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Annie Deslauriers - One of the best experts on this subject based on the ideXlab platform.
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interactive effects of Defoliation and water deficit on growth water status and mortality of black spruce picea mariana mill b s p
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:Key message Defoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce ( Picea mariana (Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.
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Interactive effects of Defoliation and water deficit on growth, water status, and mortality of black spruce (Picea mariana (Mill.) B.S.P.)
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:AbstractKey messageDefoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce (Picea mariana(Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.ContextTree vitality is influenced by multiple factors such as insect damage, water deficit, and the timing of these stresses. Under drought, positive feedback via the reduction of leaf area may improve the water status of defoliated trees. However, the effect on tree mortality remains largely unknown.AimsWe investigated the effects of Defoliation followed by a water deficit on tree growth, plant water status, and mortality in black spruce (Picea mariana (Mill.) B.S.P.) saplings.MethodsIn a controlled greenhouse setting, saplings were submitted to combined treatments of Defoliation and water stress. To assess the impact of these stresses and their interaction, we measured phenology, twig development, secondary growth of the stem, water potential, and mortality of the saplings.ResultsBoth Defoliation and water deficits reduced growth; however, the effect was not additive. During active Defoliation, we observed a higher evaporative demand and a lower midday leaf water potential Ψmd. We observed an opposite pattern of response post-stress. Drought alone increased sapling mortality immediately after the stress period, but after c.a. 20 days, mortality rates remained similar following combined drought and Defoliation.ConclusionOur results highlight two key periods during which Defoliation affects plant water relations either negatively (during active Defoliation) or positively (after Defoliation). Mortality in defoliated saplings was reduced immediately following drought because available internal water increased in the stem.
John Mackay - One of the best experts on this subject based on the ideXlab platform.
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interactive effects of Defoliation and water deficit on growth water status and mortality of black spruce picea mariana mill b s p
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:Key message Defoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce ( Picea mariana (Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.
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Interactive effects of Defoliation and water deficit on growth, water status, and mortality of black spruce (Picea mariana (Mill.) B.S.P.)
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:AbstractKey messageDefoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce (Picea mariana(Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.ContextTree vitality is influenced by multiple factors such as insect damage, water deficit, and the timing of these stresses. Under drought, positive feedback via the reduction of leaf area may improve the water status of defoliated trees. However, the effect on tree mortality remains largely unknown.AimsWe investigated the effects of Defoliation followed by a water deficit on tree growth, plant water status, and mortality in black spruce (Picea mariana (Mill.) B.S.P.) saplings.MethodsIn a controlled greenhouse setting, saplings were submitted to combined treatments of Defoliation and water stress. To assess the impact of these stresses and their interaction, we measured phenology, twig development, secondary growth of the stem, water potential, and mortality of the saplings.ResultsBoth Defoliation and water deficits reduced growth; however, the effect was not additive. During active Defoliation, we observed a higher evaporative demand and a lower midday leaf water potential Ψmd. We observed an opposite pattern of response post-stress. Drought alone increased sapling mortality immediately after the stress period, but after c.a. 20 days, mortality rates remained similar following combined drought and Defoliation.ConclusionOur results highlight two key periods during which Defoliation affects plant water relations either negatively (during active Defoliation) or positively (after Defoliation). Mortality in defoliated saplings was reduced immediately following drought because available internal water increased in the stem.
Hibat Allah Bouzidi - One of the best experts on this subject based on the ideXlab platform.
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interactive effects of Defoliation and water deficit on growth water status and mortality of black spruce picea mariana mill b s p
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:Key message Defoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce ( Picea mariana (Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.
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Interactive effects of Defoliation and water deficit on growth, water status, and mortality of black spruce (Picea mariana (Mill.) B.S.P.)
