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Morphological and Anatomical Adaptations to Soil and Ground Conditions

Last updated: June 12, 2026EspañolРусский

Morphological and anatomical adaptations of plants to soil and ground (edaphic) conditions represent a set of hereditarily fixed external (morphological) and internal (anatomical) changes in organs and tissues that arise during evolution and ontogeny in response to the complex physicochemical properties of soil and substrate. These adaptations ensure survival, growth, and reproduction of plants under specific substrate conditions – with excess or lack of water, salinity, acidic or alkaline reaction, toxicity of individual ions, nutrient deficiency or, conversely, their excess, as well as under mechanical resistance of the environment (sands, rocks) (Strasburger et al., 1971; Yakovlev et al., 2008).

Soil and ground conditions, or the edaphic factor (from Greek edaphos – soil), are among the leading abiotic factors determining plant distribution and the formation of their life forms (Yakovlev et al., 2008). Unlike climatic factors (light, temperature), the edaphic factor acts directly on underground organs and through them on the entire organism. Its influence is multifaceted and includes:

  • Physical properties – density, water-holding capacity, aeration, mechanical composition (sand, clay, gravel);

  • Chemical properties – pH reaction, salinity (presence of readily soluble salts Na+, Cl-, SO42-), content of macro- and microelements, presence of toxic elements (Al3+, Mn2+, Fe2+);

  • Biological properties – presence of humus, microorganisms, mycorrhizal fungi, which, however, are often considered as a separate biotic factor (Lee, 1998; Serebryakova et al., 2006).

Adaptations to the edaphic factor are inextricably linked with adaptations to water regime (xerophytes, hygrophytes) and temperature factor, but have their own specificity. For example, plants of saline soils (halophytes) can be simultaneously succulent, but their succulence is aimed not only at water storage but also at diluting salts in tissues (Evert, 2006; Chen et al., 2024). Plants of acidic soils (acidophiles, calcifuges) develop aluminum detoxification mechanisms that are fundamentally different from iron uptake mechanisms on calcareous soils (Lee, 1998).

Morphological and anatomical adaptations manifest at all levels of organization – from cell to organ:

  • At the cellular level – thickening of the cuticle, development of a powerful exodermis and endodermis with Casparian strips, formation of specialized cells (idioblasts with calcium oxalate crystals, mucilage cells), changes in the number and size of stomata (Sorokopudov et al., 2018; Evert, 2006).

  • At the tissue level – development of aerenchyma (air-bearing parenchyma) in plants of waterlogged soils, sclerenchyma and collenchyma – for mechanical strength on mobile substrates, water-storage parenchyma – in succulents (Strasburger et al., 1971; Evert, 2006).

  • At the organ level – formation of taproot or fibrous root systems of different depths, formation of adventitious roots, tubers, rhizomes, as well as leaf metamorphoses (reduction, pubescence, transformation into spines) and stems (thickening, lignification) (Serebryakova et al., 2006; Beck, 2010).

The key principle underlying most edaphic adaptations is a trade-off between resource use efficiency and stress protection. For example, the powerful development of the endodermis with Casparian strips, necessary for controlling ion uptake in saline soils, slows down the uptake of water and nutrients when they are deficient (Evert, 2006). Deep roots, which allow water to be extracted in arid conditions, require high energy costs for construction and maintenance (Chen et al., 2024).

In the following sections of the article, we will examine in detail specific groups of plants that have developed specialized adaptations to certain edaphic conditions: psammophytes (living on sands), halophytes (on saline soils), lithophytes (on rocks), calciphytes and calcifuges (on calcareous and acidic soils), as well as plants of specialized substrates (serpentines, peatlands). The study of these adaptations has important applied significance for agriculture (breeding of drought- and salt-tolerant varieties), phytoremediation, and soil bioindication (Ciaccia et al., 2020; Chen et al., 2024).

1. Theoretical Foundations: Types of Adaptive Morphological Syndromes

Before moving on to consider specific ecological groups of plants adapted to particular soil and ground conditions, it is necessary to introduce the fundamental concepts of adaptive morphological syndromes. An adaptive syndrome (or ecomorph) is understood as a complex of interrelated morphological and anatomical traits that arises in plants in response to a specific set of environmental factors and ensures their survival and reproduction under given conditions (Serebryakova et al., 2006).

It is important to emphasize that the edaphic factor (soil and ground properties) never acts in isolation. It is closely linked to the water regime (substrate moisture), and through it to the temperature and salinity regimes. Therefore, the adaptive syndromes listed below were first described in relation to plant responses to water and light, but they fully manifest also in response to specific soil conditions (Strasburger et al., 1971; Evert, 2006).

Three main adaptive syndromes associated with edaphic conditions are distinguished: xeromorphism, hygromorphism (including hydatomorphism), and scleromorphism. In addition, succulence occupies a special place – a specialized type of adaptation combining features of xeromorphism and hygromorphism (Evert, 2006).

1.1. Xeromorphism (from Greek xeros — dry)

Xeromorphism is a set of traits that enable plants to exist under conditions of available water deficit (both in soil and air). Such plants are called xerophytes. In the context of the edaphic factor, xeromorphic adaptations arise in plants growing on:

  • physically dry soils (sands, gravelly slopes),

  • physiologically dry soils (saline soils where water is unavailable due to high osmotic pressure),

  • freezing soils (winter "physiological dryness").

Xeromorphic traits can be aimed at:

  1. Reducing water loss (transpiration):

    • Thickening of the outer walls of epidermal cells and development of a powerful cuticle (sometimes multilayered) (Sorokopudov et al., 2018).

    • Sunken stomata in crypts (depressions often covered with hairs), which reduces the water vapor gradient between the leaf and the atmosphere (Evert, 2006).

    • Reduction in the number of stomata per unit leaf area.

    • Development of dense pubescence (trichomes), which creates a boundary layer of water vapor and reflects solar rays (Strasburger et al., 1971).

    • Rolling or curling of the leaf blade (in grasses), which brings stomata to the inner side of a closed space.

  2. Increasing water uptake and storage:

    • Development of a powerful, deeply penetrating taproot system (e.g., in camel thorn, roots reach 15 m) (Chen et al., 2024).

    • Development of a superficial but very dense fibrous root system for rapid absorption of dew and summer rains (Strasburger et al., 1971).

    • Formation of water-storage parenchyma (succulence – see below).

At the tissue level, xeromorphic plants are characterized by small cell size (reducing cell volume lowers total transpiration surface), increased proportion of sclerenchyma (mechanical tissues do not collapse upon water loss), and poorly developed intercellular spaces (Evert, 2006).

