Halophytic Plants for Animal Feed: Associated Botanical and Nutritional Characteristics

By Salah Abdelaty Attia-Ismail

Halophytic plants are a fascinating group of plants that also serve as dietary feed for livestock. Their utilization is essential for sustainable agriculture and maintaining ecological balance. This book explains the nature of halophytic plants through an in-depth presentation of their botanical and nutritional characteristics. Chapters of the book highlight different aspects of halophytes on a botanical, histological, ecological and nutritional basis when utilized as animal feed components. The issues of the histo-chemical aspects of halophytes are addressed with regard to their impact on nutrient compositions and availability to animals, while the important nutrient contents of halophytes are considered in relation to their value to animals.

Key Features:

- 10 organized chapters on halophytic plants

- Explains the relationship between botanical and nutritional characteristics of halophytes when utilized as animal feed components

- Covers information about important nutrient contents and secondary metabolites in halophytes

- Includes information on nutritional and feeding values for animals

- Includes informative diagram and tables

- Includes references for further reading

This book fills a notable gap in available literature on the subject, and will stimulate researchers to pursue the many unanswered questions in the field of biosaline agriculture. This text serves as reading material for undergraduate and graduate level courses and specializations in agriculture, animal nutrition, animal physiology, botany and plant physiology. It also serves as supplementary reading for students of taxonomy, ecology, and environmental science courses. Professional and apprentice livestock farmers will also benefit from the information presented by the book.

• Language: English
• Publisher: Bentham Science Publishers
• Release date: Jun 9, 2022
• ISBN: 9789815050387

Book preview

World Halophytes Biodiversity, Ecophysiology

Salah Abdelaty Attia-Ismail

Abstract

Halophytes are plants that initiate their growth, accomplish their life course, and outlive others in a salty environment. The word halophytes has two syllables (halo = salt, phyte = plant). However, halophytes vary greatly with respect to salt tolerance. This chapter discusses the soils in which halophytes grow and the climate as well as their effects. The halophyte biodiversity in different regions of the world is reviewed.

Keywords: Asia, Australia, Biodiversity, Climate, Ecophysiology, Europe, Halophytes, Mediterranean, Soil, The Arab region, World.

INTRODUCTION

Halophytes are plants that initiate their growth, accomplish their life course, and outlive others in a salty environment (soil and/or irrigation water); many of them survive in seawater or sometimes in higher concentrations of salts. Halophytes bear morphological, anatomical, and physiological aspects that enable them to grow in this environment. Therefore, they could be representative vegetation of these areas. Halophytes could also grow in other kinds of soils. However, salinity is not a condition for these plants to grow and survive.

Ecosystems For The Halophytes

The word halophyte has two syllables (halo = salt, phyte = plant). These plants have a tolerance to the electrical conductivity of 7.8 dS m-1 at least during critical plant growth periods (Aronson 1989). However, halophytes vary greatly in salt tolerance. The word 'halophyte' does not refer to any specific taxon or a certain geographic or Physio-geographic area. Halophytes grow in many arid and semi-arid regions around the world and are distributed from shoreline areas to inland mountains and deserts. The environment that halophytes survive in does not include soil and irrigation water alone but also includes the climate that affects other factors. Soil is, therefore, inseparable from the indispensable weather factors and other biological processes. In the following section, there is a discussion about the soils in which halophytes grow, the climate, and their effects.

Soil

The soil is the natural medium in which halophytic plants grow. Some scientists (e.g., Szabolcs 1994) consider the soil the ecosystem itself since it has most of the requirements needed for the plant to grow (e.g., solid, liquid, gaseous), living and non-living substances (plants, animals, and microbes), and has its own energy and material fluxes. Saline soils are, therefore, sinks of mineral nutrients and organic matter for the halophyte vegetation. Saline soils are zones of transition between terrestrial and aquatic ecosystems, or a "dynamic buffer between land and sea" as stated by Boorman (1999). Salt marshes are suitable for the growth of halophytes, which actually occupy these areas the most. Halophytic vegetation, on the other hand, affects the soil composition.

