How regional climate and seed traits interact in shaping stress–tolerance of savanna seeds?

2021 ◽  
pp. 1-11
Author(s):  
Leandro C. Ribeiro ◽  
Eduardo R. M. Barbosa ◽  
Fabian Borghetti
Keyword(s):  
Water Content ◽  
Regional Climate ◽  
Large Body ◽  
Seed Mass ◽  
Population Level ◽  
Distribution Patterns ◽  
Seed Traits ◽  
Environmental Filters ◽  
Regional Environment ◽  
Germination Time

Abstract Functional traits related to regeneration responses to the environment are highly determinants of distribution patterns of plant communities. A large body of studies on seed traits suggests that regional climate may act as a strong filter of plant recruitment; however, few studies have evaluated the relative importance of seed traits and environmental filters for seed persistence at the population level. We tested the role of seed mass, water content and desiccation tolerance, as well as the germination time as proxies for seed tolerance to environmental filters (water deficit, heat shock and high temperatures) by comparing the response of tree species co-occurring in savannas located in different regions: Cerrado biome of Central Brazil and the Rio Branco savannas of northern Brazil. Seeds collected in savannas of Rio Branco showed a higher tolerance to environmental filters than those collected in savannas of the Cerrado. While the germination percentages largely varied in response to the treatments, the germination times were virtually unaffected by them, irrespective of seed origin, seed mass and water content. At the population level, the regional environment was a key determinant of seed tolerance to stress, irrespective of seed traits. Germination time was shown to represent a conservative seed trait and more linked to a species-specific germination strategy than to regional characteristics. Our results suggest that recruitment patterns of Cerrado savannas may be more impacted than Rio Branco savannas by the climate scenarios predicted for the future.

scholarly journals PENGARUH LAMA PERKECAMBAHAN MILLET (Panicum milliaceum) TERHADAP KARAKTERISTIK FLAKES

2018 ◽  
Vol 7 (4) ◽  
pp. 175
Author(s):  
I Gusti Agung Ayu Sintia Padma Dewi ◽  
I Gusti Ayu Ekawati ◽  
I Desak Putu Kartika Pratiwi
Keyword(s):  
Protein Content ◽  
Water Content ◽  
Fat Content ◽  
Ash Content ◽  
Fiber Content ◽  
Crude Fiber ◽  
Tannin Content ◽  
Germination Time ◽  
Crude Fiber Content ◽  
Randomized Design

The purpose of this research was to know the effect of germination time of millet (Panicum milliaceum) on the characteristics of flakes and to know the right germination time of millet on the characteristics of flakes. The experimental design used was completely randomized design with the germination time of millet treatment, namely 24 hours (T1), 48 hours (T2), 72 hours (T3), 96 hours (T4), and 120 hours (T5). The treatment was repeated 3 repetitions then obtained 15 units of the experiment, the data obtained from the result were analyzed by variance and if the treatment had an effect on the variable then continued with Duncan test. The results showed that the germination of millet had significant effect to water content, ash content, protein content, fat content, crude fiber content, tannin content, taste level (hedonic test), and overall acceptance of flakes. 120 hours germination time of millet had the best characteristics with water content 1,36%, ash content 2,65%, protein content 9,93%, fat content 7,86%, carbohydrate content 78,20%, crude fiber content 5,93, tannin content 0,31%, color liked, flavor liked, texture crispy and liked, taste liked  and overall acceptance liked.

scholarly journals Personality and collective decision-making in foraging herbivores

2009 ◽  
Vol 277 (1684) ◽  
pp. 1093-1099 ◽  
Author(s):  
Pablo Michelena ◽  
Raphaël Jeanson ◽  
Jean-Louis Deneubourg ◽  
Angela M. Sibbald
Keyword(s):  
Group Living ◽  
Population Level ◽  
Distribution Patterns ◽  
Model Species ◽  
Social Attraction ◽  
Homogeneous Groups ◽  
Animal Distribution ◽  
Parameter Values ◽  
Vegetation Patches

The mechanisms by which group-living animals collectively exploit resources, and the role of individuals in group decisions, are central issues for understanding animal distribution patterns. We investigated the extent to which boldness and shyness affect the distribution of social herbivores across vegetation patches, using sheep as a model species. Using an experimental and a theoretical approach, we show that collective choices emerge through the nonlinear dynamics of interactions between individuals, at both short and long distances. Within a range of parameter values derived from the observation of homogeneous groups of each behavioural type, we propose a simple mechanism whereby the same interaction rules can result in different patterns of distribution across patches for bold and shy individuals. We present a mathematical model based on behavioural rules derived from experiments, in which crowding and conspecific attraction affect the probability of entering or leaving patches. Variation in the strength of social attraction is sufficient to account for differences in spatial distribution across patches. The model predicts that resource fragmentation more strongly affects the distribution patterns of shy groups, and suggests that the presence of both bold and shy individuals within groups would result in more flexible behaviour at the population level.

