ALBERT

Description: ABSTRACT Peat archives offer a diverse range of physical and chemical proxies from which it is possible to study past environmental and ecological changes. Direct numerical calibration and verification is difficult so process-based and mechanistic studies are therefore required to establish and quantify links between environmental changes and their associated proxy-responses. Traditional ‘space-for-time’ calibrations provide a solution to this calibration problem, but are often unable to isolate a single environmental variable from other potentially confounding variables. In this study, we explored the potential of a site-specific ‘space-for-time’ approach applied to a hummock-hollow transect on an ombrotrophic raised bog in Patagonia, southern Chile. Coupled stable carbon, oxygen and hydrogen isotopic measurements were made on individual samples of Sphagnum moss cellulose and compared with plant-associated waters, local hydrology, temperature and relative humidity, sampled at the same points along the study transect. Results reveal a range of environmental responses, which were supported by plant-physiological models in the case of carbon and oxygen isotopes. For hydrogen isotopes, the results obtained from cellulose indicated a need for further research into hydrogen isotope fractionation in Sphagnum . We recommend conducting site-specific characterization of plant response to support the development of peat-based isotope records for palaeoenvironmental research, and where logistically possible, that monitoring is conducted over timescales appropriate to the time-integrative nature of the Sphagnum record.

Description: Strong global demand for tropical timber and agricultural products has driven large-scale logging and subsequent conversion of tropical forests. Given that the majority of tropical landscapes have been or will likely be logged, the protection of biodiversity within tropical forests thus depends on whether species can persist in these economically exploited lands, and if species cannot persist, whether we can protect enough primary forest from logging and conversion. However, our knowledge of the impact of logging and conversion on biodiversity is limited to a few taxa, often sampled in different locations with complex land-use histories, hampering attempts to plan cost-effective conservation strategies and to draw conclusions across taxa. Spanning a land-use gradient of primary forest, once- and twice-logged forests, and oil palm plantations, we used traditional sampling and DNA metabarcoding to compile an extensive data set in Sabah, Malaysian Borneo for nine vertebrate and invertebrate taxa to quantify the biological impacts of logging and oil palm, develop cost-effective methods of protecting biodiversity, and examine whether there is congruence in response among taxa. Logged forests retained high species richness, including, on average, 70% of species found in primary forest. In contrast, conversion to oil palm dramatically reduces species richness, with significantly fewer primary-forest species than found on logged forest transects for seven taxa. Using a systematic conservation planning analysis, we show that efficient protection of primary-forest species is achieved with land portfolios that include a large proportion of logged-forest plots. Protecting logged forests is thus a cost-effective method of protecting an ecologically and taxonomically diverse range of species, particularly when conservation budgets are limited. Six indicator groups (birds, leaf-litter ants, beetles, aerial hymenopterans, flies, and true bugs) proved to be consistently good predictors of the response of the other taxa to logging and oil palm. Our results confidently establish the high conservation value of logged forests and the low value of oil palm. Cross-taxon congruence in responses to disturbance also suggests that the practice of focusing on key indicator taxa yields important information of general biodiversity in studies of logging and oil palm. # doi:10.1890/14-0010.1