Chaudhary et al. (2017) concluded that halophytes act effectively to modify the microbial structure of soils because halophyte species strongly affect the below-ground processes. These authors observed increased activity of enzymes in halophyte-covered soils. Also, since halophytes can accumulate and exclude salt, several halophyte species can remove the salt from different types of salt-affected soils through the so-called Phyto-remediation process (Hasanuzzaman et al. 2014). Karakas et al. (2017) and Shabala (2013) concluded that halophytes have the potential ability to extract significant quantities of salt from soils.

Dudal and Purnell (1986) estimated that 7-10% of the world’s land areas are salt-affected (of which 3% are saline or sodic soils (FAO 1989)). Glenn et al. (1997) demonstrated the potential areas in the global drylands and coastal deserts where halophytes might grow to exceed 150 million hectares (Squires, 1998). The estimates of the saline solonchak soil area (Fig. 1) vary from 260 to 340 million hectares (FAO 2017).

Table 1, cited from Kovda and Szabolcs (1979), shows rough estimates of the areas of salt-affected soils in the world. Clearly, not a single continent is free of that kind of soil. Salt-affected areas are found everywhere on earth. However, salt-affected soils have five main groups, according to Szabolcs (1994). These main groups are saline, alkali, magnesium, gypsiferous, and acid sulphate soils.

Fig. (1))

Distribution of saline soils (solonchak soils) based on world reference base for soil resources.

Table 1 Areas of salt-affected soils in different regions of the world.

Climate

The type of vegetation that grows in a particular area is heavily influenced by the climate. Generally, there is a close correlation between climate and vegetation, which, in turn, is a sensitive indicator of the climate. Climate, on the other hand, is the long-term weather condition in a specific area of the earth. The climate depends on the region’s latitude, altitude, and topography. There are three main climatic zones in the atmosphere: the polar zone, the temperate zone, and the tropical zone. Fig. (2) shows the distribution of these zones. Atmospheric temperature and precipitation control the distribution of these main zones. The polar zone is the coldest and most frozen zone. The temperate zone has a moderate temperature and more rain, while the tropical zone has the hottest temperature with the highest precipitation rates.

Fig. (2))

Distribution of climate zones on earth.

The climate of the temperate regions has two types: maritime and continental (inland). The maritime climate has almost constant temperatures and is affected by the oceans; it prevails on the western boundaries of the continents. Warmer summers and colder winters are characteristics of a continental climate because of the effect of land on heat. In general, the temperate climate has no extremes in either temperature or precipitation. The tropical climate is a warm, humid one and sometimes has droughts with large diurnal variations in temperature. Humid, semi-humid, semi-arid, and arid are divisions of the tropical climate.

Soil/Climate Interaction

Both climate and vegetation profoundly affect the soil. Traditional plants may not be able to grow in these types of soils (salt-affected soils), but halophytes can. There is an interrelation between the agricultural areas of the world (arid, semi-arid, humid, and sub-humid) that finally affects the growth of halophytes. Fig. (3) shows the distribution of the agricultural areas of the world, while Table 2, cited from Szabolcs (1994), shows how the soil type, which correlates with climate, affects the type of growing halophytes. The composition of each soil type affects the type of growing halophyte. For instance, Salicornia berbera, Salsola soda, S. crassa, Suaeda microphylla, Tamarixs, and Carexes grow in saline soils with high concentrations of sodium chloride and sulfate. Alkaline soils with sodium ions, which have the ability of alkaline hydrolysis, are suitable for the growth of Artemisias, Statice gmelini, various Festucas, and Melilotuses. Magnesium ion-rich soils suit the growth of Spergularia salina, Suaeda maritima, etc. The soils rich in calcium sulfate ions (Gypsiferous soils) allow Ligneum spartum, Limonium delicatulum to grow. Acid sulfate soils allow various reeds, mangroves, white cedar, etc., to grow.

Fig. (3))

Distribution of the agricultural areas of the world.

Table 2 Effect of the soil type in correlation with climate on the type of growing halophytes.