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:AbstractKey messageDefoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce (Picea mariana(Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.ContextTree vitality is influenced by multiple factors such as insect damage, water deficit, and the timing of these stresses. Under drought, positive feedback via the reduction of leaf area may improve the water status of defoliated trees. However, the effect on tree mortality remains largely unknown.AimsWe investigated the effects of Defoliation followed by a water deficit on tree growth, plant water status, and mortality in black spruce (Picea mariana (Mill.) B.S.P.) saplings.MethodsIn a controlled greenhouse setting, saplings were submitted to combined treatments of Defoliation and water stress. To assess the impact of these stresses and their interaction, we measured phenology, twig development, secondary growth of the stem, water potential, and mortality of the saplings.ResultsBoth Defoliation and water deficits reduced growth; however, the effect was not additive. During active Defoliation, we observed a higher evaporative demand and a lower midday leaf water potential Ψmd. We observed an opposite pattern of response post-stress. Drought alone increased sapling mortality immediately after the stress period, but after c.a. 20 days, mortality rates remained similar following combined drought and Defoliation.ConclusionOur results highlight two key periods during which Defoliation affects plant water relations either negatively (during active Defoliation) or positively (after Defoliation). Mortality in defoliated saplings was reduced immediately following drought because available internal water increased in the stem.
Lorena Balducci - One of the best experts on this subject based on the ideXlab platform.
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interactive effects of Defoliation and water deficit on growth water status and mortality of black spruce picea mariana mill b s p
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:Key message Defoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce ( Picea mariana (Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.
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Interactive effects of Defoliation and water deficit on growth, water status, and mortality of black spruce (Picea mariana (Mill.) B.S.P.)
Annals of Forest Science, 2019Co-Authors: Hibat Allah Bouzidi, Lorena Balducci, John Mackay, Annie DeslauriersAbstract:AbstractKey messageDefoliation followed by water deficit showed time-dependent effects on plant water status and growth in black spruce (Picea mariana(Mill.) B.S.P.). Biotic stress negatively (during active Defoliation by growing instars) and positively (after Defoliation) affected plant water relations. However, water deficit, alone or combined with Defoliation, prevails over Defoliation-related stress for radial growth and sapling vitality.ContextTree vitality is influenced by multiple factors such as insect damage, water deficit, and the timing of these stresses. Under drought, positive feedback via the reduction of leaf area may improve the water status of defoliated trees. However, the effect on tree mortality remains largely unknown.AimsWe investigated the effects of Defoliation followed by a water deficit on tree growth, plant water status, and mortality in black spruce (Picea mariana (Mill.) B.S.P.) saplings.MethodsIn a controlled greenhouse setting, saplings were submitted to combined treatments of Defoliation and water stress. To assess the impact of these stresses and their interaction, we measured phenology, twig development, secondary growth of the stem, water potential, and mortality of the saplings.ResultsBoth Defoliation and water deficits reduced growth; however, the effect was not additive. During active Defoliation, we observed a higher evaporative demand and a lower midday leaf water potential Ψmd. We observed an opposite pattern of response post-stress. Drought alone increased sapling mortality immediately after the stress period, but after c.a. 20 days, mortality rates remained similar following combined drought and Defoliation.ConclusionOur results highlight two key periods during which Defoliation affects plant water relations either negatively (during active Defoliation) or positively (after Defoliation). Mortality in defoliated saplings was reduced immediately following drought because available internal water increased in the stem.
David A. Maclean - One of the best experts on this subject based on the ideXlab platform.