1.2. Hygromorphism (from Greek hygros — moist)

Hygromorphism is a set of traits typical of plants inhabiting conditions of excessive moisture, including waterlogged, boggy, as well as very acidic soils with low aeration (hygrophytes). Paradoxically, in waterlogged acidic soils, plants often experience physiological dryness due to impaired root function and ion toxicity, so hygromorphic traits may be combined with xeromorphic ones (see section on psammophytes and oligotrophs) (Serebryakova et al., 2006).

Hygromorphic traits:

  • Thin, delicate leaves with a thin cuticle or none.

  • Large, often protruding stomata located on both sides of the leaf (amphistomatic).

  • Poor development of mechanical tissues (collenchyma and sclerenchyma), making plants soft and delicate.

  • Presence of large intercellular spaces (aerenchyma) in stems and leaves, especially pronounced in aquatic and marsh plants (Evert, 2006).

Aerenchyma is a special type of parenchyma with very large, well-connected intercellular spaces filled with air or gases. It provides buoyancy (in aquatic plants) and, most importantly, delivers oxygen to roots and other organs submerged in an anaerobic environment (Strasburger et al., 1971). Aerenchyma formation often occurs lysigenously (through programmed cell death and dissolution of cortical cells) in response to flooding, stimulated by ethylene (Evert, 2006; Ciaccia et al., 2020).

1.3. Scleromorphism (from Greek skleros — hard, tough)

Scleromorphism is a set of traits expressed in the development of hard, often spiny leaves and stems with powerful mechanical tissues. In its pure form, scleromorphism is often a consequence of nutrient deficiency, especially nitrogen and phosphorus, on poor, acidic, or peaty soils (oligotrophic substrates) (Serebryakova et al., 2006). The plant cannot grow "soft" biomass and therefore forms slow-growing but strong and long-lived leaves. A classic example is heathlands: leaves of cranberry, lingonberry, heather are small, leathery, with rolled margins, thick cuticle, and often xeromorphic features, despite adequate moisture (Evert, 2006; Lee, 1998).

Scleromorphic traits overlap with xeromorphic ones, but their cause is not water deficit but a deficit of mineral nutrients. Purely scleromorphic plants (without signs of succulence and with normal stomata) are called sclerophytes.

1.4. Succulence (from Latin succulentus — juicy)

Succulence is a special form of adaptation in which the plant stores water in specialized water-storage parenchyma. There are:

  • Leaf succulents (aloe, agave, stonecrop, houseleek) – water is stored in thickened, fleshy leaves. The epidermis is often multilayered, with a thick cuticle and waxy bloom. Stomata are few, sunken. The mesophyll is differentiated into chlorophyll-bearing (assimilatory) and colorless water-storage tissue (Evert, 2006; Chen et al., 2024).

  • Stem succulents (cacti, euphorbias) – water is stored in the parenchyma of the cortex and pith of the stem. Leaves are reduced to spines (protection and reduced transpiration). Stems have ribs that allow them to shrink when water is lost and expand after watering (Strasburger et al., 1971).

Succulence is an effective way to exist under conditions of periodic, not constant, drought (in deserts, semi-deserts, on rocks). Succulents use a special type of photosynthesis – CAM photosynthesis (Crassulacean Acid Metabolism): stomata open at night (when it is cool and humid), CO2 is absorbed and fixed as malic acid; during the day, stomata are closed, and CO2 is released for photosynthesis (Chen et al., 2024).

1.5. Interrelationships and Practical Significance

It is important to understand that the listed syndromes rarely occur in a "pure" form. For example, halophytes (salt-tolerant plants) often combine xeromorphic traits (thick cuticle, pubescence) with succulence and at the same time have specialized salt-secreting glands. And plants of acidic soils (calcifuges) may exhibit scleromorphic traits due to soil poverty and xeromorphic traits due to aluminum toxicity damaging roots and causing physiological dryness (Lee, 1998).

Knowledge of these adaptive syndromes is key to understanding plant distribution, breeding resistant varieties, and sustainable land management. In the following sections, we will show how these general patterns are realized in specific groups: psammophytes, halophytes, lithophytes, etc.

2. Adaptations to Soil Water Regime

Soil water regime is one of the key edaphic factors determining plant survival and distribution. It is characterized both by total moisture content and its availability, which depends on mechanical composition (sand loses water easily, clay retains it, but part of the water may be unavailable due to high sorption), as well as on groundwater depth. In response to the extreme manifestations of this factor – chronic waterlogging (with development of anaerobiosis) or, conversely, constant moisture deficit – plants have developed a range of specialized adaptations, which we will discuss in this section (Strasburger et al., 1971; Evert, 2006).

2.1. Adaptations to Excessive Moisture and Anaerobiosis

Soils with excessive moisture (bogs, floodplains, rice paddies, mangroves) are characterized by low oxygen content – hypoxia or anoxia of the root zone. In addition, under such conditions, toxic reduced forms of iron (Fe2+) and manganese (Mn2+), as well as hydrogen sulfide, often accumulate. The main morphological and anatomical adaptation to this stress is the formation of aerenchyma (Evert, 2006; Ciaccia et al., 2020).

Aerenchyma is a specialized parenchyma tissue with large, well-connected intercellular spaces (air cavities), which can occupy up to 70% of the organ volume. It is formed by two main pathways:

  • Schizogenously – by separation of cells along the middle lamellae without their destruction (e.g., in many sedges).

  • Lysigenously – by programmed cell death (apoptosis) and subsequent dissolution of cells. This process is stimulated by ethylene, which accumulates in roots under hypoxic conditions (Evert, 2006; Lee, 1998).

Aerenchyma performs two essential functions:

  1. Oxygen supply – oxygen diffuses from the aboveground parts (leaves, stems) through the air spaces to the roots. In some species (e.g., mangroves), specialized pneumatophores (respiratory roots) grow vertically upward and are equipped with lenticels for enhanced gas exchange (Strasburger, 1971).

  2. Mechanical protection against toxic substances – aerenchyma also serves as a barrier, reducing the entry of Fe2+ and Mn2+ into the central cylinder where conducting tissues are located (Lee, 1998).

In addition to aerenchyma, plants of waterlogged soils often exhibit:

  • Development of adventitious roots from stem nodes above the water level, allowing oxygen uptake directly from the air (Ciaccia et al., 2020).

  • Formation of giant intercellular spaces in leaves and petioles (in aquatic plants such as water lily), providing buoyancy.