World Halophytes Biodiversity

Salt-affected soils may contain saline soils, sodic soils, or both saline and sodic soils. High salinity is defined as concentrations of sodium chloride in soil water of more than 0.5% or 85 mM NaCl, and saline soils have an electrical conductivity equal to or greater than 5 mmho cm-1 (Le Houerou 1994). Halophytes, therefore, have physiological adaptations that allow for the growth and development of the plant in a saline environment. Because of this adaptation, halophytes grow in many ecosystems, especially salt-affected soils. Therefore, they have spread widely all over the world. They are found in warm areas as well. Waisel (1972) mentioned that the percentage of halophytes in many regions (multiregional) is higher than glycophytes. Most of the halophytes in the world belong to the families Chenopodiaceae, Poaceae, Leguminosae, Papiliondeae, Asteraceae, and Cyperaceae (Table 3, cited from Flowers et al., 1986 and Ghazanfar et al., 2014). However, Atriplex species seem to be the most widely spread halophytes (Table 4, cited from O’Leary and Glenn 1994).

Table 3 Families of flowering plants in which halophytic genera worldwide occur most often.

Table 4 Distribution of Atriplex species on a geographical basis.

Halophytes do not belong to a specific taxonomic group; rather, they fall into several categories. For instance, Batanouny (1994) mentioned that the Arab region’s flora comprises 150 species from 55 genera and 22 families. About 6,000 species in the world include halophytes. Halophytes have about 1500 species (O’Leary and Glenn 1994). Halophytes are present in the form of several species of trees, shrubs, forbs, and grasses. The form varies considerably (depending on the region) from grasses (predominating in temperate areas) to woody plants (predominating in warm areas and inland saline soils). They represent a major part of the natural ranges, particularly perennials and shrubs (Zahran 1982), which seem to be a characteristic of most halophytic flora. On the other hand, mangroves, which are woody halophytes, are other characteristics of the halophytes.

The term salt tolerant plants includes, in addition to halophytes, other plants that are not halophytes in nature but rather tolerate higher salt concentrations. In this context, the number of species would increase. The life form of halophytes exhibits a range of variations, giving them the great biodiversity that we experience.

Halophytes Biodiversity in the Mediterranean Basin and Arab Region

Geographically speaking, the Mediterranean area in its broad meaning refers to the area from the Aral Sea to the Atlantic Ocean. Irregular rainfall and a low annual rate (falls mostly in winter) are characteristics of the Mediterranean climate. The summer weather is dry, and the temperatures range from warm to hot. This means a high evaporation rate. The weather in the winter is mild and wet. The native vegetation of the Mediterranean is composed primarily of arboreal and shrubby sclerophyllous plants. Plant biology and ecology of the Mediterranean basin’s halophytes vary considerably. Halophytes constitute about 700 species. They include both perennial and annual species. They are also divided into shrubs and trees. Table 5, cited from Le Houerou 1993 and 1994, shows different proportions of different halophytes in the Mediterranean Basin. Chenopodiaceae is dominant among plant communities, either alone or mixed with other types of plants. Halocnemum strobilaceum, Arthrocnemum indicum, Salicornia, Salsola, Sueda, and Atriplex plants are examples of that dominance.

Table 5 Proportions of different halophytes in the Mediterranean Basin.

Batanouny (1994) reviewed communities of halophytic plants in the Arab region. The area partially includes a large proportion of the Mediterranean Basin, part of West Asia, and parts of East and West Africa. So, it has a variety of halophytes. The halophytes in the Arab area represent less than 5% of the flora of the area. Soil salinity in both the Mediterranean Basin and the Arab world varies from place to place with different types of salt distribution. This author recorded a few annual species, which are usually succulent, like Salsola europaea, Binertia cyclopetra, Sueda aegyptiaca, Sueda salsa, and Halopeplis amplexicaulis. The main halophyte families are Chenopodiaceae, Gramineae, Aizoaceae, Avicenniaceae, Caryophyllaceae. Compositae, Convolvulaceae, Cynomoriaceae, Cyperaceous, Frankeniaceae, Juncaeae, Leguminosae, Nitrariaceae, Plantaginaceae, Plumbaginaceae, Rhizophoraceae, Salvadoraceae, Tamaricaceae, Typhaceae, and Zygophyllaceae.

