Resilience of floodplain ecosystems in a semi-arid environment

Implicit to loss of ecosystem resilience is that systems can shift from one stable state to another as a result of disturbance. We present a conceptual model of ecosystem resilience of floodplains and wetlands in semi-arid environments like those of the Murray–Darling Basin. The model is based on a single state characterised by fluctuating wet and dry phases driven by episodic floods and droughts. It might appear that such a single state is inherently unstable, but stability, and the measure of resilience, is conferred by the capacity of floodplains and wetlands to undergo drought and yet return to a functioning wet phase following inundation as well as to undergo flooding and return to the dry phase following flood recession. Floodplains and wetlands are driven by strong, periodic abiotic disturbances and their ecosystem functions and biogeochemical processes are highly rate-limited, spatiotemporally variable and driven by relatively species-poor assemblages of plants and animals adapted to withstand drought and flooding. Extreme drying due to climatic change and over-allocation of water resources represents the primary mechanism via which resilience is lost.

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Long Term Hydrodynamic Effects in a Semi-Arid Mediterranean Multilayer Aquifer: Campo de Cartagena in South-Eastern Spain

Water ◽

10.3390/w10101320 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1320 ◽

Cited By ~ 2

Author(s):

Juan Domingo-Pinillos ◽

Javier Senent-Aparicio ◽

José García-Aróstegui ◽

Paul Baudron

Keyword(s):

Arid Environment ◽

Anthropogenic Activity ◽

Arid Environments ◽

Aquifer System ◽

Intensive Exploitation ◽

The Mediterranean ◽

Hydrodynamic Effects ◽

Flow Transfer ◽

Semi Arid ◽

Campo De Cartagena

The Mediterranean basin contains many semi-arid environments where aquifers are subject to intensive exploitation, generally to meet irrigation demands. The Campo de Cartagena aquifer is a clear example from such a semi-arid environment, and its hydrodynamic effects have aroused great scientific interest. The main objective of this study is to evaluate the hydrodynamic effects that have occurred in the last century of anthropogenic activity in this aquifer system. This aquifer is subject to intensive exploitation and shows clear deficits in times of drought, with recharge by irrigation playing an important role. This study’s methodology includes groundwater modelling to reconstruct the transient evolution of the aquifer system during the last century, to generate water balances and to illustrate how the evolution of irrigation has, in many ways, changed the aquifer’s groundwater flow pattern. The results delineate the hydraulic communication of the aquifer stratums through specific geological structures, as well as the flow transfer from the Quaternary layer to the Mar Menor and the Mediterranean Sea. The reconstruction of the entire system’s temporal evolution shows a fragile water balance that is supported by surface-water contributions.

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Break-crop effects on wheat production across soils and seasons in a semi-arid environment

Crop and Pasture Science ◽

10.1071/cp14166 ◽

2015 ◽

Vol 66 (6) ◽

pp. 566 ◽

Cited By ~ 13

Author(s):

T. M. McBeath ◽

V. V. S. R. Gupta ◽

R. S. Llewellyn ◽

C. W. Davoren ◽

A. M. Whitbread

Keyword(s):

Field Experiments ◽

Primary Source ◽

Arid Environment ◽

Soil Types ◽

Cereal Crops ◽

Arid Environments ◽

Beneficial Effects ◽

Cereal Production ◽

High Level ◽

Semi Arid

In low-rainfall environments, a high frequency of cereal crops has been favoured for optimising productivity and risk. However, cereals at high intensity often lead to declining water-use efficiency and increasing inputs to cope with emergent nutritional, disease and weed problems. The value of including breaks in the cropping sequence can involve a high level of uncertainty in low-rainfall areas where non-cereal crops are more risky and profitability is largely determined by the subsequent benefit to cereal productivity. In this study, we aimed to improve understanding of the magnitude and primary source of break benefits such as nutrition, water and disease management in a low-rainfall environment where a high level of within-field soil variability can also contribute to uncertainty about the value of breaks. In on-farm field experiments near Karoonda in the South Australian Mallee, breaks were grown in 2009 or 2010 on four distinct soil types across a dune–swale catena. The effect of these breaks on subsequent cereal production was measured for up to 3 years. In addition, the effect of breaks on nutrition and water available, along with disease infection in subsequent cereal crops, was explored and actual yields were compared with nitrogen and water-limited potential yields. Consistent cumulative benefits to subsequent cereal crops of at least 1 t ha–1 after 3 years accrue from breaks grown on the different soil types. The inclusion of breaks had beneficial effects on the cycling and supply of nutrients along with some short-term impacts on infection by Rhizoctonia solani AG8 in subsequent cereals, whereas there were no conclusive effects of breaks on the supply of water to subsequent crops. This study suggests that the inclusion of both legume and brassica breaks is likely to be beneficial to subsequent cereal production where nitrogen is a factor limiting productivity in low-rainfall, semi-arid environments.

