scholarly journals Diversity-Productivity Relationship in the Northeastern Tamaulipan Thornscrub Forest of Mexico

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jose Navar ◽  
F. de Jesus Rodriguez-Flores ◽  
Pedro A. Dominguez-Calleros ◽  
Gustavo Perez-Verdin
Keyword(s):  
Abiotic Stress ◽  
Mature Stage ◽  
Ecological Interactions ◽  
High Productivity ◽  
Stochastic Mortality ◽  
Mortality Model ◽  
Biomass Components ◽  
Productivity Gradients ◽  
Temporal And Spatial ◽  
Tamaulipan Thornscrub

This research examines the diversity-productivity relationship in a semiarid scrubland, initially under late successional conditions and subsequently under early successional conditions created by experimental clearing, to explore the roles that productivity and stochastic mortality play in species exclusion in this environment. A total of fifteen plots were studied by measuring environmental conditions and biomass components of shrubs and seedlings. These stands were distributed along a productivity gradient across five different landforms. A hypothesis about the stochastic self-thinning mortality model along the gradient was evaluated with the diversity-productivity-environment data. The diversity-productivity relationship was linear and reversed between the early and late succession stages. The hypothesis of stochastic mortality of species exclusion was rejected in the early stages of succession and partially accepted in the mature stage of succession. Species exclusion was negatively related to productivity gradients, suggesting that strong interspecific competition occurs in high productivity plots and that a larger number of species can survive in higher abiotic stress landscapes. Further research is needed to understand the temporal and spatial variations of the ecological interactions that shape this plant community.

Pricing longevity-linked derivatives using a stochastic mortality model

2019 ◽  
Vol 48 (24) ◽  
pp. 5923-5942
Author(s):  
Yige Wang ◽  
Nan Zhang ◽  
Zhuo Jin ◽  
Tin Long Ho
Keyword(s):  
Stochastic Mortality ◽  
Mortality Model ◽  
Stochastic Mortality Model

Weather conditions monitoring and cherry (Cerasus vulgaris L.) elite forms productivity in the Ukraine’s Western Lisosteppe

2021 ◽  
pp. 66-71
Author(s):  
D.G. Makarova ◽  
◽  
V.I. Vasylenko ◽  
N.V. Moiseichenko ◽  
◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Weather Conditions ◽  
Stress Factors ◽  
Mass Flowering ◽  
Early Exit ◽  
High Productivity ◽  
Abiotic Stress Factors ◽  
Early Ripening ◽  
The Right ◽  
Considerable Loss

Cherry is rather sensitive to the temperature and water regime violation that reflects itself primarily on the fruits quantity and quality. The weather conditions in the Right Bank subzone of the Ukraine’s Western Lisosteppe are characterized with the general air temperature increase, less expressed frosty periods during hibernation, shortening of the winter and spring seasons, greater summer duration. The enumerated conditions result in the early exit of the plants from the dormancy state with the considerable loss of the abilities of the acclimation to potential frosts in the springtime period. Due to this the decision was taken to carry out the monitoring researches of the winter and spring periods of 2018-2020 in order to obtain the operative information about the cherry orchards state. This enables to predict the potential of the investigated plants business productivity in the real time. As a result of analyzing the abiotic stress-factors influence on the crop the following unfavourable factors were noted, above all: heavy winds at the beginning and during the mass flowering, violation of the water and temperature regime in the impregnation and infructescense periods. Those factors cause the harvest decrease. However, the formation of the plants high productivity depends in full on their adaptivity to the environmental conditions. Therefore among the 7 explored hybrids the generative buds of 1/20, 1/21 and 2/60 were affected essentially in the form of the little drying of the pistils stigmas, decrease of the pollen qualitative indices and fertility. That indicates the lower trees adaptivity to the abiotic stress-factors as compared to the control cultivar Podbielska. The forms 2/39 and 2/54 distinguish themselves for the high winter-hardiness. This is connected with the high environment adaptivity and characterizes them as early-ripening large-fruited and productive hybrids.

