Plot size and number of plots needed to assess spruce budworm impact

1982 ◽  
Vol 12 (2) ◽  
pp. 332-336 ◽  
Author(s):  
Chester Karpinski Jr. ◽  
J. A. Witter
Keyword(s):  
Coefficient Of Variation ◽  
Tree Mortality ◽  
Basal Area ◽  
Spruce Budworm ◽  
Dead Volume ◽  
Patchy Distribution ◽  
Plot Size ◽  
Percent Mortality ◽  
The Mean ◽  
Parameter Precision

This study investigated size and number of plots needed to precisely estimate tree mortality, mean dead basal area, mean dead volume, mean live basal area, and mean live volume in stands infested with the spruce budworm, Choristoneurafumiferana (Clemens).Depending on the parameter, precision of four different plot sizes (0.02, 0.04, 0.08, 0.40 ha) was examined. For most parameters the 0.04-ha plot appears to be approximately as precise as the larger plot sizes. Variables which affect the precision of the plot sizes are percent mortality, patchy distribution of the character of interest, and the variability associated with the population of interest. The precision of two, three, four, and five plots per stand was investigated. The coefficient of variation of the mean is reduced the greatest between two and three plots; subsequent reductions beyond three plots are not great. The number of plots needed based on sampling theory varied according to the parameter and the variability associated with the parameter. It was determined that the time involved in evaluating three 0.04-ha plots was approximately the same as needed to evaluate two 0.08-ha plots.

Causality in mortality patterns of spruce trees during a spruce budworm outbreak

1989 ◽  
Vol 19 (5) ◽  
pp. 632-638 ◽  
Author(s):  
Akira Osawa
Keyword(s):  
Species Complex ◽  
Close Relationships ◽  
Tree Mortality ◽  
Black Spruce ◽  
Basal Area ◽  
Spruce Budworm ◽  
Red Spruce ◽  
Hybrid Index ◽  
The Mean ◽  
Spruce Mortality

Patterns of tree mortality in the species complex of red spruce (Picearubens Sarg.), black spruce (Piceamariana (Mill.) B.S.P.) and their possible hybrids that developed during a spruce budworm (Choristoneurafumiferana (Clem.)) outbreak in Maine, U.S.A., were analyzed in relation to five hypotheses of their causal mechanisms. The observed patterns of spruce mortality were primarily a result of the phenotypic variation among the spruces. Close relationships among the mean hybrid index of spruce trees in a plot and such stand variables as balsam fir (Abiesbalsamea (L.) Mill.) basal area and drainage index are likely to have created coincidental correlations between tree mortality and those variables that do not necessarily reflect causality.

Spatial and temporal patterns of balsam fir mortality in spaced and unspaced stands caused by spruce budworm defoliation

1995 ◽  
Vol 25 (6) ◽  
pp. 902-911 ◽  
Author(s):  
David A. MacLean ◽  
Harald Piene
Keyword(s):  
Temporal Patterns ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Feeding Damage ◽  
Spatial And Temporal Patterns ◽  
Cape Breton Island ◽  
Plot Size ◽  
Cape Breton ◽  
Significant Difference ◽  
Percent Mortality

Spatial and temporal patterns of balsam fir (Abiesbalsamea (L.) Mill.) mortality were studied during a spruce budworm (Choristoneurafumiferana Clem.) outbreak from 1976 to 1984 on Cape Breton Island, Nova Scotia. Natural mortality in four insecticide-protected plots was 0% in spaced and 9–15% in unspaced stands, with only the smallest trees dying. Budworm-caused mortality (i.e., total minus natural) was 31–49% and 11–32% in spaced and unspaced young fir plots, respectively, but reached 94–100% in severely defoliated spaced plots, unprecedented in the literature for young fir mortality caused by the spruce budworm. Mortality began in the fourth to sixth year of defoliation, being earliest in the severely defoliated plots. From 80 to 90% of trees that died had > 75% cumulative defoliation, and most (64–100%) of the smallest (2 cm DBH) trees died. There was no significant difference in percent mortality between 25 spaced and 13 unspaced plots (p = 0.434), although, on average, mortality was 10–22% higher in the spaced plots. About 20–30% more of the intermediate-sized and largest trees were killed in the spaced plots. High spatial plot to plot variability in mortality occurred, which was apparently related to observed differences in the amount of defoliation and especially the incidence of "back-feeding" (damage to noncurrent foliage), as well as to plot size. Because budworm-caused mortality exhibits a distribution that tends to form large "holes" in stands, the degree of between-plot variability is related to plot size, and it is recommended that small plots that may miss these patches of mortality be avoided.

