The 15N natural abundance (δ15N) of ecosystem samples reflects measures of water availability

1999 ◽  
Vol 26 (2) ◽  
pp. 185 ◽  
Author(s):  
L. L. Handley ◽  
A. T. Austin ◽  
G. R. Stewart ◽  
D. Robinson ◽  
C. M. Scrimgeour ◽  
...  
Keyword(s):  
Water Availability ◽  
Mineral Soil ◽  
Annual Rainfall ◽  
Site Factors ◽  
Data Set ◽  
Surface Mineral ◽  
Derived Data ◽  
Soil Δ15n ◽  
Foliar Δ15n ◽  
Linear Regressions

We assembled a globally-derived data set for site-averaged foliar δ15N, the δ15N of whole surface mineral soil and corresponding site factors (mean annual rainfall and temperature, latitude, altitude and soil pH). The δ15N of whole soil was related to all of the site variables (including foliar δ15 N) except altitude and, when regressed on latitude and rainfall, provided the best model of these data, accounting for 49% of the variation in whole soil δ15N. As single linear regressions, site-averaged foliar δ15N was more strongly related to rainfall than was whole soil δ15N. A smaller data set showed similar, negative correlations between whole soil δ15N, site-averaged foliar δ15N and soil moisture variations during a single growing season. The negative correlation between water availability (measured here by rainfall and temperature) and soil or plant δ15N fails at the landscape scale, where wet spots are δ15N-enriched relative to their drier surroundings. Here we present global and seasonal data, postulate a proximate mechanism for the overall relationship between water availability and ecosystem δ15N and, newly, a mechanism accounting for the highly δ15N-depleted values found in the foliage and soils of many wet/cold ecosystems. These hypotheses are complemented by documentation of the present gaps in knowledge, suggesting lines of research which will provide new insights into terrestrial N-cycling. Our conclusions are consistent with those of Austin and Vitousek (1998) that foliar (and soil) δ15N appear to be related to the residence time of whole ecosystem N.

Determinants of spatial variation in fire return period in a semiarid African savanna

2011 ◽  
Vol 20 (4) ◽  
pp. 540 ◽  
Author(s):  
T. G. O'Connor ◽  
C. M. Mulqueeny ◽  
P. S. Goodman
Keyword(s):  
Spatial Variation ◽  
Return Period ◽  
Vegetation Type ◽  
Fire Frequency ◽  
Fuel Load ◽  
Annual Rainfall ◽  
Vegetation Types ◽  
Terrestrial Vegetation ◽  
African Savanna ◽  
Data Set

Fire pattern is predicted to vary across an African savanna in accordance with spatial variation in rainfall through its effects on fuel production, vegetation type (on account of differences in fuel load and in flammability), and distribution of herbivores (because of their effects on fuel load). These predictions were examined for the 23 651-ha Mkuzi Game Reserve, KwaZulu-Natal, based on a 37-year data set. Fire return period varied from no occurrence to a fire every 1.76 years. Approximately 75% of the reserve experienced a fire approximately every 5 years, 25% every 4.1–2.2 years and less than 1% every 2 years on average. Fire return period decreased in relation to an increase in mean annual rainfall. For terrestrial vegetation types, median fire return periods decreased with increasing herbaceous biomass, from forest that did not burn to grasslands that burnt every 2.64 years. Fire was absent from some permanent wetlands but seasonal wetlands burnt every 5.29 years. Grazer biomass above 0.5 animal units ha–1 had a limiting influence on the maximum fire frequency of fire-prone vegetation types. The primary determinant of long-term spatial fire patterns is thus fuel load as determined by mean rainfall, vegetation type, and the effects of grazing herbivores.

scholarly journals A European-wide <sup>222</sup>Radon and <sup>222</sup>Radon progeny comparison study

2016 ◽  
Author(s):  
Dominik Schmithüsen ◽  
Scott Chambers ◽  
Bernd Fischer ◽  
Stefan Gilge ◽  
Juha Hatakka ◽  
...  
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Ground Level ◽  
Data Sets ◽  
Correction Factors ◽  
Comparison Study ◽  
Data Set ◽  
Parallel Data ◽  
Linear Regressions ◽  
Atmospheric Transport Model

Abstract. A European-wide 222Radon/222Radon progeny comparison study has been conducted in order to determine correction factors that could be applied to existing atmospheric 222Radon data sets for quantitative use of this tracer in atmospheric transport model validation. Two compact and easy-to-transport Heidelberg Radon Monitors (HRM) were moved around to run for at least one month at each of the nine European measurement stations that were included in the comparison. Linear regressions between parallel data sets were calculated, yielding correction factors relative to the HRM ranging from 0.68 to 1.45. A calibration bias between ANSTO (Australian Nuclear Science and Technology Organisation) two-filter radon monitors and the HRM of ANSTO/HRM = 1.11 ± 0.05 was found. For continental stations, which use one-filter systems, preliminary 214Po/222Rn disequilibrium values were estimated to lie between 0.8 at mountain stations (e.g. Schauinsland) and 0.9 at non-mountain sites for sampling heights around 20 to 30 m above ground level. Respective corrections need to be applied to obtain a consistent European 222Radon data set for further applications.

