Studies on the Population Biology of the Genus Viola: III. The Demography of Viola Blanda and Viola Pallens

Newell, Sandra J.; Solbrig, Otto T.; Kincaid, Dwight T.

doi:10.2307/2259650

Cited by 45 publications

(27 citation statements)

References 17 publications

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“…The death rate may become nearly downward-linear with respect to time (type II) as a result of shoot self-thinning (Pitelka 1984). A similar result was observed in Viola blanda ramets of various ages (Newell et al 1981). In March-May, when tallgrasses such as Miscanthus sacchariflorus and M. sinensis are in their earliest growth stages, storage organs (e.g., rhizomes) were found to allocate resources to newborn shoots (Iwaki and Midorikawa 1968;Mutoh et al 1968).…”

Section: Differences In Shoot-cohort Survivalssupporting

confidence: 62%

“…1b), which was 1-2 months later than the troughs in A. stolonifera and L. perenne, and earlier than the trough in P. anserina. The seasonal fluctuations in net shoot number were small compared with the numbers gained and lost, as has been observed in other plants (Bishop et al 1978;Lovett Doust 1981;Newell et al 1981). This was because the rates of shoot birth and death offset each other, being oppositely affected by temperature (Fig.…”

Section: Shoot Population Dynamics Of Clonesmentioning

confidence: 53%

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Shoot population dynamics of persisting clones of Miscanthus sinensis in the warm-temperate region of Japan

Kobayashi

Yokoi

2003

Journal of Plant Research

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The population dynamics of annual shoots in four clonal patches of Miscanthus sinensis was surveyed in terms of clone persistence. Over a study period of 3 years, a stable net shoot number was attained through a balanced replacement of old shoots by tillering 2-3 times a year. The birth rate was significantly correlated with the average monthly temperature. This suggests that a warm climate advances the date of tillerings, and shoots become taller as they emerge earlier. Five cohorts were identified, corresponding to shoots that were born in spring, early summer, summer, autumn and early winter. The autumn cohorts were more numerous and had a greater longevity than the other cohorts; they were thus were best suited for overwintering and, consequently, maintaining the population from one generation to the next. The shoots of earlier cohorts grew too tall to survive the cold of winter, which might cause freezing injury, while later cohorts' shoots excelled in overwintering because of their shortness. However, if the delayed shoots are very short, they will also have difficulty in surviving the early season of growth. Therefore, M. sinensis shoots have an optimum size for survival.

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Section: Differences In Shoot-cohort Survivalssupporting

confidence: 62%

Section: Shoot Population Dynamics Of Clonesmentioning

confidence: 53%

Shoot population dynamics of persisting clones of Miscanthus sinensis in the warm-temperate region of Japan

Kobayashi

Yokoi

2003

Journal of Plant Research

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“…The more categories removed, the lower was the rate of mortality. The importance of competition as a cause of seedling death was also well demonstrated by Newell, Solbrig & Kincaid (1981) for Viola species in New England forest sites. When established vegetation was removed from around the Viola seedlings their survival was approximately doubled.…”

Section: Vulnerability Of the Early Phasementioning

confidence: 80%

Seedlings

Fenner

1987

New Phytologist

212

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SUMMARYThe factors which cause the death of seedlings were examined and an attempt was made to determine the selective forces to which they are subjected in the field. After briefly dealing with the difficulties of defining a seedling, I examine a few cases from the recent literature in which the causes of seedling mortality are identified and quantified either by monitoring populations under natural conditions or by manipulating the environment experimentally. The special vulnerability of the immediate post-germination phase is illustrated and the consistent underestimation of seedling loss in many studies is suggested. Some interesting cases of the efTects of neighbours on seedling mortality are examined and it is shown that nearest neighbours may affect a seedling's chance of being grazed. It is concluded that since the causes of seedling mortality are so varied and unpredictable in most habitats, individual plasticity may provide a better strategy for survival than highly specialized adaptations to specific mortality factors.

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“…Since λ is influenced by climatic conditions, this indicates that conditions did not differ substantially (at least with respect to their effect on λ) between regions. A long-term λ of around 1 can be expected in perennials as long as the populations do not go extinct (e.g., Solbrig et al 1980;Newell et al 1981;Silvertown et al 1993;Svensson et al 1993;Oostermeijer et al 1996;Nicolè et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…Environmental conditions (both abiotic conditions and biotic interactions) exert selective forces that may lead to the development of specific suites of traits in certain habitat types, along successional trajectories or along clines from the centre to the margin of the species range (Sagarin & Gaines 2002). Across species of different families, habitat-trait relationships go hand in hand with considerable differences among species, life-forms and functional groups in their life-cycles (Silvertown et al 1993;Grime 2002) but to date there are only a few comparative studies that explicitly focused on lifecycle differences among congeneric species (Newell et al 1981;Solbrig et al 1980Solbrig et al , 1988Svensson et al 1993;Tolvanen et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Variation in life-cycle between three rare and endangered floodplain violets in two regions: implications for population viability and conservation

2009

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Abstract:We studied the demography of Viola elatior, V. pumila, and V. stagnina, three rare and endangered Central European floodplain species, to (i) analyse variation in life-cycles among congeners and between regions (Dyje-Morava floodplains, Czech Republic; Upper Rhine, Germany), (ii) to define sensitive stages in the life-cycles, and (iii) to identify possible threats for population viability and species conservation. Matrix models were based on the fate of marked individuals from a total of 27 populations over two years. We analysed population growth rate (λ), stage distribution, net reproductive rate (R0), generation time, age at first reproduction, and elasticity and calculated a life table response experiment (LTRE). Most populations were declining and λ did not differ between species or regions during the observed interval. Despite higher probabilities for survival and flowering in the Dyje populations, R0 was higher in the Rhine populations. Also other demographic traits showed consistent differences between regions and/or species. Complex life-cycles and large variation in λ precluded unequivocal identification of sensitive stages or vital rates for conservation. Variation between regions may be a consequence of differences in habitat quality. Our results suggest that deterministic processes such as reduced management, succession, habitat destruction, and lack of disturbance through reduced or eliminated flooding present the strongest threat for the viability and persistence of populations of the three floodplain violets as compared with stochastic processes. However, the persistent seed bank of the species may buffer populations against environmental variation and represents a reservoir for recovery after resumption of suitable land-use management.

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Studies on the Population Biology of the Genus Viola: III. The Demography of Viola Blanda and Viola Pallens

Cited by 45 publications

References 17 publications

Shoot population dynamics of persisting clones of Miscanthus sinensis in the warm-temperate region of Japan

Shoot population dynamics of persisting clones of Miscanthus sinensis in the warm-temperate region of Japan

Seedlings

Variation in life-cycle between three rare and endangered floodplain violets in two regions: implications for population viability and conservation

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