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Relevant bibliographies by topics / Seedling population

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Academic literature on the topic 'Seedling population'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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Journal articles on the topic "Seedling population"

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El-Keblawy, Ali, K. H. Shaltout, J. Lovett-Doust, and A. Ramadan. "Population dynamics of an Egyptian desert shrub, Thymelaea hirsuta." Canadian Journal of Botany 75, no. 12 (1997): 2027–37. http://dx.doi.org/10.1139/b97-914.

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Natural populations of the evergreen shrub, Thymelaea hirsuta (L.) Endl., were studied over 6 years at five desert habitats, in terms of seedling recruitment and adult survival and as a function of plant size and gender class. Habitat and time significantly influenced mortality of both reproductive and non-reproductive plants. Plant size also significantly affected adult mortality. Seedling recruitment varied significantly with habitat and year and approached zero some years. Significant among-year and among-population variation in population growth rates were observed over the 6 years of study, and all populations declined in size (ranging from −1.7% per year at the coastal dune site to −10.9% per year at the inland plateau site). Spearman rank correlation analysis between habitats ranked according to a north–south gradient and demographic variables indicates that this gradient is associated with a pattern of lower seedling emergence and survival and a lower population growth rate and greater mortality for all size-classes of Thymelaea plants. In experimental botanic garden plots, germination of seed collected from five natural populations, and seedling survival in the following year were assessed under conditions of high, medium, and low seedling density. Seedling emergency differed significantly according to maternal habitat. With regular watering, seeding survival to one year was 72% (averaged across habitats and densities). This compares with 64% for seedlings grown at the highest density, suggesting that the intense mortality observed under field conditions is more likely to be a result of water shortage than intraspecific competition. Key words: Egyptian desert, Thymelaea hirsuta, germination and establishment, seedlings, recruitment, competition, population growth rate.

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Mellish and B. Coulman, A. "Seed weight, emergence and seedling vigour of four tetraploid crested wheatgrass populations." Canadian Journal of Plant Science 83, no. 1 (2003): 69–70. http://dx.doi.org/10.4141/p01-119.

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This study compared the seed weight, and seedling emergence vigor of four tetraploid crested wheatgrass populations. S9240H, a population selected for seed size, had larger seeds than the cultivars Kirk and CD-II. Heavy seeds had greater emergence and heavier seedlings than light seeds, but there were no differences in these characters among the four populations. Key words: Crested wheatgrass, seed size, seedling vigour

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Windyarini, Eritrina, and Tri Maria Hasnah. "Identification and Seedlings Growth Evaluation of Shorea Species-Producing Tengkawang." Jurnal Wasian 2, no. 1 (2015): 33. http://dx.doi.org/10.20886/jwas.v2i1.868.

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Most of non timber forest product (NTFP) utilization taken from natural forests which decrease on productivity annually, including tengkawang producer species which taken from West Kalimantan natural forests. This condition needs an effort to preserve those species from natural population utilization through plantation forest development that require spesific strategy. This study was part of breeding strategy of shorea species producing tengkawang which aimed to species identify and seedling growth evaluation used genetic material from 2 (two) population from West Kalimantan. The research was arranged in 2 (two) steps, i.e.1) species identification used morphology characteristic difference, and 2) seedling growth evaluation (height,diameter,sturdiness). Seedling growth evaluation was arranged in RCBD, with 5 plot (combination of species and source population), contained 25 seedlings and 4 replications (blocks). The result showed that seedlings of shorea species producing tengkawang, i.e. S.stenoptera, S.macrophylla, and S.gysbertsiana can be different from its stipulae morphology characteristic. Growth of 10 months shorea species producing tengkawang seedlings were significantly different on height and sturdiness. Seedlings height were 67,19 – 88,79 cm, seedlings diameter 9,65 – 10,33 mm and sturdiness 7 – 9,21 in range. The best seedling growth was S.stenoptera and S.macrophylla from Gunung Bunga, West Kalimantan.

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de Steven, Diane. "Tropical tree seedling dynamics: recruitment patterns and their population consequences for three canopy species in Panama." Journal of Tropical Ecology 10, no. 3 (1994): 369–83. http://dx.doi.org/10.1017/s0266467400008038.

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ABSTRACTA study of seedling demography of three shade-tolerant canopy tree species (Quararibea asterolepis, Trichilia tuberculata, and Tetragastris panamensis) was initiated to integrate with long-term studies of tree fruit production and of tree population dynamics on Barro Colorado Island, Panama. Over a five-year period, all seedlings (height <50 cm) and small saplings (height ≥50 cm to dbh 1 cm) were measured and monitored in permanent tree-centred transects (N = 10–11 trees per species). Survival rates increased with plant size class and were similar among species. Maximum height growth rates increased with increasing plant size, but average growth rates did not; this disparity suggests the importance of release from understorey suppression for long-term recruitment success. Among the three species, Quararibea had the lowest standing seedling densities and almost no sapling recruitment, whereas Tetragastris had the highest densities of both seedlings and saplings; Trichilia seedling and sapling densities were intermediate. In all three species, a few trees produced very high seedling and sapling densities in comparison with the sample average. All three species exhibited a year of exceptionally high new seedling recruitment during the study period; these good years were not coincident among the species but instead reflected the species' phenological differences. Since seedling survival becomes relatively constant and high after the first few years of life (c. 80% y−1), such large new cohorts persist as a year-class effect in the seedling population and thus maintain seedling numbers over time. The interspecific differences in seedling and sapling dynamics were consistent with overall 10-year trends of a declining Quararibea population, a stable Trichilia population, and an increasing Tetragastris population.

