Interactions of diffusion and nonlocal delay give rise to vegetation patterns in semi-arid environments

Abstract Vegetation patterns are a characteristic feature of semi-deserts occurring on all continents except Antarctica. In some semi-arid regions, the climate is characterised by seasonality, which yields a synchronisation of seed dispersal with the dry season or the beginning of the wet season. We reformulate the Klausmeier model, a reaction–advection–diffusion system that describes the plant–water dynamics in semi-arid environments, as an integrodifference model to account for the temporal separation of plant growth processes during the wet season and seed dispersal processes during the dry season. The model further accounts for nonlocal processes involved in the dispersal of seeds. Our analysis focusses on the onset of spatial patterns. The Klausmeier partial differential equations (PDE) model is linked to the integrodifference model in an appropriate limit, which yields a control parameter for the temporal separation of seed dispersal events. We find that the conditions for pattern onset in the integrodifference model are equivalent to those for the continuous PDE model and hence independent of the time between seed dispersal events. We thus conclude that in the context of seed dispersal, a PDE model provides a sufficiently accurate description, even if the environment is seasonal. This emphasises the validity of results that have previously been obtained for the PDE model. Further, we numerically investigate the effects of changes to seed dispersal behaviour on the onset of patterns. We find that long-range seed dispersal inhibits the formation of spatial patterns and that the seed dispersal kernel’s decay at infinity is a significant regulator of patterning.

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Hydrogeomorphic flood hazard evaluation for semi-arid environments

Quarterly Journal of Engineering Geology and Hydrogeology ◽

10.1144/gsl.qjeg.1990.023.04.07 ◽

1990 ◽

Vol 23 (4) ◽

pp. 333-336 ◽

Cited By ~ 9

Author(s):

R. Kenny

Keyword(s):

Flood Hazard ◽

Hazard Evaluation ◽

Arid Environments ◽

Semi Arid

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Exogenously Used 24-Epibrassinolide Promotes Drought Tolerance in Maize Hybrids by Improving Plant and Water Productivity in an Arid Environment

Plants ◽

10.3390/plants10020354 ◽

2021 ◽

Vol 10 (2) ◽

pp. 354

Author(s):

El-Sayed M. Desoky ◽

Elsayed Mansour ◽

Mohamed M. A. Ali ◽

Mohamed A. T. Yasin ◽

Mohamed I. E. Abdul-Hamid ◽

...

Keyword(s):

Drought Tolerance ◽

Agronomic Traits ◽

Water Productivity ◽

Positive Association ◽

Net Photosynthesis ◽

Antioxidant Enzyme Activities ◽

Severe Drought ◽

Arid Environments ◽

Maize Hybrids ◽

Semi Arid

The influence of 24-epibrassinolide (EBR24), applied to leaves at a concentration of 5 μM, on plant physio-biochemistry and its reflection on crop water productivity (CWP) and other agronomic traits of six maize hybrids was field-evaluated under semi-arid conditions. Two levels of irrigation water deficiency (IWD) (moderate and severe droughts; 6000 and 3000 m3 water ha−1, respectively) were applied versus a control (well-watering; 9000 m3 water ha−1). IWD reduced the relative water content, membrane stability index, photosynthetic efficiency, stomatal conductance, and rates of transpiration and net photosynthesis. Conversely, antioxidant enzyme activities and osmolyte contents were significantly increased as a result of the increased malondialdehyde content and electrolyte leakage compared to the control. These negative influences of IWD led to a reduction in CWP and grain yield-related traits. However, EBR24 detoxified the IWD stress effects and enhanced all the above-mentioned parameters. The evaluated hybrids varied in drought tolerance; Giza-168 was the best under moderate drought, while Fine-276 was the best under severe drought. Under IWD, certain physiological traits exhibited a highly positive association with yield and yield-contributing traits or CWP. Thus, exogenously using EBR24 for these hybrids could be an effective approach to improve plant and water productivity under reduced available water in semi-arid environments.

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Mapping of soil degradation in semi-arid environments in the Ouarzazate basin in the south of the Central High Atlas, Morocco, using Sentinel 2 A data

Remote Sensing Applications Society and Environment ◽

10.1016/j.rsase.2021.100548 ◽

2021 ◽

pp. 100548

Author(s):

Abdelouhed Farah ◽

Ahmed. Algouti ◽

Abdellah. Algouti ◽

Mohammed. Ifkirne ◽

Aboubakr Ezziyani ◽

...

Keyword(s):

Soil Degradation ◽

Arid Environments ◽

The South ◽

High Atlas ◽

Central High ◽

Semi Arid ◽

Central High Atlas ◽

Sentinel 2

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Changing perceptions of the effect of plant phenolics on nutrient supply in the ruminant

Australian Journal of Agricultural Research ◽

10.1071/ar9960829 ◽

1996 ◽

Vol 47 (6) ◽

pp. 829 ◽

Cited By ~ 62

Author(s):

JB Lowry ◽

CS McSweeney ◽

B Palmer

Keyword(s):

Phenolic Compounds ◽

Acute Toxicity ◽

Protein Interactions ◽

Nutrient Supply ◽

Arid Environments ◽

Plant Phenolics ◽

Ruminant Nutrition ◽

Forage Plants ◽

Hydrolysable Tannins ◽

Semi Arid

Mammalian metabolism of plant phenolics, initially studied in monogastric animals, gave an emphasis to their toxic and antinutrient effects. Subsequent studies in tropical ruminants and wild herbivores have highlighted the high levels than can occur in some diets and the extensive microbial modification and degradation that can occur in the tract. This paper reviews aspects of plant phenolics as they relate to ruminant nutrition in tropical or semi-arid environments in which some forage plants contain high levels of phenolic compounds. Effects range from occasional acute toxicity of hydrolysable tannins, to acetate-releasing microbial degradations that apparently enable certain phenolics to act as nutrients. The most important and complex effects are those due to tannin-protein interactions. Although these can clearly reduce feed intake, nutrient digestibilities, and protein availability, many of the interactions are still not understood. The diverse effects of plant phenolics on nutrient flow probably result from the balance between adverse effects on some organisms and the rate at which they are degraded or inactivated by other organisms, and improved animal performance can likely be obtained by manipulation of rumen microbial metabolism.

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