Halophytes Biodiversity In Asia

The Region of China

China is a big country that has a great variety in latitude, longitude, and altitude, leading to an extremely diverse climate. The climate there ranges from tropical to sub-arctic. Winter temperatures vary considerably, yet the variations in summer temperatures are less. Rainfall is almost invariably concentrated in the warmer months.

About 500 species of halophytic, representing 226 genera, 58 families, and 38 orders, occur in China (Table 6, cited from Wu 1980, Hou 1982). These species are widely spread all over China in a variety of ecological zones, including marine and inland saline waters, sandbanks, seashores, and saline soils (Kefu et al. 1994).

Table 6 Percent of halophytes families present in China.

Since the area of China is vast enough and because of its unique location, all climatic zones (i.e., cold temperate, temperate, warm temperate, subtropical, and tropical) are present there. Therefore, the halophytic floristic composition and species diversity (Kefu et al. 1994) include:

Mangrove includes Rhizophora stylosa, R. apiculata, R. mucronata, Bruguiera gymnorhiza, B. cylindrica, B. sexangula, Kandelia candel and Ceriops tagal, Avicennia marina, Acanthus ebracteatus and A. ilicifolius, Myoporum bontioides, Lumnitzera racemosa, Excoecaria agallocha, Aegiceras corniculatum, Hibiscus tiliaceus, Sonneratia caseolaris, S. hainanensis, Xylocarpus granatum, Scyphiphora hydrophyllacea and Heritiera littoralis with some halophytes included like Nypa fruticans, Clerodendron inerme, Pongamia pinnata, Cerbera manghas, Barringtonia racemosa, Calophyllum inophyllum, Thespesia populnea, T. populnea, Scyphiphora hydrophyllacea, Scaevola sericea and S. hainanensis).

Halophytic shrub thicket (in six formations): formation (1) is Tamarix chinensis (include Suaeda salsa, S. glauca, Aeluropus littoralis var. sinensis, Phragmites communis, Limonium bicolor, Apocynum venetum, Imperata cylindrica var. major, Crypsis aculeata, Chenopodium album, Salsola collina and Artemisia capillaris); formation (2) is Tamarix ramosissima (including Halimodendron halodendron, Populus euphratica, Tamarix elongata, T. pseudo phragmites, Aeluropus littoralis, Alhagi sparsifolia, Sophora alopecuroides, Glycyrrhiza inflata, Poacynum hendersonii, Karelinia caspia, Scorzonera divaricata, Cynanchum sibiricum, Halocnemum strobilaceum, Phyllostachys heteroclada, Kalidium cuspidatum and tatum ruthenicum); formation (3) is Tamarix hispida (including Salicornia europaea, Suaeda spp., Karelinia caspia, Phragmites communis and Aeluropus littoralis); formation (4) is Halimodendron halodendron (including Achnatherum splendens, Aneurolepidium dasystachys, Sophora alopecuroides, Glycyrrhiza inflata, Karelinia caspia and Lycium ruthenicum); formtion (5) is Nitraria tangutorum (including Wamanx spp., Lycium ruthenicum, Alhagi sparsifolia, Karelinia carpia, Achnatherum splendens, Phragmites communis, Sophora alopecuroides and Glaux mantima), and formation (6) is Nitraria sibirica (including Lycium ruthenicum, Kalidium foliatum, Anabasis aphylla, Achnatherum splendens and Phragmites communis).

Small shrub desert: its halophytic group is semi-shrubs (like Halostachys belangeriana, Halocnemum strobilaceum, Atriplex canescens, Suaeda spp., and Kalidium spp. along with Tamarix hispida, T. ramosissima, T. elongata, Lycium ruthenicum, Nitraria sibirica, Karelinia caspia, Glycyrrhiza inflata, Limonium gmelinii, Salicornia europaea, Camphorosma lessingii, Phragmites communis, Achnatherum splendens, Cistanche salsa, Halogeton arachnoideus, Anabasis aphylla, Zygophyllum pterocarpum and Halimocnemis villosa.

