A Life Form is a group of plants having certain morphological features in common (Kuechler and Zonneveld, 1988).
For further classification the following growth form criteria are used (Kuechler and Zonneveld, 1988; Strasburger et al., 1983):
Contrary to Natural and Semi-Natural Vegetation (A12), Cultivated Areas are not described by classifiers such as Height or Cover. They are classified exclusively according to their morphology.
Contrary to the major land cover type A11, in A23 a distinction is only made between Graminoids and Non-Graminoids.
The main crop is entirely defined as the vegetative cover that is not marginal, i.e., which covers a considerable area (more than 15 percent of the surface), or which has a high economic revenue and which comprises the uppermost canopy. A second and/or third crop type can be specified, but these crops have a lower canopy than the main crop or they are a marginal crop, i.e., cover less than 15 percent of the surface or has a low economic revenue.
A tree is defined as a woody perennial plant with a single, well defined stem carrying a more-or-less-defined crown (Ford-Robertson, 1971). The plants often form a distinct block and are often planted in a regular spacing or pattern (e.g., orchards, and nursery stock). The duration of the crop cover usually lasts many years.
This category includes:
A further distinction is made as follows:
This refers to Trees of the botanical group Angiospermae, with Gingko (Gingko biloba) as an exception, as it belongs taxonomically to the Gymnospermae. Both evergreen and deciduous species come into this category.
This refers to Trees of the botanical group Gymnospermae (Ford-Robertson, 1971) carrying typical needle-shaped leaves. Both evergreen and deciduous species come into this category.
This refers to the phenology of perennial plants that are never entirely without green foliage (Ford-Robertson, 1971).
This refers to the phenology of perennial plants which are leafless for a certain period during the year (Ford-Robertson, 1971). The leaf shedding usually takes place simultaneously in connection with the unfavourable season (UNESCO, 1973).
A shrub is a woody perennial plant with persistent and woody stems and without any defined main stem (Ford-Robertson, 1971). The growth habit can be erect, spreading or prostrate. The plants often form a distinct block and are often planted in a regular spacing or pattern (e.g., orchards, and nursery stock).
This category includes:
A further distinction is made as follows:
This refers to Shrubs of the botanical group Angiospermae, with Gingko (Gingko biloba) as an exception, as it belongs to the Gymnospermae taxonomically. Both evergreen and deciduous species come into this category.
This refers to Shrubs of the botanical group Gymnospermae (Ford-Robertson, 1971) carrying typical needle-shaped leaves. Both evergreen and deciduous species come into this category.
This refers to the phenology of perennial plants that are never entirely without green foliage (Ford-Robertson, 1971).
This refers to the phenology of perennial plants which are leafless for a certain period during the year (Ford-Robertson, 1971). The leaf shedding usually takes place simultaneously in connection with the unfavourable season (UNESCO, 1973).
This applies to plants without persistent stem or shoots above ground and lacking definite firm structure (Scoggan, 1978). The cover duration is limited to the harvest stage. A further distinction is made between Graminoids and Non-Graminoids (Kuechler and Zonneveld, 1988).
This includes all grasses and other narrow-leaved, grass-like plants that are not grasses according to the taxonomic definition (Kuechler and Zonneveld, 1988).
The following crops are included:
The following crops are included:
This includes all herbaceous plants which are not Graminoids, i.e., it includes species that do not belong to the grasses according to the taxonomic definition, but excludes narrow-leaved, grass-like plants considered Graminoid for the purposes of classification here (Kuechler and Zonneveld, 1988).
A lot of species in A23 cover water surfaces with a large amount of biomass.
The following crops are included:
This class includes vegetated areas that are enclosed by any kind of urban construction. These areas form isolated patches within the urban area. According to the dominating Life Form of the particular urban vegetated, area a further distinction can be made between:
The Spatial Aspect describes cultivated fields in terms of field size (e.g., dimension) and their distribution.
This class can be applied indicatively. A distinction is made between Large-to-Medium-Sized Fields and Small-Sized Field(s). However, this does not refer to large-, medium- or small-scale farming, because it does not relate to the overall size of the farm holding.
