Short‐term soil carbon sink potential of oil palm plantations

Oil palm plantations cover ≈14.6 million ha worldwide and the total area under cultivation is expected to increase during the 21st century . Indonesia and Malaysia together account for 87% of global palm oil production and the combined harvested area in these countries has expanded by 6.5 million ha since 1990. Despite this, soil C cycling in oil palm systems is not well quantified but such information is needed for C budget inventories. We quantified soil C storage (root biomass, soil organic matter (SOM) and microbial biomass) and losses [potential soil respiration (R_s) and soil surface CO₂ flux (F_s)] in mineral soils from an oil palm plantation chronosequence (11–34 years since planting) in Selangor, Malaysia. There were no significant effects of plantation age on SOM, microbial biomass, R_s or F_s, implying soil C was in dynamic equilibrium over the chronosequence. However, there was a significant increase in root biomass with plantation age, indicating a short‐term C sink. Across the chronosequence, R_s was driven by soil moisture, soil particle size, root biomass and soil microbial biomass N but not microbial biomass C. This suggests that the nutrient status of the microbial community may be of equal or greater importance for soil CO₂ losses than substrate availability and also raises particular concerns regarding the addition of nitrogenous fertilizer, i.e. increased yields will be associated with increased soil CO₂ emissions. To fully assess the impact of oil palm plantations on soil C storage, initial soil C losses following land conversion (e.g. from native forest or other previous plantations) must be accounted for. If initial soil C losses are large, our data show that there is no accumulation of stable C in the soil as the plantation matures and hence the conversion to oil palm would probably represent a net loss of soil C.     

In vivo vitiligo induction and therapy model: double-blind, randomized clinical trial

In this study, we developed an in vivo vitiligo induction model to explore the underlying mechanisms leading to Koebner's phenomenon and to evaluate the efficacy of therapeutic strategies. The model consisted of 12 pigmented test regions on the back of generalized vitiligo patients that were exposed to three Koebner induction methods: cryotherapy, 755 nm laser therapy, and epidermal abrasion. In addition, four cream treatments (pimecrolimus, tacrolimus, steroid and placebo) were randomly applied. Koebnerization was efficiently induced by all three induction methods. In general, cryotherapy was the best method of Koebner induction, followed by 755 nm laser therapy and epidermal abrasion. Reproducible results were obtained, which showed enhanced depigmented surface areas and higher amounts of T lymphocytes in placebo-treated test zones compared to active treated areas. Tacrolimus and local steroids were better inhibitors of Koebner's process (P < 0.05) compared to pimecrolimus. Our in vivo vitiligo induction model is very informative to investigate vitiligo induction and to determine the efficacy of topical treatments in vitiligo. This proof of concept confirms the efficient comparison of head-to-head therapeutic strategies intra-individually in a standardized, specific and better timed way.     

The role of teachers' expectations in the association between children's SES and performance in kindergarten: a moderated mediation analysis

This study examines the role of teachers' expectations in the association between children's socio-economic background and achievement outcomes. Furthermore, the role of children's ethnicity in moderating this mediated relation is investigated. In the present study, 3,948 children from kindergarten are examined. Data are analysed by means of structural equation modeling. First, results show that teachers' expectations mediate the relation between children's SES and their later language and math achievement, after controlling for children's ethnicity, prior achievement and gender. This result indicates that teachers may exacerbate individual differences between children. Second, children's ethnicity moderates the mediation effect of teachers' expectations with respect to math outcomes. The role of teachers' expectations in mediating the relation between SES and math outcomes is stronger for majority children than for minority children.     

Spatial variation in vegetation and abiotic factors related to the occurrence of a ring‐forming sedge

Abstract. The clonal sedge Carex humilis forms rings of densely aggregated ramets in a dry grassland community in Central Europe. We describe the small‐scale spatial variation, both in abiotic factors and vegetation, in relation to these rings. Compared to the surrounding vegetation the cover of plants, other than C. humilis, was significantly lower both in the central area of rings and within the rings themselves. The vegetation structure was also different. The soil was more fertile in the central area and within the ring than in the surroundings, measured both directly and by the abiotic response values of the vascular plants. We conclude that neither resource depletion nor competition from other plants were likely to be responsible for the low ramet density in the central area of C. humilis rings. Instead, we suggest that the ring form is caused either by the deposition of growth inhibiting substances or by intrinsic morphological rules.     

Mitogenomics reveals high synteny and long evolutionary histories of sympatric cryptic nematode species

Species with seemingly identical morphology but with distinct genetic differences are abundant in the marine environment and frequently co‐occur in the same habitat. Such cryptic species are typically delineated using a limited number of mitochondrial and/or nuclear marker genes, which do not yield information on gene order and gene content of the genomes under consideration. We used next‐generation sequencing to study the composition of the mitochondrial genomes of four sympatrically distributed cryptic species of the Litoditis marina species complex (PmI, PmII, PmIII, and PmIV). The ecology, biology, and natural occurrence of these four species are well known, but the evolutionary processes behind this cryptic speciation remain largely unknown. The gene order of the mitochondrial genomes of the four species was conserved, but differences in genome length, gene length, and codon usage were observed. The atp8 gene was lacking in all four species. Phylogenetic analyses confirm that PmI and PmIV are sister species and that PmIII diverged earliest. The most recent common ancestor of the four cryptic species was estimated to have diverged 16 MYA. Synonymous mutations outnumbered nonsynonymous changes in all protein‐encoding genes, with the Complex IV genes (coxI‐III) experiencing the strongest purifying selection. Our mitogenomic results show that morphologically similar species can have long evolutionary histories and that PmIII has several differences in genetic makeup compared to the three other species, which may explain why it is better adapted to higher temperatures than the other species.