2.2. Adaptations to Soil Moisture Deficit (Xeromorphism)

Plants inhabiting soils with constant or seasonal moisture deficit (sands, rocky slopes, steppes, deserts) are called xerophytes. They exhibit a wide range of adaptations that can be divided into three strategies:

  1. Drought avoidance (ephemerals and ephemeroids) – plants with a very short life cycle that completes before the onset of severe drought. During the dry period, only seeds (ephemerals) or underground storage organs (ephemeroids) survive (Serebryakova et al., 2006).

  2. Active water foraging – formation of a powerful, deep root system (taproot penetrating to groundwater). In camel thorn (Alhagi maurorum), roots reach 15 m (Chen et al., 2024). In desert shrubs, roots can spread laterally for tens of meters.

  3. Economical water use – a set of xeromorphic anatomical traits (see section 1.1), namely:

    • Thick cuticle, often with a waxy bloom (Evert, 2006).

    • Sunken or deeply hidden stomata in crypts (in oleander, crypts are covered with hairs) (Sorokopudov et al., 2018).

    • Well-developed sclerenchyma (hard leaves – sclerophytes), which maintains leaf shape even under severe dehydration (Beck, 2010).

    • Reduction of the leaf blade (in some acacias, leaves are reduced to phyllodes – flattened petioles).

    • Pubescence (trichomes), creating a boundary layer of humid air and reflecting solar radiation (Strasburger, 1971).

A special case of xerophytes are psammophytes – plants adapted to life on shifting sands. In addition to common xeromorphic traits, they have specific adaptations:

  • Ability to withstand burial by sand and form adventitious roots on buried stem portions (e.g., in sand couch grass (Agropyron arenarium)).

  • Powerful development of root caps and ability to rapidly regrow roots when exposed (Serebryakova et al., 2006).

  • Presence of a cork layer on roots (rhizodermis with suberin), protecting against mechanical damage by sand grains (Evert, 2006).

2.3. Trade-offs and Interaction of Factors

It is important to note that "pure" forms are rare in nature. For example, on waterlogged but acidic and poor peat soils, plants (cranberry, wild rosemary, heather) combine hygromorphic traits (aerenchyma) with pronounced xeromorphic ones (hard, leathery leaves with thick cuticle and rolled margins). This is pseudoxeromorphism, caused not so much by water deficit as by mineral nutrient deficiency (especially nitrogen) and phytotoxicity of aluminum (Lee, 1998; Serebryakova et al., 2006). The plant simply cannot grow soft, thin leaves due to resource deficit, so it forms "defensive" hard structures.

Thus, analysis of adaptations to soil water regime requires a systemic approach, considering both direct moisture deficit or excess and associated chemical factors (salinity, acidic reaction, anaerobiosis). In the following sections, we will consider specialized groups where the chemical factor (salinity, pH, toxic elements) comes to the fore.

3. Adaptations to Soil Chemical Properties

Soil chemical composition is a powerful edaphic factor that, together with water regime, determines species distribution and the formation of their morphological and anatomical adaptations. The most significant chemical factors are:

  • Salinity – excess of readily soluble salts (NaCl, Na2SO4, MgCl2, etc.), creating high osmotic pressure of the soil solution and ionic toxicity.

  • pH reaction – acidic soils (pH 3.5–5.5) with increased solubility of toxic ions Al3+, Mn2+, Fe2+; alkaline soils (pH 7.5–8.5) with deficiency of available iron, phosphorus, and many trace elements.

  • Deficiency or excess of nutrients – nitrogen, phosphorus, potassium, calcium, as well as trace elements (B, Mo, Cu, etc.).

  • Heavy metals and other toxicants – serpentine soils with high content of Ni, Cr, Co; technogenically polluted lands.

Plants adapted to extreme chemical conditions exhibit striking examples of convergent evolution – similar morphological and anatomical solutions arise in unrelated species inhabiting similar substrates (Lee, 1998; Chen et al., 2024). The most studied and illustrative groups are halophytes (saline soils), calciphytes and calcifuges (pH reaction), as well as specialized substrates (serpentines, peatlands).

3.1. Halophytes – Plants of Saline Soils

Halophytes (from Greek halos – salt) are an ecological group of plants capable of completing their life cycle under conditions of elevated soil salinity (usually ≥ 0.5% salts in the substrate). They occur on sea coasts, salt marshes, solonetz soils, mangroves, and around salt lakes. Unlike glycophytes (most crop plants), halophytes not only tolerate high NaCl concentrations – for many, salt is a necessary element that stimulates growth (Clark, 2019, cited in Chen et al., 2024).

Edaphic stress on saline soils is twofold: osmotic (water is poorly available due to high osmotic pressure) and ionic (toxic effect of Na+ and Cl-, disrupting enzymatic processes and transport of K\+, Ca2+). Therefore, morphological and anatomical adaptations of halophytes are aimed at:

  1. Regulation of intracellular salt concentration – either by accumulating salts in vacuoles while synthesizing compatible osmolytes in the cytosol, or by excreting excess salts through special glands.

  2. Maintaining water balance – often through succulence (storing water to dilute salts).

  3. Controlling salt entry – through selective permeability of roots and endodermis.

Based on salt homeostasis strategy, halophytes are divided into three main groups (Evert, 2006; Chen et al., 2024):

Euhalophytes – Salt Accumulators

These plants absorb large amounts of NaCl from the soil and accumulate it in cell vacuoles. To protect the cytoplasm, they simultaneously synthesize compatible osmolytes (proline, glycine betaine, sugars, alcohols). High intracellular osmotic pressure allows them to efficiently absorb water even from very saline solutions. Typical examples – Russian thistle (Salsola), seablite (Suaeda), glasswort (Salicornia) (Lee, 1998).

Morphological and anatomical traits of euhalophytes:

  • Succulence of leaves or stems. In glasswort, the entire shoot is transformed into a fleshy, jointed stem with reduced scale-like leaves. Succulence serves a dual role: water storage and salt dilution (Evert, 2006).

  • Small cell size – dense packing of small cells with thick walls, which reduces the central vacuole and limits salt accumulation (Serebryakova et al., 2006).

  • Development of a powerful endodermis with Casparian strips, controlling apoplastic ion transport (Evert, 2006).

  • Presence of water-storage parenchyma (colorless, poor in chloroplasts), whose cells serve as the main depot for Na\+ (Evert, 2006; Chen et al., 2024).