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Ecotypic variation between and within two populations of Trifolium tomentosum (woolly clover) from Syria and Western Australia: its success as a colonising species

Australian Journal of Agricultural Research ◽

10.1071/ar99024 ◽

1999 ◽

Vol 50 (8) ◽

pp. 1443 ◽

Cited By ~ 11

Author(s):

Sarita Jane Bennett

Keyword(s):

Western Australia ◽

Function Analysis ◽

Acid Soils ◽

Arid Environment ◽

Arid Environments ◽

Alkaline Soils ◽

Field Station ◽

Ecotypic Variation ◽

Site Variation ◽

Semi Arid

Ecotypic variation was studied between and within populations of Trifolium tomentosum (woolly clover) using seed that was collected from 2 semi-arid environments: Tel Hadya, Syria, and Pingrup, Western Australia. The seed was collected from 64 subplots within a 40-m2 grid at each site and the material was grown at the University of Western Australia Field Station at Shenton Park, Perth. Fifteen morphological characters were scored and were analysed using analysis of variance, principal components analysis, and discriminant function analysis. Material from the 2 sites was separated using multivariate analysis, with the seed from Tel Hadya containing more within-site variation. It is suggested that the lack of within-site variation observed at Pingrup is the result of a number of factors: a limited amount of genetic diversity being present in the original introduced material, a preference of T. tomentosum for alkaline soils rather than the acid soils predominantly occurring in Western Australia, the harsh selection pressures present in a semi-arid environment, and a limited time for genotypes to adapt to specific micro-niches within each environment. The results are used to contribute to our understanding of the success of colonising species in semi-arid environments.

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Genotype by environment interactions for productivity and resistance to gastro-intestinal nematode parasites in Red Maasai and Dorper sheep

Animal Science ◽

10.1017/s1357729800090214 ◽

2004 ◽

Vol 79 (3) ◽

pp. 343-353 ◽

Cited By ~ 12

Author(s):

R. L. Baker ◽

J. M. Mugambi ◽

J. O. Audho ◽

A. B. Carles ◽

W. Thorpe

Keyword(s):

Smallholder Farmers ◽

Arid Environment ◽

Productive Efficiency ◽

Metabolizable Energy ◽

Arid Environments ◽

Genotype By Environment ◽

Nematode Parasites ◽

Humid Environment ◽

Dorper Sheep ◽

Semi Arid

AbstractRed Maasai and Dorper sheep were evaluated for their resistance to gastro-intestinal (GI) nematode parasites (predominantly Haemonchus contortus), productivity and productive efficiency (assessed on a metabolizable energy basis) in experiments undertaken at the Kenyan coast (sub-humid environment) and the Kenya highlands (semi-arid environment). In both ewes and lambs there were few significant genotype by environment (G X E) interactions for either resistance (assessed by faecal egg counts-FEC) or resilience (assessed by blood packed red cell volume-PCV) to GI nematodes. Red Maasai sheep were consistently more resistant (low FEC) and more resilient (high PCV) than Dorper sheep. However, there were significant G X £ interactions for ewe reproductive performance and for ewe and lamb mortality rates and live weights. These interactions were due to very poor performance of the Dorper compared to the Red Maasai in the sub-humid coastal environment and to the much improved performance of the Dorper in the semi-arid environment. When these component traits were combined into estimates of flock productivity and productive efficiency there were highly significant GXE interactions with the Red Maasai sheep being considerably more efficient than Dorper sheep in the sub-humid environment, while in the semi-arid environment there was a negligible breed difference in productive efficiency. The results are discussed in terms of breeding strategies for smallholder farmers and pastoralists managing sheep in low-input systems in sub-humid and semi-arid environments.