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Kelman, W. M., and R. A. Culvenor. "Seed dispersal and seedling recruitment in Phalaris aquatica populations developed by divergent selection for panicle shattering and seed retention." Australian Journal of Agricultural Research 58, no. 7 (2007): 719. http://dx.doi.org/10.1071/ar06383.

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Phalaris (Phalaris aquatica L.) is a valuable perennial grass for grazing and land-care purposes in south-eastern Australia. Population survival is predominantly by clonal spread, whereas seedling recruitment is limited by low longevity in the seedbank, ant seed harvesting, and competition from other species. We examined the possibility that breeding and selection could alter the seed dispersal pattern of phalaris, and that this change would result in an increase in seedling recruitment under reduced competition created by grazing. Using 3 phalaris populations with contrasting degrees of panicle shattering and seed retention, and the commercial cultivar, Holdfast, seed dispersal, seedling emergence, and plant establishment were followed over 3 years at a field site near Canberra, ACT. In 2 of the years, half the experimental area was grazed intensively by sheep for a 4-day period after seed dispersal in early autumn. Consistent differences in the timing of seed dispersal were demonstrated between the early, free seed dispersal of the panicle shattering/non-seed-retaining population and the more prolonged seed dispersal of the seed-retaining populations. The 2 seed-retaining populations had greater seedling emergence and recruitment than cv. Holdfast, but did not attain emergence or recruitment levels of the non-seed-retaining population, possibly because of poorer seed–soil contact. Averaged over populations, more seedlings emerged in the grazed than in the ungrazed area, but the number of established plants at the end of the experiment was similar in the 2 areas. Emerged seedlings were 1–2% of the seed rain in each season, but the proportion of established plants at the end of the third season was less than 0.1% of the seed rain in the third season and 3–5% of the number of seedlings that emerged in the 2 previous years. Final recruitment levels were 1–4 established plants/m2. The study confirmed that selection in phalaris populations can produce plants with a more prolonged seed dispersal period, and thus greater potential for seedling recruitment than current seed-retaining cultivars The work suggested that recruitment, while low, has a potential role in the persistence of phalaris pastures, but management of the established pasture base remains the most effective means of maintaining population persistence under commercial grazing.

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., SUDARMONO. "Decreased populations of Scutellaria discolor and Plectranthus galeatus (Lamiaceae) on Mount Gede, West Java, Indonesian and its surrounding." Biodiversitas Journal of Biological Diversity 19, no. 5 (2018): 1866–70. http://dx.doi.org/10.13057/biodiv/d190538.

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Sudarmono. 2018. Decreased populations of Scutellaria discolor and Plectranthus galeatus (Lamiaceae) on Mount Gede, West Java, Indonesian and its surrounding. Biodiversitas 19: 1866-1870. Scutellaria discolor Colebr. and Plectranthus galeatus Vahl. are herbs belonging to mint family (Lamiaceae) which have the potential to be used for medicinal purposes. However, their population is gradually declining. The population of the two species are now only found in the mountains or highlands or the edges of the forests that are still protected, i.e. Mount Gede and Telaga Warna protected forest. This research aimed to know the condition of parent and seedling population of Scutellaria discolor Colebr and Plectranthus galeatus Vahl. on Mount Gede and Telaga Warna vicinities, West Java Province, Indonesia. The research method used was parallel transect lines. Association of the existing plants in the vicinity of the area were also observed. In Mount Gede at altitudes about 1200 m above sea level there are 203 seedlings and 167 parents of S. discolor species, while there are 69 seedlings and 11 parents of P. galeatus. This is higher than the populations of 1100 m altitude, i.e. there are 76 seedlings and 45 parents of S. discolor and 12 seedlings and 9 parents of P galeatus. In Telaga Warna, S. discolor exist only at altitudes about 1500 m asl., i.e.. 47 seedlings and 52 parents. While for P. galeatus, there are 37 seedlings and 31 parents at altitudes about 1500 m. At altitude below 1400 m, there are 18 seedlings and 8 parents, this is very rare. Populations of S. discolor and P. galeatus in Mount Gede at an altitude between 1100-1300 m asl is a balance between the seedlings and its parent population which is the same for seedling populations of S. discolor in Telaga Warna at an altitude of 1400-1500 m asl, but for P. galeatus seedling number decreases from an altitude of 1400 to 1500 m asl.

