scholarly journals Seedling survival declines with increasing conspecific density in a common temperate tree

Ecosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
Author(s):  
Fiona V. Jevon ◽  
Sydne Record ◽  
John Grady ◽  
Ashley K. Lang ◽  
David A. Orwig ◽  
...  
Keyword(s):  
Seedling Survival ◽  
Conspecific Density

scholarly journals Impacts of logging on density-dependent predation of dipterocarp seeds in a South East Asian rainforest

2011 ◽  
Vol 366 (1582) ◽  
pp. 3246-3255 ◽  
Author(s):  
Robert Bagchi ◽  
Christopher D. Philipson ◽  
Eleanor M. Slade ◽  
Andy Hector ◽  
Sam Phillips ◽  
...  
Keyword(s):  
East Asia ◽  
Large Scale ◽  
Species Coexistence ◽  
Seedling Survival ◽  
Spatial Scales ◽  
Small Scale ◽  
South East Asia ◽  
Similar Data ◽  
Neotropical Forests ◽  
Conspecific Density

Much of the forest remaining in South East Asia has been selectively logged. The processes promoting species coexistence may be the key to the recovery and maintenance of diversity in these forests. One such process is the Janzen–Connell mechanism, where specialized natural enemies such as seed predators maintain diversity by inhibiting regeneration near conspecifics. In Neotropical forests, anthropogenic disturbance can disrupt the Janzen–Connell mechanism, but similar data are unavailable for South East Asia. We investigated the effects of conspecific density (two spatial scales) and distance from fruiting trees on seed and seedling survival of the canopy tree Parashorea malaanonan in unlogged and logged forests in Sabah, Malaysia. The production of mature seeds was higher in unlogged forest, perhaps because high adult densities facilitate pollination or satiate pre-dispersal predators. In both forest types, post-dispersal survival was reduced by small-scale (1 m 2 ) conspecific density, but not by proximity to the nearest fruiting tree. Large-scale conspecific density (seeds per fruiting tree) reduced predation, probably by satiating predators. Higher seed production in unlogged forest, in combination with slightly higher survival, meant that recruitment was almost entirely limited to unlogged forest. Thus, while logging might not affect the Janzen–Connell mechanism at this site, it may influence the recruitment of particular species.

scholarly journals Seedling survival responses to conspecific density, soil nutrients, and irradiance vary with age in a tropical forest

Ecology ◽  
2016 ◽  
Vol 97 (9) ◽  
pp. 2406-2415 ◽  
Author(s):  
Sydne Record ◽  
Richard K. Kobe ◽  
Corine F. Vriesendorp ◽  
Andrew O. Finley
Keyword(s):  
Tropical Forest ◽  
Soil Nutrients ◽  
Seedling Survival ◽  
Conspecific Density

scholarly journals Lack of negative density-dependence regulation in a dominant oak tree from a neotropical highland forest

2018 ◽  
Author(s):  
Irene Calderón-Sanou ◽  
Luis Diego Ríos ◽  
Alfredo Cascante-Marín ◽  
Gilbert Barrantes ◽  
Eric J. Fuchs
Keyword(s):  
Costa Rica ◽  
Density Dependence ◽  
Species Coexistence ◽  
Local Density ◽  
Seedling Survival ◽  
Forest Composition ◽  
Adult Density ◽  
Conspecific Density ◽  
Negative Density Dependence ◽  
Highland Forests

AbstractConspecific negative density-dependence(CNDD) is one of the main mechanisms proposed to regulate species coexistence. Tropical highland forests, in contrast to diverse lowland forests, are commonly dominated by a few tree species. Testing the importance of density-dependence effects on seedling establishment of dominant trees may provide insights on the mechanisms regulating population dynamics and forest composition of tropical highlands. We tested the importance of CNDD regulation on seedling survival and recruitment ofQuercus costaricensis, a monodominant oak in the Talamanca highland forests of Costa Rica. We used spatial statistics and generalized linear mixed models to test the effects of conspecific density, distance to the nearest adult, density ofChusqueabamboo shoots, and herbivory on the annual survival probability of 3538 seedlings between 2014 and 2017. We did not find any effect of CNDD on seedling survival. However, bamboo density and herbivory both significantly decreased seedling survival. All seedlings had signs of herbivory and predator satiation may explain the lack of density dependent regulation in this species. We argue that the lack of intraspecific density regulation at the seedling stage may explain the dominance ofQ. costaricensisin the highland forests of Costa Rica. Local density of this endemic oak is instead regulated by herbivory and the density ofChusquea.

