scholarly journals Functional traits and phenotypic plasticity modulate species coexistence across contrasting environments

2019 ◽  
Author(s):  
Ignacio Manuel Perez-Ramos ◽  
Luis Matias ◽  
Lorena Gomez Aparicio ◽  
Oscar Godoy
Keyword(s):  
Functional Traits ◽  
Field Experiments ◽  
Species Coexistence ◽  
Climatic Conditions ◽  
Competitive Dynamics ◽  
Significant Advance ◽  
Primary Role ◽  
Form And Function ◽  
Rich Diversity ◽  
Trade Offs

Functional traits are expected to modulate plant competitive dynamics. However, how traits and their plasticity in response to contrasting environments connect with the mechanisms determining species coexistence remains poorly understood. Here, we coupled field experiments under two contrasted climatic conditions to a plant population model describing competitive dynamics between 10 annual plant species in order to evaluate the associations of niche and fitness differences with 19 functional traits covering physiological, morphological and reproductive characteristics. We found a rich diversity of univariate and multidimensional relationships, in which outstand the primary role of traits related to water- and light-use-efficiency in modulating the determinants of competitive outcomes. Importantly, such traits and their plasticity promoted species coexistence across climatic conditions by enhancing stabilizing niche differences and by generating competitive trade-offs between species. Our study represents a significant advance showing how leading dimensions of plant form and function connect to the mechanisms determining the maintenance of biodiversity.

Native Advertising in Online News: Trade-Offs Among Clicks, Brand Recognition, and Website Trustworthiness

2019 ◽  
Vol 57 (1) ◽  
pp. 20-34 ◽  
Author(s):  
Anocha Aribarg ◽  
Eric M. Schwartz
Keyword(s):  
Field Experiments ◽  
Online Advertising ◽  
Online News ◽  
Editorial Content ◽  
Form And Function ◽  
Brand Recognition ◽  
Trade Offs ◽  
Conflicting Objectives ◽  
And Function ◽  
Click Through Rate

Native advertising is a type of online advertising that matches the form and function of the platform on which it appears. In practice, the choice between display and in-feed native advertising presents brand advertisers and online news publishers with conflicting objectives. Advertisers face a trade-off between ad clicks and brand recognition, whereas publishers need to strike a balance between ad clicks and the platform’s trustworthiness. For policy makers, concerns that native advertising confuses customers prompted the U.S. Federal Trade Commission to issue guidelines for disclosing native ads. This research aims to understand how consumers respond to native ads versus display ads and to different styles of native ad disclosures, using randomized online and field experiments combining behavioral clickstream, eye movement, and survey response data. The results show that when the position of an ad on a news page is controlled for, a native ad generates a higher click-through rate because it better resembles the surrounding editorial content. However, a display ad leads to more visual attention, brand recognition, and trustworthiness for the website than a native ad.

The complexity of simple tillage systems

2009 ◽  
Vol 147 (4) ◽  
pp. 399-410 ◽  
Author(s):  
A. OSWALD ◽  
S. DE HAAN ◽  
J. SANCHEZ ◽  
R. CCANTO
Keyword(s):  
Field Experiments ◽  
Smallholder Farmers ◽  
Potato Crop ◽  
Growth Conditions ◽  
Climatic Conditions ◽  
Tillage Systems ◽  
External Resources ◽  
Advantages And Disadvantages ◽  
Trade Offs ◽  
Tillage System

SUMMARYIn the Central Peruvian highlands, potatoes are commonly cultivated by smallholder farmers in fields between 3500 and 4300 m asl. Severe climatic conditions, marginal soils and limited access to inputs and infrastructure define these challenging agro-ecological environments. To prepare an adequate seed bed for the potato and mitigate climatic, topographic and labour constraints, Andean farmers have developed distinct footplough-based tillage systems: barbecho, chiwa and chacmeo. A series of field experiments was conducted in 2005/06 and 2006/07 at four different locations to investigate the effect of three different tillage systems on potato tuber yield, varying factors such as cultivars and types and amounts of fertilizer applied. The objective was to improve understanding of the effect of these factors on potato yield and study the potential advantages and disadvantages of each tillage system.The study showed that the type of tillage influenced a great variety of factors. Farmers often use a combination of tillage systems as a strategy to diversify possible risks, considering trade-offs regarding productivity v. yield stability, internal v. external resource use, labour requirement during peak times v. more uniform distribution or extensive v. intensive production. The chiwa and to some extent the chacmeo tillage systems resulted in relatively constant and stable yields for different environments and genetic materials, whereas the more intensive barbecho system sought to optimize growth conditions for the potato crop but was more liable to stress and required external resources. Currently, farmers often use the barbecho system to produce commercial cultivars for the urban markets investing the greatest share of internal and external resources. They use the chiwa and chacmeo systems to produce diverse native cultivars for their home consumption, valorizing their taste, cooking qualities and lower resource requirements.