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Watson, RJ, PY Ladiges, and AR Griffin. "Variation in Eucalyptus cypellocarpa L. Johnson in Victoria, and a new taxon form the Grampian Ranges and Anglesea." Brunonia 10, no. 2 (1987): 159. http://dx.doi.org/10.1071/bru9870159.

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Patterns of variation in adult and seedling morphology, seedling growth and root/shoot ratios were assessed for populations of E. cypellocarpa, E. goniocalyx and equivocal populations from the Grampian Ranges and Anglesea. F1 hybrids of the two species were also produced to assist evaluation of a previous hypothesis of phantom hybrid origin. The Grampians populations were similar to E. cypellocarpa in adult morphology, but had distinctly different seedlings that were not the same as the F1 hybrids. The Anglesea population, although intermediate between E. cypellocarpa and E. goniocalyx in some adult characters, had the same seedling form, including root/shoot ratio, and the same bark type as the Grampians populations. The study provided no evidence to support the hypothesis of a phantom hybrid origin for the Grampians and Anglesea forms. A more parsimonious interpretation is evolution by the splitting of an ancestral taxon. The Grampians and Anglesea populations are described as E. alaticaulis sp. nov., with minor population variation being interpreted as a result of geographic disjunction.

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Coyle, David R., William J. Mattson, Alexander L. Friend, and Kenneth F. Raffa. "Effects of an invasive herbivore at the single plant scale do not extend to population-scale seedling dynamics." Canadian Journal of Forest Research 44, no. 1 (2014): 8–16. http://dx.doi.org/10.1139/cjfr-2013-0307.

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A complex of nine invasive weevils has established in the northern hardwood forests of the Great Lakes Region. These weevils have become the numerically dominant arthropod fauna in the lower vegetation strata of this ecosystem. Effects of these folivorous adults and rhizophagous larvae on seedling survival and density are unknown. We measured the impact of adult weevil defoliation on individual sugar maple (Acer saccharum Marshall) seedlings, the numerically dominant flora in these stands. Over 14 500 seedlings were measured to examine the effects of larval abundance, adult abundance, and adult defoliation on seedling dynamics during 2005–2009. Heavy defoliation led to individual sugar maple seedling mortality. However, at the stand level there was no measureable net effect of invasive weevils against the high natural background rates of seedling mortality. Seedling growth and biomass were reduced by high adult or larval populations, which were associated with heavy leaf and root herbivory, but not by moderate adult or larval populations. We conclude that high levels of redundancy and compensatory processes in this environment allow sugar maple seedling populations to tolerate high levels of weevil damage, although additional stresses could reduce this resilience.

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Lodder, MS, RH Groves, and WJ Muller. "Early Seedling Growth of Three Species of Danthonia as Affected by Depth of Sowing and Nutrient Supply." Australian Journal of Botany 42, no. 5 (1994): 543. http://dx.doi.org/10.1071/bt9940543.

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In an experiment in a controlled environment, seedling emergence of three species of Danthonia (D. linkii var. fulva, D. tenuior and D. richardsonii) was measured in response to sowing depth. Seedlings of all three species did not emerge if seeds were buried deeper than 25 mm. At lesser depths, D. linkii var. fulva showed greatest tolerance to increasing sowing depth, whilst D. tenuior was intermediate and D. richardsonii was least tolerant of seed burial. In a separate experiment, seedlings of Danthonia linkii var. fulva and two geographically distinct populations of D. richardsonii emerged earlier, grew faster and had a higher biomass than those of D. tenuior in response to nutrient supply. The latter population grew more slowly than the others, but by day 54, the number of emergents of D. tenuior had equalled those of the other populations. Nutrient addition had little effect on seedling development, except that by day 54, four times normal nutrient level reduced root growth in all four populations. No population by nutrient interactions were found for either time to emergence or for seedling biomass up to 54 days from sowing. Increases in shoot biomass and the reversal of shoot to root ratios occurred between 41 and 54 days after sowing, by which time seedling establishment of Danthonia was complete. Some practical recommendations for field sowings are given based on the results of this and other studies.

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Cvjetkovic, Branislav, Milan Mataruga, Mirjana Sijacic-Nikolic, Vojislav Dukic, and Vladan Popovic. "Variability of Norway spruce morphometric characteristics in progeny tests in Bosnia and Herzegovina." Bulletin of the Faculty of Forestry, no. 113 (2016): 11–34. http://dx.doi.org/10.2298/gsf1613011c.

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The paper presents the results of an analysis of morphometric characteristics of Norway spruce seedlings in the progeny tests in Bosnia and Herzegovina, localities: Drinic and Srebrenica. Progeny tests were established by using seedlings originating from six natural populations from Bosnia and Herzegovina. Seedling height, root collar and whorl distance from the ground, which represents seedling heights in 2011, 2012 and 2013 were measured. The results indicate statistically significant differences between the analyzed characteristics of the observed population. Especially interesting are the populations Potoci and Olovo, which showed the highest growth during the observed period in both progeny tests. The impact of the drought in 2013 can be seen in the progeny test in Srebrenica where height growth in 2013 was lower by more than 50% in comparison to 2012. The impact of drought in the progeny test in Drinic was not observed. The research provides the baseline when selecting the starting population, where the rapid growth of seedlings is set as the main goal.