The following distinctions are made:
Spatial Distribution, or Macropattern, is concerned with the horizontal spatial arrangement of the field(s) within a defined area. A distinction is made between Continuous and Scattered field(s).
Spatial Distribution is the horizontal pattern of cultivated fields in a certain area. It can be easily measured by considering the distance between a field and the next field. A further distinction can be made into three classes: Continuous, Scattered Clustered or Scattered Isolated.
A given crop cover extends over an area without interval or break.
Continuous describes a continuum of more than 50 percent of cultivated fields. In this case the land cover mapping unit may be single (inside the mapping unit the fields take up more than 80 percent) or mixed (the fields occupy 51-80 percent of the mapping unit). Generally, when the fields occupy 51-80 percent of the mapping unit, the area in between the fields can be considered as part of the cultivated area by the user or the user can decide to make a mixed mapping unit depending upon which land cover features the user wants to highlight.
The Spatial Distribution is Scattered Clustered or Scattered Isolated when, within the cultivated fields' area, other land cover types are present.
The dominant crop may be appearing solely or in combination with other crops. A distinction is made between Single Crop and Multiple Crops in A11. In A23, the environment of the one or two additional herbaceous crop(s) can be specified.
This refers to a cultivation system in which a single crop species covers a plot of land, i.e., a monocultural cropping system. The cover duration is limited by the harvest stage.
Cultivation of two or three crops which are growing simultaneously or with a period of overlap or sequentially on the same field. Crop intensification is both in time and spatially (vertical and horizontal). No horizontal spatial arrangement of the crops (e.g., rows, strips or no arrangement) is considered.
The Multiple Crop system can be further subdivided into One Additional Crop and More Than One Additional Crop. They can be specified by Life Form and coincidence of their planting time with the main crop.
More than one crop is cultivated at the same time in a defined area. This is often indicated as mixed cropping. Therefore the different crops can be intermingled or they grow in distinct patterns on the same field.
Mixed annual crops are cultivated on one piece of land. For example: Legumes are often combined with Non-Legumes.
In the case of perennial crops (trees and shrubs), cash crops are interplanted during the period of establishment of the main crop. At a later stage the interplanted crops might be replaced by cover crops (Euroconsult, 1989).
Planting or sowing one crop into another crop which has reached an advanced growing stage but before the harvest of the first crop (Lipton, 1995).
This class applies only to crops with briefly overlapping growing periods. An overlap which lasts for the whole cultivation period (e.g., if annual or biennial plants are planted into a stand of perennial plants) is considered Simultaneous. An example of crops with an overlapping period is when root crops are planted into a stand of cereals.
The growing of two or more crops in sequence on the same field within one growing season. The succeeding crop is planted after the preceding one is harvested.
In the Aquatic or Regularly Flooded Cultivated Areas, a distinction is made between One Additional Crop and Two Additional Crops. These additional crops are always herbaceous but their growing environment can be specified, i.e., whether it is aquatic or regularly flooded or terrestrial. The cover duration of these additional herbaceous crops is limited to the harvest stage similar to the Terrestrial Cultivated Areas.
The cultivation of additional crops is either simultaneous with the main crop or in sequence on the same field as specified by the Cover-related Cultural Practices. Crop intensification is both temporally and spatially (vertical and horizontal). No horizontal spatial arrangement of the crops (e.g., rows, strips or no arrangement) is considered.
If the option Sequential is selected under Cover-related Cultural Practices, the additional crop can be either aquatic or terrestrial. If the option Relay Intercropping is selected, the additional crop grows at the same time as the main crop on the field and therefore the environment can only be aquatic.
A distinction is made between rainfed, post-flooding and irrigated cultural practices.
Crop establishment and development is completely determined by rainfall.
After rainwater has flooded the field, the water infiltrated into the soil is used intentionally as a water reserve for crop cultivation. The crop(s) use(s) this water reserve for establishment.
Any of several means of providing an artificial regular supply of water, in addition to rain, to the crop(s).
