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Mast Year (mast + year)

Distribution by Scientific Domains
Life Sciences100%

Selected Abstracts

Is there a higher risk for herbivore outhreaks after cold mast years?

ECOGRAPHY, Issue 6 2000
An analysis of two plant/herbivore series from southern Norway
Historical data on two plant-herbivore interactions from southern Norway were used to test the hypothesis that the degree of herbivore outbreaks in post-mast years is negatively related to summer temperatures in the mast year, because plants are more depressed after a high seed production if temperatures and thus the photosynthetic activity is low. The plant species were the sessile oak Quercus petraea and the bilberry Vaceinium myrtillus. For the former species post-mast years were identified from reports given by the local forest authorities for the period 1930,48, and from acorn export curves for the period 1949,98, For the latter species, post-mast years were identified mainly from bilberry export curves for the period 1920,31, from game reports for the period 1932,78. and from diary notes for the period 1979,87. The herbivore species used were the green oak leaf roller moth Tortrix viridana and the capercaillie Tetrao urogallus. Eight moth outbreaks on oak forests were reported by the forest authorities in the period 1930,98, and they all started in a post-mast year of the sessile oak. There were however also eleven post-mast years without moth outbreaks. According to game reports, observations and autumn counts, all increases in the autumn population size of capercaillie during 1920 88 occurred in or after a year with high bilberry production. Among i8 post-mast years, there were seven with strong increase, seven with slight or moderate increase, and four with no increase. For both herbivore species, post-mast years with marked population increases had significantly lower summer temperatures in the preceding (mast) year than had post-mast years with no or slight increases. For moth populations there also was a negative effect of high temperatures in April, possibly because moth eggs tend to hatch too early relative lo budburst if spring temperatures are high. For the capercaillie, high amount of precipitation in June , July seemed to have some negative impact on the autumn population sizes, as also found in previous studies. [source]

Local-scale synchrony and variability in mast seed production patterns of Picea glauca

JOURNAL OF ECOLOGY, Issue 5 2007
JALENE M. LAMONTAGNE
Summary 1Mast seeding is the synchronous and highly variable production of seed by a population of plants. Mast seeding results from the behaviour of individuals; however, little is known about the synchrony of individuals at local scales. 2We address two primary questions at a within-population (17,36 ha study plots) and individual level: (i) How variable is seed production between and within years? (ii) How synchronized is seed production between individuals? 3We monitored annual cone production of 356 Picea glauca (white spruce) from 1990 to 2005 within four plots spanning a total distance of 5.3 km in the Yukon Territory, Canada. 4Spearman correlations (rs) were conducted to test for synchrony. Overall, the trees were moderately synchronous (mean rs (± SE) of 0.52 ± 0.14), and synchrony was statistically detectable (rs > 0) over all distances. Individuals < 75 m apart were highly synchronous (0.64 ± 0.18), and correlations dropped to 0.33 ± 0.07 for trees > 3 km apart. There was considerable variation in cone production patterns among pairs of individuals. 5The number of mast years per plot varied from one to three. During a mast year, many individuals within plots produced large cone crops, with more variability between individuals in low mean cone years. Individual trees had dominant endogenous cycles varying from none to 1,5 years. Forty-four per cent of trees had no significant lag, 23% a negative 1-year lag, and 20% a positive 3-year lag. Basal area did not influence lags, but trees with higher mean cone production throughout the study were more likely to have a 3-year lag compared with no lag. 6The scale of highest synchrony coincided with the scale at which the dominant seed predator in the area, the territorial red squirrel (Tamiasciurus hudsonicus), operates. This may be the scale at which selection for synchrony occurs. 7Based on high synchrony locally, high synchrony within a mast year, and multiple lags in cone production by individuals, both available resources and strong weather cues appear to play roles in the observed patterns. [source]

Is there a higher risk for herbivore outhreaks after cold mast years?

ECOGRAPHY, Issue 6 2000
An analysis of two plant/herbivore series from southern Norway
Historical data on two plant-herbivore interactions from southern Norway were used to test the hypothesis that the degree of herbivore outbreaks in post-mast years is negatively related to summer temperatures in the mast year, because plants are more depressed after a high seed production if temperatures and thus the photosynthetic activity is low. The plant species were the sessile oak Quercus petraea and the bilberry Vaceinium myrtillus. For the former species post-mast years were identified from reports given by the local forest authorities for the period 1930,48, and from acorn export curves for the period 1949,98, For the latter species, post-mast years were identified mainly from bilberry export curves for the period 1920,31, from game reports for the period 1932,78. and from diary notes for the period 1979,87. The herbivore species used were the green oak leaf roller moth Tortrix viridana and the capercaillie Tetrao urogallus. Eight moth outbreaks on oak forests were reported by the forest authorities in the period 1930,98, and they all started in a post-mast year of the sessile oak. There were however also eleven post-mast years without moth outbreaks. According to game reports, observations and autumn counts, all increases in the autumn population size of capercaillie during 1920 88 occurred in or after a year with high bilberry production. Among i8 post-mast years, there were seven with strong increase, seven with slight or moderate increase, and four with no increase. For both herbivore species, post-mast years with marked population increases had significantly lower summer temperatures in the preceding (mast) year than had post-mast years with no or slight increases. For moth populations there also was a negative effect of high temperatures in April, possibly because moth eggs tend to hatch too early relative lo budburst if spring temperatures are high. For the capercaillie, high amount of precipitation in June , July seemed to have some negative impact on the autumn population sizes, as also found in previous studies. [source]

Local-scale synchrony and variability in mast seed production patterns of Picea glauca

JOURNAL OF ECOLOGY, Issue 5 2007
JALENE M. LAMONTAGNE
Summary 1Mast seeding is the synchronous and highly variable production of seed by a population of plants. Mast seeding results from the behaviour of individuals; however, little is known about the synchrony of individuals at local scales. 2We address two primary questions at a within-population (17,36 ha study plots) and individual level: (i) How variable is seed production between and within years? (ii) How synchronized is seed production between individuals? 3We monitored annual cone production of 356 Picea glauca (white spruce) from 1990 to 2005 within four plots spanning a total distance of 5.3 km in the Yukon Territory, Canada. 4Spearman correlations (rs) were conducted to test for synchrony. Overall, the trees were moderately synchronous (mean rs (± SE) of 0.52 ± 0.14), and synchrony was statistically detectable (rs > 0) over all distances. Individuals < 75 m apart were highly synchronous (0.64 ± 0.18), and correlations dropped to 0.33 ± 0.07 for trees > 3 km apart. There was considerable variation in cone production patterns among pairs of individuals. 5The number of mast years per plot varied from one to three. During a mast year, many individuals within plots produced large cone crops, with more variability between individuals in low mean cone years. Individual trees had dominant endogenous cycles varying from none to 1,5 years. Forty-four per cent of trees had no significant lag, 23% a negative 1-year lag, and 20% a positive 3-year lag. Basal area did not influence lags, but trees with higher mean cone production throughout the study were more likely to have a 3-year lag compared with no lag. 6The scale of highest synchrony coincided with the scale at which the dominant seed predator in the area, the territorial red squirrel (Tamiasciurus hudsonicus), operates. This may be the scale at which selection for synchrony occurs. 7Based on high synchrony locally, high synchrony within a mast year, and multiple lags in cone production by individuals, both available resources and strong weather cues appear to play roles in the observed patterns. [source]