Global trade-offs in tree functional traits

2021 ◽  
Author(s):  
Daniel S. Maynard ◽  
Lalasia Bialic-Murphy ◽  
Constantin M. Zohner ◽  
Colin Averill ◽  
Johan van den Hoogen ◽  
...  
Keyword(s):  
Functional Traits ◽  
Seed Mass ◽  
Tree Height ◽  
Woody Species ◽  
Tree Size ◽  
Form And Function ◽  
Plant Trait ◽  
Trade Offs ◽  
Structure Tree ◽  
And Function

AbstractDue to massive energetic investments in woody support structures, trees are subject to unique physiological, mechanical, and ecological pressures not experienced by herbaceous plants. When considering trait relationships across the entire plant kingdom, plant trait frameworks typically must omit traits unique to large woody species, thereby limiting our understanding of how these distinct ecological pressures shape trait relationships in trees. Here, by considering 18 functional traits—reflecting leaf economics, wood structure, tree size, reproduction, and below-ground allocation—we quantify the major axes of variation governing trait expression of trees worldwide. We show that trait variation within and across angiosperms and gymnosperms is captured by two independent processes: one reflecting tree size and competition for light, the other reflecting leaf photosynthetic capacity and nutrient economies. By exploring multidimensional relationships across clusters of traits, we further identify a representative set of seven traits which captures the majority of variation in form and function in trees: maximum tree height, stem conduit diameter, specific leaf area, seed mass, bark thickness, root depth, and wood density. Collectively, this work informs future trait-based research into the functional biogeography of trees, and contributes to our fundamental understanding of the ecological and evolutionary controls on forest biodiversity and productivity worldwide.

scholarly journals Effect of Temperature on Sowing Dates of Wheat under Arid and Semi-Arid Climatic Regions and Impact Quantification of Climate Change through Mechanistic Modeling with Evidence from Field

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 927
Author(s):  
Jamshad Hussain ◽  
Tasneem Khaliq ◽  
Muhammad Habib ur Rahman ◽  
Asmat Ullah ◽  
Ishfaq Ahmed ◽  
...  
Keyword(s):  
Climate Change ◽  
Grain Yield ◽  
Arid Region ◽  
Field Experiments ◽  
Climatic Conditions ◽  
Seasonal Temperature ◽  
Sowing Dates ◽  
Rcp 8.5 ◽  
Semi Arid Region ◽  
Semi Arid

Rising temperature from climate change is the most threatening factor worldwide for crop production. Sustainable wheat production is a challenge due to climate change and variability, which is ultimately a serious threat to food security in Pakistan. A series of field experiments were conducted during seasons 2013–2014 and 2014–2015 in the semi-arid (Faisalabad) and arid (Layyah) regions of Punjab-Pakistan. Three spring wheat genotypes were evaluated under eleven sowing dates from 16 October to 16 March, with an interval of 14–16 days in the two regions. Data for the model calibration and evaluation were collected from field experiments following the standard procedures and protocols. The grain yield under future climate scenarios was simulated by using a well-calibrated CERES-wheat model included in DSSAT v4.7. Future (2051–2100) and baseline (1980–2015) climatic data were simulated using 29 global circulation models (GCMs) under representative concentration pathway (RCP) 8.5. These GCMs were distributed among five quadrants of climatic conditions (Hot/Wet, Hot/Dry, Cool/Dry, Cool/Wet, and Middle) by a stretched distribution approach based on temperature and rainfall change. A maximum of ten GCMs predicted the chances of Middle climatic conditions during the second half of the century (2051–2100). The average temperature during the wheat season in a semi-arid region and arid region would increase by 3.52 °C and 3.84 °C, respectively, under Middle climatic conditions using the RCP 8.5 scenario during the second half-century. The simulated grain yield was reduced by 23.5% in the semi-arid region and 35.45% in the arid region under Middle climatic conditions (scenario). Mean seasonal temperature (MST) of sowing dates ranged from 16 to 27.3 °C, while the mean temperature from the heading to maturity (MTHM) stage was varying between 12.9 to 30.4 °C. Coefficients of determination (R2) between wheat morphology parameters and temperature were highly significant, with a range of 0.84–0.96. Impacts of temperature on wheat sown on 15 March were found to be as severe as to exterminate the crop before heading. The spikes and spikelets were not formed under a mean seasonal temperature higher than 25.5 °C. In a nutshell, elevated temperature (3–4 °C) till the end-century can reduce grain yield by about 30% in semi-arid and arid regions of Pakistan. These findings are crucial for growers and especially for policymakers to decide on sustainable wheat production for food security in the region.