This category is further subdivided into the main irrigation methods:
Under Irrigated, systems are also included in which an additional watergift depends on the actual rains and in which this watergift is essential for establishment and/or flowering of the crop. The aim of the additional watergift is to help the plants through a period of drought-stress (examples of this practice can be found in (semi-)arid climates).
Water is supplied to the field(s) to form a water layer that infiltrates slowly into the soil. The field may be wetted completed (borders, basins) or partly (furrows, corrugations). The water layer may be moving during irrigation (flow irrigation) or it may be mainly stagnant (check irrigation).
Water is pumped up from a source into a closed distribution network and then conveyed over the soil surface and crops. The irrigation water is applied by means of rotating sprinklers, perforated pipes, sprayers, or spinners that are connected to the network. The distribution networks may be permanent, portable or a combination of the two.
This type of irrigation is also called trickle, dribble or localized irrigation. The water is applied at very low pressure through a network of plastic tubes running along the surface or buried. The network consists of main lines and laterals (Euroconsult, 1989). The water trickles onto the soil near the plant(s) at a confined spot.
This classifier indicates for how much of the growing season(s) the land is covered by crops. A distinction is made between shifting cultivation, fallow system and permanent cultivation.
This describes the growing of crops for a few years on selected and cleared plots, alternating with a lengthy period of vegetative fallow when the soil is rested. The land is cultivated for less than 33 percent of the time (Ruthenberg, 1980). This cover by is followed by the vegetative and/or bare cover of the fallow period that can also last for several years (Shaner et al., 1982).
The traditional system of the shifting cultivation results in various cover appearances (WAU, 1985)
An agricultural system with an alternation between a cropping period of several years and a fallow period. The land is cultivated for between 33 and 66 percent of the years, which means a percentage of 50 percent is given by three, five or ten years of crop cover followed by three, five or ten years of fallow vegetative cover (Ruthenberg, 1980).
Because the fallow period is short, the cover consists mostly of grass and light bush vegetation. Areas covered with a distinct closed fallow vegetation without visible field delineations are classed under Natural and Semi-Natural Terrestrial Vegetation. These visible field divisions are characteristic of Fallow Systems. Annual and biennial crops dominate the cover of this cultivation system. The cover of a fallow system is composed of a staple crop (like millet or maize), or a dominating cash crop (like cotton, groundnut, rice or tobacco), and a fallow area.
This applies to the growing of crops that are not replanted for several years after each harvest (e.g., trees and shrubs). The crop should cover the land for at least two years. The first harvest takes usually place after one year or later. Under this cultivation system the land is cultivated for more than 66 percent of the years (Ruthenberg, 1980).
In the case of annual plants, the crop covers the land only part of the year and is followed by a short fallow period or by another crop or covercrop. Examples are vegetables and rice.
In the case of perennials, the crop covers the land throughout the year.
The following crops are included (WAU, 1985):
A distinction is made between Relay Intercropping and Sequential cultivation.
Planting or sowing one crop into another, maturing crop (Ruthenberg, 1980).
The growing of two or more crops in sequence on the same field within one growing season. The succeeding crop is planted after the preceding one is harvested.
The crop type can be added optionally with different levels of detail. Initially a distinction is made between Food Crops and Non-Food Crops. A further subdivision is made specifying the most common crop species: Food Crops can be differentiated into Cereals, Roots and Tubers, Pulses and Vegetables, Fruits and Nuts, Fodder, Beverages and Other.
Non-Food Crops comprise Industrial Crops, Wood/Timber and Other Non-Food Crops. The species are grouped according to the main product being harvested.
For A11 the following groupings have been made:
Food Crops can be differentiated into Cereals, Roots and Tubers, Pulses and Vegetables, Fruits and Nuts, Fodder, Beverages and Other.
In addition to Cereals in the narrow sense, the so-called pseudo-cereals are also included:
As there is an enormous list of species of fodder plants (Rehm and Espig, 1991) a division is only made into fodder grasses and fodder legumes. Fodder as a by-product of other crops is not considered here.
This includes also stimulants that are not beverages. Not included are beverages produced from fruit crops even if this is the main use in certain regions. Therefore grapes, citrus and others are listed under Fruits and Nuts.