Description: Eclogite facies cataclasite is recognized at Yangkou in the Chinese Su-Lu ultrahigh-pressure metamorphic belt. The cataclasite dykes (5−15 cm wide) are bounded by mylonite/ultramylonite zones, cutting through unfoliated metagabbro and/or eclogite. The cataclasite veins (generally 2−4 cm wide) are free of mylonite boundary zones, cutting through the foliation of the high-pressure host rock. The dykes and veins are dominated by eclogite fragments consisting of debris of omphacite, garnet, quartz, phengite and kyanite, in a matrix of variable amounts of a schist rich in quartz, phengite and kyanite. Garnet clasts in the fragments are welded and overgrown by more Ca-rich garnet containing different mineral inclusions than those in the garnet cores. The micropoikilitic texture of garnet is typical of eclogitic pseudotachylytes. Crack-sealing K-feldspar veinlets in the cataclasite dykes also imply frictional or shock induced melting of K-mica. The modal abundances in the cataclasite and the schist imply that the dykes formed by flow of the omphacite and garnet-dominated cataclasites into the fractures during seismic faulting, while the lower density minerals (quartz, phengite and kyanite) were largely left in the ultramylonite boundary zones. The dykes have the same composition as their host rocks, except for slightly lower Si and large ion lithophile elements and higher Mg, Ca, Cr, Co and Ni. Chromite, probably spurted from the nearby ultramafic rock, is found as rare particles in the cataclasite fragments. This implies that material exchange occurred by mechanical mixing between the dykes and the ultramafic rock during seismic faulting. The Cr-rich eclogite minerals grown on the chromite are evidence for coseismic high-pressure crystallization. Short-lived crystal growth is implied by the fine grain sizes of the eclogite minerals and very limited element diffusion between the garnet clasts and their overgrowths. The fact that the host rocks are more hydrated implies that the dyke formation was not related to fluid infiltration. It appears, therefore, that stress was the key factor inducing the high-pressure metamorphic reactions in the dykes. Both the stress and the temperature were only transiently high in the dykes, which have been metastable since they were formed. This article is protected by copyright. All rights reserved.

Description: The most important petroleum exploration target in the Tarim Basin, northwest China, is the paleokarst reservoir. To understand the source and evolution of brine in this type of reservoir, a total of 37 formation-water samples were collected from the Middle-Lower Ordovician paleokarst reservoir in the Lunnan oilfield. The δD-δ 18 O correlation and Cl/Br ratios reflect the mixture of two fluids: meteoric water and evaporated seawater. The different degree of mixture divided samples into two groups. Group 1 samples, from deep strata (5150–6667 m.b.s.l.) in the east of the field, with elevated δD (−53.5 to −38.0‰), δ 18 O values (0.66–5.99‰), and lower Cl/Br ratios (336–478 for Cl/Br, except LN634-1 and LN631-1) were formed by evaporation of seawater plus a small contribution from meteoric water. Group 2 samples, from shallow strata (5038–6067 m.b.s.l.), in the west of the field, have contrasting features (−59.6 to −48.5‰ for δD, −0.47 to 2.17‰ for δ 18 O, and 501 to 871 for Cl/Br), which reflect a mixture of evaporated seawater with a high proportion of meteoric water. Both of the fluid types exchanged oxygen isotope with minerals. The investigation into cation composition reveals that, before entering into the current reservoir, waters suffered albitization of plagioclase; moreover, meteoric water dissolved evaporites and seawater experienced dolomitization. A mixing trend showed by strontium isotopes (0.709801–0.711628) gave further evidence for the mixture of two fluid types. Based on the correlation of geological history with our data, two infiltration models of meteoric waters can be constructed. According to the chemical and isotopic compositions of the waters, an east fluid regime (Group 1) and a west fluid regime (Group 2) have thus been defined. Better understanding of the subsurface fluid movement patterns may be helpful for the local exploration. Based on the water chemistry, the oilfield waters in the Middle-Lower Ordovician paleokarst reservoir of the Lunnan oilfield is proposed as a mixed result between diagenetically-altered meteoric waters and diagenetically-altered evaporated seawaters in the past. Figure A and B show the possible times of meteoric water entering the reservoir.

Description: This article investigated the effect of soil texture, i.e. 5-min Food and Agriculture Organization soil texture (ST FAO ) and 30' Harmonized World Soil Database soil texture (ST HWSD ), and hydraulic parameters, i.e. US Department of Agriculture soil hydraulic parameters (SP US ) and China soil hydraulic parameters (SP CH ), on the Weather Research and Forecasting (WRF) model simulation in summer in eastern China. Near-surface meteorological fields from 365 automatic weather stations were used to evaluate the performance of WRF. Obvious differences between the two soil texture datasets and the two soil hydraulic parameter datasets were found. The simulated 2-m temperature, 2-m specific humidity, and 10-m wind speed were improved significantly at a 95% confidence interval via bootstrap test when ST HWSD was used. The agreement is weaker as SP US was replaced by SP CH . Soil texture and hydraulic parameters affect surface energy partitioning and the distribution of precipitation. The influence of wilting point on WRF's performance is more significant than other soil hydraulic parameters.

