scholarly journals Annual variability in sound acorn production was regulated by a generalist seed predator weevil in Quercus serrata

2021 ◽  
Author(s):  
Kimiko Hirayama ◽  
Kenta Mizo ◽  
Manaka Tatsuno ◽  
Mizuki Yoshikawa ◽  
Chieri Tachikawa
Keyword(s):  
Seed Production ◽  
Quercus Serrata ◽  
Annual Production ◽  
Acorn Production ◽  
Seed Predator ◽  
Annual Variability ◽  
Key Factor ◽  
Demographic Processes ◽  
Western Japan ◽  
Female Flowers

Abstract Highly variable and synchronous seed production within a population (‘masting’) could be from either synchronised high annual variability in floral initiation (‘flower masting’) or synchronised floral abortion until maturity (‘fruit maturation masting’). We investigated the demographic processes of the female organs from flowering to seed maturity, including each type of insect damage identified, in Quercus serrata in six individuals within a stand from 2014 to 2020, western Japan. Although the annual production of sound acorns was significantly correlated with that of female flowers, the annual variability in sound acorn production within an individual was significantly higher and their synchrony increased, compared to those of female flowers. The annual production of female flowers was positively correlated with the temperature difference in April between the previous and flowering years. However, their fluctuation was low, which was neither affected by seed and flower production in the previous year nor contributed to predator starvation. Key-factor analyses revealed that reproductive loss due to oviposition and sap suction by Mechoris ursulus , a generalist seed predator weevil for oak species, was the largest and most important factor that contributed to the annual variation in the total pre-dispersal loss of Q. serrata . The survival rate from female flowers to sound acorns was strongly predicted by the temperature in June, corresponding to the emergence of adult M. ursulus . This study suggests that highly variable and synchronous sound seed production can be proximately regulated by seed predation when the main predator is a generalist.

What determines the number of seed produced in a flowering event? A case study of Calyptrogyne ghiesbreghtiana (Arecaceae)

2000 ◽  
Vol 48 (5) ◽  
pp. 659 ◽  
Author(s):  
Saul A. Cunningham
Keyword(s):  
Resource Allocation ◽  
Seed Production ◽  
Natural Variation ◽  
Seed Set ◽  
Plant Seed ◽  
Flower Production ◽  
Number Of Seeds ◽  
Female Flowers

Calyptrogyne ghiesbreghtiana Linden ex. H. Wendl. is an understorey palm that occurs at La Selva Biological Station, Costa Rica. In this paper I combine analysis of natural variation and results of experimental manipulations to ask (1) what limits seed production? and (2) what processes cause variation in seed production by C. ghiesbreghtiana? The number of seed produced per inflorescence ofC. ghiesbreghtiana was limited substantially by the loss of female flowers to floral herbivores. Much variation in the number of seed produced perinflorescence of C. ghiesbreghtiana was due to losses of developing fruits to predators. Together these phenomena illustrate the influential role of natural enemies in the reproductive success of this plant. Seed-set efficiency (number of seeds/number of female flowers) was highly variable in this species, and such high levels of variation appear to be common in other species. For species with highly variable seed-set efficiency, the role of resource allocation to flower production in determining differences in seed production among individual plants is likely to be relatively small.

Seed production in forests of Chamaecyparislawsoniana

1979 ◽  
Vol 9 (3) ◽  
pp. 327-335
Author(s):  
Donald B. Zobel
Keyword(s):  
Seed Production ◽  
Reproductive Potential ◽  
Basal Area ◽  
Annual Production ◽  
Forest Community ◽  
Regional Pattern ◽  
Crop Size ◽  
Seed Collection ◽  
Open Forest ◽  
Seed Crops