Non-Food Crops comprise Industrial Crops and Wood/Timber crops.
This class includes crops, which provide raw materials that generally have to pass further mechanization or industrial processing, like fibre crops and oil crops. Oils that can be considered as by-products, for example oil from grain embryos or from the seeds of vegetables, fibre plants, etc., are not mentioned here.
For A23 the following groupings have been made:
Food Crops can be differentiated into Cereals, Fodder and Other Food Crops.
Rice (Oryza sativa)
Water hyacinth (Eichhornia crassipes)
Non-Food Crops are subdivided into Biological Filtration, Fibre and Structural Material and Other Non-Food Crops. The species are grouped according to their main product being harvested.
Water hyacinth (Eichhornia crassipes)
Duckweed (Lemna spp.)
Bulrush (Scirpus spp.)
Reed (Phragmites spp.)
Reed (Phragmites spp.)
The surface aspect of areas with an artificial or associated cover is described. Two main classes are distinguished: built-up areas and non built-up areas.
Built-up areas are characterized by the substitution of the original (semi-)natural cover or water surface by an artificial, often impervious, cover. This artificial cover is characterized usually by a long cover duration.
This class can be subdivided into linear and non-linear areas.
This category contains exclusively any transport, communication or supply system that is built as a linear structure (its length is greater than its width) in order to connect two locations. The perimeters of the structure and the material of the cover can be further defined. Subdivision is made into roads, railways and communication lines/pipelines.
This category is typified by natural or artificial materials continuously covering the surface, or the soil surface is modified to such an extent that it can no longer be considered as land. In many cases, these structures form a network that covers the land surface. This surface can consist of hard artificial materials, concrete, gravel or densified soil, or a mixture of any of these materials.
A more or less uniform material forms a linear structure which covers the land surface over long distances (its length is greater than its width). It is further subdivided into Paved and Unpaved roads.
Paved roads are covered with an artificial material to consolidate the soil surface, whereas Unpaved roads are either bare and consist of a compressed surface, or are covered with unconsolidated material like gravel.
The land cover consists of a combination of materials (e.g., wood, gravel, concrete, iron) with different permeability to form a very specific linear structure.
The land cover is characterized by a combination of point-like elements, such as masts, poles, etc., and linear elements. The linear element(s) (e.g., electric wire, pipe) are situated aboveground, supported by the point-like elements. Examples are telephone wires and electric power transmission lines.
This category describes built up areas where non-linear artificial constructions cover the surface and which have an impervious (e.g., concrete, thatch) surface. Subdivision is made into industrial and/or other areas and urban areas. This subdivision is based on the elements making up this land cover.
Non-linear impervious surfaces are included in this class which are related to trade, manufacturing, distribution and commerce (e.g., airports, ports, factories). The density of the artificial constructions in relation to the surrounding area can be described separately.
Urban areas are non-linear built up areas covered by impervious structures adjacent to or connected by streets. This cover is related to centres of population. Linear elements like (main) roads, railways and communication lines/pipelines occur but are not a dominant feature. The density of the artificial constructions in relation to the surrounding area can be described separately.
This class usually occurs in combination with:
Density is applicable to Industrial and/or other Areas and Urban Areas. Subdivision is made into the following classes based upon the occurrence of impervious surfaces compared to permeable surfaces:
This class is defined by absence of the original (semi-) natural cover or water surface.
It is subdivided into:
The user should note that these areas are considered as "soils" in various soils classification systems (e.g., Anthrosols in the FAO Revised Soil Legend (FAO/UNESCO, 1988) and Anthropogenic Soils).
This free text field provides the possibility to enter information up to a maximum of 154 characters. A list with a set of standardized options is provided.
The surface aspect of Bare Areas describes the land rather than the land cover because the land is not covered by (semi-)natural or artificial cover. As far as possible, internationally accept guidelines and names have been followed.
The surface aspect of Bare Areas is subdivided into: Consolidated and Unconsolidated surface
Consolidated bare areas are characterized by the solid and firm consistency of their surface, or by the presence of coarse fragments with these properties. These surfaces are impenetrable with a spade or a hoe. The surface and the coarse materials remain coherent and hard even when moist.