Tree mortality and radial growth losses caused by the western spruce budworm in a Douglas-fir stand in British Columbia

1982 ◽  
Vol 12 (4) ◽  
pp. 780-787 ◽  
Author(s):  
R. I. Alfaro ◽  
G. A. Van Sickle ◽  
A. J. Thomson ◽  
E. Wegwitz
Keyword(s):  
Radial Growth ◽  
Tree Mortality ◽  
Small Diameter ◽  
Basal Area ◽  
Spruce Budworm ◽  
Douglas Fir ◽  
Radial Increment ◽  
Western Spruce Budworm ◽  
Number Of Stems ◽  
The Relationship

The effects of defoliation by western spruce budworm (Choristoneuraoccidentalis (Freeman)), on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) radial growth at breast height and tree mortality are given. Four hundred and twenty trees were marked in an 81-year-old stand, and their defoliation levels were recorded annually from 1970 to 1980 in an outbreak that lasted from 1970 to 1974, inclusive. Forty-one trees were felled and dissected in 1977, 3 years after recovery began. The number of stems per hectare was reduced by 39.3% and basal area by 11.6% through mortality, most occurring among the small diameter, suppressed, and intermediate trees. Relationships were established between mortality and defoliation. Radial increments were examined, and the presence of four outbreaks during the life of the stand was detected. The combined effect of these infestations amounted to a loss of about 12% of the estimated potential diameter had not the insects been active. The most recent outbreak (1970–1974) caused a total of 10 years of subnormal growth, including 5 years due to defoliation and 5 years of recovery. The relationship between radial increment losses and defoliation intensity and duration is studied and quantified.

scholarly journals Plot Size and Number of Replications for Evaluation of the Yield of Grains in Cultivars and Dates of Sowing of Rye

2017 ◽  
Vol 10 (1) ◽  
pp. 122 ◽  
Author(s):  
Gabriela Görgen Chaves ◽  
Alberto Cargnelutti Filho ◽  
Cláudia Marques de Bem ◽  
Cirineu Tolfo Bandeira ◽  
Daniela Lixinski Silveira ◽  
...  
Keyword(s):  
Secale Cereale ◽  
Coefficient Of Variation ◽  
Tukey Test ◽  
Plot Size ◽  
Maximum Curvature ◽  
Sowing Dates ◽  
Secale Cereale L ◽  
The Mean ◽  
Uniformity Trials ◽  
Variation Model

The objectives of this study were to determine the optimum plot size (Xo) and the number of replications to evaluate the grains yield of rye (Secale cereale L.) and investigate the variability of Xo between two cultivars and three sowing dates. Eighteen uniformity trials were conducted with rye. The Xo was determined by the method of maximum curvature of the coefficient of variation model. The number of repetitions was determined in scenarios formed by combinations of i treatments (i = 3, 4, ... 50) and d minimum differences between means of treatments to be detected as significant at 0.05 of probability, by Tukey test, expressed in percentage of the average of the experiment (d = 10, 12, ... 30%). There is variability in optimum plot size to evaluate the grains yield among the cultivars BRS Progresso and Temprano and among sowing dates in the rye crop. The optimum plot size to evaluate the grains yield of rye is 6.08 m2. Seven replicates are sufficient to evaluate the grains yield of rye in experiments with up to 50 treatments, and identify, as significant at 5% probability by Tukey test, differences among averages of treatments of 29.65% of the mean of the experiment in designs completely randomized and randomized block.

Structural differences between forests regenerating following spruce budworm defoliation and clear-cut harvesting: implications for marten

2000 ◽  
Vol 30 (12) ◽  
pp. 1965-1972 ◽  
Author(s):  
David C Payer ◽  
Daniel J Harrison
Keyword(s):  
Habitat Quality ◽  
Coarse Woody Debris ◽  
Tree Mortality ◽  
Woody Debris ◽  
Choristoneura Fumiferana ◽  
Basal Area ◽  
Natural Disturbance ◽  
Spruce Budworm ◽  
Understory Vegetation ◽  
Clear Cut

American marten (Martes americana Turton) avoid recent clearcuts when establishing territories but do not avoid similarly aged stands with a history of extensive tree mortality caused by the eastern spruce budworm (Choristoneura fumiferana Clem.). We quantified differences in overstory vegetation, understory vegetation, and coarse woody debris between stands that were clear-cut or defoliated by spruce budworms 10-20 years prior to our study. Our objectives were to identify habitat features with functional significance for marten that were lacking in managed stands and to propose goals for silvicultural practices that more closely resemble a natural disturbance (insect defoliation), thus improving habitat quality for marten. In contrast to regenerating clearcuts, defoliated stands had greater volumes of snags, downed logs, and root masses and included taller trees. Although live-tree basal area was similar between stand types, our results suggest that vertical structure provided by large snags can offset limited availability of live trees for marten, particularly where coarse woody debris and understory vegetation are plentiful. In stands under even-aged management, habitat quality for marten may be enhanced by retention of >18 m2/ha cull trees and snags. Uneven-aged silvicultural systems, which more closely mimic natural disturbance by defoliating insects, may have particular promise for maintaining marten habitat.

