Long-term influence of mowing on population dynamics in the rare orchid Dactylorhiza lapponica: The importance of recruitment and seed production

2010 ◽  
Vol 143 (3) ◽  
pp. 747-755 ◽  
Author(s):  
Nina Sletvold ◽  
Dag-Inge Øien ◽  
Asbjørn Moen
Keyword(s):  
Population Dynamics ◽  
Seed Production

Modeling Population Dynamics of Kochia (Bassia scoparia) in Response to Diverse Weed Control Options

Weed Science ◽  
2019 ◽  
Vol 67 (1) ◽  
pp. 57-67 ◽  
Author(s):  
O. Adewale Osipitan ◽  
J. Anita Dille ◽  
Muthukumar V. Bagavathiannan ◽  
Stevan Z. Knezevic
Keyword(s):  
Population Dynamics ◽  
Population Growth ◽  
Weed Control ◽  
Seed Production ◽  
Seedling Recruitment ◽  
Control Strategies ◽  
Effective Control ◽  
Parameter Estimates ◽  
Herbicide Resistant

AbstractKochia [Bassia scoparia(L.) A. J. Scott] is a problematic weed species across the Great Plains, as it is spreading fast and has developed herbicide-resistant biotypes. It is imperative to understand key life-history stages that promote population expansion ofB. scopariaand control strategies that would provide effective control of these key stages, thereby reducing population growth. Diversifying weed control strategies has been widely recommended for the management of herbicide-resistant weeds. Therefore, the objectives of this study were to develop a simulation model to assess the population dynamics ofB. scopariaand to evaluate the effectiveness of diverse weed control strategies on long-term growth rates ofB. scopariapopulations. The model assumed the existence of a glyphosate-resistant (GR) biotype in theB. scopariapopulation, but at a very low proportion in a crop rotation that included glyphosate-tolerant corn (Zea maysL.) and soybean [Glycine max(L.) Merr.]. The parameter estimates used in the model were obtained from various ecological and management studies onB. scoparia. Model simulations indicated that seedling recruitment and survival to seed production were more important than seedbank persistence forB. scopariapopulation growth rate. Results showed that a diversified management program, including glyphosate, could provide excellent control ofB. scopariapopulations and potentially eliminate already evolved GRB. scopariabiotypes within a given location. The most successful scenario was a diverse control strategy that included one or two preplant tillage operations followed by preplant or PRE application of herbicides with residual activities and POST application of glyphosate; this strategy reduced seedling recruitment, survival, and seed production during the growing season, with tremendous negative impacts on long-term population growth and resistance risk inB. scoparia.

Phenology, Population Dynamics, and Flowering Dynamics of Case's Ladies'-tresses, Spiranthes casei var. casei (Orchidaceae), in Ottawa, Ontario

2009 ◽  
Vol 123 (1) ◽  
pp. 19 ◽  
Author(s):  
Joyce M. Reddoch ◽  
Allan H. Reddoch
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Seed Production ◽  
Late Summer ◽  
Early Summer ◽  
Population Trends ◽  
Life History Stages ◽  
Deer Herbivory ◽  
Cloudy Weather

We describe a seven-year study (2002–2008) of a population of Case’s Ladies’-tresses (Spiranthes casei var. casei) in the western Greenbelt in Ottawa, Ontario, that had been extant since at least 1972. We also record a temporary colonization in the eastern Greenbelt for 11 years (1998–2008). The seven life history stages identified were seed, juvenile, immature, flowering, vegetative, offshoot (ramet), and non-emergent. Mature plants present in the first two years of the study had mean half lives of 9.4 years. Flowering and seed production were limited by damp, cloudy weather when fall rosettes develop, by gastropod herbivory in early summer, by drought in mid-summer, and by deer herbivory in late summer. Given the resulting wide fluctuations in the fractions of plants flowering, as well as the lack of visibility of vegetative plants, this study demonstrates the limitations of annual censuses of flowering stems for determining the actual sizes of populations and for detecting long-term population trends.

Long-term population dynamics of the red deer and European roe deer at the protected and not-protected areas in Mountain Crimea

2017 ◽  
Vol 7 (4) ◽  
pp. 65-72
Author(s):  
V. N. Shmagol' ◽  
V. L. Yarysh ◽  
S. P. Ivanov ◽  
V. I. Maltsev
Keyword(s):  
Population Dynamics ◽  
Protected Areas ◽  
Red Deer ◽  
Nature Reserve ◽  
Roe Deer ◽  
Precipitation Amount ◽  
Annual Precipitation ◽  
Population Number ◽  
The Impact