scholarly journals Niches, rather than neutrality, structure a grassland pioneer guild

2005 ◽  
Vol 272 (1570) ◽  
pp. 1357-1364 ◽  
Author(s):  
Lindsay A Turnbull ◽  
Liz Manley ◽  
Mark Rees
Keyword(s):  
Seed Size ◽  
Adult Stage ◽  
Niche Differentiation ◽  
Competitive Dynamics ◽  
Similar Species ◽  
Adult Density ◽  
Pioneer Species ◽  
Trade Offs ◽  
Very High ◽  
Early Establishment

Pioneer species are fast-growing, short-lived gap exploiters. They are prime candidates for neutral dynamics because they contain ecologically similar species whose low adult density is likely to cause widespread recruitment limitation, which slows competitive dynamics. However, many pioneer guilds appear to be differentiated according to seed size. In this paper, we compare predictions from a neutral model of community structure with three niche-based models in which trade-offs involving seed size form the basis of niche differentiation. We test these predictions using sowing experiments with a guild of seven pioneer species from chalk grassland. We find strong evidence for niche structure based on seed size: specifically large-seeded species produce fewer seeds but have a greater chance of establishing on a per-seed basis. Their advantage in establishment arises because there are more microsites suitable for their germination and early establishment and not directly through competition with other seedlings. In fact, seedling densities of all species were equally suppressed by the addition of competitors' seeds. By the adult stage, despite using very high sowing densities, there were no detectable effects of interspecific competition on any species. The lack of interspecific effects indicates that niche differentiation, rather than neutrality, prevails.

scholarly journals Improved Rice Technology Adoption: The Role of Spatially-Dependent Risk Preference

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 691
Author(s):  
Omotuyole Isiaka Ambali ◽  
Francisco Jose Areal ◽  
Nikolaos Georgantzis
Keyword(s):  
Field Experiments ◽  
Climatic Factors ◽  
Risk Preferences ◽  
Risk Preference ◽  
Probit Model ◽  
Climatic Conditions ◽  
High Yield ◽  
Risk Attitudes ◽  
Policy Action ◽  
Rice Varieties

This study analyses farmers’ adoption of improved rice technology, taking into account farmers’ risk preferences; the unobserved spatial heterogeneity associated with farmers’ risk preferences; farmers’ household and farm characteristics; farm locations, farmers’ access to information, and their perceptions on the rice improved varieties (i.e., high yield varieties, HYV). The study used data obtained from field experiments and a survey conducted in 2016 in Nigeria. An instrumental-variable probit model was estimated to account for potential endogenous farmers’ risk preference in the adoption decision model. Results show that risk averse (risk avoidant) farmers are less likely to adopt HYV, with the spatial lags of farmers’ risk attitudes found to be a good instrument for spatially unobserved variables (e.g., environmental and climatic factors). We conclude that studies supporting policy action aiming at the diffusion of improved rice varieties need to collect information, if possible, on farmers’ risk attitudes, local environmental and climatic conditions (e.g., climatic, topographic, soil quality, pest incidence) in order to ease the design and evaluation of policy actions on the adoption of improved agricultural technology.

An experiment in the control of the ground water-level in a fen peat soil

1951 ◽  
Vol 41 (1-2) ◽  
pp. 149-162 ◽  
Author(s):  
H. H. Nicholson ◽  
G. Alderman ◽  
D. H. Firth
Keyword(s):  
Ground Water ◽  
Water Level ◽  
Large Scale ◽  
Field Experiments ◽  
Peat Soil ◽  
Climatic Conditions ◽  
Ground Water Level ◽  
Effective Control ◽  
Soil Conditions ◽  
Local Soil

1. The methods of investigation of the effect of ground water-level on crop growth, together with tho field installations in use, are discussed.2. Direct field experiments are handicapped by the difficulties of achieving close control on a sufficiently large scale, due to considerable variations of surface level and depth of peat within individual fields and to rapid fluctuations in rainfall and evaporation. Many recorded experiments are associated with climatic conditions of substantial precipitation during the growing season.3. Seasonal fluctuations of ground water-level in Fen peat soils in England, in natural and agricultural conditions, are described.4. The local soil conditions are outlined and the implications of profile variations are discussed.5. The effective control of ground water-level on a field scale requires deep and commodious ditches and frequent large underdrains to ensure the movement of water underground with sufficient freedom to give rapid compensatory adjustment for marked disturbances of ground water-level following the incidence of heavy rain or excessive evaporation.6. A working installation for a field experiment in ordinary farming conditions is described and the measure of control attained is indicated.

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