Too tied to fail: a multidimensional approach to social capital in crowdfunding campaigns. Evidences from Italian agri-food businesses

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ulpiana Kocollari ◽  
Alessia Pedrazzoli ◽  
Maddalena Cavicchioli ◽  
Andrea Girardi
Keyword(s):  
Social Capital ◽  
Design Methodology ◽  
Multidimensional Approach ◽  
Data Set ◽  
Content Type ◽  
Different Types ◽  
Linear Regressions ◽  
Practical Implications

PurposeThe authors investigate the contributions of social capital (SC) dimensions (bridging, bonding and linking) in crowdfunding campaigns by comparing the dynamics of agri-food businesses with those of two other sectors – cultural and technological.Design/methodology/approachThe authors develop linear regressions on a proprietary data set of 5,290 projects launched on the Italian platform “Produzionidalbasso.com”, from 2014 to 2020.FindingsThe authors’ findings suggest that combining the three social capital dimensions (bridging, bonding and linking) has a more substantial overall effect on the number of backers involved in agri-food projects than in cultural and technological projects. Agri-food entrepreneurs effectively mobilize all resources embedded in the SC dimensions and therefore create the conditions to develop new ties that financially support the project.Practical implicationsAgri-food entrepreneurs may benefit from those results improving their funding strategies. Therefore, agri-food entrepreneurs can explore and exploit the instruments available on the CFD platform – video and rewards associated with the campaign – gaining more benefit from the backers involved compared with other project categories.Originality/valueThe study proposes a broader perspective regarding SC that encompasses the proponent, the company and the campaign with three different types of ties: bonding, bridging and linking. These SC dimensions can differently shape diverse sectors and this eclectic configuration can differentiate the effects of SC in crowdfunding campaigns. This study pinpoints how crowdfunding determinants change, based on project categories.

scholarly journals Biodiversity of Active and Inactive Bacteria in the Gut Flora of Wood-Feeding Huhu Beetle Larvae (Prionoplus reticularis)

2011 ◽  
Vol 77 (19) ◽  
pp. 7000-7006 ◽  
Author(s):  
Nicola M. Reid ◽  
Sarah L. Addison ◽  
Lucy J. Macdonald ◽  
Gareth Lloyd-Jones
Keyword(s):  
Genomic Dna ◽  
Data Sets ◽  
Data Set ◽  
Content Type ◽  
Dna And Rna ◽  
New Information ◽  
Related Organism ◽  
The Family ◽  
Insect Symbionts ◽  
Derived Data

ABSTRACTHuhu grubs (Prionoplus reticularis) are wood-feeding beetle larvae endemic to New Zealand and belonging to the family Cerambycidae. Compared to the wood-feeding lower termites, very little is known about the diversity and activity of microorganisms associated with xylophagous cerambycid larvae. To address this, we used pyrosequencing to evaluate the diversity of metabolically active and inactive bacteria in the huhu larval gut. Our estimate, that the gut harbors at least 1,800 phylotypes, is based on 33,420 sequences amplified from genomic DNA and reverse-transcribed RNA. Analysis of genomic DNA- and RNA-derived data sets revealed that 71% of all phylotypes (representing 95% of all sequences) were metabolically active. Rare phylotypes contributed considerably to the richness of the community and were also largely metabolically active, indicating their participation in digestive processes in the gut. The dominant families in the active community (RNA data set) includedAcidobacteriaceae(24.3%),Xanthomonadaceae(16.7%),Acetobacteraceae(15.8%),Burkholderiaceae(8.7%), andEnterobacteriaceae(4.1%). The most abundant phylotype comprised 14% of the active community and affiliated withDyella ginsengisoli(Gammaproteobacteria), suggesting that aDyella-related organism is a likely symbiont. This study provides new information on the diversity and activity of gut-associated microorganisms that are essential for the digestion of the nutritionally poor diet consumed by wood-feeding larvae. Many huhu gut phylotypes affiliated with insect symbionts or with bacteria present in acidic environments or associated with fungi.

