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1.
Growing woody biomass for bioenergy in a tree-based intercropping system in southern Ontario, Canada
Rémi Cardinael Naresh Thevathasan Andrew Gordon Rachelle Clinch Idris Mohammed Derek Sidders 《Agroforestry Systems》2012,86(2):279-286
During the spring of 2006, three willow varieties (SV1, SX67 and 9882-41) were established on marginal land in an agroforestry tree-intercropping arrangement where plots of short rotation willows were planted between rows (spaced 15?m apart) of 21-year-old mixed tree species. As a control, the same varieties were established on an adjacent piece of land without established trees (conventional willow system). This study investigated the magnitude of carbon pools, fine root and leaf biomass inputs and clone yields in both the tree-based intercropping (agroforestry) and conventional monocropping systems. Willow biomass yield was significantly higher in the agroforestry field (4.86?odt?ha?1?y?1) compared to the conventional field (3.02?odt?ha?1?y?1). In both fields, varieties SV1 and SX67 produced higher yields than the variety 9882-41. Willow fine root biomass in the top 20?cm of soil was significantly higher in the intercropping system (3,062?kg?ha?1) than in the conventional system (2,536?kg?ha?1). Differences in fine root biomass between clones were similar to that observed for differences in biomass yield: SV1?>?SX67?>?9882-41. Leaf input was higher in the intercropping system (1,961?kg?ha?1) than in the conventional system (1,673?kg?ha?1). Clonal differences in leaf inputs followed the same trends as those for root biomass and yield: SV1?>?SX67?>?9882-41. Soil organic carbon was significantly higher in the agroforestry field (1.94?%) than in the conventional field (1.82?%). A significant difference in soil organic carbon was found between the three clones: soils under clone 9882-41 had the lowest soil organic carbon at 1.80?%. 相似文献
2.
Earthworms are known to increase soil bulk density, soil porosity, mixing of organic matter, and to strengthen aggregation
of soil particles. They perform important functions in the maintenance and stabilization of the soil matrix. Historically,
temperate intercropping research has focused on the above-ground benefits of adding trees into the agricultural landscape.
Earthworm research in temperate intercropping systems has been non-existent to date. More emphasis on studying below-ground
components, such as earthworms, is required in order to better understand the mechanisms of intercropping ecosystem function.
The purpose of this study was to examine seasonal changes in distribution and abundance of earthworms under a temperate intercropping
system in southwestern Ontario, Canada. Sampling occurred during the spring and summer of 1997 at the University of Guelph's
Agroforestry Research Station, Guelph, Ontario. Earthworm samples were collected at various distances from the tree rows.
Significant variation in both earthworm biomass and density were found between the three tree species sampled. Total mean
earthworm density was 182 m-2 within the poplar rows, 71 m-2 within the silver maple rows, and 90 m-2 within the white ash rows. A marked difference was also observed in the distribution of earthworms within the tree rows and
the field area. For example, total mean density within the tree rows for poplar was 182 individuals m-2, as compared to total mean densities of 117 and 95 individuals m-2, two metres and six metres into the field from the tree, respectively.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Agroforestry Systems - Agroforestry practices in northern latitudes, although less diverse than those in warmer regions, have unique advantages over conventional land-use systems in the region in... 相似文献
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Vertical root separation and light interception in a temperate tree-based intercropping system of Eastern Canada 总被引:1,自引:0,他引:1
Léa Bouttier Alain Paquette Christian Messier David Rivest Alain Olivier Alain Cogliastro 《Agroforestry Systems》2014,88(4):693-706
We analysed the spatial distribution of fine roots and light availability in a tree-based intercrop system (TBI) composed of Quercus rubra L. (QUR), hybrid poplar (Populus deltoides × Populus nigra—HYP) and hay (CROP) in southern Québec (Canada) to evaluate interactions between trees and crop. Trees in the 8-year-old TBI system had superficial fine root profiles, which is common in tree species grown in conventional plantations and natural forests. More than 95 % of fine roots were found within the first 25 and 45 cm for QUR and HYP, respectively, and 35 cm for CROP. However, vertical separation between the fine root systems of QUR and CROP was evident, as QUR allocated less fine roots to the top 10 cm of soil, and more to depths between 10 and 30 cm, as opposed to CROP which had a greater proportion of fine roots in the top 10 cm. HYP fine roots showed no adaption when intercropped with hay. High tree fine root length density (FRLD) in the top soil layer was observed near the tree stems while hay FRLD was reduced by 45 %, suggesting strong competition for resources. Hay yield analysis revealed significant reduction near trees, particularly HYP. However, light did seem to be the main driver of intercrop yield, as it not only accounted for the effect of competition by roots (being correlated), but also had a singular effect. 相似文献
