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Drylands are characterised by patchy vegetation, erodible surfaces and erosive aeolian processes. Empirical and modelling studies have shown that vegetation elements provide drag on the overlying airflow, thus affecting wind velocity profiles and altering erosive dynamics on desert surfaces. However, these dynamics are significantly complicated by a variety of factors, including turbulence, and vegetation porosity and pliability effects. This has resulted in some uncertainty about the effect of vegetation on sediment transport in drylands. Here, we review recent progress in our understanding of the effects of dryland vegetation on wind flow and aeolian sediment transport processes. In particular, wind transport models have played a key role in simplifying aeolian processes in partly vegetated landscapes, but a number of key uncertainties and challenges remain. We identify potential future avenues for research that would help to elucidate the roles of vegetation distribution, geometry and scale in shaping the entrainment, transport and redistribution of wind-blown material at multiple scales. Gaps in our collective knowledge must be addressed through a combination of rigorous field, wind tunnel and modelling experiments.

Uncertainties over future climatic conditions pose significant challenges when selecting appropriate conservation strategies for heritage sites. Choosing effective strategies is especially important for earthen heritage sites located in dryland regions, as many are experiencing rapid environmentally-driven deterioration. We use a newly developed cellular automaton model (ViSTA-HD), to evaluate the environmental deterioration risk, over a 100-year period, under a range of potential climate and conservation scenarios. Results show increased wind velocities could substantially increase the overall deterioration risk, implying the need for wind-reducing conservation strategies. In contrast, predicted increases in rainfall are not likely to increase the overall deterioration risk, despite greater risk of rain-driven deterioration features. Of the four conservation strategies tested in our model, deterioration risk under all climatic scenarios was best reduced by increasing the coverage of natural, randomly-distributed vegetation to 80%. We suggest this approach could be an appropriate long-term conservation strategy for other earthen sites in dryland regions.

Global drylands host more than USD 1 trillion in resource extraction investments, which serve to reconfigure communities and landscapes. In Mongolia’s Gobi Desert mega-mining brings social challenges and environmental changes that question if nomadic herding and mining can co-exist. Whilst company and community conflict are common, nascent frameworks and mediation models suggest alternate ways to resolve the mining–community conundrum. Here we investigate environmental transformations that herders encounter in the presence of the Oyu Tolgoi mega-mine in Mongolia’s Khanbogd soum (district). Using socio-economic and physical data collected through interviews, field studies and climate records, we assessed local engagement and adaptation to large-scale mining. Combining qualitative and quantitative methods enabled us to examine the implications of mining for herder lives and lands in an integrated way. This study presents a holistic assessment of the roles of herders, governments and mines in reshaping pastoralism. In our chosen case study, we find that—contrary to common narratives—mining and herding can, and do, coexist in Khanbogd soum, though ongoing challenges exist which deserve critical attention.

Drylands are home to over 2 billion people globally, many of whom use the land for agricultural and pastoral activities. These vulnerable livelihoods could be disrupted if desert dunefields become more active in response to climate and land use change. Despite increasing knowledge about the role that wind, moisture availability and vegetation cover play in shaping dryland landscapes, relatively little is known about how drylands might respond to climatic and population pressures over the 21 st century. Here we use a newly developed numerical model, which fully couples vegetation and sediment-transport dynamics, to simulate potential landscape evolution at three locations in the Kalahari Desert, under two future emissions scenarios: stabilising (RCP 4.5) and high (RCP 8.5). Our simulations suggest that whilst our study sites will experience some climatically-induced landscape change, the impacts of climate change alone on vegetation cover and sediment mobility may be relatively small. However, human activity could strongly exacerbate certain landscape trajectories. Fire frequency has a primary impact on vegetation cover, and, together with grazing pressure, plays a significant role in modulating shrub encroachment and ensuing land degradation processes. Appropriate land management strategies must be implemented across the Kalahari Desert to avoid severe environmental and socio-economic consequences over the coming decades.