  • At the cellular level – high activity of vacuolar Na+/H\+ antiporters (NHX) and vacuolar H+-pyrophosphatases (V-PPase), ensuring efficient sequestration of Na\+ into the vacuole (Chen et al., 2024).

Cryptohalophytes – Salt Excreters

These plants absorb salts but do not accumulate them in tissues; instead, they excrete them to the outside through specialized salt glands (trichomes or epidermal cells). As a result, intracellular Na\+ concentration remains low, and the plant avoids ionic toxicity. Examples – sea lavender (Limonium), tamarisk (Tamarix), orache (Atriplex) (Lee, 1998).

Morphological and anatomical adaptations:

  • Presence on the surface of leaves and stems of salt-secreting glands – cells with dense cytoplasm and a well-developed endoplasmic reticulum system that actively excrete a concentrated salt solution. Upon drying, salt forms crusts or crystals on the surface (Evert, 2006).

  • In tamarisk, salt glands are arranged as dots on "scale-like" leaves. In orache, salt is excreted by vesicular hairs (trichomes), which then die and fall off.

  • Xeromorphic traits – thick cuticle, often with a waxy bloom, which prevents re-dissolution and reabsorption of excreted salt (Sorokopudov et al., 2018).

  • Well-developed sclerenchyma and lignification (in tamarisk, sea lavender) – protection against wind and sun in open saline areas (Strasburger, 1971).

Haloxerophytes – Salt-Tolerant Xerophytes

They inhabit conditions of both salinity and severe aridity (desert salt marshes, dry solonetz soils). They combine traits of halophytes and xerophytes: deep roots, small hard leaves, thick cuticle, but often without obvious succulence. Their salt tolerance mechanisms can be mixed – partial salt accumulation in roots and old leaves, partial excretion. Examples – black saxaul (Halocnemum), many species of wormwood (Artemisia) on solonetz soils (Lee, 1998).

Anatomical and Physiological Basis of Salt Tolerance at the Cellular Level (data from molecular studies)

Modern comparative studies at the molecular level show that halophytes (and xerophytes) differ from salt-sensitive glycophytes in the following traits (Chen et al., 2024):

  • Increased copy number of genes of the NHX family (vacuolar Na+/H\+ antiporters) and V-PPase (vacuolar H+-pyrophosphatases). This provides a stronger proton gradient and efficient Na\+ sequestration into vacuoles.

  • Lower basal abscisic acid (ABA) content in leaves and altered structure of ABA receptors (PYR/PYL), allowing stomata to respond more quickly to osmotic stress without closing for prolonged periods (Chen et al., 2024).

  • In salt excreters – increased expression of genes encoding plasma membrane and tonoplast Na\+ transporters in gland cells.

Thus, halophytes represent an exceptionally diverse group in morphological and anatomical terms, demonstrating different evolutionary paths to the same goal – survival under high salinity. Their study has paramount applied significance: genes responsible for salt tolerance are increasingly used to create salt-tolerant varieties of crop plants through genetic engineering or marker-assisted selection (Chen et al., 2024). In the next subsection, we will consider adaptations to acidic and alkaline soils (calciphytes and calcifuges).

3.2. Calciphytes and Calcifuges – Adaptations to Soil pH Reaction

Soil acidity (pH) is one of the most important chemical factors determining nutrient availability and solubility of toxic compounds. Depending on the soil solution reaction, plants are divided into three broad ecological groups: acidophiles (prefer acidic soils, pH < 5.5), neutrophiles (optimum pH 6–7), and calciphiles (prefer alkaline or neutral soils, often rich in calcium, pH > 7). However, in classical botanical literature, the dichotomy is well-established: calciphytes (plants of calcareous soils) and calcifuges (plants that avoid calcareous soils and grow mainly on acidic silicate substrates) (Lee, 1998; Serebryakova et al., 2006).

The adaptations of these two groups are diametrically opposed and are associated with two main problems:

  1. On acidic soils – high solubility and toxicity of aluminum ions (Al3+) and manganese (Mn2+), calcium deficiency, molybdenum and phosphorus deficiency (due to binding into insoluble aluminum and iron phosphates), and disruption of the nitrogen cycle (nitrification suppressed, ammonium nitrogen predominates).

  2. On calcareous (limestone) soils – iron (Fe3+) and phosphorus deficiency (due to binding into insoluble calcium phosphate), as well as possible toxicity of bicarbonate ions (HCO3-) and inhibition of K+, Mg2+ uptake due to excess Ca2+ (Lee, 1998; Evert, 2006).

Calciphytes (Calcium-Loving Plants)

Calciphytes (from Latin calx – lime, phileo – to love) are plants that inhabit soils rich in calcium carbonate (CaCO3), with neutral or slightly alkaline reaction (pH 7.0–8.5). Calciphytes can be obligate (grow only on limestones, chalks, dolomites) or facultative (prefer calcareous soils but occasionally occur on other substrates). Typical examples: feather grass (Stipa pennata), woolly cerastium (Cerastium tomentosum), many species of astragalus, as well as crop plants – alfalfa (Medicago sativa), sunflower (Helianthus annuus) at optimal pH (Lee, 1998).

Main stress factors on calcareous soils:

  • Low iron availability: at high pH, Fe3+ forms insoluble hydroxides. Plants develop lime chlorosis (yellowing of leaves due to iron deficiency).

  • Low phosphorus availability: binding into insoluble calcium phosphate (Ca3(PO4)2).

  • High concentration of Ca2+ in the soil solution can inhibit K+ and Mg2+ uptake.

  • Bicarbonate (HCO3-) toxicity at high concentrations.

Morphological, anatomical, and physiological adaptations of calciphytes (Lee, 1998; Evert, 2006):

  1. Adaptations to iron deficiency: calciphytes use Strategy I (in dicots, except grasses) – release of H+ protons by roots to acidify the rhizosphere (which increases Fe3+ solubility), enhanced activity of Fe3+-reductase on the plasma membrane, and release of chelators (phenolic compounds). Some calciphytes (e.g., species of Knautia, Scabiosa) are distinguished by high efficiency of iron transport to shoots (Lee, 1998).

  2. Adaptations to phosphorus deficiency: calciphytes release di- and tricarboxylic acids (citric, oxalic, malonic) into the rhizosphere, which dissolve sparingly soluble calcium phosphates, releasing phosphorus. Studies have shown that calciphytes release 3–4 times more low-molecular-weight organic acids per unit seed weight than calcifuges (Lee, 1998; Tyler & Strom, 1995).