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Amanda D. Bambrick Joann K. Whalen Robert L. Bradley Alain Cogliastro Andrew M. Gordon Alain Olivier Naresh V. Thevathasan 《Agroforestry Systems》2010,79(3):343-353
Land use affects the carbon sequestration potential of soils across landscapes. Tree-based intercropping (TBI) systems where
annual crops are grown between established tree rows are expected to exhibit spatial heterogeneity in the soil organic carbon
(SOC) content due to differences in carbon input and decomposition rates of litter from trees and herbaceous plants. This
study aimed to quantify variability in the SOC of TBI systems, compare the SOC content of TBI and nearby conventional agroecosystems,
and determine if SOC was related to soil fertility. The TBI research sites were established 4 years (St. Paulin and St. Edouard,
Quebec, Canada), 8 years (St. Remi, Quebec, Canada) and 21 years (Guelph, Ontario, Canada) before soil samples were collected
for this study. The SOC content was greater within 0.75 m of the tree row than in the intercropped space at the St. Edouard
and St. Remi sites. At the Guelph site, the SOC was spatially heterogeneous in plots with Norway spruce (Picea abies L.) but not hybrid poplar (Populus deltoides × P. nigra clone DN-177), probably due to litterfall distribution. Formerly a tree plantation, the TBI system at St. Remi contained
77% more SOC than a nearby conventional agroecosystem, while there was 12% more SOC in the TBI system than the conventional
agroecosystem at Guelph. There was no difference in the SOC content of 4-year old TBI sites and nearby conventional agroecosystems.
However, an increase in SOC at all TBI sites was positively related to the plant-available N concentrations, indicating the
benefit of temperate TBI systems for soil fertility. 相似文献
9.
Daniel A. Jefferies Richard J. Heck Naresh V. Thevathasan Andrew M. Gordon 《Agroforestry Systems》2014,88(4):645-656
The objective of this work was to characterize differences in the soil surface (top 3.5 cm) microstructure, as influenced by four tree species, within a temperate tree based intercropping (TBI) system. Soils adjacent to walnut (Juglans nigra), poplar (Populus spp.), red oak (Quercus rubra), Norway spruce (Picea abies), as well as three types of ground cover [row crop, willow (Salix spp.), and perennial grass tree rows] were analyzed. X-ray computed micro –tomography (µCT) was employed to evaluate soil void phase characteristics, as well as heterogeneity of soil matrix radiodensity. X-ray µCT identified void phase parameters were not affected by tree species due to confounding effects caused by perennial vegetation and mixed leaf litter inputs.. A positive correlation was found between traditionally measured soil bulk density and bulk X-ray radiodensity (rs = 0.53, p < 0.01) and a negative correlation between mean intra-aggregate X-ray radiodensity and soil organic carbon (rs = ?0.48, p = 0.03). It was determined, through the use of geostatistics, that there were no distinct or consistent anisotropic structures, in directional semivariograms, evident for the various species. However, the semivariograms revealed greater variability, correlated with less directional anisotropy within the tree row as compared to cropping alley soils. It was interpreted that processes within soils in the tree rows were leading to a homogenous type of structure, and that soils under row crops exhibited a greater tendency for destruction of surface structure, leading to more directional anisotropy (trends). 相似文献
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Gas exchange, tissue water relations, and leaf/root dry weight ratios were compared among young, container-grown plants of five temperate-zone, deciduous tree species (Acer negundo L., Betula papyrifera Marsh, Malus baccata Borkh, Robinia pseudoacacia L., and Ulmus parvifolia Jacq.) under well-watered and water-stressed conditions. There was a small decrease (mean reduction of 0.22 MPa across species) in the water potential at which turgor was lost (Psi(tlp)) in response to water stress. The Psi(tlp) for water-stressed plants was -1.18, -1.34, -1.61, -1.70, and -2.12 MPa for B. papyrifera, A. negundo, U. parvifolia, R. pseudoacacia, and M. baccata, respectively. Variation in Psi(tlp) resulted primarily from differences in tissue osmotic potential and not tissue elasticity. Rates of net photosynthesis declined in response to water stress. However, despite differences in Psi(tlp), there were no differences in net photosynthesis among water-stressed plants under the conditions of water stress imposed. In A. negundo and M. baccata, water use efficiency (net photosynthesis/transpiration) increased significantly in response to water stress. Comparisons among water-stressed plants showed that water use efficiency for M. baccata was greater than for B. papyrifera or U. parvifolia. There were no significant differences in water use efficiency among B. papyrifera, U. parvifolia, A. negundo, and R. pseudoacacia. Under water-stressed conditions, leaf/root dry weight ratios (an index of transpiration to absorptive capacity) ranged from 0.77 in R. pseudoacacia to 1.05 in B. papyrifera. 相似文献
13.