<p>The long-term population dynamics of the red deer (<em>Cervus elaphus</em> L.) and European roe deer (<em>Capreolus</em> <em>capreolus</em> L.) at the mountain and forest zone of Crimea during 1980-2017 is presented. Fluctuations in numbers of both species are cyclical and partly synchronous. Period of oscillations in the population of red deer is about 25 years, the average duration of the oscillation period of number of roe deer is 12.3 years. During the fluctuations in the number the increasing and fall in population number of the red deer had been as 26-47 %, and roe deer – as 22-34 %. Basing on the dada obtained we have assumed that together with large-scale cycles of fluctuations in population number of both red deer and roe deer the short cycles of fluctuations in the number of these species with period from 3.5 to 7.5 years take place. Significant differences of the parameters of cyclical fluctuations in the number of roe deer at some sites of the Mountainous Crimea: breaches of synchronicity, as well as significant differences in the duration of cycles are revealed. The greatest deviations from the average values of parameters of long-term dynamics of the number of roe deer in Crimea are noted for groups of this species at two protected areas. At the Crimean Nature Reserve the cycle time of fluctuations of the numbers of roe deer was 18 years. At the Karadag Nature Reserve since 1976 we can see an exponential growth in number of roe deer that is continued up to the present time. By 2016 the number of roe deer reached 750 individuals at a density of 437 animals per 1 thousand ha. Peculiarity of dynamics of number of roe deer at some sites proves the existence in the mountain forest of Crimea several relatively isolated groups of deer. We assumed that "island" location of the Crimean populations of red deer and European roe deer, their relatively little number and influence of permanent extreme factors of both natural and anthropogenic origination have contributed to a mechanism of survival of these populations. The elements of such a mechanism include the following features of long-term dynamics of the population: the reduction in the period of cyclic population fluctuations, while maintaining their amplitude and the appearance of additional small cycles, providing more flexible response of the population to the impact of both negative and positive environmental factors. From the totality of the weather conditions for the Crimean population of roe deer the recurring periods of increases and downs in the annual precipitation amount may have relevance. There was a trend of increase in the roe deer population during periods of increasing annual precipitation.</p>

Long-term population dynamics of Dactylorhiza incarnata (L.) Soó after abandonment and re-introduction of mowing

Flora ◽  
2011 ◽  
Vol 206 (7) ◽  
pp. 622-630 ◽  
Author(s):  
Joachim Schrautzer ◽  
Andreas Fichtner ◽  
Aiko Huckauf ◽  
Leonid Rasran ◽  
Kai Jensen
Keyword(s):  
Population Dynamics

scholarly journals Increasing frequency of low summer precipitation synchronizes dynamics and compromises metapopulation stability in the Glanville fritillary butterfly

2015 ◽  
Vol 282 (1806) ◽  
pp. 20150173 ◽  
Author(s):  
Ayco J. M. Tack ◽  
Tommi Mononen ◽  
Ilkka Hanski
Keyword(s):  
Population Dynamics ◽  
Population Change ◽  
Temporal Dynamics ◽  
Summer Precipitation ◽  
Life History Stage ◽  
General Effect ◽  
Spatial Synchrony ◽  
Glanville Fritillary Butterfly ◽  
Spatio Temporal

Climate change is known to shift species' geographical ranges, phenologies and abundances, but less is known about other population dynamic consequences. Here, we analyse spatio-temporal dynamics of the Glanville fritillary butterfly ( Melitaea cinxia ) in a network of 4000 dry meadows during 21 years. The results demonstrate two strong, related patterns: the amplitude of year-to-year fluctuations in the size of the metapopulation as a whole has increased, though there is no long-term trend in average abundance; and there is a highly significant increase in the level of spatial synchrony in population dynamics. The increased synchrony cannot be explained by increasing within-year spatial correlation in precipitation, the key environmental driver of population change, or in per capita growth rate. On the other hand, the frequency of drought during a critical life-history stage (early larval instars) has increased over the years, which is sufficient to explain the increasing amplitude and the expanding spatial synchrony in metapopulation dynamics. Increased spatial synchrony has the general effect of reducing long-term metapopulation viability even if there is no change in average metapopulation size. This study demonstrates how temporal changes in weather conditions can lead to striking changes in spatio-temporal population dynamics.

Long-term data indicates that supplementary food enhances the number of breeding pairs in a Cape Vulture Gyps coprotheres colony

2016 ◽  
Vol 27 (1) ◽  
pp. 140-152 ◽  
Author(s):  
DANA G. SCHABO ◽  
SONJA HEUNER ◽  
MICHAEL V. NEETHLING ◽  
SASCHA RÖSNER ◽  
ROGER UYS ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Breeding Success ◽  
Food Sources ◽  
Breeding Colony ◽  
Supplementary Food ◽  
Adequate Food ◽  
Vulture Conservation ◽  
Positive Effect ◽  
Term Data

SummaryThe number of vultures is declining in many parts of the world due to numerous threats, such as poisoning and collisions with power-lines as well as the lack of adequate food sources. Vulture restaurants, i.e. supplementary feeding stations, have become a widespread conservation tool aimed at supporting vulture colonies. However, it is poorly understood how vulture restaurants influence population dynamics and whether they affect breeding success of vulture populations. We used a 12-year dataset from a breeding colony of the Cape Vulture Gyps coprotheres and a nearby vulture restaurant in South Africa to investigate the effect of supplementary food on population dynamics and breeding success. We found a significantly positive effect of supplementary food during the nest-building stage on the number of breeding pairs. However, breeding success, i.e. the proportion of successful nests, did not depend on supplementary food during the incubation and rearing stage. Especially during the critical rearing stage, the amount of food supplied might not have been sufficient to meet food demands of the colony. Still, our results indicate that carefully managed vulture restaurants might stabilise vulture colonies and can therefore aid vulture conservation.

Results of selection and seed-growing work on onion crops at the Federal Scientific Center of Vegetable Growing

2021 ◽  
Author(s):  
T.M. Seredin ◽  
◽  
A.F. Agafonov ◽  
Keyword(s):  
Seed Production ◽  
High Quality ◽  
Scientific Center ◽  
New Varieties ◽  
Seed Growing

the article summarizes the long-term research on the selection and seed production of onion crops of the Federal Scientific Center of Vegetable Growing. The prospects of using new varieties to obtain high-quality products for different zones are shown.

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