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Bats of a semi-arid environment in south-eastern Australia: biogeography, ecology and conservation

Wildlife Research ◽

10.1071/wr9950217 ◽

1995 ◽

Vol 22 (2) ◽

pp. 217 ◽

Cited By ~ 27

Author(s):

IF Lumsden ◽

AF Bennet

Keyword(s):

Species Richness ◽

Conservation Status ◽

Activity Patterns ◽

Arid Environment ◽

Arid Environments ◽

Minor Variation ◽

South Eastern ◽

Eastern Australia ◽

Semi Arid ◽

South Eastern Australia

A total of 2075 captures of 11 taxa of bats was recorded during an extensive survey of the vertebrate fauna of the semi-arid Mallee region of Victoria. A further two species, Pteropus scapulatus and Saccolaimus flaviventris, are known from previous records, thus bringing the total to 13 taxa known from the region. There was a marked seasonality in activity patterns and in reproduction. Activity, as revealed by trap captures, peaked over the spring to early autumn months when daytime temperatures are high and nights are mild. Births occurred from October to December, lactating females were recorded from November to February, and juveniles were trapped between December and late February, with minor variation in timing between species. Morphometric measurements revealed that females were generally larger and heavier than males. There was a high level of overlap of species between broad vegetation types. Woodland habitats, especially Riverine Woodland, tended to have a higher frequency of capture and a greater species richness of bats per trapping event than did Mallee Shrubland. The assemblage of bats in the Mallee region, Victoria, like those in other semi-arid regions of southern Australia, includes species that are widespread in Australia (e.g. Chalinolobus gouldii and Nyctophilus geoffroyi), together with species that primarily occur in semi-arid and arid environments (e.g. N. timoriensis, Scotorepens balstoni and Vespadelus baverstocki). This region, which includes mesic riverine habitats, also supports a group of species that are characteristic of temperate south-eastern Australia (e.g. C. morio, V. regulus and V. vulturnus). In comparison with assemblages from temperate and tropical environmental regions, those from the semi-arid region tend to have a lower species richness with fewer families represented, a higher level of insectivory, and a smaller modal body size. The conservation status of bats from the Mallee region, Victoria, is believed to be secure, although the status of N. timoriensis warrants further attention.

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Impacts of grazing on vegetation dynamics in a sediment transport complex model

Earth Surface Dynamics ◽

10.5194/esurf-9-29-2021 ◽

2021 ◽

Vol 9 (1) ◽

pp. 29-45

Author(s):

Phillipe Gauvin-Bourdon ◽

James King ◽

Liliana Perez

Keyword(s):

Sediment Transport ◽

Vegetation Cover ◽

Current Knowledge ◽

Dynamic Balance ◽

Landscape Management ◽

Arid Environment ◽

Grazing Pressure ◽

Complex Model ◽

Arid Environments ◽

Semi Arid

Abstract. Arid environments are characterized by the complex interaction between vegetation cover, surface soil properties, and the climate. The dynamic balance between these components makes arid environments highly susceptible to swift changes in vegetation cover and surface morphology in response to climate change. Furthermore, arid environments often support grazing activities, which influence other ecogeomorphic processes and alter the stability of vegetation cover in these environments. Despite growing knowledge and the parallel modeling advances to simulate the sediment transport, vegetation distribution, and grazing, in arid environments, relatively little progress has been accomplished on the interaction between all these components. Here we present an adaptation of an already established sediment transport–vegetation cellular automata model (Vegetation and Sediment TrAnsport or ViSTA) that represents landscape dynamics with an agent-based model (GrAM) representing the activity of grazers on the landscape. In this study, our resulting model, ViSTA_GrAM, is subjected to a series of 100-year-long tests that aim to highlight the capacity of the model to represent ecogeomorphic processes linked to vegetation composition, rainfall, wind speed, and grazing pressure. While these simulations do not allow us to evaluate the performance of the new model to reproduce realistic semi-arid environments, they present the capacity of the model to reproduce and explain major feedback complexities between grazers and the vegetation, in addition to providing insight on the vegetation and wind shear sensitivity of the original model. The simulations reinforce our current knowledge of the resilience of grass-based landscapes to foraging activities and highlight the need to identify growth response rates at the species level to fully understand the complexity of the interactions between individual components within arid environments. Overall, the ViSTA_GrAM model presents the foundation for a better assessment of semi-arid environment response to landscape management measures and a better understanding of the complex interactions shaping semi-arid landscapes.

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Does Elevated [CO2] Only Increase Root Growth in the Topsoil? A FACE Study with Lentil in a Semi-Arid Environment

Plants ◽

10.3390/plants10040612 ◽

2021 ◽

Vol 10 (4) ◽

pp. 612

Author(s):

Maryse Bourgault ◽

Sabine Tausz-Posch ◽

Mark Greenwood ◽

Markus Löw ◽

Samuel Henty ◽

...