A mass-based carbon (C) concentration ([C]) of 50% in dry wood is widely accepted as a constant factor for conversion of biomass to C stock. However, the [C] varies with tree species, and few data on [C] are available for the Chinese temperate tree species. In this study, we examined inter- and intra-specific variations of [C] in biomass tissues for 10 co-occurring temperate tree species in northeastern China. The species were Korean pine (Pinus koraiensis Sieb. et Zucc.), Dahurian larch (Larix gmelinii Rupr.), Mongolian oak (Quercus mongolica Fisch.), white birch (Betula platyphylla Suk.), Amur cork-tree (Phellodendron amurense Rupr.), Manchurian walnut (Juglans mandshurica Maxim.), Manchurian ash (Fraxinus mandshurica Rupr.), aspen (Populous davidiana Dode), Mono maple (Acer mono Maxim.), and Amur linden (Tilia amurensis Rupr.). The mean tissue [C] across the species varied from 47.1% in fine root to 51.4% in foliage. The mean stem [C] of the 10 species was 49.9 ± 1.3% (mean ± SE). The weighted mean C concentration (WMCC) for the species ranked as: Amur cork-tree (55.1%) > Amur linden (53.9%) > Korean pine (53.2%) > Manchurian ash (52.9%) > Manchurian walnut (52.4%) > Mongolian oak (47.6%) > Dahurian larch (46.9%) > Mono maple (46.4%) > white birch (46.1%) > aspen (43.7%). The WMCC of the dominant trees was negatively correlated to mean annual increment of biomass (MAI), suggesting that planting fast-growing tree species for C sequestration in afforestation and reforestation practices sacrifice some C gain from increasing MAI due to decreasing [C]. Failing to account for the inter- and intra-specific variations in [C] will introduce a relative error of −6.7% to +7.2% in estimates of biomass C stock from inventory data, of which >93% is attributed to ignoring the inter-specific variation in [C]. 相似文献
14.
Denys Yemshanov Daniel McKenney Saul Fraleigh Steve D'Eon 《Forest Policy and Economics》2007,10(1-2):48-59
This study explores the economic feasibility of several long-rotation afforestation scenarios for southern Ontario, Canada. Three species, red pine (Pinus resinosa Ait.), Norway spruce (Picea abies L.) and black walnut (Juglans nigra L.) are examined. We integrate growth and yield models, site suitability maps, and several management scenarios to investigate the investment attractiveness of these species inclusive and exclusive of carbon sequestration values. We report net present values (NPV), internal rates of return (IRR) and two break-even price metrics. For wood value only scenarios the IRRs range from 4.3 to 4.6% for red pine and 3.4–3.6% for Norway spruce (for the most attractive 10,000 ha, in a single rotation scenario). Black walnut had rates of return 3.5–3.7% for the most attractive 10,000 ha area. Adding carbon valued at Cdn $3.4 per metric ton CO2 − e (roughly 2005 prices in the Chicago Climate Exchange) increases rates of return by about 0.6% for red pine and Norway spruce and 0.4% for black walnut scenarios. Perhaps surprisingly these returns are comparable and better than 20-year rotation hybrid poplar plantations. To achieve a 6% real rate of return break-even carbon prices were $10.7/t CO2 − e for red pine, $12.6/t CO2 − e for Norway spruce and $17.2/t CO2 − e for black walnut (again for the “best” 10,000 ha). Although somewhat unremarkable, the results suggest that these longer-rotation species may be a better investment than perhaps previously expected if landowners have the appropriate site conditions. 相似文献
15.