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Dissertations / Theses on the topic "Seedling population"

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Cordazzo, Cesar Vieira. "Comparative population studies of four dominant plants of southern Brazilian coastal dunes." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241475.

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Lukic, Veronika. "Examination of physiological and morphological parameters of a population of lodgepole pine, Pinus contorta Dougl. spp. latifolia, seedling roots in relation to first year seedling growth." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/mq22629.pdf.

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小川, 一治, and Kazuharu OGAWA. "Analysis of leaf arrangement and light penetration in a Japanese cypress seedling population by the point quadrat method." 名古屋大学農学部付属演習林, 1987. http://hdl.handle.net/2237/8665.

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Piechowski, Daniel. "Reproductive ecology, seedling performance, and population structure of Parkia pendula in an Atlantic forest fragment in Northeastern Brazil." [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-60306.

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Vidaller, Christel. "Quels facteurs limitent l’installation de Brachypodium retusum : une espèces clé pour la restauration écologique des steppes méditerranéennes ?" Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0349/document.

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Le brachypode rameux (Brachypodium retusum) est une espèce herbacée pérenne qui domine les pelouses sèches de Méditerranée occidentale. Dans notre zone d’étude du Sud de la France, la recolonisation spontanée est très faible après perturbation du sol. Cette observation ne correspond pas aux résultats d'études menées dans d'autres régions montrant une capacité de colonisation élevée. L'objectif principal de cette thèse était donc de tester les différentes hypothèses pouvant expliquer les différents patrons de colonisation.Dans un premier chapitre, nous avons testé si ces différents patrons de colonisation résultent d'une différenciation génétique entre les populations. Des marqueurs AFLP ont été utilisés pour analyser la structure génétique de 17 populations de Méditerranée occidentale dont la différenciation neutre entre populations. Dans un sous-échantillon de 13 populations françaises, la différenciation de traits phénotypiques sous sélection a été testée dans un jardin commun et comparée à la différenciation neutre. Dans le deuxième chapitre, nous présentons une étude sur la différenciation adaptative des traits phénotypiques et avons testé une potentielle réponse différentielle à la manipulation de facteurs environnementaux clés. Les deux derniers chapitres de la thèse ont analysé les facteurs environnementaux qui limitent la recolonisation in situ, indépendamment du génotype ou de la population. Dans le troisième chapitre, nous avons testé l’effet du pâturage et du feu sur le recouvrement végétatif ainsi que sur la reproduction sexuée de B. retusum installé. Enfin, dans le quatrième chapitre, nous avons mesuré l’effet de l’arrosage initial et du pâturage sur l’installation de plantules transplantées initialement germées en serre et de plantules issues de semis in situ. Nos résultats ont montré que les populations de B. retusum sont génétiquement différenciées pour les marqueurs neutres mais également pour les traits phénotypiques. Cette différenciation est supérieure à la dérive seule et suggère une adaptation aux conditions environnementales, en particulier aux températures estivales et à la fréquence du gel en hiver. Une réponse différentielle à la manipulation expérimentale de facteurs environnementaux (sol, pâturage, humidité du sol) a confirmé le caractère adaptatif de la différenciation génétique. Les expériences in situ ont montré que le feu a un effet positif sur la reproduction de B. retusum et sur la communauté végétale associée, alors que son recouvrement végétatif n’était pas supérieur à la moyenne de la communauté. L'exclusion du pâturage pendant deux saisons n'a eu d'incidence sur aucun des paramètres mesurés chez les populations adultes. L'arrosage initial a affecté l’installation des plantules au cours de la première saison. Au cours de la deuxième saison, l'effet seul de l’arrosage n'était pas significatif, cependant son effet est resté positif sur la survie uniquement dans les parcelles pâturées. Le pâturage, au début du cycle de vie de B. retusum, a eu un effet négatif sur le recrutement et la croissance des plantules. En conclusion, la différenciation adaptative entre les populations peut avoir contribué aux différences régionales en termes de capacité de colonisation et doit être prise en compte lors du ciblage des populations sources pour l'introduction de plantes en restauration écologique. La réponse positive de B. retusum a indiqué que le feu était une force sélective importante dans le passé qui pourrait être utilisée pour favoriser l'espèce et la communauté végétale associée dans des opérations de conservation et de restauration. L'exclusion du pâturage à court terme est tolérée par les populations adultes de B. retusum, mais l'abandon à long terme entraîne une diminution de son recouvrement par rapport aux graminées pérennes à croissance rapide<br>Ramose false brome (Brachypodium retusum) is a perennial herbaceous species that dominates dry grasslands of the Western Mediterranean. In our southern French study area, spontaneous re-colonisation is very low after soil disturbance. This observation does not correspond to the results of studies from other regions showing a high colonisation capacity. The major objective of this PhD thesis was to test different hypotheses potentially explaining the different colonisation patterns.In the first chapter, we tested whether these different colonisation patterns are the result of genetic differentiation among populations. AFLP markers were used to analyse genetic structure including neutral population differentiation in 17 Western Mediterranean populations. In a sub-sample of 13 French populations, differentiation in phenotypic traits under selection was tested in a common garden and compared to neutral differentiation. In the second chapter, we present a study on adaptive differentiation in phenotypic traits testing a potentially differential response to the manipulation of key environmental factors. The last two chapters of the PhD analysed environmental factors that limit re-colonisation in the field independent of genotype or population. In the third chapter, we tested the effect of grazing and fire on vegetative recovery as well as on sexual reproduction of established B. retusum and in the fourth chapter we measured the effect of initial watering and grazing on the establishment of transplanted seedlings pre-grown in a greenhouse and of field-sown seedlings.Our results showed that populations of B. retusum are genetically differentiated in neutral markers but also in phenotypic traits. This differentiation is superior to drift alone and suggests adaptation to environmental conditions, particularly to summer temperature and winter frost frequency. A differential response to experimental manipulation of environmental factors (soil, pasture, soil moisture) confirmed the adaptive character of genetic differentiation. The field experiments showed that fire has a positive effect on B. retusum reproduction and on the associated community whereas vegetative recovery was not higher than community average. Two seasons of grazing exclosure did not affect any of the measured parameters in adult populations. Initial watering affected seedling establishment in the first season. In the second season, the watering main effect was not significant but interestingly the effect remained positive on survival in grazed plots whereas no such effect was observed in exclosures. Grazing in early life cycle stages of B. retusum had a negative effect on seedling recruitment and growth.In conclusion, adaptive differentiation between populations may have contributed to regional differences in colonisation capacity and needs to be taken into account in targeting source populations for plant introduction in ecological restoration. The positive response of B. retusum indicated that fire was an important selective force in the past which may be used to favour the species and its associated plant community in current conservation and restoration management. Short-term grazing exclosure is tolerated by mature B. retusum populations but long-term abandonment results in a decrease of cover relative to high-growing perennial grasses. In early stages of seedling establishment grazing should be avoided to guarantee introduction success - or grazing stress needs to be compensated by watering

