Trends in woody vegetation cover in the Kruger National Park, South Africa, between 1940 and 1998

Changes in the cover and density of shrubs and trees were assessed from aerial photographs (1940, 1974 and 1998) as well as from fixed-point photographs taken in 1984 and 1996 in the Kruger National Park, South Africa. Woody cover (trees and shrubs combined) increased by 12% on granite substrates but decreased by 64% on basalt substrates over the past 58 years. Both these figures are expressed in terms of the initial values, respectively. The density of the large tree component of woody vegetation decreased on both substrates. Woody vegetation cover declined as fire return periods became shorter, but the relationship was weak. The increases in woody plant density and cover on granite are thought to be the result of decreased competition from grasses, which in turn is a result of overgrazing by wild herbivores whose numbers have been kept high through the provision of surface water. These effects were not seen on the relatively nutrient-rich basalts, where grasses can recover rapidly even after heavy grazing. The decline in overall woody cover on basalts is interpreted as a result of regular, short-interval prescribed burning over the past 40 years, while the universal decline in large trees seems to result from an interaction between regular, frequent fires and utilization by elephants. The implications for management are discussed.     

Biochar in Co-Contaminated Soil Manipulates Arsenic Solubility and Microbiological Community Structure,and Promotes Organochlorine Degradation

We examined the effect of biochar on the water-soluble arsenic (As) concentration and the extent of organochlorine degradation in a co-contaminated historic sheep-dip soil during a 180-d glasshouse incubation experiment. Soil microbial activity, bacterial community and structure diversity were also investigated. Biochar made from willow feedstock (Salix sp) was pyrolysed at 350 or 550°C and added to soil at rates of 10 g kg^-1 and 20 g kg^-1 (representing 30 t ha^-1 and 60 t ha^-1). The isomers of hexachlorocyclohexane (HCH) alpha-HCH and gamma-HCH (lindane), underwent 10-fold and 4-fold reductions in concentration as a function of biochar treatment. Biochar also resulted in a significant reduction in soil DDT levels (P < 0.01), and increased the DDE:DDT ratio. Soil microbial activity was significantly increased (P < 0.01) under all biochar treatments after 60 days of treatment compared to the control. 16S amplicon sequencing revealed that biochar-amended soil contained more members of the Chryseobacterium, Flavobacterium, Dyadobacter and Pseudomonadaceae which are known bioremediators of hydrocarbons. We hypothesise that a recorded short-term reduction in the soluble As concentration due to biochar amendment allowed native soil microbial communities to overcome As-related stress. We propose that increased microbiological activity (dehydrogenase activity) due to biochar amendment was responsible for enhanced degradation of organochlorines in the soil. Biochar therefore partially overcame the co-contaminant effect of As, allowing for enhanced natural attenuation of organochlorines in soil.     

Long-Term Cognitive and Behavioral Outcomes following Resolution of Sleep Disordered Breathing in Preschool Children

This study aimed to determine the long term effects of resolution of SDB in preschool children, either following treatment or spontaneous recovery, on cognition and behavior. Children diagnosed with SDB at 3-5y (N = 35) and non-snoring controls (N = 25), underwent repeat polysomnography (PSG) and cognitive and behavioral assessment 3 years following a baseline study. At follow-up, children with SDB were grouped into Resolved and Unresolved. Resolution was defined as: obstructive apnea hypopnea index (OAHI) ≤1 event/h; no snoring detected on PSG; and no parental report of habitual snoring. 57% (20/35) of children with SDB received treatment, with SDB resolving in 60% (12/20). 43% (15/35) were untreated, of whom 40% (6/15) had spontaneous resolution of SDB. Cognitive reduced between baseline and follow-up, however this was not related to persistent disease, with no difference in cognitive outcomes between Resolved, Unresolved or Control groups. Behavioral functioning remained significantly worse in children originally diagnosed with SDB compared to control children, regardless of resolution. Change in OAHI did not predict cognitive or behavioral outcomes, however a reduction in nocturnal arousals, irrespective of full resolution, was associated with improvement in attention and aggressive behavior. These results suggest that resolution of SDB in preschool children has little effect on cognitive or behavioral outcomes over the long term. The association between sleep fragmentation and behavior appears independent of SDB, however may be moderated by concomitant SDB. This challenges the assumption that treatment of SDB will ameliorate associated cognitive and behavioural deficits and supports the possibility of a SDB phenotype.     

The Effect of Intermittent Antenatal Iron Supplementation on Maternal and Infant Outcomes in Rural Viet Nam: A Cluster Randomised Trial

Background

Anemia affects over 500 million women, and in pregnancy is associated with impaired maternal and infant outcomes. Intermittent antenatal iron supplementation is an attractive alternative to daily dosing; however, the impact of this strategy on infant outcomes remains unclear. We compared the effect of intermittent antenatal iron supplementation with daily iron supplementation on maternal and infant outcomes in rural Viet Nam.

Methods and Findings

This cluster randomised trial was conducted in Ha Nam province, Viet Nam. 1,258 pregnant women (<16 wk gestation) in 104 communes were assigned to daily iron–folic acid (IFA), twice weekly IFA, or twice weekly multiple micronutrient (MMN) supplementation. Primary outcome was birth weight. Mean birth weight was 3,148 g (standard deviation 416). There was no difference in the birth weights of infants of women receiving twice weekly IFA compared to daily IFA (mean difference [MD] 28 g; 95% CI −22 to 78), or twice weekly MMN compared to daily IFA (MD −36.8 g; 95% CI −82 to 8.2). At 32 wk gestation, maternal ferritin was lower in women receiving twice weekly IFA compared to daily IFA (geometric mean ratio 0.73; 95% CI 0.67 to 0.80), and in women receiving twice weekly MMN compared to daily IFA (geometric mean ratio 0.62; 95% CI 0.57 to 0.68), but there was no difference in hemoglobin levels. Infants of mothers who received twice weekly IFA had higher cognitive scores at 6 mo of age compared to those who received daily IFA (MD 1.89; 95% CI 0.23 to 3.56).

Conclusions

Twice weekly antenatal IFA or MMN did not produce a clinically important difference in birth weight, when compared to daily IFA supplementation. The significant improvement in infant cognitive outcomes at 6 mo of age following twice weekly antenatal IFA requires further exploration, and provides additional support for the use of intermittent, rather than daily, antenatal IFA in populations with low rates of iron deficiency.

Trial registration

Australia New Zealand Clinical Trials Registry 12610000944033 Please see later in the article for the Editors'' Summary