scholarly journals Self-organization of chemoattractant waves in Dictyostelium depends on F-actin and cell–substrate adhesion

2016 ◽  
Vol 13 (119) ◽  
pp. 20160233 ◽  
Author(s):  
Fumihito Fukujin ◽  
Akihiko Nakajima ◽  
Nao Shimada ◽  
Satoshi Sawai
Keyword(s):  
Travelling Waves ◽  
Large Body ◽  
Cyclic Adenosine Monophosphate ◽  
Population Level ◽  
Adenosine Monophosphate ◽  
Isolated Cells ◽  
Substrate Adhesion ◽  
Temporal Cues ◽  
Cell Substrate Adhesion ◽  
In Cells

In the social amoeba Dictyostelium discoideum , travelling waves of extracellular cyclic adenosine monophosphate (cAMP) self-organize in cell populations and direct aggregation of individual cells to form multicellular fruiting bodies. In contrast to the large body of studies that addressed how movement of cells is determined by spatial and temporal cues encoded in the dynamic cAMP gradients, how cell mechanics affect the formation of a self-generated chemoattractant field has received less attention. Here, we show, by live cell imaging analysis, that the periodicity of the synchronized cAMP waves increases in cells treated with the actin inhibitor latrunculin. Detail analysis of the extracellular cAMP-induced transients of cytosolic cAMP (cAMP relay response) in well-isolated cells demonstrated that their amplitude and duration were markedly reduced in latrunculin-treated cells. Similarly, in cells strongly adhered to a poly- l -lysine-coated surface, the response was suppressed, and the periodicity of the population-level oscillations was markedly lengthened. Our results suggest that cortical F-actin is dispensable for the basic low amplitude relay response but essential for its full amplification and that this enhanced response is necessary to establish high-frequency signalling centres. The observed F-actin dependence may prevent aggregation centres from establishing in microenvironments that are incompatible with cell migration.

scholarly journals Morphological and germination response variability in seeds of wild yellow gentian (Gentiana lutea L.) accessions from northwest Spain

Botany ◽  
2012 ◽  
Vol 90 (8) ◽  
pp. 731-742 ◽  
Author(s):  
Félix Pérez-García ◽  
Federico Varela ◽  
M. Elena González-Benito
Keyword(s):  
Seed Germination ◽  
Water Content ◽  
Germination Rate ◽  
Seed Mass ◽  
Germination Percentage ◽  
Gentiana Lutea ◽  
Moist Chilling ◽  
Mean Germination Time ◽  
Wild Accessions ◽  
Seed Water Content

Gentiana lutea L. (yellow gentian, Gentianaceae) is an important medicinal plant under protection as endangered species in most European countries. The aim of this work was to evaluate variation in seed mass, seed water content, and seed germination among 56 wild accessions of G. lutea. The effect of gibberellic acid (GA3), putrescine, moist chilling, and level of ripeness of seeds on subsequent germination was also investigated. Seeds of G. lutea showed physiological dormancy (final germination percentages ranged from 0% to 11%, depending on the accession) and GA3 enhanced seed germination drastically in all the accessions. The highest germination (99%) of GA3-treated seeds was reached at 15 °C. Final germination percentage and germination rate (as expressed by mean germination time), as well as seed mass and seed water content, varied significantly among accessions. In general, 1 year moist chilling did not significantly enhance G. lutea seed germination. For most accessions, no significant differences were found between fully ripe seeds and less ripe seeds for seed water content, seed mass, and seed germination. Applications of GA3 were always most effective than those of putrescine for increasing seed germination.

Ressources en maïs et stationnement hivernal des grues cendrées (Grus grus) dans le sud-ouest de la France

1991 ◽  
Vol 69 (9) ◽  
pp. 2295-2299 ◽  
Author(s):  
Michel Génard ◽  
Denis Lanusse ◽  
Thierry Béreyziat
Keyword(s):  
Mass Loss ◽  
Feeding Behaviour ◽  
Seed Mass ◽  
Distribution Patterns ◽  
Seed Stock ◽  
Time And Space ◽  
Seed Availability ◽  
Grus Grus ◽  
Common Crane ◽  
Over Time

The influence of distribution and abundance of food (maize) on Common Crane behaviour and distribution patterns in time and space was analysed in the farmlands of south-western France. The maize stock most likely to be exploited by cranes gradually decreases from November to March because of autumnal germination, seed mass loss during winter, and burial during tilling of the soil. The variation of crane numbers over time does not depend on seed stock changes. The feeding behaviour of these birds does not change with decreasing seed availability, whereas gregariousness increases. The plots most likely to be selected by cranes offer accessibility to seeds and the best food supplies: crushed maize, in the first instance, and when this is not available, pulverized maize. Feeding behaviour and gregariousness do not vary with plot quality.