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Mogollones, Barrera Sol C. "Seed dispersal, seedling emergence and bird community structure in a human-modified landscape mosaic in Sri Lanka." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=202126.

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Németh, M. Barbara. "Pollen Performance and Seedling Vigor in Laboratory and Natural Populations of Clarkia Unguiculata (Onagraceae)." Miami University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=miami1117816212.

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Alzérreca-Angelo, Humberto. "Spatial and Temporal Dynamics of Plant Populations in Salt-Desert Shrub Vegetation Grazed by Sheep." DigitalCommons@USU, 1996. https://digitalcommons.usu.edu/etd/4661.

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I studied the effect of moderate sheep grazing on a shadscale plant community at the Desert Experimental Range, southwestern Utah, USA, using a 61-yr data set with two grazing treatments (yes vs. no), two seasons (spring vs. winter), and two soil types (loamy-skeletal vs. coarse-loamy). I studied precipitation, total species cover, annuals, shrub survival, seedling recruitment, plant succession, and plant spatial relationships./p> Precipitation showed high variability (CV=31%) masking on short-term cycles, resulting in study intervals with average (1935-58), dry (1958-69), driest (1969-75), and wet (1980-94[5]) regimes. Total cover in both grazed and ungrazed pastures increased between 1935 and 1975 before decreasing to 1994. Treatments diverged with time, however, so cover was higher in ungrazed pastures in 1975 and 1994. Individually, Atriplex confertifolia decreased from 1958-94 and Ceratoides lanata from 1975-94. Artemisia spinescens increased in ungrazed pastures from 1935-94, while remaining very low in grazed pastures. Grasses increased from 1935-94 with little grazing effects. Annuals increased from absence in 1935 to 63% frequency in 1994; precipitation may be related to this increase. Grazing and soil type had few long-term or short effects on shrub survival. Similarly, only C. lanata showed a microhabitat effect, with greater seedling survival in vegetated than open patches. Seedling recruitment was positively correlated with precipitation. Only A. confertifolia recruitment responded to grazing; it was higher in grazed pastures. A fuzzy graph analysis showed a moderate grazing effect on succession. Clumped distributions were common and were unaffected by grazing but increased in wet years. Plant establishment occurred disproportionally in sites occupied or formerly occupied by plants, suggesting facilitation. Negative interference, however, was suggested by new recruitment occurring further from larger existing individuals. Moderate grazing had little effect on spatial relationships. In conclusion, the multivariate approach yielded broader conclusions than any individual factors. Although some factors showed more grazing effects than others, grazing could not completely explain observed changes; climate and inherent plant attributes must also be considered. Management at moderate grazing levels may only play a limited role in shadscale communities.

