نتایج جستجو برای: soil seed bank classification
تعداد نتایج: 795075 فیلتر نتایج به سال:
We identify a new natural coalescent structure, the seed-bank coalescent, which describes the gene genealogy of populations under the influence of a strong seedbank effect, where ‘dormant forms’ of individuals (such as seeds or spores) may jump a significant number of generations before joining the ‘active’ population. Mathematically, our seed-bank coalescent appears as scaling limit in a Wrigh...
Seed banks are a common characteristics to many plant species, 1 which allow storage of genetic diversity in the soil as dormant seeds for various 2 periods of time. We investigate an above-ground population following a Fisher3 Wright model with selection coupled with a deterministic seed bank assuming 4 the length of the seed bank is kept constant and the number of seeds is large. 5 To assess ...
The species composition of grazing lands can be influenced by livestock and grazing pressure. A study on manure seed bank was conducted in Ghinchi highland Research Site in Ethiopia between 1995 and 1997. The data on species composition and life-form of the plants germinating in pots receiving air dried manure were compared with species composition of experimental plots in natural grassland sub...
Few studies have been conducted in annual and perennial forage legumes to investigate the development of hardseededness and the subsequent pattern of seed softening in temperate and subtropical regions of South America. Experiments were conducted during 2007 and 2008 in central Uruguay to follow the pattern of seed softening in 35 annual and perennial forage legumes, including three native spec...
Germination from the soil seed bank (SSB) is an important determinant of species composition in tropical forest gaps, with seed persistence in the SSB allowing trees to recruit even decades after dispersal. The capacity to form a persistent SSB is often associated with physical dormancy, where seed coats are impermeable at the time of dispersal. Germination literature often speculates, without ...
We attempted to confirm that seed banks can be viewed as an important genetic reservoir by testing the hypothesis that standing (aboveground) plants represent a nonrandom sample of the seed bank. We sampled multilocus allozyme genotypes from three species with different life history strategies: Amaranthus retroflexus, Carduus acanthoides, Pastinaca sativa. In four populations of each species we...
Cecropia (Cecropiaceae) is a Neotropical genus of pioneer plants. A review of bat/plant dispersal interactions revealed that 15 species of Cecropia are consumed by 32 species of bats. In French Guiana, bats were captured in primary and secondary forests, yielding 936 fecal samples with diaspores, among which 162 contained fruits of C. obtusa, C. palmata, and C. sciadophylla. A comparative morph...
The fire-prone shrublands of southwestern Australia are renowned for their high plant species diversity and prominence of canopy seed storage (serotiny). We compared species richness, abundance, and life history attributes for soil and canopy seed banks in relation to extant vegetation among four sites with different substrate conditions and high species turnover (50-80%) to identify whether th...
Seed mass in species-rich moist tropical forests often varies over six or more orders of magnitude (Foster, 1982; Foster and Janson, 1985; Hammond and Brown, 1995). Most of these species, including some with the minutest seeds (Metcalfe, 1996; Metcalfe and Grubb, 1997), can be classified as ‘shade-tolerant’ with the ability to establish beneath a closed canopy. Seeds of the shade-tolerators var...
We present a mathematical framework that combines extinction-colonization dynamics with the dynamics of patch succession. We draw an analogy between the epidemiological categorization of individuals (infected, susceptible, latent and resistant) and the patch structure of a spatially heterogeneous landscape (occupied-suitable, empty-suitable, occupied-unsuitable and empty-unsuitable). This appro...
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