Sample size – precision relationships for use in estimating stand characteristics and spruce budworm caused tree mortality

1983 ◽  
Vol 13 (4) ◽  
pp. 548-555 ◽  
Author(s):  
David A. MacLean ◽  
Donald P. Ostaff
Keyword(s):  
Sample Size ◽  
Tree Mortality ◽  
Total Mortality ◽  
Spruce Budworm ◽  
Cape Breton ◽  
Mortality Estimate ◽  
Rough Approximation ◽  
Precision Level ◽  
Fixed Area ◽  
Stand Characteristics

Data on spruce budworm (Choristoneurafumiferana (Clem.)) caused tree mortality and stand characteristics collected between 1977 and 1981 from 25 plots on the Cape Breton Highlands, Nova Scotia, were used to derive relationships between sample size and precision level. Comparison of three plot types (prism point samples with BAF = 2.3, 0.01-ha circular fixed area plots, and 0.05-ha fixed area plots) indicated that using larger numbers of small plots (either prism or fixed area) within each sampled stand would be the best method for estimating tree mortality. Curves relating required number of plots to desired precision level (specified as a bound on the mortality estimate) were presented for estimating both annual mortality and cumulative (total) mortality. These relationships will assist in choosing sample size in future studies determining stand characteristics and bud worm-caused tree mortality. As a rough approximation, sampling about 15 prism points within each stand should result in estimation of cumulative mortality to about ±10% precision.

Spruce budworm populations, defoliation, and changes in stand condition during an uncontrolled spruce budworm outbreak on Cape Breton Island, Nova Scotia

1989 ◽  
Vol 19 (9) ◽  
pp. 1077-1086 ◽  
Author(s):  
Donald P. Ostaff ◽  
David A. MacLean
Keyword(s):  
Nova Scotia ◽  
Tree Mortality ◽  
Total Mortality ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Dead Trees ◽  
Spruce Mortality ◽  
Third Instar Larvae

Effects of an uncontrolled spruce budworm (Choristoneurafumiferana (Clem.)) outbreak in 20 mature balsam fir (Abiesbalsamea (L.) Mill.) stands on Cape Breton Island, Nova Scotia, were studied from 1976 to 1985. Spruce budworm populations were extremely high, higher than peak levels recorded for other outbreaks, and averaged over 380 third-instar larvae per square metre of foliage from 1976 to 1980. As many as 1570 third-instar larvae per square metre occurred 5 to 7 years after the start of the outbreak, resulting in complete current defoliation and back-feeding on older foliage. Stands were divided into three groups, based on the pattern of cumulative current defoliation; the sum of current annual defoliation during the outbreak was 343, 445, and 543% for these groups, equivalent to the removal of 3.5 to 5.5 age-classes of foliage. Budworm defoliation caused the death of 78, 80, and 89% of the merchantable balsam fir volume in the three groups of stands, respectively, as well as 27% of the spruce (Picea sp.) volume; another 39% of the spruce volume died as a result of spruce beetle (Dendroctonusrufipennis Kby.) activity. Fir mortality commenced 3 years after the start of the outbreak and spruce mortality 2 to 3 years later. About one-half of the total mortality occurred in the 4 years after budworm populations and defoliation returned to low levels. Tree mortality and loss of foliage opened the stands, and 4 years after the collapse of the outbreak, 4% of the surviving trees and 17% of the dead trees had blown down, whereas 60% of all trees had broken tops.

scholarly journals Development of a New TRIPLEX-Insect Model for Simulating the Effect of Spruce Budworm on Forest Carbon Dynamics

Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 513 ◽  
Author(s):  
Zelin Liu ◽  
Changhui Peng ◽  
Louis De Grandpré ◽  
Jean-Noël Candau ◽  
Xiaolu Zhou ◽  
...  
Keyword(s):  
Tree Mortality ◽  
Spruce Budworm ◽  
Published Data ◽  
Insect Management ◽  
Cape Breton Island ◽  
North Shore ◽  
The North ◽  
Cape Breton ◽  
Conifer Trees ◽  
Forest C