The historical reconstruction of growth efficiency and its relationship to tree mortality in balsam fir ecosystems affected by spruce budworm

1994 ◽  
Vol 24 (11) ◽  
pp. 2208-2221 ◽  
Author(s):  
Marie R. Coyea ◽  
Hank A. Margolis
Keyword(s):  
Leaf Area ◽  
Tree Mortality ◽  
Basal Area ◽  
Spruce Budworm ◽  
Growth Efficiency ◽  
Balsam Fir ◽  
Tree Age ◽  
Basal Area Growth ◽  
Annual Growth Rings ◽  
Area Growth

The growth efficiencies (E; stemwood growth per unit leaf area) of balsam fir (Abiesbalsamea (L.) Mill.) trees from 20 stands were reconstructed over the 30-year period from 1960 to 1989 in order to determine if E could be used to predict tree mortality occurring during and after an epidemic of eastern spruce budworm (Choristoneurafumiferana (Clem.)). Growth efficiencies were reconstructed based on the relationship between age and the number of annual growth rings in the cross-sectional area of heartwood at breast height (R2 = 0.97) and on the previously demonstrated relationship between sapwood area and leaf area of balsam fir across a wide geographic area. Profile and logistic regression analyses demonstrated that apparent E (i.e., the historically reconstructed E) of surviving trees was greater than that of dead trees for every year of the 30-year analysis period. For trees in the 25- to 35-year age-class in 1960, apparent E was the only variable measured prior to the epidemic that was significantly related to balsam fir mortality. For all trees (aged 11 to 46 years in 1960), both tree age and apparent E were significant factors prior to the epidemic. During and following the epidemic, several of the more standard mensurational variables (e.g., diameter and basal area growth) were also significantly associated with balsam fir mortality, but apparent E had the highest levels of significance. Using logistical regression, critical E values below which trees would be predicted to die were calculated as 5-year running averages for the period prior to the epidemic (1960–1968). These were stable at around 0.17 × 10−4 m2 basal area growth•(m2 leaf area)−1•year−1. Following the epidemic, critical E values were again stable but at a lower level of around 0.07. There was a negative exponential relationship between apparent E and leaf area. Furthermore, for the same level of leaf area, surviving trees had a higher apparent E than trees that died, up to approximately 30 m2 of leaf area. These results suggest that growth efficiency should be considered as part of standard forest inventories in the balsam fir zone because of its ease of measure and its apparent ability to provide a sensitive, physiologically based index of forest health. Furthermore, the technique of historically reconstructing E demonstrated in this study may be of interest for other types of dendrochronological research.

scholarly journals Plot size and number of replications in Sudan grass

2020 ◽  
Vol 41 (3) ◽  
pp. 783
Author(s):  
Alberto Cargnelutti Filho ◽  
Cirineu Tolfo Bandeira ◽  
Gabriela Görgen Chaves ◽  
Jéssica Andiara Kleinpaul ◽  
Rafael Vieira Pezzini ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Iterative Process ◽  
Block Design ◽  
Mean Value ◽  
Fresh Weight ◽  
Sudan Grass ◽  
Plot Size ◽  
Maximum Curvature ◽  
The Mean ◽  
Uniformity Trials

The aim of this study was to determine the optimal plot size and the number of replications to evaluate fresh weight in Sudan grass [Sorghum sudanense (Piper) Stapf.]. Twenty-six uniformity trials were carried out in two cultivars (BRS Estribo and CG Farrapo), in four sowing seasons (20 Dec, 20 Jan, 7 Feb and 24 Feb) and two methods for evaluating fresh weight (cutting and at flowering). The fresh weight was evaluated in 936 basic experimental units (BEU) (26 trials × 36 BEU per trial). One BEU comprised three rows of plants, 1 m in length (1.2 m2). The optimal plot size was determined using the maximum curvature method of the model of the coefficient of variation. For experiments in a completely randomised or randomised block design, in combinations of number of treatments and levels of experimental precision, the number of replications was determined by an iterative process. The optimal plot size to evaluate fresh weight in Sudan grass is 7.95 m2. Eight replications, to evaluate up to 50 treatments in a completely randomised or randomised block design, are sufficient to identify as significant at 0.05% probability by Tukey’s test, differences between the mean value of each treatment of 30.2% of the mean value of the experiment.

scholarly journals Plot size and number of replicates in times of sowing and cuts of millet

2016 ◽  
Vol 20 (2) ◽  
pp. 119-127 ◽  
Author(s):  
Cláudia Burin ◽  
Alberto Cargnelutti Filho ◽  
Bruna M. Alves ◽  
Marcos Toebe ◽  
Jéssica A. Kleinpaul
Keyword(s):  
Coefficient Of Variation ◽  
Iterative Process ◽  
Block Design ◽  
Probability Level ◽  
Fresh Matter ◽  
Tukey Test ◽  
Plot Size ◽  
Randomized Block Design ◽  
The Mean ◽  
Uniformity Trials