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Still, Margaret Jean. "Population dynamics and spatial patterns of Dipterocarp seedlings in a tropical rain forest." Thesis, University of Stirling, 1993. http://hdl.handle.net/1893/26682.

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Population dynamics and spatial pattern of dipterocarp seedlings were investigated in lowland dipterocarp forest in Danum Valley Conservation Area, Sabah, East Malaysia. Seedlings (< 10 cm gbh) were enumerated in two areas (2.0 and 0.48 ha) within the tree enumeration plots established by the University of Stirling project, and surveyed over 22 months. Seedlings of the major canopy and emergent dipterocarps in the area were common: Shorea johorensis (Red Meranti); S. argentifolia, S. leprosula, S. parvifolia (Light Red Merantis, LRM) and Parashorea maleanonan, all light demanding species; S. fallax,S. pauciflora (Dark Red Meranti, DRM), more shade tolerant emergent species; and Hopea nervosa, Vatica dulitensis and V. sarawakensis, shade tolerant canopy species. Total seedling densities were 2000-2500 ha-1. Mortality rates varied from 0 to 16% yr-1 in different species, and were highest in the LRMs and lowest in the canopy species. Temporal and spatial variation in mortality rates was greatest in the LRMs. In both plots, seedling mortality rates were significantly positively correlated with basal area of conspecific trees ≥10cm gbh. Net growth rates were very variable, even within size classes in the same species. Median growth rates were highest in the LRMs and lowest in canopy species. Frequency distributions of growth rates were strongly leptokurtic in slow-growing species, with most seedlings having growth rates around zero, although individual seedlings could produce large increments. In fast-growing species, more seedlings achieved high growth rates. A significant proportion of seedlings suffered height loss due to falling debris, and almost half the seedlings showed evidence of previous stem damage. Large growth increments were recorded in most species in response to canopy openings, usually very small gaps caused by branch falls. Individual increments exceeded 1 m yr-1 in seven species. Growth and mortality rates were significantly positively correlated across species in Plot 1, but not in Plot 2. Seedling spatial patterns were examined in eleven species in Plot 1, and covered a wide range of degrees of aggregation. Seedlings of the light-demanding emergent species were we1l-distributed throughout the study area, though some showed aggregation at a small scale. DRM seedlings were strongly clumped around adult trees. Seedlings of two of the canopy species were very strongly aggregated around adult trees, while the third species, V. sarawakensis, had randomly distributed seedlings.

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Ates, Serkan. "Grazing management of subterranean clover (Trifolium subterraneum L.) in South Island (New Zealand)." Diss., Lincoln University, 2009. http://hdl.handle.net/10182/1338.

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This study consisted of two sheep grazed dryland pasture experiments. Experiment l compared sheep production from 3-year-old cocksfoot based pastures grown in combination with white, Caucasian, subterranean or balansa clover with a ryegrass-white clover pasture and a pure lucerne forage. Sheep liveweight gain per head from each pasture treatment and the pure lucerne stand was recorded in the 2006/07 and 2007/08 seasons. The cocksfoot-subterranean clover pasture provided equal (381 kg LW/ha in 2006) or higher (476 kg LW/ha in 2007) animal production in spring and gave the highest total animal production (646 kg LW/ha) averaged across years of the five grass based pastures. However, total annual liveweight production from lucerne was higher than any grass based pasture mainly due to superior animal production during summer when lucerne provided 42-85% higher animal production than any of the grass based pastures. In Experiment 2, the effect of stocking rate (8.3 (low) and 13.9 (high) ewes + twin lambs/ha) and time of closing in spring on lamb liveweight gain, pasture production and subterranean clover seedling populations was monitored over 2 years for a dryland cocksfoot-subterranean clover and ryegrass-subterranean clover pasture in Canterbury. In both years, twin lambs grew faster (g/head/d) in spring at low (327; 385) than high (253; 285) stocking rate but total liveweight gain/ha (kg/ha/d) was greater at high (7.26; 7.91) than low (5.43; 6.38) stocking rate. Ewes also gained 0.5 and 1.5 kg/head at the low stocking rate in 2006 and 2007 respectively but lost 0.2 kg/head in 2006 and gained 0.3 kg/head at high stocking rate in 2007. Mean subterranean clover seedling populations (per m²) measured in autumn after grazing treatments in the first spring were similar at both low (2850) and high (2500) stocking rate but declined with later closing dates in spring (3850, 2950, 2100 and 1700 at 2, 4, 6, 8 weeks after first visible flower). Seedling populations measured in autumn after grazing treatments in the second spring were also unaffected by stocking rate (low 1290, high 1190) but declined with later closing dates in spring (1470, 1320 and 940 at 3, 5 and 8 weeks after first flowering, respectively). The effect of stocking rate and closing dates in spring on pasture and clover production in the following autumn was similar to the effects on seedling numbers in both years. However, clover production in the following spring was unaffected by stocking rate or closing date in the previous year at the relatively high seedling populations generated by the treatments. This was presumably due to runner growth compensating for lower plant populations in pastures that were closed later in spring. Subterranean clover runner growth in spring may not compensate in a similar manner if seedling numbers in autumn fall below 500/m². Mean annual dry matter production from cocksfoot and ryegrass pastures grown with and without annual clovers pasture production ranged from 6.4 to 12.4 t DM/ha/y but stocking rate (8.3 vs. 13.9 ewes/ha) during spring did not affect annual pasture production. Pastures overdrilled with annual clovers yielded 23-45% more dry matter production than pastures grown without annual clovers. The study confirms the important role of subterranean clover in improving pasture production and liveweight gains of sheep in dryland cocksfoot and ryegrass pastures. Lowering stocking rate from 13.9 to 8.3 ewes/ha was a less effective method of increasing seed production of subterranean clover in dryland pastures although it did lead to increased liveweight gain per head.