Tree ring analysis investigates growth processes at time horizons of several weeks to millennia, but lacks the detail of short-term fluctuation in cambial activity. This study used electronic high-precision dendrometry for analyzing the environmental factors controlling stem diameter variation and radial growth in daily resolution in five co-existing temperate broad-leaved tree species (genera Fraxinus, Acer, Carpinus, Tilia and Fagus) with different growth and survival strategies. Daily stem radius change (SRC(d)) was primarily influenced by the atmospheric demand for water vapor (expressed either as vapor pressure deficit (D) or relative air humidity (RH)) while rainfall, soil matrix potential, temperature and radiation were only secondary factors. SRC(d) increased linearly with increasing RH and decreasing D in all species. The positive effect of a low atmospheric water vapor demand on SRC(d) was largest in June during the period of maximal radial growth rate and persisted when observation windows of 7 or 21 days instead of 1 day were used. We found a high synchronicity in the day-to-day growth rate fluctuation among the species with increment peaks corresponding to air humidity maxima, even though the mean daily radial growth rate differed fivefold among the species. The five -species also differed in the positive slope of the growth/RH relationship with the steepest increase found in Fraxinus and the?lowest in Fagus. We explain the strong positive effect of high RH and low D on radial stem increment by lowered transpiration which reduces negative pressure in the conducting system and increases turgor in the stem cambium cells, thereby favoring cell division and expansion. The results suggest that mechanistic models of tree growth need to consider the atmospheric water status in addition to the known controlling environmental factors: temperature, soil moisture and precipitation. The results further have implications for sensitivity analyses of tree growth to climatic changes. 相似文献
16.
Over the last few decades, several phenomena contributed to modify the structure and composition of the eastern North American forests. Along with forest management, disturbances such as insect defoliation, global environmental changes, acid deposition, and rising atmospheric CO2 concentrations, have been identified as phenomena that could affect forest structure and composition. Currently, there is very little quantitative information on the resulting effect of multiple disturbances on the main parameters of forest dynamics (growth, mortality, and recruitment). Using available data from the Quebec permanent sample plots network, we analyzed the ecological response of tree species populations to the combined effect of contemporary global environmental changes, disturbance regimes, and forest management practices over the last 30 years in southern Quebec. The results indicate that the main parameters of forest dynamics changed considerably over the last three decades. The last spruce budworm outbreak initiated a successional change in coniferous stands. The basal area of Abies balsamea and Picea glauca, the most abundant coniferous species, decreased by 29.7%, while pioneer species abundance increased. For late successional deciduous species, observed changes in forest dynamics appear to be mainly associated with global environmental changes rather than with natural disturbances or forest harvesting. The results indicate that inferring responses of tree population dynamics to global environmental changes can be very complex or even misleading considering the confounding effects of other disturbance agents. The results also suggest that the ecosystem-based management approach promoted by forest ecologists, aimed at maintaining landscape stand composition and structures similar to those characterizing natural environments, will not be easily achieved. Forest ecosystems are highly dynamic and disturbances other than tree harvesting appear to have been the major factors affecting their pattern of change over the last three decades. Forest managers should consider adaptive management approaches that will consider the contemporary evolution of forest ecosystems in a changing environment. 相似文献
17.
Poplar leaf biomass distribution and nitrogen dynamics in a poplar-barley intercropped system in southern Ontario, Canada 总被引:3,自引:0,他引:3
The effect of hybrid poplar (Populus spp. clone DN 177) leaf biomass distribution on soil nitrification was investigated in two experiments during the 1993, 1994
and 1995 growing seasons in a poplar-barley (Hordeum vulgare cv. OAC Kippen) intercropping experiment established at Guelph, Ontario, Canada. In experiment 1, poplar was intercropped
with barley during all three years and the poplar leaves shed during the fall season were removed from the soil surface during
1993 and 1994. In experiment 2, poplar was intercropped with barley in 1993 and with corn (Zea mays cv. Pioneer 3917) in 1994 an 1995, respectively, and the shed poplar leaves were not removed. In experiment 1, the nitrification
rates were lower during 1994 and 1995 when the dropped leaves were removed from the field. The total above-ground biomass
of barley within 2.5 m of the tree row was 517, 500 and 450 g×m−2, respectively during the three years, whereas in the middle of the crop row (4–11 m), the corresponding figures were 491,
484 and 464 g×m–2. Mean nitrification rates, N availability and carbon content were higher in soils close to the poplar tree
rows (2.5 m) compared to the corresponding values in the middle of the crop alley (4–11 m from the tree row). In experiment
2, where poplar leaves were not removed from the field, nitrification rates in soils within 2.5 m distance from the poplar
row were fairly constant (range 100 to 128 μg 100 g−1 dry soil day−1) during the three years. Results suggest that soil nitrification rates, soil carbon content and plant N uptake adjacent to
the poplar tree rows are influenced by poplar leaf biomass input in the preceding year.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
Mélanie Bergeron Simon Lacombe Robert L. Bradley Joann Whalen A. Cogliastro Marie-France Jutras Paul Arp 《Agroforestry Systems》2011,83(3):321-330
Tree-based intercropping (TBI) systems, combining agricultural alley crops with rows of hardwood trees, are largely absent
in Canada. We tested the hypothesis that the roots of 5–8 years old hybrid poplars, growing in two TBI systems in southern
Québec, would play a “safety-net” role of capturing nutrients leaching below the rooting zone of alley crops. TBI research
plots at each site were trenched to a depth of 1 m on each side of an alley. Control plots were left with tree roots intact.