  3. Regulation of calcium excess: calciphytes accumulate high concentrations of Ca in tissues, but it is not toxic because it is bound as insoluble calcium oxalate in vacuoles or in specialized cells – crystal idioblasts (druses, raphides). In some species (e.g., mistletoe), Ca is excreted onto the leaf surface as calcium carbonate (Evert, 2006; Strasburger, 1971).

  4. Control of Ca2+ entry into the cytosol: in calciphytes, the plasma membrane of root cells has reduced permeability to Ca2+ (fewer channels), and Ca2+ efflux from the cytosol is enhanced by Ca2+-ATPases. This prevents cytotoxic increases in Ca2+ concentration (Lee, 1998).

  5. Stomatal conductance management under high Ca in xylem: in calciphytes (e.g., Centaurea scabiosa, Leontodon hispidus), deposition of calcium oxalate in leaf trichomes (hairs) has been observed, protecting guard cells from excess Ca2+ and preventing pathological stomatal closure (Lee, 1998).

  6. Anatomical traits: often – hard, leathery leaves with a thick cuticle (scleromorphism associated with nutrient deficiency), well-developed root system (deep, taproot) capable of penetrating fractured limestones.

Calcifuges (Calcium-Avoiding Plants)

Calcifuges (from Greek phobos – fear) are plants that avoid soils with high calcium content and grow on acidic silicate (or sometimes peaty) soils. For most calcifuges, calcareous substrates are harmful even at neutral pH. Calcifuges are typically acidophiles. Typical representatives: heather (Calluna vulgaris), marsh Labrador tea (Ledum palustre), many species of buttercups (Ranunculus), sheep sorrel (Rumex acetosella), as well as crops – potato (Solanum tuberosum), lupine (Lupinus), tea (Camellia sinensis) (Lee, 1998; Serebryakova et al., 2006).

Main stress factors on acidic soils (important for calcifuges, but they are adapted to them):

  • Aluminum toxicity (Al3+) – suppresses root growth, blocks Ca2+ channels, disrupts phosphorus uptake.

  • Manganese toxicity (Mn2+) – at low pH, manganese becomes soluble.

  • Calcium deficiency – Ca2+ is needed as a signaling molecule and structural element of cell walls.

  • Phosphorus deficiency – binding into insoluble aluminum phosphates.

  • Predominance of ammonium nitrogen (NH4\+) over nitrate (NO3-), which for many species requires additional costs for ammonium utilization.

Morphological, anatomical, and physiological adaptations of calcifuges (Lee, 1998; Evert, 2006):

  1. Adaptation to aluminum toxicity – key mechanism! Resistant calcifuges use external binding of aluminum – release of organic acids (malate, citrate, oxalate) into the rhizosphere, which chelate Al3+ and prevent its entry into the root (e.g., in wheat, genetically determined malate release). In addition, in calcifuges (e.g., heather), Al3+ can accumulate in roots without being transported to shoots, or be bound in cell walls in a non-toxic form (Lee, 1998). Important: Al-sensitive species (many calciphytes) experience rapid root growth inhibition when aluminum enters the cytosol.

  2. Adaptation to excess Mn: calcifuges can accumulate Mn in vacuoles or excrete it into old, senescing leaves. Some species are capable of Mn hyperaccumulation (e.g., Alyxia rubriccaulis on ultramafic soils) (Lee, 1998).

  3. Efficient phosphorus uptake: in acidic soils, P is poorly available, so calcifuges often have mycorrhiza (especially arbuscular) that helps extract phosphorus. Root exudation of oxalic acid can dissolve aluminum phosphates (Lee, 1998).

  4. Adaptation to low calcium content: cells of calcifuges have higher permeability to Ca2+ (more channels) and less capacity for Ca2+ efflux than calciphytes. This allows efficient Ca2+ uptake from poor solutions but makes them sensitive to Ca2+ excess on limestones (Lee, 1998).

  5. Symbiotrophic nutrition: many calcifuges (Ericaceae, orchids, Vaccinium) are mycorrhizal. The fungal symbiont helps absorb nitrogen from organic compounds (amino acids) and phosphorus, compensating for mineral nutrient deficiency (Lee, 1998).

  6. Anatomical traits: in calcifuges on acidic soils, features of scleromorphism (hard leaves, thick cuticle) are often observed due to substrate poverty, as well as aerenchyma in roots under waterlogging. In heather, leaves are small, leathery, with rolled margins (ericoid type) and have a thick cuticle – this simultaneously protects against water deficit (since acidic soils often dry out quickly) and excess light (Evert, 2006).

Role of Organic Acids in Adaptation – A Common Feature

Interestingly, organic acids play a key role in the adaptations of both groups, but with different orientations:

  • In calciphytes, release of citric and oxalic acids helps dissolve calcium phosphates and mobilize iron.

  • In calcifuges, release of malate, citrate, oxalate binds toxic aluminum and can also dissolve aluminum phosphates (Lee, 1998).

Thus, calciphytes and calcifuges represent two contrasting adaptive strategies that evolved in response to opposite edaphic conditions (alkaline vs. acidic soils). Studying their mechanisms is of great importance for agriculture: maintaining optimal soil pH (liming acidic soils, applying physiologically acidic fertilizers on alkaline soils) can shift the balance in favor of crop plants, and breeding for resistance to Al and Mn (calcifuge traits) for acidic soils of the world (tropics, podzols) remains a priority task (Lee, 1998; Chen et al., 2024).

The next section will be devoted to plants of specialized substrates – lithophytes, chasmophytes, serpentinophytes, and oligotrophs.

3.3. Concept of Psychrophytes and Thermophytes – Adaptations to Soil Temperature Regime

Soil temperature is a crucial edaphic factor closely related to water regime and chemical processes. Low temperatures (even positive, close to 0 °C) slow down or stop water uptake by roots, and also reduce the activity of enzymes and ion transporters. Extremely high temperatures (above +40…+50 °C in the surface soil layer) cause protein denaturation, membrane damage, and, most dangerously, heat shock to the root system. In response to these stresses, two contrasting ecological groups have formed: psychrophytes (cold-tolerant) and thermophytes (heat-tolerant), with thermotolerant plants sometimes distinguished (Yakovlev et al., 2008; Chen et al., 2024).

Psychrophytes – Plants of Cold and Freezing Soils

The term psychrophytes (from Greek psychros – cold) is used in two senses:

  1. Narrow – plants that vegetate at low positive temperatures (0…+10 °C) and cannot tolerate prolonged heating. Found in Arctic and Antarctic deserts, high mountains, on cold volcanic soils (Strasburger, 1971).