In 3 years of seed collection throughout the range of Chamaecyparislawsoniana (A. Murr.) Parl., 30 seed crops varied from 20 000 to 4 600 000 seeds per hectare. The overall mean was 829 000 seeds per hectare per year. Annual production per square metre of basal area (BA) varied from 600 to 185 000. Only 6 of 30 seed crops exceeded 50 000 seeds/m2 BA per year but these were produced by the youngest (65 year old) and oldest (450 + year old) stands and throughout the environmental range of the species. Of other seed crops, 11 had 10 000–50 000 seeds/m2 BA per year and 13 had fewer than 10 000 seeds/m2 BA per year. Year-to-year variation had a local, not regional, pattern. An open-forest community produced more seed per square metre of basal area than a denser one at two mixed evergreen zone sites. Seedfall peaked from October to November, with a smaller spring peak, but some seeds fell throughout the year. Most sites differed little in the timing of peaks. Germination of trapped seed from seven sites in 1 year was 11–44% and showed no correlation with crop size. Other species in this genus produce many more seeds per hectare than C. lawsoniana but there is no evidence that seed production limits reproductive potential of this species. In mixed forests, C. lawsoniana and especially Tsugaheterophylla (Raf.) Sarg. were over represented in the seedfall (compared with their basal area), whereas Pseudotsugamenziesli (Mirb.) Franco and Abiesconcolor (Gordon and Glend.) Lindl. ex Hildebr. produced less than their share.

scholarly journals Fire effects on acorn production are consistent with the stored resource hypothesis for masting behavior

2016 ◽  
Vol 46 (1) ◽  
pp. 20-24 ◽  
Author(s):  
Kyle A. Funk ◽  
Walter D. Koenig ◽  
Johannes M.H. Knops
Keyword(s):  
Seed Production ◽  
Fire Effects ◽  
Internal Dynamics ◽  
Acorn Production ◽  
Wild Tree ◽  
Resource Storage ◽  
Controlled Burns ◽  
Baseline Levels ◽  
Resource Hypothesis

Highly variable patterns of seed production (“masting”) have been hypothesized to be driven by internal dynamics of resource storage and depletion. This hypothesis predicts that if seed production is artificially reduced, then the availability of unused stored resources should result in subsequent enhancement of the seed crop. We tested this prediction in two oak species with contrasting patterns of annual seed production (highly variable and relatively constant) by means of controlled burns at various frequencies over a 17-year period. We found that controlled burns reduced acorn production by both species in the year of the burn. In the species with relatively constant productivity, acorn production returned to baseline levels in the year following a burn; however, in the species with highly variable productivity, acorn production significantly increased the year following a burn. These results support a key prediction of the stored resource hypothesis by means of a long-term experimental test in wild tree populations.

scholarly journals Unexpected parasitism of Douglas-fir seed chalcid limits biocontrol options for invasive Douglas-fir in New Zealand

2021 ◽  
Vol 74 (1) ◽  
pp. 70-77
Author(s):  
Sonia Lee ◽  
Simon V. Fowler ◽  
Claudia Lange ◽  
Lindsay A. Smith ◽  
Alison M. Evans
Keyword(s):  
Biological Control ◽  
New Zealand ◽  
Seed Production ◽  
Biocontrol Agent ◽  
Biological Control Agent ◽  
Parasitoid Wasp ◽  
Control Agent ◽  
Douglas Fir ◽  
Seed Predator ◽  
High Level

Douglas-fir seed chalcid (DFSC) Megastigmus spermotrophus, a small (3 mm long) host-specific seed-predatory wasp, was accidentally introduced into New Zealand in the 1920s. Concern over DFSC reducing Douglas-fir seed production in New Zealand led to an attempt at biocontrol in 1955 with the release, but failed establishment, of the small (2.5 mm long) parasitoid wasp, Mesopolobus spermotrophus. We investigated why DFSC causes little destruction of Douglas-fir seed in New Zealand (usually <20%) despite the apparent absence of major natural enemies. Douglas-fir seed collections from 13 New Zealand sites yielded the seed predator (DFSC) but also potential parasitoids, which were identified using morphology and partial COI DNA sequencing. DFSC destroyed only 0.15% of Douglas-fir seed. All parasitoids were identified as the pteromalid wasp, Mes. spermotrophus, the host-specific biocontrol agent released in 1955. Total parasitism was 48.5%, but levels at some sites approached 90%, with some evidence of density-dependence. The discovery of the parasitoid Mes. spermotrophus could indicate that the biocontrol agent released in 1955 did establish after all. Alternatively, Mes. spermotrophus could have arrived accidentally in more recent importations of Douglas-fir seed. The high level of parasitism of DFSC by Mes. spermotrophus is consistent with DFSC being under successful biological control in New Zealand. Suppression of DFSC populations will benefit commercial Douglas-fir seed production in New Zealand, but it also represents the likely loss of a potential biological control agent for wilding Douglas-fir.