In each treatment at each site, leachate at 70 cm soil depth was repeatedly sampled over two growing seasons using porous
cup tension lysimeters, and analyzed for nutrient concentrations. Daily water percolation rates were estimated with the forest
hydrology model ForHyM. Average nutrient concentrations for all days between consecutive sampling dates were multiplied by
water percolation rates, yielding daily nutrient leaching loss estimates for each sampling step. We estimated that tree roots
in the TBI system established on clay loam soil decreased subsoil NO3
− leaching by 227 kg N ha−1 and 30 kg N ha−1 over two consecutive years, and decreased dissolved organic N (DON) leaching by 156 kg N ha−1 year−1 in the second year of the study. NH4
+ leaching losses at the same site were higher when roots were present, but were 1–2 orders of magnitude lower than NO3
− or DON leaching. At the sandy textured site, the safety net role of poplar roots with respect to N leaching was not as effective,
perhaps because N leaching rates exceeded root N uptake by a wider margin than at the clay loam site. At the sandy textured
site, significant and substantial reductions of sodium leaching were observed where tree roots were present. At both sites,
tree roots reduced DON concentrations and the ratio of DON to inorganic N, perhaps by promoting microbial acquisition of DON
through rhizodeposition. This study demonstrated a potential safety-net role by poplar roots in 5–8 year-old TBI systems in
cold temperate regions. 相似文献
19.
New Forests - Insufficient winter chilling related to rising temperatures has raised questions about its potential effects on budburst timing (growth initiation) and subsequent tree growth. We... 相似文献
20.
Estimating coarse root biomass with ground penetrating radar in a tree-based intercropping system 总被引:1,自引:0,他引:1
Kira A. Borden Marney E. Isaac Naresh V. Thevathasan Andrew M. Gordon Sean C. Thomas 《Agroforestry Systems》2014,88(4):657-669
Conventional measurements of tree root biomass in tree-based intercropping (TBI) systems can be inadequate in capturing the heterogeneity of rooting patterns or can be highly destructive and non-repeatable. In this study, we estimated coarse root biomass using ground penetrating radar (GPR) of 25-year-old trees inclusive of five species (Populus deltoides × nigra clone DN-177, Juglans nigra L., Quercus rubra L., Picea abies L. Karst, and Thuja occidentalis L.) at a TBI site in Southern Ontario, Canada. Subsurface images generated by GPR were collected in grids (4.5 × 4.5 m) centred on tree stems. The predictive relationship developed between GPR signal response and root biomass was corrected for species effects prior to tree-scale estimates of belowground biomass. Accuracy of the tree-scale estimates was assessed by comparing coarse root biomass measured from complete excavations of the corresponding tree. The mean coarse root biomass estimated from GPR analysis was 54.1 ± 8.7 kg tree?1 (mean ± S.E.; n = 12), within 1 % of the mean coarse root biomass measured from excavation. Overall there was a root mean square error of 14.4 kg between measured and estimated biomass with no detectable bias despite variable conditions within the in-field and multi-species study. Root system C storage by species, calculated with species-specific root carbon concentrations, is estimated at 5.4 ± 0.7–34.8 ± 6.9 kg C tree?1 at this site. GPR is an effective tool for non-destructively predicting coarse root biomass in multi-species environments such as temperate TBI systems. 相似文献