Spartina alterniflora: Potential Bio-Energy Source for Biofuel Production in China

2011 ◽  
Vol 142 ◽  
pp. 247-251
Author(s):  
Rui Li Li ◽  
Guo Yu Qiu
Keyword(s):  
Energy Source ◽  
Spartina Alterniflora ◽  
Photosynthetic Efficiency ◽  
Spatial Scales ◽  
Sewage Treatment ◽  
Structure And Function ◽  
Biofuel Production ◽  
High Productivity ◽  
Temporal And Spatial ◽  
And Function

Spartina alternifloracan be widely used for fodder, sewage treatment and as a substantial source of bioactive material. As an invader, it strongly disturbs the structure and function of native ecosystem in China. However, it is also a promising bio-energy source. We analyzed the potential ofS. alternifloraas a bio-energy source, including the superiority at both temporal and spatial scales, advantages in high photosynthetic efficiency and high productivity. Meanwhile, its exploitation for biofuel production was introduced.

scholarly journals A Square-Root Factor-Based Multi-Population Extension of the Mortality Laws

Mathematics ◽  
2021 ◽  
Vol 9 (19) ◽  
pp. 2402
Author(s):  
Petar Jevtić ◽  
Luca Regis
Keyword(s):  
Maximum Likelihood ◽  
Model Parameters ◽  
Time Varying ◽  
Square Root ◽  
Stochastic Mortality ◽  
Mortality Model ◽  
Model Based ◽  
Males And Females ◽  
Quasi Maximum Likelihood ◽  
Stochastic Mortality Model

In this paper, we present and calibrate a multi-population stochastic mortality model based on latent square-root affine factors of the Cox-Ingersoll and Ross type. The model considers a generalization of the traditional actuarial mortality laws to a stochastic, multi-population and time-varying setting. We calibrate the model to fit the mortality dynamics of UK males and females over the last 50 years. We estimate the optimal states and model parameters using quasi-maximum likelihood techniques.

scholarly journals Comparison of Stochastic Mortality Model for Wider Age Range

MATEMATIKA ◽  
2018 ◽  
Vol 34 (2) ◽  
pp. 227-233
Author(s):  
Siti Rohani Mohd Nor ◽  
Fadhilah Yusof ◽  
Arifah Bahar
Keyword(s):  
Risk Exposure ◽  
Longevity Risk ◽  
Model Structure ◽  
Research Directions ◽  
Linear Pattern ◽  
Stochastic Mortality ◽  
Mortality Model ◽  
New Research ◽  
Age Range ◽  
Stochastic Mortality Model

The incorporation of non-linear pattern of early ages has opened new research directions on improving the existing stochastic mortality model structure. Several authors have outlined the importance of encompassing the full age range in dealing with longevity risk exposure by not to ignore the dependence between young and old age. In this study, we consider the two extensions of Cairns, Blake and Dowd model that incorporate the irregularity profile seen at the mortality of lower ages which are Plat and O’Hare and Li. The models’ performances in terms of in-sample fitting and out-sample forecasts were examined and compared. The results indicated that O’Hare and Li model performs better as compared to Plat model

scholarly journals Selection of upland rice lines in advanced yield trials and response to abiotic stress

2021 ◽  
Vol 22 (10) ◽  
Author(s):  
Arif Tirtana ◽  
Bambang Sapta Purwoko ◽  
ISWARI SARASWATI DEWI ◽  
Trikoesoemaningtyas Trikoesoemaningtyas
Keyword(s):  
Abiotic Stress ◽  
Drought Stress ◽  
Drought Tolerance ◽  
Aluminum Toxicity ◽  
Upland Rice ◽  
Yield Potential ◽  
Research Station ◽  
High Productivity ◽  
Yield Trials ◽  
Selection Of

Abstract. Tirtana A, Purwoko BP, Dewi IS, Trikoesoemaningtyas. 2021. Selection of upland rice lines in advanced yield trials and response to abiotic stress. Biodiversitas 22: 4694-4703. Breeding programs to obtain superior upland rice varieties with high productivity and adaptive in dryland must be prioritized to maximize the potential of dryland. This research aimed to obtain information on the agronomic performance of upland rice lines in advanced yield trials and select the best lines with high productivity and tolerance to drought stress and aluminum toxicity. Advanced yield trials were conducted from November 2016 until March 2017 in Bogor and Sukabumi using a randomized complete block design, where three replications were nested in the environments. Aluminum and drought stress evaluations were conducted at Muara Research Station, Bogor, in May-June 2018 and September-October 2018. Based on the selection index, twelve lines were selected with superior agronomic characters and high yield potential. These lines had characteristics as follows: days to harvesting (110.2-116.0 days), number of filled grains (70.6-101.3 grains), number of unfilled grains (27.9-58.4 grains), and productivity (2.2-2.9 tons ha-1). Evaluation of drought tolerance showed four lines with better drought tolerance than the drought-sensitive check IR20. The aluminum tolerance evaluation obtained two tolerant lines and nine lines with moderate responses to aluminum toxicity. The selected lines need to be further evaluated in multilocation trials.

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