Local seed rain and seed bank in a species-rich grassland: effects of plant abundance and seed size

2006 ◽  
Vol 84 (12) ◽  
pp. 1870-1881 ◽  
Author(s):  
Anna Jakobsson ◽  
Ove Eriksson ◽  
Hans Henrik Bruun
Keyword(s):  
Seed Size ◽  
Seed Bank ◽  
Negative Relationship ◽  
Seed Rain ◽  
Positive Relationships ◽  
Plant Abundance ◽  
M 10 ◽  
Seed Trap ◽  
Perennial Grassland ◽  
The Relationship

In this study, we examined the relationship between seed size, seed rain, and seed bank in a species-rich perennial grassland in Sweden. The seed rain was monitored by 100 seed traps placed in a 10 m × 10 m area for 1 year. The seed bank was sampled by taking 100 soil samples, each in close vicinity to a seed trap. Abundance of reproductive ramets in the area was estimated, since this is likely to affect the proportion of hit seed traps and seed bank samples. When abundance of reproductive ramets was accounted for, we found a negative relationship between seed size and proportion of hit seed bank samples, but we found no relationship between seed size and proportion of hit seed traps. We found strong positive relationships between the abundance of reproductive ramets and proportion of hit seed traps and seed bank samples. We also found strong positive relationships between abundance of reproductive ramets and abundance of seeds in the seed rain and the seed bank, but no relationship between seed size and abundance of seeds in the seed rain or the seed bank. We discuss these results in the context of theory suggesting that large-seeded and small-seeded species may coexist because of a trade-off between colonization and competitive abilities, where smaller-seeded species are able to reach more sites than seeds of larger-seeded species, because they are more numerous and (or) better dispersed.

scholarly journals PSII-17 Program Chair Poster Pick: Effect of ruminal protozoa on methane emissions in ruminants – a meta-analysis

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 397-398
Author(s):  
Xiaoxia Dai ◽  
Kenneth Kalscheur ◽  
Pekka Huhtanen ◽  
Antonio Faciola
Keyword(s):  
Dairy Cows ◽  
Meta Analysis ◽  
Random Effect ◽  
Negative Relationship ◽  
Small Ruminants ◽  
Methane Emissions ◽  
Mitigation Strategies ◽  
Positive Relationships ◽  
Ruminal Fermentation ◽  
The Relationship

Abstract The effects of ruminal protozoa (RP) concentration on methane emissions from ruminants were evaluated in a meta-analysis using 67 publications reporting data from 85 in vivo experiments. Experiments included in the database reported methane emissions (g/kg DMI) and RP (log10 cells/mL) from the same group of animals. Quantitative data including diet chemical composition, ruminal fermentation, total tract digestibility, and milk production; and qualitative information including methane mitigation strategies, animal type, and methane measurement methods were also collected. The studies were conducted in dairy cows (51%), beef steers (32%) and small ruminants (32%). 70% of the studies reported a reduction in methane emissions. Supplemental lipids reduced methane emissions 95% of the time. The relationship between methane emissions and RP concentration was evaluated as a random coefficient model with the experiment as a random effect and weighted by the inverse pooled SEM squared, including the possibility of covariance between the slope and the intercept. A quadratic effect of RP concentration on methane emissions was detected: CH4= -28.8 + 12.2 × RP-0.64 × RP2. To detect potential interfering factors in the relationship, the influence of several qualitative and quantitative factors were separately tested. Acetate, butyrate, and isobutyrate molar proportions had positive relationships with methane emissions and influenced the relationship between RP concentration and methane emissions, where the presence of ruminal fermentation variables reduced the effects of RP concentration in methane emissions. Total tract digestibility of DM, OM, and CP had negative relationships while NDF digestibility had a positive relationship with methane emissions; however, they only changed the magnitude of intercept and slope of RP and RP2 for the relationship. For dairy cows, milk fat and protein concentrations had positive relationships and milk yield had a negative relationship with methane emissions and changed the magnitude of intercept and slope of RP and RP2 for the relationship.

