49 research outputs found
Increased root oxygen uptake in pea plants responding to non-self neighbors
No full textRecent studies have demonstrated that plants alter root growth and decrease competition with roots of the same individual (self); however, the physiological traits accompanying this response are still widely unknown. In this study, we investigated the effect of root identity on gas exchange in the model species pea (Pisum sativum L.). Split-root plants were planted so that each pot contained either two roots of the same plant (self) or of two different plants (non-self), and the responses of biomass, photosynthesis, and respiration were measured. The photosynthetic rate was not affected by the identity of the root neighbor. We found a reduction of leaf dark respiration by half, accompanied by an increase in nocturnal root respiration by 29 % in plants neighboring with non-self. The activity of the alternative oxidase (AOX) pathway increased when plants responded to non-self neighbors. The increased activity of AOX in plants responding to non-self indicates carbon imbalances in roots, possibly as a consequence of increased root exudation and communication between individuals. If such an effect occurs more widely, it may change the assumptions made for the quantity of respiration as used in carbon budget models
Observing soil organic carbon spatial and seasonal variability at the Golan Heights using CO2/O2 fluxes measurements in an incubation experiment
No full textSoil organic matter (SOM) stores most of the terrestrial carbon, and changes in this storage can have a significant effect on the global carbon cycle. Various approaches have been used to understand the SOM transformations and stability. Here we measured the respiratory CO2 and O2 fluxes, and their ratio (the Apparent Respiratory Quotient - ARQ) in soil incubations at different temperatures, to learn about the short-term processes affecting SOM stability. To study in detail the spatial and temporal variability, we examine soil samples from two sample sets: a regional set, and a local set that was used to study the seasonality and environmental variability within a site. The regional set was taken from 11 sites located in the north and center of the Golan Heights, the samplings took place in two campaigns in October 2020 and in January 2021. In each site, the sample was pooled from 2 sub-samples taken by a trowel from A-horizon at 0-10 cm depth in adjacent locations. The local soil samples set was taken from Mt. Baron, a volcanic cinder cone which is located in the north of Golan Heights. The sampling took place in October 2021, February 2022, and June 2022, which represent the beginning, middle, and end of the rainy season. Each sample was pooled from 2 locations and taken by a trowel from A-horizon at 0-10 cm depth. At each campaign, the soil was sampled at 4 heights along the north and south slopes, under tree canopy, and in open grassland. The incubations were conducted on fresh sieved soil (2mm), wetted with distilled water to different levels. To explore the effect of anaerobic microsites on ARQ we incubated artificial clods (1 cm diameter) with wetted soil from Mt. Baron (The local set). To further test the effects of O2 limitation we conducted an experiment in which we mitigated this limitation by enriching in oxygen the atmosphere of the incubation headspace. All the incubations were carried out at the Hebrew University of Jerusalem
Observing soil organic carbon spatial and seasonal variability at the Golan Heights using Rock-Eval measurements
No full textSoil organic matter (SOM) stores most of the terrestrial carbon, and changes in this storage can have a significant effect on the global carbon cycle. Various approaches have been used to understand the SOM transformations and stability. Here, we estimated the long-term SOM stability, and the effect of decomposition on the stability and composition of the remaining fraction, by Rock-Eval pyrolysis. The sampling took place in Mount Baron, the Golan Heights, in October 2021, February 2022, and June 2022, which represent the beginning, middle, and end of the rainy season. . Each sample was pooled from 2 locations and taken by a trowel from A-horizon at 0-10 cm depth.. At each campaign, the soil was sampled at 4 heights along the north and south slopes, under tree canopy, and in open grassland. In addition, to study the different fractions of organic matter, we analyzed soil separated into particulate organic matter (POM) and mineral-associated organic matter (MAOM). The samples were dried to 55°C and were ground with a mortar and pestle before the Rock-Eval analysis (Rock Eval 6, Vinci Technologies, at Ben Gurion University of the Negev for October samples and Rock Eval 7S, Vinci Technologies, at the Geological Survey of Israel for February and June samples)
Replication Data for: Do Personality Traits Predict Voter Attitudes When Politics Is Structured Around Conflict? Lessons From Israel
No full textThe relationship between personality traits and political attitudes has been studied extensively. However, existing accounts largely study personality’s links to liberal-conservative divisions on social and economic issues. We know far less about its attitudinal influences when politics is organized around other issue domains, particularly ethnonational conflicts. Addressing this gap, we examine the relationship between the Big Five personality traits, policy preferences, and political orientation in Israel, where the main ideological cleavage involves the Israeli-Palestinian conflict. Using original survey data, we find that the known relationships with social and economic attitudes operate only partly and more weakly in this context. Unlike these domains, conflict-related preferences in Israel correlate primarily with greater conscientiousness, largely through authoritarian tendencies. General Left-Right orientations mimic this relationship, reflecting conflict-related views rather than social or economic inclinations. These findings expand the scope of current debates about personality and political attitudes and underscore the importance of national ideological contexts for future research
Oxygen Isotope Signatures of Phosphate in Wildfire Ash
No full textAtmospheric aerosol deposition is
a significant source of phosphorus (P) in many terrestrial and marine
ecosystems worldwide, influencing their biogeochemistry and primary
production. Particles emitted from wildfires (hereafter, ash) are
the second most important source of atmospheric P after airborne dust.
In this study, we aim to identify the signature of ash oxygen isotopes
in phosphate. This will enable the use of this signature for the separation
of ash from other atmospheric P sources. We measured P concentrations
and δ18OP in ash from natural and experimental
fires and also from ash heated at different temperatures. The HCl
and resin P concentrations (average ± SE) were 3.15 ± 0.35
and 1 ± 0.1 mg g–1, respectively. The HCl and
resin δ18OP were 15.5 ± 0.4 and 14.7
± 0.4‰ (average ± SE), respectively. Based on previous
studies, we suggest possible isotope exchange reactions during the
combustion process, between oxygen in phosphate and oxygen from other
probable sources (i.e., the atmosphere, and CaCO3 and CaO
formed in the ash). The unique isotopic signature in the ash, ranging
from 11.5 to 19.4‰ in the HCl and resin P fractions, is different
from that of other atmospheric P sources such as airborne tree pollen,
which has δ18OP values between 19.2‰
and 29.6‰, and Saharan-dust samples collected in Israel, which
have δ18OP values ranging from 20.7‰
to 22.6‰. Thus, the δ18OP can be
used as a marker for identifying atmospheric P from wildfires and
for estimating its importance to the global P cycle
Determining the relationship between tree-stem respiration and CO<sub>2</sub> efflux by δO<sub>2</sub> /Ar measurements
No full textFractionation of oxygen isotopes by root respiration: Implications for the isotopic composition of atmospheric O2
No full textUse of<sup>13</sup>C- and phosphate<sup>18</sup>O-labeled substrate for studying phosphorus and carbon cycling in soils: a proof of concept
No full textdata set for Carbonyl sulfide sulfur isotope fractionation during uptake by C3 and C4 plants
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This data set is used in the manuscript “Carbonyl sulfide sulfur isotope fractionation during uptake by C3 and C4 plants” submitted to JGR-biogeosciences. It contains results from plant chamber and carbonyl sulfide (COS) diffusion experiments, end calculated fractionations (ε), and leaf scale relative uptake (LRU) values. The rows marked with * contain data of plant chamber experiments that were presented previously (Davidson et al., 2021).
Fractionation are calculated as ε=-1000*ln(R/R0)/ln(f). Where f is the ratio of final/initial COS concentrations, and R and R0 are the 34S/32S ratios for the final and initial samples respectively.
LRU is calculated as (As/Ac)*(Cc/Cs) where Cc and Cs represents the ambient concentration for CO2 (ppm) and COS (ppt) respectively, and Ac and As represents the uptake flux for CO2 (ppm*s-1) and COS (ppt*s-1) respectively. Cc and Cs are calculated as the average value between initial and final concentrations for each experiment, and Ac and As are calculated as (initial concentration – final concentration)/(experiment time).</p
Use of Phosphate Oxygen Isotopes for Identifying Atmospheric-P Sources: A Case Study at Lake Kinneret
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