Halophytic grassland (perennial halophytes divided into five principal communities, e.g., clump grass, rhizome grass, Cyperus, perennial herbaceous, and annual herbaceous halophytes). They include different formations like Achnatherum splendens, Puccinellia tenuiflora and P. distans, Fimbristylis sericea, Iris lactea var, Apocynum lancifolium, Alhagi sparsifolia, and

Aquatic vegetation has seven forms of five families: the formation (Zostera spp.) include Z. marina and Z. nana, the formation Ruppia rostellata, the formation Halodule spp., the Cymodocea spp., the formation Halophila spp., and the formation Enhalus spp. (Kefu et al. 1994).

The Region of Central Asia

The area of Central Asia has different ecological habitats and high plant diversity. Toderich et al. (2009) surveyed the floristic composition of vegetation of salt-affected lands and found more than 380 species of different groups of salt-tolerant plants with wild halophytes representing 19 taxonomical families. Percentages of halophytes, including families of rangelands in Central Asia, are present in Table 7, cited from Toderich et al., 2009. These authors described the halophytes there in terms of certain criteria. The halophytes that grow in high salt environments (100 dS m-1) include Climacoptera longistylosa, Climacoptera kasakorum, Climacoptera bucharica, Climacoptera crassa, Climacoptera subcrassa, Salsola transoxana, Climacoptera ferganica, Climacoptera aralensis, Climacoptera turcomanica, Climacoptera turgaica, Climacoptera intricata, Climacoptera turcomanica, Plantago coronopus L., Salicornia spp., Halostachys belangeriana Botsch; Halocnemum strobilaceum, Petrosimonia crassifolia, Petrosimonia litwinowi, Halocladius variabilis, and Halogeton glomeratus. Halophytes that grow in salt concentration up to 10,000 ppm include Phragmites australis, Phragmites communis, Arundo spp., Typha ssp. Hippophae rhamnoides, Populus diversifolia, Elaeagnus angustifolia.

Table 7 Percent of halophytes including families of rangelands in Central Asia.

Other halophytic species include Suaeda, annual Salsola spp.; Aeluropus repens (Desf.) Parl., Aeluropus littoralis (Gouan) Parl, Aeluropus villosus Hook, Aeluropus littoralis; Tamarix hispida, Tamarix androssowii, Tamarix ramosissima; Dactylis littoralis (Gouan) Wild, Kochia scoparia L.

Li-Yun et al. (1994) mentioned that the Chenopodiaceae family is the richest among others in diversity, with over 100 species. They classified almost 150 species from nearly 20 families of halophytes in the area located in Inner Asia into seven communities of halophyte plants. These are

1- Succulent semi-shrub deserts such as Halocnemum strobilaceum, Halostachys caspica, Kalidium foliatum, K. caspicum, K. gracile, K. cuspidatum, Suaeda physophora, S. dendroides, and S. microphylla (dominating spp.).

2- Semi-shrub and mini-shrub deserts such as Reaumuria soongorica, Atriplex cana, Camphorosma lessingii, Anabasis salsa, A. brevifolia and Salsola passerina (dominating spp.).

3- Mini-semi tree desert such as Haloxylon ammodendron (dominating spp.).

4- Annual halophytic herbosa such as Halogeton glomeratus, H. arachnoideus, Salicornia europaea, Salsola lanata, S. ruthenica, S. collina, S. subcrassa, S. nitraria, S. foliosa, Suaeda acuminata, Suaeda salsa, Petrosimonia sibirica, P. brachiata, and P. glaucescens (dominating spp.)

5- Salinized scrub such as Tamarix ramosissima,T. hispida, T. laxa, T. leptostachya, T. elongata, T. hohenackeri, T. ladachensis, Nitraria sibirica, N. schoberi, Lycium ruthenicum, and Halimodendron halodendron.

6- Salinized meadow such as Achnatherum splendens, Phragmites australis, Aeluropus littoralis, Aneurolepidium dasystachys, Poacynum hendersonii, Sophora alopecuroides, Alhagi sparsifolia, Glycyrrhiza inflata, G. glabra, Oxytropis glabra, Limonium gmelinii and Karelinia caspica.

7- Salinized tugayi like Populus euphratica, P. pruinosa and Elaeagnus oxycarpa.