A seed trap for monitoring the seed rain in terrestrial communities

1995 ◽  
Vol 73 (5) ◽  
pp. 794-796 ◽  
Author(s):  
Gary W. Schott
Keyword(s):  
Life History ◽  
Seed Bank ◽  
Soil Surface ◽  
Seed Rain ◽  
Andropogon Gerardii ◽  
Sampling Methodology ◽  
Grassland Community ◽  
Species Population ◽  
Seed Trap ◽  
Pvc Pipe

Monitoring the seed rain of a species, population, or community is important to quantify that component of life history that follows anthesis yet precedes establishment in the seed bank or as a seedling. I have developed a unique seed trap that is ideal for monitoring the seed rain of a grassland community. The trap consists of a 10-cm diameter funnel attached by Velcro to one end of a 15-cm long PVC pipe. The trap is sunk into the ground with 1.5–2 cm protruding above the soil surface to prevent soil and ground-dwelling insects from entering the trap. A small cotton bag is attached to the stem of the funnel and acts as the reservoir for trapped seeds. I was able to trap propagules ranging in size from 0.5-mm seeds (Juncus interior) to > 2 cm long awned spikelets (Andropogon gerardii). Because this trap minimizes prédation, is easy to construct and monitor, and is inexpensive, it is superior to traps used by previous researchers. Key words: seed trap, seed rain, sampling methodology.

Post-dispersal seed predation and seed bank persistence

1998 ◽  
Vol 8 (4) ◽  
pp. 513-519 ◽  
Author(s):  
P. E. Hulme
Keyword(s):  
Seed Size ◽  
Seed Bank ◽  
Seed Predation ◽  
Negative Relationship ◽  
Seed Mass ◽  
Seed Banks ◽  
Seed Removal ◽  
Seed Predators ◽  
Grassland Plants ◽  
Buried Seeds

AbstractThis study examines whether post-dispersal seed predators could be an important selective force in determining the seed bank strategies of grassland plants. It tests the hypothesis that species with persistent seed banks should sustain proportionally less predation of buried seeds than species which have transient seed banks and that this should be true irrespective of seed size. Results are drawn from a field experiment examining the relative susceptibility of surface versus buried seeds for 19 herbaceous taxa exhibiting different degrees of seed bank persistence. The data were consistent with the hypothesis that seed predators (rodents) influence the seed bank characteristics of seeds. Rodents removed proportionally more large seeds than small seeds and removed a smaller proportion of seeds with persistent rather than transient seed banks, independently of seed size. On average, burial reduced seed removal by almost 50%. The decrease in rates of seed removal following burial was marked for seeds with persistent seed banks but negligible for seeds with transient seed banks. Herbaceous plants with relatively large seeds (seed mass > 1 mg) that form persistent seed banks were either completely avoided or only consumed in small quantities by rodents. In contrast, large-seeded species with transient seed banks suffer high rates of seed predation. Models of life-history evolution predict trade-offs between seed dormancy and seed mass since dormancy and seed size are correlated traits that both reduce risk in variable environments and thus will show patterns of negative covariation. This paper presents an alternative explanation for this trade-off based on experimental evidence of a negative relationship between seed bank persistence and predation risk.

A meta-analysis on the relationship between seed size, seed shape and persistence in soil seed bank

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Yaya Guo ◽  
Weihua Lu ◽  
Zhaobi Che ◽  
Jiamin Cao ◽  
Hanjun Yang ◽  
...  
Keyword(s):  
Seed Size ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Meta Analysis ◽  
Seed Shape ◽  
The Relationship

Risk Attitude and Corporate Investment under Output Market Uncertainty: Evidence from The Mekong River Delta, Vietnam

2016 ◽  
pp. 59-70
Author(s):  
Ninh Le Khuong ◽  
Nghiem Le Tan ◽  
Tho Huynh Huu
Keyword(s):  
Negative Relationship ◽  
Risk Attitude ◽  
Business Strategies ◽  
Risk Averse ◽  
Market Uncertainty ◽  
Firm Investment ◽  
Output Market ◽  
The Impact ◽  
The Relationship

This paper aims to detect the impact of firm managers’ risk attitude on the relationship between the degree of output market uncertainty and firm investment. The findings show that there is a negative relationship between these two aspects for risk-averse managers while there is a positive relationship for risk-loving ones, since they have different utility functions. Based on the findings, this paper proposes recommendations for firm managers to take into account when making investment decisions and long-term business strategies as well.