ABSTRACT The objective of this study was to determine the optimum plot size (Xo) and number of replicates to evaluate millet shoot fresh matter in times of sowing and cuts. Uniformity trials of 6 × 4 m (24 m2) were carried out in three sowing times, in the agricultural year of 2013-2014. Each uniformity trial was divided into 24 basic experimental units (BEU) of 1 × 1 m (1 m2) and the shoot fresh matter of plants in each BEU was weighed. The Xo was determined by the method of maximum curvature of the coefficient of variation model. The number of replicates for experiments in completely randomized and randomized block design, in scenarios of combinations of i treatments (i = 3, 4, ..., 50) and d minimal differences between treatment means, to be detected as significant at 0.05 probability level by Tukey test, expressed in percentage of the experiment mean (d = 10, 12, ..., 30%), was determined by iterative process until convergence. The optimum plot size to evaluate millet shoot fresh matter is 4.97 m2, for the three times of sowing and cuts. For the evaluation of up to 50 treatments, in completely randomized and randomized block design, five replicates are sufficient to identify as significant, at 0.05 probability level by Tukey test, differences between treatment means of 28.66% of the mean of the experiment.

FACTORS AFFECTING CATCH IN PHEROMONE TRAPS FOR MONITORING THE WESTERN SPRUCE BUDWORM, CHORISTONEURA OCCIDENTALIS FREEMAN

1990 ◽  
Vol 122 (6) ◽  
pp. 1119-1130 ◽  
Author(s):  
J.D. Sweeney ◽  
J.A. McLean ◽  
R.F. Shepherd
Keyword(s):  
Larval Density ◽  
Basal Area ◽  
Spruce Budworm ◽  
Trapping Efficiency ◽  
Choristoneura Occidentalis ◽  
Pheromone Traps ◽  
Western Spruce Budworm ◽  
Trap Design ◽  
Factors Affecting ◽  
The Mean

AbstractThe effects of trap design, lure concentration, lure age, and trap maintenance on the catch of western spruce budworm moths, Choristoneura occidentalis Freeman, in pheromone traps were tested in light to moderate infestations near Ashcroft, B.C. High cumulative moth catches reduced the trapping efficiency of both the sticky traps and the non-sticky Uni-traps relative to traps from which the moths were removed every 2 days. Correlations between the total season’s catch and larval density per plot in the same and following generations were not significant (P>0.05) for any of the eight combinations of trap design, lure concentration, and maintenance regimen tested. However, by dividing the mean moth catch in Uni-traps by either the basal area or foliage biomass per hectare in each plot, correlations with the following year’s larval density were significant (r2 = 0.77–0.98; P<0.05; n=5).

Seedling responses to forest canopy disturbance following a spruce budworm outbreak in Maine

1994 ◽  
Vol 24 (4) ◽  
pp. 850-859 ◽  
Author(s):  
Akira Osawa
Keyword(s):  
Forest Canopy ◽  
Tree Mortality ◽  
Basal Area ◽  
Patch Dynamics ◽  
Spruce Budworm ◽  
Distribution Patterns ◽  
Balsam Fir ◽  
White Birch ◽  
Canopy Disturbance ◽  
Long Run

Patterns of tree mortality and seedling responses to canopy disturbance were investigated in northern Maine, where an outbreak of the spruce budworm (Choristoneurafumiferana (Clem.)) affected the forests of balsam fir (Abiesbalsamea (L.) Mill.) and spruce (Picea spp.) continuously between 1972 and 1984. The outbreak created a gradient of canopy tree mortality that ranged between 8.5 and 100% of the cumulative basal area in 1984. This was a result of the difference in vulnerability among the host species (balsam fir > spruce) and of their spatial distribution patterns along the site drainage gradient. Two groups of plant species responded differently to the gradient of canopy disturbance: balsam fir, spruce, and white birch (Betulapapyrifera Marsh.) regenerated mostly at the intermediate levels of mortality (≈20%by basal area) of the canopy balsam fir; raspberry (Rubusidaeus L.) and pin cherry (Prunuspensylvanica L.) were most abundant at ≈100% fir mortality. Overall, the observed responses in space and time of the seedlings to budworm-caused canopy disturbance could be mostly explained by the concept of patch dynamics. Long-term changes in species composition of the spruce–fir forests cannot be predicted with precision with the present knowledge. However, I hypothesize, based on the species-specific vulnerability to budworm damage and patterns of regeneration, that the proportion of spruce to fir trees would not differ very much in the long run regardless of extensive tree mortality by the spruce budworm.

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