Description: Six-month coupled hindcasts show the central equatorial Pacific cold tongue bias development in a GCM to be sensitive to the atmospheric convective parameterization employed. Simulations using the standard configuration of the Community Earth System Model version 1 (CESM1) develop a cold bias in equatorial Pacific sea surface temperatures (SSTs) within the first two months of integration due to anomalous ocean advection driven by overly strong easterly surface wind stress along the equator. Disabling the deep convection parameterization enhances the zonal pressure gradient leading to stronger zonal wind stress and a stronger equatorial SST bias, highlighting the role of pressure gradients in determining the strength of the cold bias. Superparameterized hindcasts show reduced SST bias in the cold tongue region due to a reduction in surface easterlies despite simulating an excessively strong low-level jet at 1-1.5 km elevation. This reflects inadequate vertical mixing of zonal momentum from the absence of convective momentum transport in the superparameterized model. Standard CESM1simulations modified to omit shallow convective momentum transport reproduce the superparameterized low-level wind bias and associated equatorial SST pattern. Further superparameterized simulations using a three-dimensional cloud resolving model capable of producing realistic momentum transport simulate a cold tongue similar to the default CESM1. These findings imply convective momentum fluxes may be an underappreciated mechanism for controlling the strength of the equatorial cold tongue. Despite the sensitivity of equatorial SST to these changes in convective parameterization, the east Pacific double-Intertropical Convergence Zone rainfall bias persists in all simulations presented in this study.

Description: [1]  We present a comprehensive statistical analysis of small solar wind transients (STs) in 2007-2009. Extending work on STs by Kilpua et al. (2009) to a three-year period we arrive at the following identification criteria: (i) a duration 〈 12 hours, (ii) a low proton temperature, and/or a low proton beta, and (iii) enhanced field strength relative to the three-year average.In addition, it must have at least one of the following: (a) decreased magnetic field variability; (b) large, coherent rotation of the field vector; (c) low Alfvén Mach number; and (d) T e / T P higher than the three-year average. These criteria include magnetic flux ropes. We searched for STs using Wind and STEREO data. We exclude Alfvénic fluctuations. Case studies illustrate features of these configurations. In total, we find 126 examples, ~81% of which lie in the slow solar wind (≤ 450 km s -1 ). Many start or end with sharp field and flow gradients/discontinuities. Year 2009 had the largest number of STs. The average ST duration is ~4.3 hours, 75% 〈 6 hours. Comparing with ICMEs in the same solar minimum, we find the major difference to be that T P in STs is not significantly less than the expected T P . Thus, whereas a low T P is generally considered a very reliable signature of ICMEs, it is not a robust signature of STs. Finally, since the total thermal pressure is comparable to the magnetic pressure (plasma β  ~ 1) force-free modeling of those STs having a magnetic flux rope geometry may be inappropriate.

Description: This paper discusses small solar wind transients (STs) from 1995 to 2014. Using STEREO data, we have more sites from which to study STs near 1 AU. STEREO measurements are compared with Wind observations near the Sun-Earth line. We examined statistically the dependence of ST occurrence frequency on (i) solar cycle phase, as monitored by the sunspot number (SSN), and (ii) solar wind speed. We find dependencies on both: an anti-correlation with SSN, an opposite trend to that of ICMEs, and correlation with slow solar wind (over 80 % in the slow wind). We compare ST distributions during solar maximum year 2003, which had the lowest percentage of slow wind, and minimum year 2009, which had the highest percentage thereof, and show evidence of both dependencies. We give a statistical overview of ST parameters: field strength, B , Alfvén Mach number, M A , and proton beta, β p . They show the same temporal trends as the ambient solar wind, but have twice ( B ) or one half ( M A , β p ) of its average values. In STs, the proton temperature is not below the temperature expected from corotating solar wind expansion. Non-force free models should be used in solar minimum years where β p l a s m a ≈ 1, while the force free models could be used in solar maximum when β p l a s m a 〈〈1. We find that only ∼ 5 % of STs show enhanced values of iron charge states. Our work further supports the 2-source origin of STs, i.e., the solar corona and the interplanetary medium.