The Region of West Asia

This area falls mainly within the class of arid environments. The rainfall rate is less than 400 mm in most of the area. In southwest Asia, records of halophytes (Table 8, cited by Ghazanfar et al. (2014) and Flowers et al., (1986) total 728 taxa. This number of taxa of halophytes is combined with almost half that of the world (Aronson 1989). The Black Sea coastal salt marsh includes Aeluropus littoralis, Artemisia caerulescens, A. caerulescens, A. santonicum, Athrocaulon macrostachyum, Tripolium pannonicum, Atriplex calotheca, Spirobassia hirsuta, Carex extensa, C. distachya, Centaurium tenuiflorum, Centaurea dracunculifolia, Elymus athericus, Elymus elongatus, Limbarda crithmoides, Iris spuria, Juncus acutus, J. maritimus, J. subulatus, Gladiolus communis, Gypsophila tomentosa, Halocnemum strobilaceum, Halimione portulacoides, Frankenia hirsuta, F. pulverulenta, Limoniastrum monopetalum, Limonium oblanceolatum, L. bellidifolium, L. gmelini, L. narbonense, L. ovalifolium, Limonium supinum, L. virgatum, Linum maritimum, Lotus preslii, L. tenuis, Plantago crassifolia, P. cornuti, P. maritima, Rumex pulcher, Puccinellia convoluta, P. festuciformis, Schoenus nigricans, Salsola soda, Salicornia fruticosa, S. perennis, Jacobaea aurícula, Sonchus crassifolius, S. maritimus, Suaeda maritima, S. splendens, S. vera, and Triglochin bulbosa.

Table 8 Some halophytic families in SW Asia.

Al-Jaloud et al. (2001) listed some of the halophytic plants present in Saudi Arabia and found that these halophytes are diverse (shrubs, annual herbs, perennial grasses, perennial rush, and perennial sedge). Table 9 (cited from Al-Jaloud et al. 2001) shows halophytes in different parts of this country.

Table 9 Some botanical and ecological information on the halophytes in Saudi Arabia.

Halophytes Biodiversity in Europe

Sciandrello and Tomaselli (2014) recorded plant communities of the Salicornia fruticosa class in Apulia (Italy). They divided halophytes into halophilous and halo-nitrophilous communities. The halophilous include the hypersaline communities of Arthrocnemum glaucum, Athrocaulon macrostachyum communities, and Halocnemum strobilaceum communities, Salicornia alpini communities and Aeluropus littoralis communities, Salicornia fruticosa and Inula crithmoides, Artemisia caerulescens. The other class of halophyte communities is the halo-subnitrophilous, which includes communities of Sedum brevifolium.

Sera (2017) reviewed salt-tolerant trees used in Central European cities and divided them into either tolerant to contact with salt, tolerant to saline soil, or tolerant to both saline soil and contact with salt. The list of these species includes Acer campestre, Acer platanoides, Acer pseudoplatanus, Acer tataricum, Aesculus carnea, Aesculus hippocastanum, Ailantus altissimus, Alnus cordata, Alnus glutinosa, Alnus spp., Amelanchier spp., Betula pendula, Caragana arborescens, Colutea arborescens, Corylus colurna, Elaeagnus angustifolia, Fraxinus excelsior, Fraxinus spp., Gleditsia triacanthos, Hippophae rhamnoides, Hippophae salicifolia, Juniperus spp., Laburnum spp., Ligustrum vulgare, Lonicera spp., Lonicera tatarica, Lonicera xylosteum, Lycium barbarum, Picea pungens, Pinus mugo, Pinus nigra, Platanus spp., Populus alba, Populus balsamifera, Populus nigra, Populus simonii, Populus tremula, Prunus spinosa, Quercus robur, Quercus rubra, Quercus spp., Ribes alpinum, Ribes aureum, Robinia pseudoacacia, Robinia spp., Rosa rugosa, Salix alba, Sambucus nigra, Styphnolobium japonicum, Sorbus aria, Sorbus aucuparia, Sorbus intermedia, Spirea vanhouttei, Symphoricarpos albus, Syringa vulgaris, Tamarix spp., Ulmus glabra, Ulmus minor, Ulmus pumila, and Viburnum lantana.

