Plastic film (PF) mulching is widely applied in agriculture to improve water-use efficiency (WUE) and crop production. However, without efficient recovery, the residual plastic fragments in arable land threaten soil health and food security. Degradable films are generally considered as alternatives to conventional PF to mitigate PF pollution. A 2-year field experiment was conducted in 2016 and 2017 to evaluate the effects of various film mulching treatments (conventional PF mulching, transparent degradable film (TDF) mulching, and black degradable film (BDF) mulching, and no mulching) on soil water availability and summer maize yield in the North China Plain (NCP). Soil moisture, soil water storage, water use, and grain yield were recorded. Below 20 cm depth, soil moisture and soil water storage were higher in film mulching than in no mulching. Conventional PF mulching yielded the best water conservation, especially from sowing to jointing. TDF and BDF were similar in their regulation of soil moisture. Comparing to no mulching, conventional PF and degradable transparent film significantly reduced maize grain yield by 15.4 and 8.0% (average over 2 years), and reduced WUE by 9.4 and 7.8% (average 2 years), respectively. The observed reduction of grain yield in transparent film mulching might be caused by excessive soil temperature, especially at vegetative stages, which potentially accelerates crop senescence. Black film mulching reduced the soil cumulative temperature and prevent crops from being overheated. As consequence, grain yield and WUE of summer maize under BDF covering were significantly increased by 11.1 and 15.6%, respectively, over the 2 years. Therefore, we suggest that BDF can be used to replace conventional plastics to improve crop yield and control environmental pollution in the NCP.

Hydration traits determine much of a lichen’s distribution pattern along a climatic gradient but the mechanisms involved are still incompletely known. A higher abundance of large external cephalodia in wet oceanic than in drier climates has previously been reported in Lobaria amplissima. This study aims to quantify how much more rain L. amplissima thalli with external cephalodia would need to fill their internal water holding capacity (WHCinternal) than thalli without. The mean WHCinternal was 1·8 times higher in thalli with external cephalodia than in those without. The WHCinternal when converted to mm rain needed to saturate an average specimen was 1·37 mm (min–max: 0·55–3·8 mm) for a cephalodiate thallus, whereas an average thallus without external cephalodia needed just 0·76 mm (min–max: 0·36–1·3 mm). Known dewfall rates and rates of water uptake from humid air are far below what is needed to saturate even the cephalodiate thallus with the lowest WHCinternal, implying a stronger dependency on rain for thalli with external cephalodia. Thus, the observed trends in this study are consistent with earlier reports of decreasing frequency of external cephalodia from wet to drier climates.

This study aims to quantify the size-dependency of important hydration traits in Lobaria amplissima, L. pulmonaria and L. virens sampled in sympatric populations on deciduous tree trunks in southern Norway, and to discuss possible implications of species-specific traits for the ecological niches of these old forest cephalolichens. Traits measured were thallus size (area and mass), specific thallus mass (STM), internal (WHCinternal) and external water-holding capacity (WHCexternal), and water content (WC) after shaking and after blotting. Lobaria amplissima had the highest WHCinternal, 2·6 times higher than L. pulmonaria with the lowest WHCinternal. WHCinternal, driven by STM, strongly depended on size. WHCexternal was 28% (L. virens) to 47% (L. pulmonaria) of the WHCinternal. Unlike WHCinternal, WHCexternal did not depend on thallus area, meaning that WHCexternal is proportionally higher for smaller compared with larger thalli. The most widespread species, L. pulmonaria, benefits from a flexible hydration strategy due to low STM, facilitating the use of more diverse water sources than the other two species that depend more on rain, particularly L. amplissima with the highest STM and thus relatively high WHCinternal. For L. virens, a combination of less specialized hydration traits and a low tolerance to higher light intensity probably jeopardizes its survival outside rainforest habitats.

Epiphytes and their associated decomposing litter and arboreal soils (herein, epiphytic material, EM) are ubiquitous features of tropical montane cloud forests (TMCF) and play important roles in ecosystem function. EM intercepts water and nutrients from the atmosphere and from intercepted host tree sources, and may contribute significant inputs of these resources to the forest floor. Despite the importance of EM in the TMCF, a systematic review of the ecosystem roles of EM has not been compiled before. We have synthesized the literature that documents functions of EM in undisturbed TMCFs and discuss how these roles may be affected by disturbances, including changes in climate and land use. The range of EM biomass and water storage in the TMCF varies greatly across sites, with different amounts associated with stand age and microclimate. EM is important as habitat and food for birds and mammals, with over 200 species of birds documented as using EM in the Neotropics. Given its sensitivity to moisture, projected shifts in cloud base heights or precipitation due to changes in climate will likely have a large impact on this community and changes in EM diversity or abundance may have cascading impacts on the ecosystem function of the TMCF.

This study explored whether the yard environment and child hygiene and play behaviours were associated with presence and intensity of Ascaris and hookworm in preschool children and with eggs and larvae in soil. Data were collected using questionnaires, a visual survey of the yard, soil samples and fecal samples collected at baseline and following re-infection. The presence of eggs/larvae in soil was associated negatively with water storage (eggs) but positively with dogs (eggs) and distance from home to latrine (larvae). Baseline and re-infection prevalences were: hookworm (28·0%, 3·4%); Ascaris (16·9%, 9·5%); Trichuris (0·9%, 0·7%). Zero-inflated negative binomial regression models revealed a higher baseline hookworm infection if yards had eggs or larvae, more vegetation or garbage, and if the child played with soil. Baseline Ascaris was associated with dirt floor, dogs, exposed soil in yard, open defecation and with less time playing outdoors, whereas Ascaris re-infection was associated with water storage, vegetation cover and garbage near the home and not playing with animals. Our results show complex interactions between infection, the yard environment and child behaviours, and indicate that transmission would be reduced if latrines were closer to the home, and if open defecation and water spillage were reduced.

We propose a discrete state-space model for storage of urban stormwater in two connected dams using an optimal pump-to-fill policy to transfer water from the capture dam to the holding dam. We assume stochastic supply to the capture dam and independent stochastic demand from the holding dam. We find new analytic formulae to calculate steady-state probabilities for the contents of each dam and thereby enable operators to better understand system behaviour. We illustrate our methods by considering some particular examples and discuss extension of our analysis to a series of three connected dams.