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Spatial-Temporal Patterns of Spruce Budworm Defoliation within Plots in Québec
MDPI AG, 2019Co-Authors: David A. Maclean, Chris R. Hennigar, Jae OgilvieAbstract:We investigated the spatial-temporal patterns of spruce budworm (Choristoneura fumiferana (Clem.); SBW) Defoliation within 57 plots over 5 years during the current SBW outbreak in Québec. Although spatial-temporal variability of SBW Defoliation has been studied at several scales, the spatial dependence between individual defoliated trees within a plot has not been quantified, and effects of Defoliation level of neighboring trees have not been addressed. We used spatial autocorrelation analyses to determine patterns of Defoliation of trees (clustered, dispersed, or random) for plots and for individual trees. From 28% to 47% of plots had significantly clustered Defoliation during the 5 years. Plots with clustered Defoliation generally had higher mean Defoliation per plot and higher deviation of Defoliation. At the individual-tree-level, we determined ‘hot spot trees’ (highly defoliated trees surrounded by other highly defoliated trees) and ‘cold spot trees’ (lightly defoliated trees surrounded by other lightly defoliated trees) within each plot using local Getis-Ord Gi* analysis. Results revealed that 11 to 27 plots had hot spot trees and 27% to 64% of them had mean Defoliation <25%, while plots with 75% to 100% Defoliation had either cold spot trees or non-significant spots, which suggested that whether Defoliation was high or low enough to be a hot or cold spot depended on the Defoliation level of the entire plot. We fitted individual-tree balsam fir Defoliation regression models as a function of plot and surrounding tree characteristics (using search radii of 3–5 m). The best model contained plot average balsam fir Defoliation and subject tree basal area, and these two variables explained 80% of the variance, which was 2% to 5% higher than the variability explained by the neighboring tree Defoliation, over the 3–5 m search radii tested. We concluded that plot-level Defoliation and basal area were adequate for modeling individual tree Defoliation, and although clustering of Defoliation was evident, larger plots were needed to determine the optimum neighborhood radius for predicting Defoliation on an individual. Spatial autocorrelation analysis can serve as an objective way to quantify such ecological patterns
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Effects of Hardwood Content on Balsam Fir Defoliation during the Building Phase of a Spruce Budworm Outbreak
MDPI AG, 2018Co-Authors: Bo Zhang, David A. Maclean, Rob C. Johns, Eldon S. EveleighAbstract:Defoliation by spruce budworm (Choristoneura fumiferana Clem.) on balsam fir (Abies balsamea (L.) Mill.) is more severe in fir than in mixed fir-hardwood stands. Previous studies assumed that Defoliation in fir-hardwood stands was reduced in proportion to percent hardwood regardless of outbreak severity. We tested the influence of stand composition on Defoliation during the first 5 years of a spruce budworm outbreak near Amqui, Quebec, by sampling 27 fir-hardwood plots selected to represent three percent hardwood basal area classes (0%–25%, 40%–65%, and 75%–95%). Balsam fir Defoliation was significantly lower (p < 0.001) as hardwood content increased, but the relationship varied with overall Defoliation severity each year. Annual plot Defoliation in fir-hardwood plots, estimated using: (1) Defoliation in pure fir plots and the assumption that Defoliation in fir-hardwood plots was reduced in proportion to percent hardwood; (2) a generalized linear mixed-effects model with Defoliation in pure fir plots, percent hardwood, and interaction as fixed-effects; and (3) Random Forests prediction incorporating 11 predictor variables, resulted in r = 0.77, 0.87, and 0.92 versus measured Defoliation, respectively. Average Defoliation severity in softwood plots and percent hardwood content were the most important variables in Random Forests analysis. Data on average Defoliation level in softwood stands, as an indicator of overall outbreak severity, improves prediction of balsam fir Defoliation in mixed stands
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Detection of Annual Spruce Budworm Defoliation and Severity Classification Using Landsat Imagery