Stevanovic et al. (2016) analyzed the continental halophytic grassland vegetation of Southeastern Europe. They grouped halophytic vegetation into four classes according to the salinity degree of the soils. The first class includes communities on extremely saline and wet soils like Thero-Salicornietea. The second class includes highly saline grasslands (Puccinellietalia). The third class is heterogeneous (different types of saline and alkaline vegetation), steppe grasslands (Artemisio-Festucetalia), and halophytic plants from southern Serbia and R. Macedonia (Puccinellion convolutae). The fourth class includes sub-Mediterranean grasslands from the Molinio-Arrhenatheretea class occurring in habitats with a low salinity level.

Halophyte Biodiversity in the Region of Australia

Wilson (1994) reviewed the halophytic shrubs in semi-arid regions of Australia. He found that the prevailing family in Australia is Chenopodiaceae and that there are about 200 species within the genera Arthrocnemum, Atriplex, Chenopodium, Enchylaena, Maireana, Pachycornia, Rhagodia, Sclerolaena, etc. Table 10 (cited from Cunningham et al., 1981, and Mitchell and Wilcox, 1988) shows the main perennial chenopod species that are grazed by livestock in Australia.

Table 10 The main perennial chenopod species that serve as graze for livestock in Australia.

Halophyte Biodiversity in the Region of the Americas

North America

Glenn et al. (1994) mentioned that North America is a rich continent in halophytes because it has over 200 distinct species occurring in coastal and inland regions. However, inland saline lands have several halophyte species that are closely related to coastal marshes, especially the genera Suaeda, Salicornia, Sesuvium, Spartina, Puccinellia, and Baccharis (Chapman 1974). Jefferies (1977) studied the vegetation of salt marshes at six coastal sites in Arctic North America and found that the existing vegetations were Puccinellia phryganodes, Dupontia fisheri, Carex ramenskii, C. subspathacea, C. ursina, C. misandra, C. aquatilis, Eriophrum angustifolium, Juncus biglumis, J. arcticus, Carex glareosa, Hippuris tetraphylla, Armeria maritima, Cochlearia officinalis, Plantago eriopoda, Potentilla egedii, Primula borealis, Stellaria humifusa, Salix glauca, Elymus athericus, Puccinellia andersonii, Sedum rosea, Alopecurus alpinus, Salix spp., Pedicularis hirsuta, Saxifraga oppositifolia, Tortella fragilis, Tomenthypnum nitens, Cetraria aculeata, Ditrichum flexicaule, Drepanocladus uncinatus, and Nostoc spp.

On the other hand, Ungar (1974) listed halophytic communities in the prairie plains and desert regions of North America as follows: Pascopyrum smithii, Puccinellia nuttalliana, Allenrolfea occidentalis, Ambrosia artemisiifolia, Rumex crispus, Ambrosia psilostachya, Ruppia maritima, Atriplex argentina, Salicornia rubra, Atriplex patula, Schoenoplectus americanus, Chenopodium rubrum, C. album, Scirpus paludosus, Sesuvium verrucosum, Distichlis stricta, Sonchus arvensis, Eleocharis palustris, Spartina gracilis, S. pectinata, Hordeum jubatum, Iva annua, Sporobolus airoides, S. texanus, Kochia scoparia, Phragmites communis, Suaeda depressa, Poa arida, Tamarix pentandra, Polygonum aviculare, P. ramosissimum, Triglochin maritima, Typha anguttsifolia, T. latifolia, and Potamogeton pectinatus.

South America

Brevedan et al. (1994) found that about 150 species can grow in a salt environment. They published a list of halophytes present in South America. Table 11 is an edited version of that table by Brevedan et al. (1994).

Table 11 The species name and life form (LF) of South American halophytes.

Conclusion

Halophytes grow and spread all over the world. They are present on every continent. They grow in salty environments. They, therefore, tolerate high concentrations of salts. They have special mechanisms to adapt to their surrounding environment. The salty environments include salty soils and/or salty irrigation water. They have the ability to survive in nonsalty environments.

Halophytes vary greatly in salt tolerance. Halophytes have the potential ability to extract significant quantities of salt from soils.

However, the type of salty vegetation that grows in a particular area is heavily influenced by the climate. Climate and vegetation combine to have a significant impact on the soil. Also, the composition of each soil type affects the type of growing halophyte.

REFERENCES