The spruce budworm (SBW) defoliates and kills conifer trees, consequently affecting carbon (C) exchanges between the land and atmosphere. Here, we developed a new TRIPLEX-Insect sub-model to quantify the impacts of insect outbreaks on forest C fluxes. We modeled annual defoliation (AD), cumulative defoliation (CD), and tree mortality. The model was validated against observed and published data at the stand level in the North Shore region of Québec and Cape Breton Island in Nova Scotia, Canada. The results suggest that TRIPLEX-Insect performs very well in capturing tree mortality following SBW outbreaks and slightly underestimates current annual volume increment (CAI). In both mature and immature forests, the simulation model suggests a larger reduction in gross primary productivity (GPP) than in autotrophic respiration (Ra) at the same defoliation level when tree mortality was low. After an SBW outbreak, the growth release of surviving trees contributes to the recovery of annual net ecosystem productivity (NEP) based on forest age if mortality is not excessive. Overall, the TRIPLEX-Insect model is capable of simulating C dynamics of balsam fir following SBW disturbances and can be used as an efficient tool in forest insect management.

An evaluation of growth response of young, spaced balsam fir to 3 years of spruce budworm spraying with Bacillusthuringiensis

1984 ◽  
Vol 14 (3) ◽  
pp. 404-411 ◽  
Author(s):  
H. Piene ◽  
D. A. MacLean
Keyword(s):  
Growth Response ◽  
Tree Mortality ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Growth Responses ◽  
Average Volume ◽  
Cape Breton ◽  
Volume Increment ◽  
Total Gain

Growth response of young, spaced balsam fir (Abiesbalsamea (L.) Mill.) to 3 successive years (1979–1981) of treatment with Bacillusthuringiensis Berliner for spruce budworm (Choristoneurafumiferana (Clem.)) control was examined in 20 plots on the Cape Breton Highlands, Nova Scotia. Defoliation commenced in 1976, 3 years before control operations began. Five plots were established both inside and outside the spray block, in areas that had been severely defoliated by budworm and in areas moderately defoliated. All plots in the severely defoliated area suffered heavy tree mortality, but mortality was significantly lower in the protected plots. In contrast, the moderately defoliated plots suffered virtually no tree mortality. The average volume increment of stem-analyzed trees from 1979 to 1981 was 0.63 dm3/tree for protected and 0.43 dm3/tree for unprotected trees in the severely defoliated area versus 4.15 dm3/tree for protected and 3.08 dm3/tree for unprotected trees in the moderately defoliated area. These volume increment values are equivalent to 8.8 m3/ha of growth between 1979 and 1981 for protected plots in the moderately defoliated area, compared with 6.1 m3/ha for unprotected plots. Therefore, a total gain of 2.7 m3/ha can be attributed to the 3 years of B. thuringiensis spraying. Long-term growth responses toB. thuringiensis spraying were not evaluated. Better results would be expected had protection started at the beginning of the budworm outbreak, instead of after 3 years of severe defoliation.

scholarly journals Efficacy of Insecticide Aerial Spraying Programs to Reduce Tree Mortality During a Spruce Budworm Outbreak (1967‒1992) in the Quebec Province.

2021 ◽  
Author(s):  
Alvaro Fuentealba ◽  
Alain Dupont ◽  
Roberto Quezada-Garcia ◽  
Éric Bauce
Keyword(s):  
Tree Mortality ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Stand Age ◽  
Similar Reduction ◽  
Forest Protection ◽  
Protection Goal ◽  
Aerial Spraying ◽  
Stand Characteristics

Abstract Spruce budworm (Choristoneura fumiferana) is the most important pest of conifer forests in Eastern North America. The main approach to protect Quebec forests against this defoliator is aerial spraying of insecticides. Despite the crucial role of aerial spraying of insecticides in the global forest protection strategy, little is known about its real impact on tree mortality reduction or the stand characteristics that may affect its long-term efficacy. We evaluate the efficacy of the protection program implemented between 1967 and 1992 in reducing tree mortality during the previous outbreak in Quebec and how its efficacy is affected by stand characteristics such as drainage quality and stand age. We established 422 plots in Eastern Quebec based on the following parameters: insecticide application (0-13 years), stand composition, drainage quality, and stand age at the beginning of the previous outbreak. Our results show that unprotected plots exhibited in average between 18 and 32.6% higher mortality than protected plots. Insecticide efficacy was affected by drainage quality. For example, protected plots established on sites with bad drainage quality exhibited 49% less balsam fir mortality than unprotected plots. Furthermore, immature and mature protected stands exhibited a similar reduction in balsam fir mortality (32.2 and 32.1% less mortality respectively) compare to unprotected stands. Our results may be useful for decision-makers not only to decide where and when apply insecticides during a spruce budworm outbreak but also, they may help to determine the pertinence of continuous protection during longer than usual outbreaks depending on protection goal.