  2. Broad – any cold-tolerant plants, including cryophytes (from Greek kryos – frost, ice) – plants inhabiting conditions of permanent negative temperatures (permafrost) and short cold summers. In modern ecological literature, the term cryophytes is more often used for plants of polar and high-mountain regions (Yakovlev et al., 2008).

For simplicity, we will use the term psychrophytes in a broad sense, as plants adapted to low soil and air temperatures, with subdivision into cryophytes (extreme cold) and true psychrophytes (moderate cold with prolonged snow cover).

Morphological and anatomical adaptations of psychrophytes (Serebryakova et al., 2006; Evert, 2006):

  1. Pressed, cushion-like, and prostrate life forms. Strong branching and very short internodes form dense cushions (e.g., Silene acaulis, Saxifraga oppositifolia). Such a form reduces heat loss, protects buds from wind, and allows use of heat reflected from the soil and snow surface.

  2. Dwarfism (nanism). Slow growth is a result of low enzymatic activity at low temperatures. Plants do not accumulate large biomass but allocate resources to protective structures.

  3. Autotrophic moss cover – many psychrophytes (especially mosses and lichens) retain photosynthetic activity even at subzero air temperatures, under snow cover.

  4. Anatomical features of leaves:

    • Small, often evergreen, leathery leaves with thick cuticle and waxy bloom (protection against frost dehydration – water loss through ice-damaged tissues).

    • Stomata sunken, often only on the lower side.

    • Well-developed sclerenchyma (leaves do not wilt upon freezing).

  5. Root system: superficial, widely branched, but not deep (permafrost is inaccessible). Mycorrhiza often present, helping to absorb elements from cold soils.

  6. Protection of renewal buds: in cryophytes, buds are located at the very soil surface (chamaephytes, hemicryptophytes) or underground (geophytes), protected by snow cover. Snow is an excellent heat insulator, maintaining a temperature around 0 °C even during severe frosts (Yakovlev et al., 2008).

  7. Physiological adaptations (not morpho-anatomical, but briefly mentioned): accumulation of antifreeze proteins, non-freezing sugars and alcohols in the cytoplasm, membrane stabilization.

Thermophytes – Plants of Hot Soils

Thermophytes (from Greek therme – heat) are plants inhabiting soils with very high temperatures (often above +50…+60 °C in the upper horizon). This is a rare group, found at thermal springs, geyser fields, volcanic grounds, as well as on strongly heated desert and semi-desert soils. It is important to distinguish:

  • Obligate thermophytes – cannot tolerate cooling; their life cycle is tied to constantly high soil temperature (e.g., some cyanobacteria in hot springs – up to +75 °C, but almost none among higher plants).

  • Facultative thermophytes – tolerate short-term soil overheating but prefer moderate temperatures. Most plants referred to as "thermophytes" in botanical literature are actually xerophytes with high thermotolerance (Yakovlev et al., 2008; Strasburger, 1971).

For higher plants, there are two main pathways of adaptation to high soil temperatures:

A. Morphological and anatomical adaptations that reduce heating of the root collar and aboveground organs:

  • Light coloration – white, silvery pubescence or shiny smooth bark (cork) reflect solar radiation (Evert, 2006).

  • Cork layer on the bark – suberin is a good heat insulator, protecting the cambium and phloem from overheating (Strasburger, 1971).

  • Vertically hanging leaves (in eucalypts) – their surface is not perpendicular to the sun’s rays at noon.

  • Powerful development of bark with a large number of dead cork cells containing air – a poor heat conductor.

B. Adaptations related to water regime (transpirational cooling):

  • Intensive transpiration through stomata allows leaf temperature to be lowered by 5–10 °C below air temperature.

  • Deep roots reaching cooler, moist soil horizons.

Examples of plants often called thermophytes (or thermotolerant xerophytes): cacti (Cactaceae), agaves (Agave), many species of euphorbias (Euphorbia) in deserts. Their stems and leaves are covered with a thick cuticle and waxy bloom (protection against IR radiation), and stomata open at night (CAM photosynthesis). However, true higher plant thermophytes growing in soil with temperatures above +60 °C do not exist – proteins and membranes would be destroyed. Record holders – desert shrubs (saxaul) withstand heating of the surface sand layer up to +70 °C, but their roots are at depths where temperatures are significantly lower.

Significance for Understanding Edaphic Adaptations

The study of psychrophytes and thermophytes is directly relevant to edaphic adaptations because:

  • Frozen (cryogenic) soils are not only low temperature but also physiological dryness (water as ice is unavailable) and poor aeration. Therefore, psychrophytes exhibit the same xeromorphic traits as desert plants (thick cuticle, pubescence).

  • Hot desert soils combine high temperature, water deficit, and often salinity. Therefore, thermotolerant plants are inextricably linked with xeromorphism and salt tolerance mechanisms.

Thus, the concepts of "psychrophytes" and "thermophytes" in the edaphic context should be considered together with water and chemical regimes, which emphasizes the complex nature of adaptations (Yakovlev et al., 2008; Chen et al., 2024).

In the next section, we will consider adaptations to specialized substrates – rocky soils (lithophytes and chasmophytes), serpentines, and peatlands.

3.4. Specialized Substrates

In addition to widespread soil types (sands, clays, chernozems, podzols, etc.), there exist specialized substrates with extreme properties that require unique morphological and anatomical adaptations from plants. Such substrates include:

  • Rocky substrates (lithophytic and chasmophytic habitats) – almost complete absence of fine earth, extremely poor mineral composition, sharp fluctuations in temperature and humidity.

  • Serpentines (ultramafic rocks) – high content of heavy metals (Ni, Cr, Co), Ca deficiency and Mg excess, often low Ca/Mg ratio.

  • Peatlands (oligotrophic bogs) – excessive moisture, anaerobiosis, very low content of nitrogen, phosphorus, potassium, and trace elements, acidic reaction (pH 3.5–4.5).

These substrates represent edaphic islands with specialized floras rich in endemics. Plants colonizing them display highly specialized adaptations, often combining features of xeromorphism, hygromorphism, and scleromorphism.

Lithophytes and Chasmophytes – Plants of Rocky Substrates

Lithophytes (from Greek lithos – stone) are plants that live on the surface of rocks and stones. Chasmophytes (from Greek chasma – fissure, crevice) are plants that grow in cracks and crevices of rocks, where a little fine earth and moisture accumulate (Strasburger, 1971; Serebryakova et al., 2006). These two groups are often combined under the common name petrophytes (from Greek petra – rock).