Screening of F1 progeny for selection of superior hybrids in mulberry (Morus spp.) - A simple approach PART I: Screening of seedlings in relation to seed size

2017 ◽  
Vol 6 (2) ◽  
pp. 5256
Author(s):  
Daryoush Shafiei ◽  
Prof. Basavaiah*
Keyword(s):  
Seed Size ◽  
Seedling Survival ◽  
Size Class ◽  
Medium Size ◽  
Screening Process ◽  
Size Classes ◽  
Morus Spp ◽  
In The Beginning ◽  
Selection Of ◽  
Size Grading

In mulberry (Morus spp.), the process of selection of promising hybrids from F1 population requires the screening of a large number of progenies and a long period. To develop a simple and faster approach for screening, studies were conducted using F1 seeds of two crosses. The details of screening studies conducted in relation to seed-size and seedling-size are reported separately in two parts. In this part, the F1 seeds were size-graded as small, medium and large seeds; their progenies were raised separately and screened in nursery. There was a considerable degree of variation in size of seeds and medium-size class seeds were in high percentage in both the crosses. The length, width and weight of seeds were also varied between the seed size classes significantly in both the crosses. The seed size classes differ with high significance in shoot length and Root collar diameter and also differ significantly in root length and weight of seedlings. The positive correlation between the seed size and growth of seedlings, seed size and germination, seed size and seedling survival in nursery indicated that size-grading of seeds and rejection of small seeds in the beginning of screening process may help to increase the efficiency of screening by increasing the chances of getting superior hybrids from limited progenies. However, confirmation on the performance of large seedlings from small seed size class may help to draw conclusion. Hence, the studies are continued with size- grading of seedlings in the next part of screening study.

Lethal Dose (LD50) Fixation and Sensitivity of Fenugreek (Trigonellafoenum-graecumL.) to Gamma Radiation for Induction of Mutation

2017 ◽  
Vol 4 (04) ◽  
Author(s):  
ANURADHA PATEL ◽  
POONAM VERMA ◽  
SHARDA CHOUDHARY ◽  
ARVIND KUMAR VERMA
Keyword(s):  
Genetic Variability ◽  
Gamma Rays ◽  
Growth Parameters ◽  
Seedling Survival ◽  
Lethal Dose ◽  
Germination Percentage ◽  
Mutation Breeding ◽  
Vigour Index ◽  
Small Flower ◽  
Dose Dependent

Fenugreek (Trigonella foenum-graecumL.) is an annual crop, mainly used as a spiceand leafy vegetable crop in many parts of the world. Classical breeding in fenugreek is restricted due to its low genetic variability and small flower size which hamper manual emasculation and pollination. Mutation breeding is an effective way to enrich genetic variability in crop plants. An experiment was conducted to determine the lethal dose of the physical mutagen gamma rays in fenugreek. The dry seeds of fenugreek were exposed to different doses of gamma rays i.e. 150Gy, 200Gy, 250Gy, 300Gy and 350Gy. These irradiated seeds were sown in the Petri plates with non-irradiated seeds (control). As the dose of gamma rays increased, there was a decrease in germination percentage, seedling survival, root length, shoot length and vigour index. Among five doses of gamma rays, the maximum seed germination was observed at lowest dose 150Gy (93%), followed by 200Gy (83%), 250Gy (76%), 300Gy (76%) and 350Gy (64%). The seedling survival was decreased from 90% (in control) to 56% in 350Gy dose of gamma rays. The gamma rays dose of 150Gy gave stimulatory effect on seedlings growth. The growth parameters were dose dependent, as the dose of gamma rays increased from 200Gy to 350Gy. The gamma rays dose of 350Gy showed 64% seeds germination and 56% of seedlings survival. Therefore, it is concluded that the LD50 dose for fenugreek is close to 350Gy. This information would be highly useful for initiating mutation breeding programme in fenugreek

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