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Books on the topic "Seedling population"

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James, Robert L. Effects of preplant soil treatments on Fusarium and Trichoderma populations and fungal root colonization of 2-0 nondiseased western white pine seedlings - USDA Forest Service Nursery, Coeur d'Alene, Idaho. U.S. Dept. of Agriculture, Forest Service, Northern Region, 2002.

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Smith, Julia P. Differential growth of roots and shoots of Douglas-fir (Pseudotsuga menziesii) seedlings infested with Cinara pseudotsugae, and population dynamics of a parasitoid wasp (Pauesia sp.) of C. pseudotsugae. 1997.

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Book chapters on the topic "Seedling population"

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Williams, Martin M., Gerhards Roland, S. Reichart, David A. Mortensen, and Alex R. Martin. "Weed Seedling Population Responses to a Method of Site-Specific Weed Management." In Proceedings of the Fourth International Conference on Precision Agriculture. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, 2015. http://dx.doi.org/10.2134/1999.precisionagproc4.c11.

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Hanke, Viola. "Selection in seedling populations and clonal progenies of strawberry (Fragaria ananassa Duch.)." In Developments in Plant Breeding. Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0467-8_39.

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Huston, Michael A., Milena Holmgren, and Michelle B. Kreh. "Response of Understory Tree Seedling Populations to Spatiotemporal Variation in Soil Moisture." In Ecological Studies. Springer New York, 2003. http://dx.doi.org/10.1007/978-1-4613-0021-2_14.

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Yahya, Yasmin, and Roslan Ismail. "Randomized Technique to Determine the New Seedlings for Simulation of Population Dynamic." In Advances in Intelligent Systems and Computing. Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-19063-7_57.

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Wiles, L. J., and E. E. Schweizer. "Mapping Weed Populations: The Cost of Counting and Identifying Seedlings and Seeds." In Proceedings of the Fourth International Conference on Precision Agriculture. American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, 2015. http://dx.doi.org/10.2134/1999.precisionagproc4.c44.

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Wekesa, Chemuku, Leila Ndalilo, and Carolyne Manya. "Reconciling Community Livelihood Needs and Biodiversity Conservation in Taita Hills Forests for Improved Livelihoods and Transformational Management of the Landscape." In Fostering Transformative Change for Sustainability in the Context of Socio-Ecological Production Landscapes and Seascapes (SEPLS). Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6761-6_2.

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AbstractThe fragmented forests of Taita Hills form an exceptional multi-functional socio-ecological production landscape with outstanding diversity of flora and fauna that provide ecosystem goods and services supporting human wellbeing and livelihood systems. However, these forests are threatened by illegal logging for wood products and encroachment for crop farming. A study was conducted in villages surrounding five forest fragments to establish the conservation programmes responsible for keeping these forests intact for provision of goods and services to the local communities. Semi-structured questionnaires were used to collect data from 250 respondents in 25 villages surrounding the five forest fragments. Twenty-five focus group discussions (FGDs) were held with key informants actively involved in conservation activities. Results showed that the Taita community conserves the forest fragments through management practices that integrate livelihood needs in conservation, such as butterfly farming, bee-keeping and ecotourism. Additionally, community tree nurseries have been established to produce seedlings for restoring degraded areas, and agroforestry belts have been established on the forests’ edges to provide wood products and protect the forests from encroachment. Likewise, village committees have been established to oversee conservation activities inside the village jurisdictional area. The integrated conservation and livelihood approach has reduced forest destruction, enhanced landscape connectivity for biodiversity conservation, increased incomes, enhanced capacity of the community to adapt to climate change, improved food security, enhanced carbon storage, strengthened traditional knowledge and practices, and ensured availability of clean water for the local population.

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Cheplick, G. P. "Seed dispersal and seedling establishment in grass populations." In Population Biology of Grasses. Cambridge University Press, 1998. http://dx.doi.org/10.1017/cbo9780511525445.005.