Stress factors of rocky habitats:

  • Sharp diurnal temperature fluctuations (heating by day, rapid cooling at night).

  • Rapid drying of the surface after rain (water is not retained).

  • Mechanical instability (scree, mobile stones).

  • Extremely low content of humus and available nutrients.

  • Absence of a developed soil profile.

Morphological and anatomical adaptations of lithophytes and chasmophytes (Evert, 2006; Lee, 1998):

  1. Root system:

    • In lithophytes – disc-shaped or crust-like roots that tightly adhere to the stone surface (e.g., in rock ferns, some saxifrages). Roots penetrate the smallest irregularities and cracks, sometimes secreting mucus that enhances adhesion (Strasburger, 1971).

    • In chasmophytes – long, penetrating roots that grow deep into crevices (up to 0.5–1 m in some bellflowers, bugleweeds). Roots often have the anatomical ability to contract and expand, adapting to the size of the crack.

  2. Shoots and leaves:

    • Often cushion-like or prostrate form – protection against wind and mechanical damage, minimization of water loss (Serebryakova et al., 2006).

    • Small, hard, leathery leaves with thick cuticle (scleromorphism), often with waxy bloom or pubescence. In many chasmophytes, leaves are gathered into a dense rosette.

    • In some species, CAM photosynthesis develops (e.g., in rock-dwelling Crassulaceae and Cactaceae), allowing CO2 to be stored at night and stomata closed during the day (Chen et al., 2024).

    • On the surface of leaves and stems, silicon or calcium deposits may occur (in some lithophytic lichens and algae, as well as in angiosperms – e.g., Saxifraga).

  3. Vegetative reproduction and regeneration:

    • High ability to root shoot fragments (lithophytic saxifrages, stonecrops). Any part of the plant can give rise to a new plant – an important adaptation under mechanical damage.

Serpentine (Ultramafic) Substrates

Serpentinites are rocks rich in magnesium and heavy metals (nickel, chromium, cobalt) and poor in calcium. Serpentine soils have a low Ca/Mg ratio, high Ni, Cr, Co content, often acidic or neutral reaction but with low buffering capacity. They occur as scattered outcrops worldwide (Urals, Balkans, California, New Caledonia, Cuba) and are characterized by a high degree of endemism (Lee, 1998; Evert, 2006).

Stress factors:

  • Toxicity of heavy metals (Ni, Cr, Co) – the main toxicants.

  • Calcium deficiency with magnesium excess – disruption of calcium signaling and cell wall structure.

  • Often – drought (serpentine outcrops heat up and dry out quickly).

  • Poorness in nutrients (especially N, P).

Morphological and anatomical adaptations of serpentine plants (serpentinophytes):

  1. Nickel accumulation (Ni hyperaccumulation) – in some species (e.g., Alyssum serpyllifolium, Sebertia acuminata – "nickel tree"), Ni concentration can reach 0.5–3% of leaf dry mass. Nickel is accumulated in vacuoles, cell walls, or as malate and citrate complexes. This serves as protection against herbivores (Lee, 1998).

  2. Binding of toxic metals in roots – many serpentinophytes retain most of the Ni, Cr, Co in the roots, not transporting them to shoots. In roots, metals may be precipitated as insoluble phosphates or bound to cell walls (Evert, 2006).

  3. Tolerance to low Ca/Mg ratio – plants develop mechanisms to maintain calcium homeostasis under Ca deficiency and Mg excess. This includes enhanced Mg2+ efflux and more efficient Ca2+ uptake (Lee, 1998).

  4. Xeromorphic traits – small hard leaves, thick cuticle, pubescence – as a response to the dry conditions of serpentine outcrops (Serebryakova et al., 2006).

  5. Dwarfism and twisted growth forms – classic phenomenon on serpentines ("serpentine dwarf forest").

Oligotrophic Substrates – Peatlands

Oligotrophic substrates are substrates extremely poor in mineral nutrients, primarily nitrogen and phosphorus. The most striking example is peatlands (raised sphagnum bogs) with pH 3.5–4.5, anaerobic conditions in depth, and almost complete absence of available nitrogen and phosphorus (Lee, 1998). Other oligotrophic substrates – quartz sands (poor in elements), leached podzols.

Stress factors:

  • Acute deficiency of nitrogen and phosphorus.

  • Acidic reaction (high H+ concentration, toxicity of Al3+ and Mn2+ in solution).

  • Anaerobiosis (in lower peat layers).

  • Chronic waterlogging (but water is often unavailable due to low temperature and high acidity – physiological dryness).

Morphological and anatomical adaptations of oligotrophs (example of Ericaceae and sphagnum bogs):

  1. Scleromorphism and "pseudoxeromorphism": in plants of oligotrophic bogs (cranberry, marsh Labrador tea, heather, cottongrass), leaves are hard, leathery, with rolled margins, thick cuticle, deeply sunken stomata. This is not protection against drought but a consequence of slow growth under nitrogen deficiency – the plant simply cannot build a thin, soft leaf blade; it constructs "defensive" structures (Serebryakova et al., 2006; Evert, 2006).

  2. Aerenchyma in stems and especially in roots (in cranberry, cottongrass) – to provide oxygen in an anaerobic environment (Evert, 2006).

  3. Mycorrhiza (ericoid, arbuscular) – almost all Ericaceae and orchids in peatlands are in symbiosis with fungi that help extract nitrogen from organic peat compounds (proteins, amino acids) and phosphorus from unavailable forms (Lee, 1998).

  4. Insectivory (carnivory) – as a radical way to compensate for nitrogen deficiency. On peatlands (and on poor quartz sands), sundew (Drosera), butterwort (Pinguicula), sarracenia (Sarracenia), Venus flytrap (Dionaea) are found. Their leaves are transformed into trapping devices (sticky hairs, snap traps, pitchers) that digest insects and assimilate the breakdown products (Strasburger, 1971; Lee, 1998).

  5. Ability to use organic nitrogen – even non-carnivorous oligotrophs (e.g., Eriophorum, Carex) can absorb amino acids and short peptides directly through roots, bypassing the mineralization stage (Lee, 1998).

Thus, plants of specialized substrates – lithophytes, chasmophytes, serpentinophytes, and oligotrophs – demonstrate that the edaphic factor can be so strong that it shapes unique morphological and anatomical complexes not found in plants of ordinary habitats. The study of these adaptations enriches our understanding of the limits of plant plasticity and provides material for biotechnological use (Ni-hyperaccumulation genes for phytoremediation, genes for tolerance to P and Fe deficiency for creating varieties for poor soils).