A Population Level Temperature-Dependent Model of Seedling Johnsongrass (Sorghum halepense) Flowering

Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 471-477 ◽  
Author(s):  
David C. Bridges ◽  
James M. Chandler
Keyword(s):  
Water Availability ◽  
Nitrogen Availability ◽  
Nitrogen Concentration ◽  
Population Level ◽  
Effect Of Temperature ◽  
Weibull Function ◽  
Data Sets ◽  
Data Set ◽  
Independent Field ◽  
Temperature Dependent Model

A population level, two-compartment, temperaturedependent model that predicts date of seedling johnsongrass flowering was formulated. The model consisted of a fourparameter poikilotherm rate equation to describe development rate as a function of temperature and a temperature-independent Weibull function to distribute flowering times for the population. Experiments were conducted to determine the effect of temperature, nitrogen availability, and water availability on development of seedling johnsongrass. Development was most sensitive to temperature while the effect of nitrogen concentration and water availability was minimum and inconsistent. The model was tested against three independent field data sets and provided accurate prediction of flowering dates for each data set.

scholarly journals Fuzzy rule-based model to optimize outflow in single reservoir operation

2019 ◽  
Vol 270 ◽  
pp. 04015
Author(s):  
Edy Anto Soentoro ◽  
Nina Pebriana
Keyword(s):  
Water Availability ◽  
Reservoir Operation ◽  
Life Experiences ◽  
Real Life ◽  
Fuzzy Rule ◽  
Basic Pattern ◽  
Output Data ◽  
Data Set ◽  
Rule Based

Reservoir operations, especially those which regulate the outflow (release) volume, are crucial for the fulfillment of the purpose to build the reservoir. To get the best results, outflow (release) discharges need to be optimized to meet the objectives of the reservoir operation. A fuzzy rule-based model was used in this study because it can deal with uncertainty constraints and objects without clear or well-defined boundaries. The objective of this study is to determine the maximum total release volume based on water availability (i.e., a monthly release is equal to or more than monthly demand). The case study is located at Darma reservoir. A fuzzy rule-based model was used to optimize the monthly release volume, and the result was compared with that of NLP and the demand. The Sugeno fuzzy method was used to generate fuzzy rules from a given input-output data set that consisted of demand, inflow, storage, and release. The results of this study showed that the release of Sugeno method and the demand have the same basic pattern, in which the release fulfill the demand. The overall result showed that the fuzzy rule-based model with Sugeno method can be used for optimization based on real-life experiences from experts that are used to working in the field.

scholarly journals Hydrologic impact of climate change on Murray–Hotham catchment of Western Australia: a projection of rainfall–runoff for future water resources planning

2014 ◽  
Vol 18 (9) ◽  
pp. 3591-3614 ◽  
Author(s):  
S. A. Islam ◽  
M. A. Bari ◽  
A. H. M. F. Anwar
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Western Australia ◽  
Water Availability ◽  
Rainfall Data ◽  
Annual Rainfall ◽  
Emission Scenarios ◽  
Runoff Reduction ◽  
The Mean ◽  
Hydrologic Impact

Abstract. Reduction of rainfall and runoff in recent years across southwest Western Australia (SWWA) has attracted attention to the climate change impact on water resources and water availability in this region. In this paper, the hydrologic impact of climate change on the Murray–Hotham catchment in SWWA has been investigated using a multi-model ensemble approach through projection of rainfall and runoff for the periods mid (2046–2065) and late (2081–2100) this century. The Land Use Change Incorporated Catchment (LUCICAT) model was used for hydrologic modelling. Model calibration was performed using (5 km) grid rainfall data from the Australian Water Availability Project (AWAP). Downscaled and bias-corrected rainfall data from 11 general circulation models (GCMs) for Intergovernmental Panel on Climate Change (IPCC) emission scenarios A2 and B1 was used in LUCICAT model to derive rainfall and runoff scenarios for 2046–2065 (mid this century) and 2081–2100 (late this century). The results of the climate scenarios were compared with observed past (1961–1980) climate. The mean annual rainfall averaged over the catchment during recent time (1981–2000) was reduced by 2.3% with respect to the observed past (1961–1980) and the resulting runoff reduction was found to be 14%. Compared to the past, the mean annual rainfall reductions, averaged over 11 ensembles and over the period for the catchment for A2 scenario are 13.6 and 23.6% for mid and late this century respectively while the corresponding runoff reductions are 36 and 74%. For B1 scenario, the rainfall reductions were 11.9 and 11.6% for mid and late this century and the corresponding runoff reductions were 31 and 38%. Spatial distribution of rainfall and runoff changes showed that the rate of changes were higher in high rainfall areas compared to low rainfall areas. Temporal distribution of rainfall and runoff indicate that high rainfall events in the catchment reduced significantly and further reductions are projected, resulting in significant runoff reductions. A catchment scenario map has been developed by plotting decadal runoff reduction against corresponding rainfall reduction at four gauging stations for the observed and projected periods. This could be useful for planning future water resources in the catchment. Projection of rainfall and runoff made based on the GCMs varied significantly for the time periods and emission scenarios. Hence, the considerable uncertainty involved in this study though ensemble mean was used to explain the findings.

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