Vulnerability of Fir-Spruce Stands During Uncontrolled Spruce Budworm Outbreaks: A Review and Discussion

1980 ◽  
Vol 56 (5) ◽  
pp. 213-221 ◽  
Author(s):  
David A. MacLean
Keyword(s):  
Tree Mortality ◽  
Host Density ◽  
Spruce Budworm ◽  
Mortality Rates ◽  
General Sense ◽  
Spruce Stands ◽  
Expected Mortality ◽  
Available Information ◽  
Mature Stands ◽  
Stand Characteristics

The concept of vulnerability to spruce budworm refers to the probability of tree mortality resulting from a given level of budworm attack. This paper reviews and analyses available information from the literature on stand vulnerability and timing of mortality during several budworm outbreaks. Timing of mortality during outbreaks appears to be fairly straightforward when considered in a general sense, with trees usually starting to die after four or five years of severe defoliation. Prediction of the total expected mortality in a given stand is more difficult, however, and attempts to relate mortality to stand characteristics have not shown strong relationships. Nevertheless, the data analysed suggest that for approximation purposes in a management sense, we can probably treat mortality during uncontrolled budworm outbreaks as a host-density dependent process. This is particularly so for fir in mature stands, where mortality approaches 100%, while fir in immature stands and spruce show lower, more variable mortality rates.

Patterns of balsam fir mortality caused by an uncontrolled spruce budworm outbreak

1989 ◽  
Vol 19 (9) ◽  
pp. 1087-1095 ◽  
Author(s):  
David A. MacLean ◽  
Donald P. Ostaff
Keyword(s):  
Tree Mortality ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
Regression Equations ◽  
Cape Breton Island ◽  
Diameter At Breast Height ◽  
Breast Height ◽  
Cape Breton ◽  
Dead Trees ◽  
Site Characteristics

Tree mortality caused by spruce budworm (Choristoneurafumiferana (Clem.)) defoliation was assessed annually from 1976 to 1985 in 20 mature balsam fir (Abiesbalsamea (L.) Mill.) stands on Cape Breton Island, Nova Scotia, and was related to defoliation and to tree, stand, and site characteristics. Ten to 12 years after the start of the budworm outbreak, fir mortality averaged 87% of the merchantable volume (range 60–100%) among the stands. Timing of mortality was similar to that found in studies of previous outbreaks. In the first 4 years of the outbreak, virtually all the trees that died had more than 90% cumulative defoliation but, overall, 64, 21, and 14% of the dead trees had cumulative defoliation >90, 76 to 90, and 51 to 75%, respectively. Early in the outbreak, fir mortality was generally negatively correlated with tree vigor, relative crown position, or diameter at breast height, but in later years, trees were killed irrespective of these factors. Fir mortality was evenly distributed among different sized trees, and 73 to 86% of the trees in each 5 cm diameter at breast height class died. A linear regression equation between dead fir volume and total fir volume explained 89% of the variability in mortality among stands. Percent fir mortality was correlated (r = 0.84) with visual estimates of cumulative defoliation (including all age-classes of foliage) in 1981, but mortality was not correlated with cumulative current annual defoliation or with site characteristics. Using regression equations, fir mortality during this budworm outbreak was predicted to within ±6 m2/ha in 14 of 18 (78%) of the stands, with a relative accuracy of 17.7%.