Drylands are characterised by patchy vegetation, erodible surfaces and erosive aeolian processes. The extreme nature of dryland environments means that semi-arid vegetation cover is often dynamic through time and space, due to complex relationships among plants, soil and transport processes. Understanding how ecogeomorphic processes interact and shape landscape evolution is critical for managing potential environmental and anthropogenic impacts in drylands, since these vulnerable regions are often used for pastoralism, agriculture and habitation. Despite a wealth of vegetation distribution models that simulate distinctive patterning that is often observed in drylands, relatively little is known about the effects of vegetation patch distribution, geometry and scale on the entrainment and transport of aeolian sediment. Empirical and modelling studies have shown that vegetation elements provide drag on the overlying airflow, thus affecting wind velocity profiles and altering erosive dynamics on desert surfaces. However, these dynamics are significantly complicated by turbulence, porosity and pliability effects in canopies. This thesis therefore presents new high-resolution field data for parameterising wind flow around individual plants and vegetation patches. Wind transport models have played a key role in simplifying aeolian processes in partly vegetated landscapes, but they remain challenging in some respects. Most models do not recognise the heterogeneous nature of desert surfaces, and those that do are often computationally expensive to run. Cellular automaton (CA) modelling has been successfully used to simulate dryland ecogeomorphic processes over large spatial and temporal scales. However, no existing CA model explicitly links vegetation growth, wind flow dynamics and sediment flux over a surface. This thesis presents a new CA approach that couples a sophisticated vegetation distribution model with a sediment transport model. The Vegetation and Sediment TrAnsport model (ViSTA) is verified and validated against existing dunefield theory and field datasets. ViSTA is then forced with potential 21st century climate and land use change scenarios, to characterise possible transition scenarios between environmental states in the Kalahari Desert. ViSTA is shown to be a robust geomorphological tool for predicting landscape responses to a variety of human and environmental stresses.

Drylands are home to over 2 billion people globally, many of whom use the land for agricultural and pastoral activities. These vulnerable livelihoods could be disrupted if desert dunefields become more active in response to climate and land use change. Despite increasing knowledge about the role that wind, moisture availability and vegetation cover play in shaping dryland landscapes, relatively little is known about how drylands might respond to climatic and population pressures over the 21 century. Here we use a newly developed numerical model, which fully couples vegetation and sediment-transport dynamics, to simulate potential landscape evolution at three locations in the Kalahari Desert, under two future emissions scenarios: stabilising (RCP 4.5) and high (RCP 8.5). Our simulations suggest that whilst our study sites will experience some climatically-induced landscape change, the impacts of climate change alone on vegetation cover and sediment mobility may be relatively small. However, human activity could strongly exacerbate certain landscape trajectories. Fire frequency has a primary impact on vegetation cover, and, together with grazing pressure, plays a significant role in modulating shrub encroachment and ensuing land degradation processes. Appropriate land management strategies must be implemented across the Kalahari Desert to avoid severe environmental and socio-economic consequences over the coming decades.

BackgroundThere is an increasing interest in beta-blockade as a therapeutic approach to sepsis following consistent experimental findings of attenuation of inflammation and improved survival with beta1 selective antagonist. However, the mechanism of these beneficial effects remains very uncertain. Thus, this study is aimed at investigating the effects of a beta-1 selective blockade on sympathetic/parasympathetic activity in endotoxin-challenged pigs using heart rate variability. The hypothesis is that an adrenergic blockade could promote parasympathetic activity. Indeed, the increase of parasympathetic activity is a mechanism recently described as beneficial in septic states.MethodsFifty-one endotoxin-challenged pigs were studied. After 30 min of endotoxin infusion and 30 min of evolution without intervention, the pigs were randomly assigned the placebo or esmolol treatment and were observed for 200 min. Overall heart rate variability was assessed continuously, in the temporal domain by standard deviation of RR intervals (SDNN, ms),and in the frequency domain by spectral powers of low frequency (LF, ms2 × 103/Hz) and high frequency (HF, ms2 × 103/Hz) bands.ResultsVariations of power in these frequency bands were interpreted as putative markers of sympathetic (LF) and parasympathetic (HF) activity. In LPS treated animals, Esmolol did not increase SDNN, but instead decreased LF and increased HF power.ConclusionThese spectral modifications associated to a beta-blocker treatment after an endotoxemic challenge are interpreted as a significant decrease of sympathetic activity and an indirect increase of vagal autonomic tone.

Following publication of the original article [1], the author reported these required corrections to Fig. 5 and Fig. 6: