15 research outputs found
Estimating spatial variation in the effects of climate change on the net primary production of Japanese cedar plantations based on modeled carbon dynamics
Spatiotemporal prediction of the response of planted forests to a changing climate is increasingly important for the sustainable management of forest ecosystems. In this study, we present a methodology for estimating spatially varying productivity in a planted forest and changes in productivity with a changing climate in Japan, with a focus on Japanese cedar (Cryptomeria japonica D. Don) as a representative tree species of this region. The process-based model Biome-BGC was parameterized using a plant trait database for Japanese cedar and a Bayesian optimization scheme. To compare productivity under historical (1996â2000) and future (2096â2100) climatic conditions, the climate scenarios of two representative concentration pathways (i.e., RCP2.6 and RCP8.5) were used in five global climate models (GCMs) with approximately 1-km resolution. The seasonality of modeled fluxes, namely gross primary production, ecosystem respiration, net ecosystem exchange, and soil respiration, improved after two steps of parameterization. The estimated net primary production (NPP) of stands aged 36â40 years under the historical climatic conditions of the five GCMs was 0.77 ± 0.10 kgC m-2 year-1 (mean ± standard deviation), in accordance with the geographical distribution of forest NPP estimated in previous studies. Under the RCP2.6 and RCP8.5 scenarios, the mean NPP of the five GCMs increased by 0.04 ± 0.07 and 0.14 ± 0.11 kgC m-2 year-1, respectively. The increases in annual NPP were small in the southwestern region because of the decreases in summer NPP and the small increases in winter NPP under the RCP2.6 and RCP8.5 scenarios, respectively. Under the RCP2.6 scenario, Japanese cedar was at risk in the southwestern region, in accordance with previous studies, and monitoring and silvicultural practices should be modified accordingly
The discovery and follow-up of four transiting short-period sub-Neptunes orbiting M dwarfs
Sub-Neptunes with radii of 2â3 Râ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of close-in small planets. In this paper, we present the discovery and follow-up of four sub-Neptunes orbiting M dwarfs (TOI-782, TOI-1448, TOI-2120, and TOI-2406), three of which were newly validated by ground-based follow-up observations and statistical analyses. TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b have radii of Rp = 2.740 +0.082-0.079 Râ, 2.769+0.073-0.068 Râ, 2.120 ± 0.067 Râ, and 2.830+0.068-0.066 Râ and orbital periods of P = 8.02, 8.11, 5.80, and 3.08 days, respectively. Doppler monitoring with the Subaru/InfraRed Doppler instrument led to 2Ï upper limits on the masses of <19.1 Mâ, <19.5 Mâ, <6.8 Mâ, and <15.6 Mâ for TOI-782 b, TOI-1448 b, TOI-2120 b, and TOI-2406 b, respectively. The massâradius relationship of these four sub-Neptunes testifies to the existence of volatile material in their interiors. These four sub-Neptunes, which are located above the so-called "radius valley," are likely to retain a significant atmosphere and/or an icy mantle on the core, such as a water world. We find that at least three of the four sub-Neptunes (TOI-782 b, TOI-2120 b, and TOI-2406 b), orbiting M dwarfs older than 1 Gyr, are likely to have eccentricities of e ⌠0.2â0.3. The fact that tidal circularization of their orbits is not achieved over 1 Gyr suggests inefficient tidal dissipation in their interiors.Peer reviewe
Association of auditory Charles Bonnet syndrome with increased blood flow in the nondominant Brodmann area 22
Abstract Aim Auditory Charles Bonnet syndrome (aCBS) is characterized by musical hallucinations (MHs) that accompany acquired hearing impairments. This hallucination is the acoustic perception of music, sounds, or songs in the absence of an outside stimulus, and it may be associated with hyperactivity of the superior temporal lobes. Some studies have reported the possibility of improving MH with antiepileptics. To elucidate in detail the brain regions responsible for aCBS, we analyzed the regions that changed functionally after treatment. Methods Before and after treatment with carbamazepine (four cases), clonazepam (one case), and a hearing aid (one case), cerebral perfusion singleâphoton emission computed tomography (SPECT) and the Auditory Hallucination Rating Scale (AHRS) were applied to six patients with hearingâlossâassociated MHs. Results Cerebral blood flow analysis using SPECT revealed hyperperfusion in Brodmann area (BA) 22âthe posterior region of the superior temporal gyrusâin the nondominant hemisphere in all six patients in the pretreatment phase. After treatment, the hyperperfusion region improved in all patients. The area percentages with hyperperfusion in the nondominant BA22 were strongly positively correlated with the AHRS score. Conclusion The results suggest that aCBS, which was treatable with antiepileptics or hearing aids, was involved in hyperexcitement in BA22, and that MH strength was correlated with degree of excitement
High potential for increase in CO flux from forest soil surface due to global warming in cooler areas of Japan
The CO fluxes from the forest floor were measured using a closed
chamber method at 26 sites from 26° N Lat. to 44° N Lat. in Japan.
Seasonal fluctuation in CO flux was found to correlate exponentially
with seasonal fluctuation in soil temperature at each site. Estimate of
annual carbon emission from the forest floor ranged from 3.1 to 10.6 Mg C ha. The emission rate of soil-organic-carbon-derived CO,
obtained by incubation of intact soil samples, correlated closely with the
carboxymethylcellulase (CMCase) activity in the soil. The sum of cool-water
soluble polysaccharides, hot-water soluble polysaccharides, hemicellulose,
and cellulose content in the soil was greater at the sites with low CMCase
activity than that at the sites with high CMCase activity. Because the sites
in cooler-climate sites had a high content of easily decomposable soil
organic carbon and organic litter, the potential increase in CO efflux
from forest floor with increasing soil temperature would be greater in
cooler-climate sites.Fort potentiel d'accroissement de flux de CO issu de
la surface du sol forestier en relation avec le réchauffement global
dans les régions fraßches du Japon. Le flux de CO issu du sol forestier a été
mesuré dans 26 sites, allant du 26° au 44° de latitude Nord dans
l'archipel japonais, en utilisant la méthode des chambres fermées.
Il a pu ĂȘtre mis en Ă©vidence que la fluctuation saisonniĂšre du
flux de CO était corrélée de façon exponentielle avec celle
de la température du sol de chacun des sites étudiés.
L'estimation annelle de l'Ă©mission de carbone venant du sol variait de
3,1 à 10,6 Mg C ha. Le taux d'émission de CO obtenu par
incubation d'échantillons intacts de sol est corrélé
positivement avec l'activité de la carboxyméthacellulase (CMCase),
dans le sol. La somme totale des polysaccharides solubles dans l'eau froide,
des polysaccharides solubles dans l'eau chaude, des hémicelluloses et de
la cellulose contenus dans le sol Ă©tait plus grande dans les sites
caractérisés par une faible activité CMCase que dans les sites
avec une forte activité CMCase. Du fait que les sites en climat frais
ont un contenu élevé en carbone organique du sol facilement
décomposable et une litiÚre organique, le potentiel d'accroissement
du flux de CO avec l'accroissement de la température du sol
devrait ĂȘtre plus grand dans les sites Ă climat frais