Spruce budworm defoliation and growth loss in young balsam fir: defoliation in spaced and unspaced stands and individual tree survival

1989 ◽  
Vol 19 (10) ◽  
pp. 1211-1217 ◽  
Author(s):  
Harald Piene
Keyword(s):  
Tree Mortality ◽  
Spruce Budworm ◽  
Shoot Elongation ◽  
Balsam Fir ◽  
Individual Tree ◽  
Cape Breton ◽  
Tree Survival ◽  
Growth Loss ◽  
Individual Trees ◽  
Foliar Biomass

A severe outbreak of spruce budworm (Choristoneurafumiferana (Clem.)) began in 1976 in young, spaced and unspaced stands of balsam fir (Abiesbalsamea (L.) Mill.) located on the Cape Breton Highlands, Nova Scotia, Canada. A study was initiated that year to relate decreases in foliar biomass, caused by defoliation, to reductions in annual volume increment. Detailed defoliation assessments on individual trees from 1976 to 1984 showed severe defoliation of the current foliage in 1976. In 1977 and 1978, current foliage was destroyed in the early part of shoot elongation and severe back-feeding occurred on older age-class needles. After 1978, defoliation decreased as a result of a decline in budworm populations and, in general, only the current foliage was defoliated until the populations decreased to low levels in 1983. Defoliation was significantly higher in spaced than in unspaced stands in 1977, 1978, and 1980, and as a result, by 1984, average tree mortality caused by spruce budworm was 43.8% in spaced and 18.9%.in unspaced stands. The survival of some balsam fir trees and not others following a budworm outbreak is not related to differential defoliation, but to the ability of some balsam fir trees to rapidly increase foliar biomass through prolific epicormic shoot growth.

CHANGES IN SPRUCE BUDWORM DEFOLIATION WITH CROWN LEVEL

1996 ◽  
Vol 128 (6) ◽  
pp. 1109-1113 ◽  
Author(s):  
Harald Piene
Keyword(s):  
Nova Scotia ◽  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Cost Effective ◽  
Balsam Fir ◽  
Crown Length ◽  
Cape Breton ◽  
Cost Effective Approach ◽  
The Common

AbstractDetailed estimates of defoliation caused by spruce budworm [Choristoneura fumiferana (Clem.)] over the crown length of young balsam fir [Abies balsamea (L.) Mill.] were made throughout a spruce budworm outbreak from 1976 to 1984 in the Cape Breton Highlands, Nova Scotia. The results show no clear tendency for a particular level of the crown to be damaged more heavily than any other. Thus, there is no reason to continue the common practice of taking samples from the mid-crown level on the assumption that they represent an ‘average’ level of defoliation either for high or low populations. Sampling from the bottom of the crown should provide a more convenient and cost-effective approach for estimating defoliation.

scholarly journals Spatial distribution pattern and sequential sampling plans for Bactrocera oleae (Gmelin) (Dip: Tephritidae) in olive orchards

2016 ◽  
Vol 48 (1) ◽  
pp. 23
Author(s):  
A. Arbab ◽  
F. Mirphakhar
Keyword(s):  
Spatial Distribution ◽  
Sample Size ◽  
Sequential Sampling ◽  
Bactrocera Oleae ◽  
Sampling Plans ◽  
Optimum Sample Size ◽  
Precision Level ◽  
The Individual ◽  
Optimum Sample ◽  
Basic Distribution

The distribution of adult and larvae <em>Bactrocera oleae</em> (Diptera: Tephritidae), a key pest of olive, was studied in olive orchards. The first objective was to analyze the dispersion of this insect on olive and the second was to develop sampling plans based on fixed levels of precision for estimating <em>B. oleae</em> populations. The Taylor’s power law and Iwao’s patchiness regression models were used to analyze the data. Our results document that Iwao’s patchiness provided a better description between variance and mean density. Taylor’s <em>b</em> and Iwao’s <em>β</em> were both significantly more than 1, indicating that adults and larvae had aggregated spatial distribution. This result was further supported by the calculated common <em>k</em> of 2.17 and 4.76 for adult and larvae, respectively. Iwao’s a for larvae was significantly less than 0, indicating that the basic distribution component of <em>B. oleae</em> is the individual insect. Optimal sample sizes for fixed precision levels of 0.10 and 0.25 were estimated with Iwao’s patchiness coefficients. The optimum sample size for adult and larvae fluctuated throughout the seasons and depended upon the fly density and desired level of precision. For adult, this generally ranged from 2 to 11 and 7 to 15 traps to achieve precision levels of 0.25 and 0.10, respectively. With respect to optimum sample size, the developed fixed-precision sequential sampling plans was suitable for estimating flies density at a precision level of D=0.25. Sampling plans, presented here, should be a tool for research on pest management decisions of <em>B. oleae</em>.

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.

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