Keyword(s):

Root Growth ◽

Soil Profile ◽

Root Length ◽

Atmospheric Carbon Dioxide ◽

Co2 Enrichment ◽

Grain Filling ◽

Arid Environment ◽

Yield Response ◽

Arid Environments ◽

Semi Arid

Atmospheric carbon dioxide concentrations [CO2] are increasing steadily. Some reports have shown that root growth in grain crops is mostly stimulated in the topsoil rather than evenly throughout the soil profile by e[CO2], which is not optimal for crops grown in semi-arid environments with strong reliance on stored water. An experiment was conducted during the 2014 and 2015 growing seasons with two lentil (Lens culinaris) genotypes grown under Free Air CO2 Enrichment (FACE) in which root growth was observed non-destructively with mini-rhizotrons approximately every 2–3 weeks. Root growth was not always statistically increased by e[CO2] and not consistently between depths and genotypes. In 2014, root growth in the top 15 cm of the soil profile (topsoil) was indeed increased by e[CO2], but increases at lower depths (30–45 cm) later in the season were greater than in the topsoil. In 2015, e[CO2] only increased root length in the topsoil for one genotype, potentially reflecting the lack of plant available soil water between 30–60 cm until recharged by irrigation during grain filling. Our limited data to compare responses to e[CO2] showed that root length increases in the topsoil were correlated with a lower yield response to e[CO2]. The increase in yield response was rather correlated with increases in root growth below 30 cm depth.

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Seven new vagrant eriophyoid species (Acari: Eriophyoidea) from semi-arid and arid environment in East Iran

Systematic and Applied Acarology ◽

10.11158/saa.25.12.4 ◽

2020 ◽

Vol 25 (12) ◽

pp. 2190-2211

Author(s):

Arash Honarmand ◽

Hussein Sadeghi-namaghi ◽

Enrico De Lillo

Keyword(s):

New Species ◽

Host Plants ◽

Arid Environment ◽

Mite Species ◽

Arid Environments ◽

Field Surveys ◽

Eriophyid Mite ◽

Eriophyid Mites ◽

South Khorasan ◽

Semi Arid

During field surveys of eriophyid mites associated with autochthonous plants species in semi-arid and arid environments in East Iran (Birjand, South Khorasan, Iran, summer 2016 and 2017), seven new eriophyid mite species (Acari: Eriophyidae) were discovered. They are Aceria astratorae sp. nov. on Astragalus pinetorum Boiss. (Leguminosae), Aceria astracanthae sp. nov. on Astracantha echidna (Bunge) Podlech (Leguminosae), Aceria furgae sp. nov. on Ephedra major Host (Ephedraceae), Aceria runicae sp. nov. on Rubia caramanica Bornm. (Rubiaceae), Aculus birsutum sp. nov. on Epilobium hirsutum L. (Onagraceae), Phyllocoptes birreae sp. nov. on Centaurea virgata Lam. (Compositae), and Neophytoptus semenovis sp. nov. on Semenovia suffruticosa (Freyn & Bornm.) Manden (Apiaceae), which are illustrated and described herein. All seven new species appear to be vagrants on green parts of their host plants with no particular symptom.

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Morphological and Chemical Profile of Three Tomato (Solanum lycopersicum L.) Landraces of A Semi-Arid Mediterranean Environment

Plants ◽

10.3390/plants8080273 ◽

2019 ◽

Vol 8 (8) ◽

pp. 273 ◽

Cited By ~ 1

Author(s):

Massimiliano Renna ◽

Massimiliano D’Imperio ◽

Maria Gonnella ◽

Miriana Durante ◽

Angelo Parente ◽

...

Keyword(s):

Great Part ◽

Arid Environment ◽

International Standards ◽

Arid Environments ◽

Quality Traits ◽

Local Varieties ◽

Solanum Lycopersicum L ◽

New Varieties ◽

Chemical Traits ◽

Semi Arid

Puglia (Southern Italy), particularly rich in tomato agro-biodiversity, can be considered a typical region of the semi-arid Mediterranean environments. In this study, three local varieties of tomato (Manduria, Giallo di Crispiano and Regina) were characterized by using morphological descriptors according to international standards. Chemical (isoprenoids, ascorbic acid, total phenols, sugars and mineral content) and agronomic assessment were carried out to highlight the specific traits of these local varieties well adapted to a semi-arid environment. Data of morphological traits according to the “International Union for the Protection of New Varieties of Plants” (UPOV) guideline evidenced a clear distinctness among all three landraces, especially as regards fruits. Results also highlighted that a great part of variation in chemical traits was almost exclusively due to genotypes, while in a few cases observed differences resulted from the interaction between genotype and harvest time. The results of the present study may represent the first step toward the recognition of “conservation variety” status for Regina, Giallo di Crispiano and Manduria tomato landraces. At the same time, both quality traits and agronomic performance of these tomato genotypes suggest the possibility of their cultivation in other semi-arid environments also considering their quality traits, in view of a sustainable production.

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