 8 to year 13, highlighting the need for high quality abandoned farmland site selection in terms of climate and soil fertility. Although clone selection could optimize yield across the studied environmental gradient, it cannot fully compensate for inadequate site selection. © 2014 by the authors, licensee MDPI, Basel, Switzerland. Source


Fortier J.,Eastern Townships Forest Research Trust | Fortier J.,University of Quebec at Montreal | Truax B.,Eastern Townships Forest Research Trust | Gagnon D.,Eastern Townships Forest Research Trust | And 2 more authors.
Journal of Environmental Management | Year: 2015

In many temperate agricultural areas, riparian forests have been converted to cultivated land, and only narrow strips of herbaceous vegetation now buffer many farm streams. The afforestation of these riparian zones has the potential to increase carbon (C) storage in agricultural landscapes by creating a new biomass sink for atmospheric CO2. Occurring at the same time, the storage of nitrogen (N) and phosphorus (P) in plant biomass, is an important water quality function that may greatly vary with types of riparian vegetation. The objectives of this study were (1) to compare C, N and P storage in aboveground, belowground and detrital biomass for three types of riparian vegetation cover (9-year-old hybrid poplar buffers, herbaceous buffers and natural woodlots) across four agricultural sites and (2) to determine potential vegetation cover effects on soil nutrient supply rate in the riparian zone. Site level comparisons suggest that 9-year-old poplar buffers have stored 9-31 times more biomass C, 4-10 times more biomass N, and 3-7 times more biomass P than adjacent non managed herbaceous buffers, with the largest differences observed on the more fertile sites. The conversion of these herbaceous buffers to poplar buffers could respectively increase C, N and P storage in biomass by 3.2-11.9t/ha/yr, 32-124kg/ha/yr and 3.2-15.6kg/ha/yr, over 9 years. Soil NO3 and P supply rates during the summer were respectively 57% and 66% lower in poplar buffers than in adjacent herbaceous buffers, potentially reflecting differences in nutrient storage and cycling between the two buffer types. Biomass C ranged 49-160t/ha in woodlots, 33-110t/ha in poplar buffers and 3-4t/ha in herbaceous buffers. Similar biomass C stocks were found in the most productive poplar buffer and three of the four woodlots studied. Given their large and varied biomass C stocks, conservation of older riparian woodlots is equally important for C balance management in farmland. In addition, the establishment of poplar buffers, in replacement of non managed herbaceous buffers, could rapidly increase biomass C, N and P storage along farm streams, which would be beneficial for water quality protection and global change mitigation. © 2015 The Authors. Source


Fortier J.,Eastern Townships Forest Research Trust | Fortier J.,University of Quebec at Montreal | Truax B.,Eastern Townships Forest Research Trust | Gagnon D.,Eastern Townships Forest Research Trust | And 3 more authors.
Sustainability (Switzerland) | Year: 2013

This study had three main objectives: (1) to evaluate the aboveground biomass and volume yield of three unrelated hybrid poplar clones in 9 year-old riparian buffer strips located on four farms of southern Québec, Canada; (2) to compare yield data at 9 years with previous data (at 6 years); (3) to evaluate how soil fertility, measured using three different soil testing methods (soil nutrient stocks, soil nutrient concentrations, soil nutrient supply rates), is related to yield. Across the four sites, hybrid poplar productivity after 9 years ranged from 116 to 450 m3ha-1, for stem wood volume, and from 51 to 193 megagrams per hectare (Mg ha-1), for woody dry biomass. High volume and woody dry biomass yields (26.3 to 49.9 m3ha-1yr-1, and 11.4 to 21.4 Mg ha-1yr-1) were observed at the three most productive sites. From year 6 to 9, relatively high yield increases (8.9-15.1 m3ha-1yr-1) were observed at all sites, but the productivity gap between the less fertile site and the three other sites was widened. Clone MxB-915311 was the most productive across the four sites, while clone DxN-3570 was the least productive. However, at the most productive site, clone MxB-915311 experienced severe stem and branch breakages. Independently of the soil testing method used, available soil P was always the first soil factor explaining volume yield. © by the authors. Source