scholarly journals Demographic Situation and the Level of Human Development of the Republic of Kazakhstan: Regional Aspects

2011 ◽  
Vol 16 (16) ◽  
pp. 75-87 ◽  
Author(s):  
Gulnara Nyussupova ◽  
Irina Rodionova
Keyword(s):  
Human Development ◽  
Spatial Organization ◽  
Scientific Work ◽  
Human Potential ◽  
Demographic Situation ◽  
Potential Development ◽  
Key Factor ◽  
Demographic Processes ◽  
The Republic ◽  
The Moment

Demographic Situation and the Level of Human Development of the Republic of Kazakhstan: Regional Aspects The objects of research are indicators of human development in Kazakhstan from the moment of independence acquisition by the republic until today. The subject of scientific research is spatial-existential patterns of socio-demographic processes as a key factor of human potential development in the Republic of Kazakhstan. The importance of scientific work is that the results permit to estimate the level of human development of the Republic of Kazakhstan on the basis of socio-demographic processes. For the first time the basic indicators defining human potential in Kazakhstan have been studied in detail and systematized. The aim of the work is to define the laws of the spatial organization of human potential and its basic spatial analyses of human development of Kazakhstan. The database, created with the help of ArcGIS, allows to monitor the changes of human development level, to analyze, estimate and manage human potential of the Republic of Kazakhstan.

scholarly journals Spatial and temporal patterns of a pulsed resource dynamically drive the distribution of specialist herbivores

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Violette Doublet ◽  
Cindy Gidoin ◽  
François Lefèvre ◽  
Thomas Boivin
Keyword(s):  
Seed Production ◽  
Temporal Variations ◽  
Host Tree ◽  
Natural Ecosystems ◽  
Spatial And Temporal Patterns ◽  
Seed Predator ◽  
Resource Concentration ◽  
Seed Predators ◽  
Spatio Temporal ◽  
Seed Infestation

AbstractPatterns and drivers of the spatio-temporal distribution of herbivores are key elements of their ecological and evolutionary impacts on plant populations. Herbivore spatial distributions may be influenced by increased (RCH: resource concentration hypothesis) or decreased (RDH: resource dilution hypothesis) resource densities, but the effect of temporal variations in resource densities on such distributions remains poorly documented. We used a survey of a masting tree species and its seed predators in Southeastern France to address the effect of a host’s pulsed resource on the spatio-temporal distributions of highly specialized insect herbivores feeding on seeds. Variations in both resource and seed predator densities were assessed by estimating seed production and seed infestation rates in focus trees during 10 consecutive years. We found increasing seed infestation rates with decreasing host tree densities in years of low seed production, indicating a RDH pattern of seed predators. However, such pattern was not persistent in years of high seed production during which seed infestation rates did not depend on host tree densities. We showed that temporal variations in resource density can lead to transience of seed predator spatial distribution. This study highlights how predictions of plant-herbivore interactions in natural ecosystems may rely on temporal components underlying RCH and RDH hypotheses.

Implications of Differences Between Hermaphrodite and Female Flowers for Attractiveness To Pollinators and Seed Production

1990 ◽  
Vol 41 (2-3) ◽  
pp. 130-143 ◽  
Author(s):  
Peter G.L. Klinkhamer ◽  
Tom J. De Jong ◽  
Renate A. Wesselingh
Keyword(s):  
Seed Production ◽  
Female Flowers
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