scholarly journals Seasonal monitoring of melt and accumulation within the deep percolation zone of the Greenland Ice Sheet and comparison with simulations of regional climate modeling

2018 ◽  
Author(s):  
Achim Heilig ◽  
Olaf Eisen ◽  
Michael MacFerrin ◽  
Marco Tedesco ◽  
Xavier Fettweis
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Pore Space ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Liquid Water Content ◽  
Water Infiltration ◽  
Near Surface ◽  
Percolation Zone

Abstract. Increasing melt over the Greenland ice sheet (GrIS) recorded over the past years has resulted in significant changes of the percolation regime of the ice sheet. It remains unclear whether Greenland's percolation zone will act as meltwater buffer in the near future through gradually filling all pore space or if near-surface refreezing causes the formation of impermeable layers, which provoke lateral runoff. Homogeneous ice layers within perennial firn, as well as near-surface ice layers of several meter thickness are observable in firn cores. Because firn coring is a destructive method, deriving stratigraphic changes in firn and allocation of summer melt events is challenging. To overcome this deficit and provide continuous data for model evaluations on snow and firn density, temporal changes in liquid water content and depths of water infiltration, we installed an upward-looking radar system (upGPR) 3.4 m below the snow surface in May 2016 close to Camp Raven (66.4779° N/46.2856° W) at 2120 m a.s.l. The radar is capable to monitor quasi-continuously changes in snow and firn stratigraphy, which occur above the antennas. For summer 2016, we observed four major melt events, which routed liquid water into various depths beneath the surface. The last event in mid-August resulted in the deepest percolation down to about 2.3 m beneath the surface. Comparisons with simulations from the regional climate model MAR are in very good agreement in terms of seasonal changes in accumulation and timing of onset of melt. However, neither bulk density of near-surface layers nor the amounts of liquid water and percolation depths predicted by MAR correspond with upGPR data. Radar data and records of a nearby thermistor string, in contrast, matched very well, for both, timing and depth of temperature changes and observed water percolations. All four melt events transferred a cumulative mass of 56 kg/m2 into firn beneath the summer surface of 2015. We find that continuous observations of liquid water content, percolation depths and rates for the seasonal mass fluxes are sufficiently accurate to provide valuable information for validation of model approaches and help to develop a better understanding of liquid water retention and percolation in perennial firn.

scholarly journals Socio-cultural adaptation of international students in the Siberian region

2021 ◽  
Vol 10 (4) ◽  
pp. 4212-4222
Author(s):  
S. L. Vasilyeva ◽  
A. A. Abramova ◽  
M. G. Volkova ◽  
N. A. Dmitrienko ◽  
N. S. Kovalenko
Keyword(s):  
International Students ◽  
Cultural Adaptation ◽  
Regional Climate ◽  
General Medicine ◽  
Siberian Region ◽  
Regional Environment ◽  
Cultural Conditions ◽  
Social Events ◽  
Regional Universities ◽  
Medical University

The problem relevance of socio-cultural adaptation of international students in the Siberian region is determined by several factors: rising interest of international students to regional universities (demand for certain educational programs); special characteristics of the Siberian region (climate, peculiarities of university, urban, regional environment); little experience of regional universities in teaching international students required constant monitoring for adaptation difficulties; need to optimize support to international studentsconsidering socio-cultural difficulties. The study aims to establish, analyze and classify the problems of socio-cultural adaptation; to define spheres particularly demanding support for international students in a Siberian region. The research methods were theoretical (analysis, synthesis, concretization, generalization); diagnostic (questionnaire); statistical ones. The questionnaire was carried onwith participation of 83 students from far-abroad countries studying the bilingual program (General Medicine Department, Siberian State Medical University) based on the international scale of socio-cultural adaptation. The calculations were madeusing IBM SPSS Statistics software. It resulted in revealing the factors contributing to psychological, socio-cultural, didactic barriers impeded learning process; identifying various types of difficulties affecting the process of socio-cultural adaptation were pointed out: basic, ethno-cultural (humor perception), regional (climate, searching familiar food), individual (participation in social events). The study establishes directions to support international students, ensure their successful integration into new cultural and educational community. The results should be useful for specialists of social and psychological services for timely assistance to international students of the Siberian regional universities; in preparing international students for learning and living in new socio-cultural conditions.

scholarly journals Multi-scale environmental filters and niche partitioning govern the distributions of riparian vegetation guilds