Fortier J.,Eastern Townships Forest Research Trust | Truax B.,Eastern Townships Forest Research Trust | Gagnon D.,Eastern Townships Forest Research Trust | Gagnon D.,University of Regina | Lambert F.,Eastern Townships Forest Research Trust
Forests | Year: 2016

In temperate agricultural watersheds, the rehabilitation of tree vegetation in degraded riparian zones can provide many ecosystem services. This study evaluated ecosystem service provision potential following the conversion of non-managed herbaceous buffers to hybrid poplar (Populus spp.) buffers in three watersheds (555-771 km2) of southern Québec (Canada), with contrasting agricultural land uses. To extrapolate services at the watershed level, total stream length where hybrid poplars could be established was calculated using GIS data from hydrological and land cover maps. After nine years, a 100% replacement of herbaceous buffers by hybrid poplar buffers along farm streams could lead to the production of 5280-76,151 tons of whole tree (stems + branches) biomass, which could heat 0.5-6.5 ha of greenhouses for nine years, with the potential of displacing 2-29 million litres of fuel oil. Alternatively, the production of 3887-56,135 tons of stem biomass (fuelwood) could heat 55-794 new farmhouses or 40-577 old farmhouses for nine years. Producing fuelwood in buffers rather than in farm woodlots could create forest conservation opportunities on 300-4553 ha. Replacing all herbaceous buffers by poplar buffers could provide potential storage of 2984-42,132 t C, 29-442 t N and 3-56 t P in plant biomass, if woody biomass is not harvested. The greatest potential for services provision was in the Pike River watershed where agriculture is the dominant land use. A review of the potential services of poplar buffers is made, and guidelines for managing services and disservices are provided. © 2016 by the authors. Source


Boothroyd-Roberts K.,University of Quebec at Montreal | Gagnon D.,University of Quebec at Montreal | Gagnon D.,University of Regina | Gagnon D.,Eastern Townships Forest Research Trust | Truax B.,Eastern Townships Forest Research Trust
Forest Ecology and Management | Year: 2013

Multi-functional plantations using fast-growing tree species can potentially be used to accelerate the restoration of forest habitat on abandoned farmland. However, few studies have directly compared the ecological effects of active afforestation using plantations to natural afforestation. The present study compares the effects of the establishment and the first 10. years of growth of two different hybrid poplar clones to adjacent abandoned fields and natural second-growth forests, in terms of abiotic attributes and understory vegetation communities. Experimental plantations of a Populus maximowiczii×. P. balsamifera (M. ×. B) hybrid and a P. deltoides×. P. nigra (D. ×. N) hybrid were established in 2000 on abandoned fields at 8 sites in southern Quebec, Canada. In 2009, soil chemical properties, soil moisture, canopy openness, leaf litter biomass, and understory vegetation communities were sampled in the plantations and in neighboring unmanaged abandoned fields and second-growth woodlots. Canopy development was greatly accelerated by the plantations of both hybrid poplar clones, compared to the unplanted portions of abandoned fields, and in the more productive plantations of both clones, canopy openness and leaf litter biomass were similar to those measured in the woodlots. No difference was detected in soil chemical properties between the abandoned fields and either type of plantation. The plantation soils were drier than those of both the abandoned fields and the secondary forests, possibly due to increased transpiration by the hybrid poplars. The plantations favored the colonization of the sites by native tree seedlings compared to the unmanaged fields, producing a nurse stand effect. Among herbaceous and shrub species, native species richness was slightly higher in the plantations than in the fields. The understories of the fastest growing plantations had species in common with both the fields and the woodlots, while the understory of the slowest growing plantations was very similar to the field vegetation. The plantation understories had lower covers of open-habitat species than the fields, while the M. ×. B plantations had slightly greater covers of native, shade-tolerant species. Plantations of the M. ×. B clone were more distinct from the abandoned fields than were plantations of the D. ×. N clone. In conclusion, hybrid poplar plantations appear capable of accelerating the restoration of certain understory attributes, which in turn favors their colonization by tree seedlings and suppresses competition from light-demanding herbaceous species. © 2012 Elsevier B.V. Source

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