The next section (4 – Applied Significance) will summarize and show how knowledge of edaphic adaptations can be used in agriculture, breeding, and nature conservation.

4. Applied Significance

The study of morphological and anatomical adaptations of plants to the edaphic factor has not only fundamental importance for understanding patterns of plant evolution and distribution, but also a wide range of practical applications in agriculture, breeding, phytoremediation, landscape design, and nature conservation (Lee, 1998; Chen et al., 2024). The main directions of applied use of this knowledge are listed below.

4.1. Breeding and Biotechnology of Drought- and Salt-Tolerant Varieties

Modern agriculture urgently needs varieties resistant to abiotic stresses – drought, salinity, acidic and alkaline soils. Understanding the mechanisms evolved in halophytes, xerophytes, and calciphytes/calcifuges allows:

  • Use of resistance genes from wild relatives of crop plants. For example, genes of vacuolar Na+/H\+ antiporters (NHX) and H\+-pyrophosphatases (V-PPase), characteristic of halophytes, have already been successfully transferred into tomatoes, wheat, rice, and maize, increasing their salt and drought tolerance (Chen et al., 2024). Similarly, genes responsible for organic acid secretion (malate, citrate) in calciphytes and Al-tolerant calcifuges can be used to create varieties that efficiently use phosphorus from sparingly soluble phosphates (Lee, 1998).

  • Apply marker-assisted selection (MAS) for resistance traits such as root system depth, cuticle thickness, stomatal density and type, degree of sclerenchyma and aerenchyma development. For example, selection for reduced stomatal density in rice and barley led to increased drought tolerance without significant yield loss (Hepworth et al., 2015, cited in Chen et al., 2024).

  • Genome editing (CRISPR/Cas9) of key genes controlling edaphic adaptations. In particular, modifying ABA receptor (PYR/PYL) structure to optimize stomatal function, modifying NHX and HKT transporters for better control of Na\+ accumulation, and editing genes responsible for organic acid secretion by roots (Chen et al., 2024; Lee, 1998).

4.2. Phytoremediation and Restoration of Degraded Lands

Knowledge of edaphic adaptations allows targeted selection of plants for:

  • Stabilization of shifting sands (psammophytes) – such as sand couch grass (Agropyron arenarium), marram grass (Ammophila arenaria), saxaul (Haloxylon). These plants have a powerful root system with corky rhizodermis and the ability to quickly regrow after sand burial, making them ideal "sand stabilizers" (Serebryakova et al., 2006; Evert, 2006).

  • Desalination and phytoremediation of saline soils (halophytes) – use of salt excreters (tamarisk, sea lavender) and salt accumulators (glasswort, seablite) to extract salts from upper soil horizons. After vegetation, plants are mown and removed, gradually reducing salinity (Lee, 1998).

  • Phytoremediation of heavy metals (serpentinophytes, Ni hyperaccumulators) – such as Alyssum and Sebertia, capable of accumulating up to 3% Ni in dry mass. These plants are used for cleaning (phytoextraction) of soils contaminated with nickel, chromium, cobalt (Lee, 1998).

  • Drainage and aeration of waterlogged soils – plants with powerful aerenchyma (reed, cattail) promote rhizosphere oxygenation and partial drying of marshy lands (Evert, 2006).

  • Greening of dumps and rock outcrops (lithophytes and chasmophytes) – species undemanding to soil, capable of establishing on steep slopes, preventing erosion (Strasburger, 1971).

4.3. Bioindication of Soil Properties

The presence or absence of certain species, as well as their morphological features, can serve as indicators of edaphic conditions (Lee, 1998; Yakovlev et al., 2008):

  • Indicator plants of salinity (halophytes) – appearance of glasswort, seablite, black saxaul, tamarisk indicates high soil salinity.

  • Calciphytes and calcifuges – predominance of calciphytes (feather grass, cerastium, alfalfa) indicates neutral or alkaline, calcium-rich soils; presence of calcifuges (heather, sheep sorrel, marsh Labrador tea) indicates acidic, poor soils (Lee, 1998).

  • Serpentine indicators – presence of endemic species of genera Alyssum, Noccaea, Streptanthus indicates serpentinite outcrops.

  • Oligotrophic indicators – sphagnum mosses, sundew, cranberry, heather, cottongrass indicate extremely poor, acidic peat soils.

  • Morphological indicators – for example, plants on calcareous soils often show chlorosis (due to Fe deficiency), while on serpentines – dwarfism, twisted growth forms (Lee, 1998).

4.4. Forestry and Agroforestry

When creating shelterbelts, protective plantings, and restoring forests, it is necessary to take into account the edaphic affinity of species. For example, on sandy soils, Scots pine (Pinus sylvestris) is planted, which has drought tolerance and ability to grow on poor substrates; on calcareous soils – black pine (Pinus nigra), downy oak (Quercus pubescens); on saline soils – tamarisk, oleaster (Elaeagnus). Knowledge of the root system and its adaptations allows predicting the compatibility of species in mixed plantings.

4.5. Sustainable Agriculture and Adaptation to Climate Change

Under conditions of global warming and increasing drought frequency, the use of edaphically adapted varieties and agronomic practices becomes critically important (Chen et al., 2024). Main recommendations:

  • Optimization of soil pH (liming of acidic soils, aluminum sulfate on alkaline soils) – creating favorable conditions for crop plants and suppressing indicator weeds of unfavorable conditions.

  • Implementation of minimum and zero tillage (No-Till, Strip-Till) – preserving soil structure, accumulating moisture and carbon. For weed control under zero tillage, cover crops (green manures) are used followed by rolling (ILRC technology), selected based on their edaphic plasticity (Ciaccia et al., 2020).

  • Use of succulent crops (CAM plants) – agave, prickly pear, cacti as potential sources of biofuel and food in arid regions (Chen et al., 2024).

  • Biofortification and breeding for efficient nutrient use – creation of varieties with low requirements for nitrogen, phosphorus, iron based on mechanisms of calcifuges and sclerophytes.

4.6. Biodiversity Conservation and Specially Protected Natural Areas

Many endemic species are confined to specialized substrates (serpentinites, limestones, gypsum, quartz sands). Knowledge of their edaphic adaptations is necessary for:

  • Identification of Key Biodiversity Areas with high endemism.

  • Development of conservation measures (ban on mining, prevention of eutrophication and salinization, control of recreational load).

  • Reintroduction of rare and endangered species of lithophytes, chasmophytes, and serpentinophytes.

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