Relationship of Organizational Citizenship Behavior and Production Deviance: Role of Perceived Organizational Politics

2019 ◽  
Vol 34 (2) ◽  
pp. 367-382
Author(s):  
Irsa Fatima Makhdoom ◽  
Mohsin Atta ◽  
Najma Iqbal Malik
Keyword(s):  
Organizational Citizenship ◽  
Organizational Citizenship Behavior ◽  
Negative Relationship ◽  
Civic Virtue ◽  
Organizational Politics ◽  
Work Behavior ◽  
Citizenship Behavior ◽  
Production Deviance ◽  
Relationship Of ◽  
The Relationship

The present study was an endeavor to extend the literature of perceived organizational politics by examining its moderating role between the relationship of organizational citizenship behavior and production deviance. Organizational Citizenship Behavior Scale (Mackenzie, Podsakoff, & Paine, 1999), Production Deviance sub-scale of Counterproductive Work Behavior Checklist-32 (Spector et al., 2006), and Perception of Organizational Politics Scale (Kacmar & Carlson, 1997) were used in present study. Hierarchical regression analyses revealed that low levels of perceived organizational politics moderated the relationship between courtesy and production deviance by strengthening the negative relationship of these behaviors while perceived organizational politics did not act as a moderator for the relationship of civic virtue and conscientiousness with production deviance. High level of go-along-to-get-ahead as a moderator strengthened the relationship of civic virtue and conscientiousness with production deviance and its low level was found to be moderating the relationship between courtesy and production deviance. Future implications of the study were also discussed.

Work Stress and Organisational Citizenship Behaviours (OCBs) in Call Centers Employees

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
Sunita ◽  
Urvashi Singh ◽  
Shalini Singh ◽  
Rajnee Sharma
Keyword(s):  
Negative Impact ◽  
Call Centers ◽  
Negative Relationship ◽  
Married Couples ◽  
Call Centre ◽  
Simple Correlation ◽  
Nuclear Families ◽  
Set Up ◽  
Stress At Work ◽  
The Relationship

The present study was conducted to examine the relationship between organisational stress and organisational citizenship behaviours (OCBs) in employees of call centers. The study also further explored as how stress at work set-up has negative impact on OCBs. A sample of 250 employees working in call centre of Gurgaon belonging to an age group of 25-30 years were selected on availability basis. All were working married couples living in nuclear families. Job stress survey (Spielberger & Vagg, 1999) and Organisational Citizenship Behaviour (Bateman & Organ, 1983) were administered. Data was analysed by using simple correlation and multiple regression. Results showed the negative relationship between organisational stress and OCBs. Results of regression analysis also exhibited the negative impact of stress on OCBs. The implications for the employees are discussed.

The Relationship Among Job Satisfaction, Oreganizational Commitiment and Employees’ Turnover at Unilever Corporation in Nigeria

2017 ◽  
Vol 5 (1) ◽  
pp. 370
Author(s):  
Chiemeke Kingsley Chiedu ◽  
Choi Sang Long ◽  
Hapriza BT Ashar
Keyword(s):  
Job Satisfaction ◽  
Organizational Commitment ◽  
Organizational Performance ◽  
Employee Turnover ◽  
Turnover Intentions ◽  
Pearson Correlation ◽  
Negative Relationship ◽  
Survey Method ◽  
Employee Turnover Intentions ◽  
The Relationship

Employee turnover has become a key performance indicator for many organizations as they struggle to retain talented employees. The negative impact of turnover on organizational performance has continually forced organizational leaders to seek better ways of retaining valuable employees. The relationship between man and work has always attracted the attention of philosophers. A major part of men’s life is spent at work. Work is social reality and social expectation to which men seem to conform. It not only provides status to the individual but also binds him to the society. An employee who is satisfied with his job would perform his duties well and be committed to his job, and subsequently to his organization. This paper examines relationship among job satisfaction, organizational commitment and employees’ turnover intentions at Unilever Corporation in Nigeria. The data for this study was collected from 117 employees currently working at Unilever Nigeria PLC using the survey method via the questionnaire. Pearson Correlation and the multiple regression analysis techniques using the SPSS version 22.0 was used for the data analysis. The findings of the study revealed that both job satisfaction and organizational commitment have significant negative relationship with employee turnover intentions. In addition, organizational commitment was revealed to have a more dorminant influence on employee turnover intentions than job satisfaction. Based on these findings, the implications, recommendations, practice, and theory were discussed.

Sign in / Sign up

Export Citation Format

Share Document