2014 ◽  
Author(s):  
Nate W Hough-Snee ◽  
Brian Laub ◽  
David M. Merritt ◽  
A. Lexine Long ◽  
Lloyd L. Nackley ◽  
...  
Keyword(s):  
Life History ◽  
Regional Climate ◽  
Morphological Characteristics ◽  
Species Traits ◽  
Life History Strategies ◽  
Rooting Depth ◽  
Environmental Filters ◽  
Support Tool ◽  
Channel Form ◽  
Riparian Plant

Across landscapes, riparian plant communities assemble under varying levels of disturbance, environmental stress, and resource availability, leading to the development of distinct riparian life-history guilds. Identifying the environmental filters that exert selective pressures and favor specific vegetation guilds within riverscapes is a critical step in setting baseline expectations for how riparia may respond to the environmental conditions anticipated under future global change scenarios. In this study, we ask (1) what functional riparian plant guilds exist across two major North American river basins? (2) What environmental filters shape riparian guild distributions? (3) Does resource partitioning between guilds influence guild distributions and co-occurrence? We identified riparian plant guilds, examining relationships between regional climate and watershed hydrogeomorphic characteristics, stream channel form, and co-occurring riparian guilds. Woody species composition was measured at 703 streams and each species’ traits were extracted from a database in five functional areas: life form, persistence and growth, reproduction, and resource use. We clustered species into guilds by morphological characteristics and attributes related to environmental tolerances, modeling guild distributions as a product of environmental filters (stressors and resources) and guild co-existence. We identified five guilds, i) a tall, deeply rooted, long-lived, evergreen tree guild, ii) a xeric disturbance tolerant shrub guild, iii) a hydrophytic, thicket-forming shrub guild, iv) a low-statured, shade-tolerant, understory shrub guild and v) a flood tolerant, mesoriparian shrub guild. Guilds were most strongly discriminated by one another species’ rooting depth, canopy height and potential to resprout and grow following biomass-removing disturbance. Hydro-climatic variables including precipitation, watershed area, water table depth, and channel form attributes reflective of hydrologic regime were predictors of guilds whose life history strategies had affinity or aversion to flooding, drought, and fluvial disturbance. Biotic interactions excluded guilds with divergent life history strategies and/or allowed for the co-occurrence of guilds that partition resources differently in the same environment. We conclude that riparian guilding provides a useful framework for assessing how disturbance and bioclimatic gradients shape riparian functional plant diversity. Multiple processes should be considered when the riparian response guilds framework is to be used as a land-use decision-support tool framework

scholarly journals The Norwegian Sea Gyre – A Regulator of Iceland-Scotland Ridge Exchanges

2021 ◽  
Vol 8 ◽  
Author(s):  
Hjálmar Hátún ◽  
Léon Chafik ◽  
Karin Margretha Húsgarð Larsen
Keyword(s):  
Regional Climate ◽  
Large Body ◽  
Atlantic Water ◽  
Meridional Overturning Circulation ◽  
Intermediate Water ◽  
Norwegian Sea ◽  
Sea Surface Heights ◽  
Meridional Overturning ◽  
Standard Section ◽  
Key Aspects

The Norwegian Sea gyre (NSG) is a large body of Arctic intermediate water and deep dense overflow waters, which circulate counterclockwise within the Norwegian Sea. Argo float trajectories presented in this study suggest that the NSG attains its strongest and most focused flow downstream of a confluence of subarctic waters from the Iceland Sea and the Jan Mayen Ridge at steep bathymetry north of the Faroe slope. Based on hydrographic data from a meridional standard section across this flow (1988 to present), the first baroclinic estimate of the NSG circulation strength is provided. We, furthermore, show that the NSG circulation regulates key aspects of both the poleward Atlantic Water (AW) currents and the equatorward near-bottom and mid-depth flows in the Norwegian Sea – the main arteries of the Meridional Overturning Circulation. More specifically, we demonstrate close links between the NSG circulation and (i) the observed Faroe Bank Channel Overflow (FBCO) transport, (ii) variable depth of the main thermocline separating AW from the underlying colder and denser subarctic water masses, and (iii) satellite-derived sea-surface heights (SSHs) in the southern Nordic Seas. In general, a strong NSG and weak FBCO transport are associated with an uplifted thermocline and depressed SSH. Along a narrow band near the Norwegian and Shetland slopes, a strong NSG – oppositely – links to a depressed interface. Daily records of the FBCO transport, and satellite altimetry in a sensitive region north of the Iceland-Faroe Ridge, complement our hydrographic monitoring of the NSG strength. Together these records constitute valuable indicators for aspects of the Norwegian Sea physical oceanography, which likely have an impact on regional climate, ecology and biological productivity.

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