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Bryant, John P., and Roger W. Ruess. "Mammalian Herbivory, Ecosystem Engineering, and Ecological Cascades in Alaskan Boreal Forests." In Alaska's Changing Boreal Forest. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195154313.003.0019.

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The mammalian herbivores of the taiga forests include members of the largest (moose) and smallest (microtines) vertebrates that inhabit North American terrestrial biomes. Their abundance in a particular area fluctuates dramatically due to seasonal use of particular habitats (moose) and external factors that influence demographic processes (microtines). The low visibility of herbivores to the casual observer might suggest that these animals have minimal influence on the structure and the function of boreal forests. On the contrary, seedling herbivory by voles, leaf stripping by moose, or wholesale logging of mature trees by beaver can profoundly change forest structure and functioning. These plant-herbivore interactions have cascading effects on the physical, chemical, and biological components of the boreal ecosystem that shape the magnitude and direction of many physicochemical and biological processes. These processes, in turn, control the vertical and horizontal interactions of the biological community at large. Herbivores act as ecosystem engineers (Jones et al. 1994) in that they reshape the physical characteristics of the habitat, modify the resource array and population ecology of sympatric species, and influence the flux of energy and nutrients through soils and vegetation. Additionally, many herbivores are central to a variety of human activities. Both consumptive and nonconsumptive use of wildlife represents a pervasive aspect of life in the North. In this chapter, we examine the interactions of mammalian herbivores with their environment, with an emphasis on moose, and attempt to delineate the biotic and abiotic conditions under which herbivores influence the phenotypic expression of vegetation. We also examine the role of herbivores, and of wildlife in general, in the context of human perceptions and interactions with their environment. Human-environment interactions are both direct and indirect and pertain to a variety of social expressions. The relationship between humans and wildlife has economic, cultural, and psychological dimensions, which underscore the importance of these animals in a broader social, as well as ecological, context. Northern ecosystems such as the boreal forest are characterized by extreme seasonality and pronounced change in resource availability between summer and winter. Not surprisingly, these conditions are reflected in the population dynamics of the animals that inhabit these environments, particularly in smaller-bodied herbivores.

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Gloser, Jan. "Impact of Elevated CO2 Concentration on Interactions between Seedlings of Norway Spruce (Picea abies) and a Perennial Grass Calamagrostis epigejos." In Carbon Dioxide, Populations, and Communities. Elsevier, 1996. http://dx.doi.org/10.1016/b978-012420870-4/50053-0.

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Benjamin, L. R. "Variation in Time of Seedling Emergence Within Populations: A Feature that Determines Individual Growth and Development." In Advances in Agronomy Volume 44. Elsevier, 1990. http://dx.doi.org/10.1016/s0065-2113(08)60816-0.

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Conference papers on the topic "Seedling population"

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Liang, Shichu. "Multifractal analysis of seedling population patterns of the mangrove, Avicennia marina (Forssk.) Vierh., in Southern China." In 2011 International Conference on Remote Sensing, Environment and Transportation Engineering (RSETE). IEEE, 2011. http://dx.doi.org/10.1109/rsete.2011.5966156.

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Beletskaia, Ekaterina Iakovlevna, Svetlana Petrovna Chibis, Liudmila Anatolevna Krotova, and Vladimir Aleksandrovich Shelontsev. "The study of chemical compounds influence on morphological and population traits of soft wheat." In All-Russian scientific conference. Publishing house Sreda, 2019. http://dx.doi.org/10.31483/r-32850.

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The paper deals with the use of chemical compounds in soft wheat breeding, the role of induced mutations in plant improvement. The paper presents the effects of fungicides influence on morpho-logical and population traits of soft wheat. Laboratory experiments revealed the effects of disinfect-ants, the concentrations of their active components and the period from treatment to the formation sprouts of soft spring wheat Pavlogradka. The effect of systemic fungicides Comfort, AltSil, Ter-rasil and Alcasar was studied whet applied at recommended dose and greater than twice the normal values. They were compared with control samples without treatment. The sowing qualities of treated seeds were unstable, morphological and population traits of wheat seedlings were not homogeneous.

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Lupascu, Galina, and Svetlana Gavzer. "Considerații cu privire la interacțiunile grâu – patogeni fungi în contextul schimbărilor climatice." In International Scientific Symposium "Plant Protection – Achievements and Prospects". Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2020. http://dx.doi.org/10.53040/9789975347204.06.

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It was established that the environmental conditions strongly influence the fungal spectrum that causes the root rot of the stem base to common wheat in the conditions of the Republic of Moldova. In more severe conditions (high temperature, drought) the incidence of Fusarium equiseti increases. The interaction of common wheat with one of the causative agents of stem rot – F. oxysporum is determined by the combination, the orientation of the cross to obtain F1 hybrids, the temperature factor, which has a direct impact on seedling growth and transgressive potential of F2 segregating populations, a phenomenon with major importance for the improvement programs.

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