MDPI AG, 2018Co-Authors: Parinaz Rahimzadeh-bajgiran, Aaron R. Weiskittel, Daniel Kneeshaw, David A. MacleanAbstract:Spruce budworm (SBW) is the most destructive forest pest in eastern forests of North America. Mapping annual current-year SBW Defoliation is challenging because of the large landscape scale of infestations, high temporal/spatial variability, and the short period of time when detection is possible. We used Landsat-5 and Landsat-MSS data to develop a method to detect and map SBW Defoliation, which can be used as ancillary or alternative information for aerial sketch maps (ASMs). Results indicated that Landsat-5 data were capable of detecting and classifying SBW Defoliation into three levels comparable to ASMs. For SBW Defoliation classification, a combination of three vegetation indices, including normalized difference moisture index (NDMI), enhanced vegetation index (EVI), and normalized difference vegetation index (NDVI), were found to provide the highest accuracy (non-defoliated: 77%, light Defoliation: 60%, moderate Defoliation: 52%, and severe Defoliation: 77%) compared to using only NDMI (non-defoliated: 76%, light Defoliation: 40%, moderate Defoliation: 43%, and severe Defoliation: 67%). Detection of historical SBW Defoliation was possible using Landsat-MSS NDVI data, and the produced maps were used to complement coarse-resolution aerial sketch maps of the past outbreak. The method developed for Landsat-5 data can be used for current SBW outbreak mapping in North America using Landsat-8 and Sentinel-2 imagery. Overall, the work highlights the potential of moderate resolution optical remote sensing data to detect and classify fine-scale patterns in tree Defoliation
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Spatial variability of spruce budworm Defoliation at different scales
Forest Ecology and Management, 2014Co-Authors: Kai Zhao, David A. Maclean, Chris R. HennigarAbstract:Abstract Aerial survey records of Defoliation by spruce budworm (Choristoneura fumiferana (Clem.)) in New Brunswick, Canada taken annually from 1965 to 1992, were analyzed at four scales (66 × 66 km, 10 × 10 km, 2 × 2 km, 1 × 1 km) to determine patterns and spatial variability of Defoliation. Spruce budworm defoliated 92% of the 7.4 million ha study area in at least one year. Cluster analysis was used to group similar Defoliation patterns, and 51% of the variation in the 28-year record was described by 28 representative Defoliation patterns, at 1 × 1 km cell size. Individual Defoliation patterns were grouped into five spruce budworm outbreak classes (termed A–E), which each covered 12–27% of the area. These differed substantially in Defoliation duration and severity: classes A–B had only 1–3 years of moderate–severe Defoliation and 42–75% cumulative Defoliation; class C had 8 years and 127% cumulative Defoliation; and classes D–E had 13–16 years and 170–208% cumulative Defoliation. Given the degree of ‘averaging out’ of high Defoliation occurrences that cause the largest impacts, larger 10 × 10 km and 66 × 66 km cells were inappropriate for impact analysis. Defoliation variability was highest at 20–60% mean Defoliation than at lower or higher Defoliation levels. Distributions of area in each class in 1 × 1 km cells for 66 × 66 km areas throughout the province showed that with the exception of several small coastal areas, four or five of the above outbreak classes occurred in all areas. The wide variation in spruce budworm outbreak patterns is important in making management decisions that differentiate insecticide or salvage treatments based on Defoliation severity, and emphasizes the importance of accurate annual aerial survey or remote sensing-based Defoliation assessment.
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Estimating cumulative Defoliation of balsam fir from hemlock looper and balsam fir sawfly using aerial Defoliation survey in western Newfoundland, Canada
Forest Ecology and Management, 2010Co-Authors: Javed Iqbal, David A. MacleanAbstract:Abstract Both hemlock looper ( Lambdina fiscellaria fiscellaria (Guen.)) and balsam fir sawfly ( Neodiprion abietis (Harris)) undergo periodic outbreaks in eastern Canada and cause significant growth and mortality losses to forests. Tree growth and mortality are closely related to cumulative Defoliation estimates, which integrate annual Defoliation over multiple years. Our objective was to determine a method to estimate cumulative Defoliation of balsam fir ( Abies balsamea [L.] Mill) due to these insects in western Newfoundland, using aerial Defoliation survey data, as an essential input to modeling impacts for Decision Support Systems. Interpretation of aerial Defoliation survey data for hemlock looper and balsam fir sawfly is problematic because both insects feed upon multiple age classes of foliage. Current-year (2008) aerial Defoliation survey data were compared with ground estimates of Defoliation by age class from 45 plots (450 trees and 395 mid-crown branch samples), representing a range of Defoliation severity classes for each insect. Cumulative Defoliation was calculated using Defoliation per foliage age class, weighted by relative foliage mass for a given age of foliage. Three significantly different severity classes were defined based on cumulative Defoliation values derived from aerial Defoliation survey: (i) 1-year moderate (30–70%) Defoliation, (ii) 1-year severe (71–100%) Defoliation with calculated cumulative Defoliation values of 19 and 39%, respectively, for balsam fir sawfly, 21 and 34% respectively for hemlock looper; and (iii) 2–3 years of moderate–severe Defoliation, with cumulative Defoliation ranging between 59 and 64% for balsam fir sawfly and 49% for hemlock looper. Defoliation severity from aerial Defoliation survey alone hence can be misleading if Defoliation measurements are not converted to cumulative Defoliation values.