This class contains areas which are either dominated by a continuous rock surface or covered by coarse rock fragments with a subdivision into Bare Rock and Gravel, Stones and Boulders.
The rock surface is continuous except perhaps for a few cracks in the material. The remainder of the area may be covered by shallow layers of soil or by isolated pockets of soil or a mixture of both.
This class describes areas where rock or mineral fragments cover the surface. The remainder may be covered by shallow soils. Gravel, Stones or Boulders can be specified individually if at least 60 percent of the total coarse fragments consist of any of the three.
The different types of coarse fragments are defined as follow (FAO, 1990):
Hardpans are particular soil layers or surfaces that have been indurated due to chemical or physical processes. Their hardness at the surface is irreversible. They form impenetrable layers for water and/or plant roots.
In the context of the Land Cover Classification System, these layers are only described when occurring at the surface.
Soils rich in iron are irreversibly hardened. Iron is the "cement" and contains little or no organic matter.
The surface of the soil is cemented or indurated by calcium carbonate to the extent that dry fragments do not slake in water and plant roots cannot penetrate.
The surface of the soil is cemented or indurated by gypsum to the extent that dry fragments do not slake in water and plant roots cannot penetrate.
A defined area is covered with materials that are neither solid nor firm. The surface can be penetrated with a spade or a hoe.
A distinction is made between Bare Soil and/or other Unconsolidated Material and Loose and Shifting Sands. A Stony or Very Stony surface can be specified.
Unconsolidated materials cover the earth's surface, resulting from weathering of parent material (including the effects of moisture and temperature) and/or macro- and micro-organisms. A Stony or Very Stony surface can be further specified.
Between 5 and 40 percent of the soil surface is covered with stones. This class can be applied to both Bare Soil and/or Other Unconsolidated Materials and Loose and Shifting Sands.
Between 40 to 80 percent of the soil surface is covered with stones. This class can only be applied in combination with Bare Soil and/or Other Unconsolidated Materials.
These areas are covered by soil particles. These particles may be moved by regularly occurring winds and form distinct patterns (see Macropattern - Sand). A Stony surface can be specified.
The Macropattern describes the horizontal pattern/arrangement of a specific surface aspect of soil or sand. This pattern is formed by the elements that form the bare surface (e.g. sand-sand, soil-soil). Therefore, a distinction is made between Macropattern - Sand and Macropattern - Soil.
Dunes are defined as low ridges or hillocks of drifted sand mainly moved by wind. They occur in deserts or along coasts. The formation of the dunes is dependent on the load of sand, strength and direction of wind, nature of the surface on which sand is moved (sand or rock), presence of an obstacle and the presence of groundwater. Therefore, three types of dunes and two types of occurrence are distinguished:
Crescent-shaped sand dunes, lying transversely to the wind direction with the `horns' trailed downwind.
Elongated dunes with `horns' pointing upwind.
Long, narrow, symmetrical dunes running parallel with the prevailing wind direction.
The area is covered with clustered dunes. This class can be applied to all three types of dunes.
The area is covered by dunes occurring in isolation (contrary to the above). This class can be applied to all three types of dunes.
Cone-shaped hills of hardened earth up to several metres high built by termite insects. The termite mounds may be built around tree trunks or poles.
This is the micro-relief typical of Vertisols, which expand and contract largely with distinct seasonal changes in moisture content. Gilgai consists of a succession of enclosed micro-basins and micro-heaps in nearly level areas, or of micro-valleys and micro-ridges that run parallel to the direction of the slope (FAO/UNESCO, 1988).
Depending on the physical status of water a distinction is made into Water, Snow or Ice. These should cover at least 80 percent of the surface of the total area.
Furthermore, it can be specified whether the water or ice is moving or not: Flowing or Standing Water, and Moving or Stationary Ice.
The amount and duration of flooding may be dependent on climate and rainfall or controlled by structures like dikes or dams and/or by means of pumps or siphons. A distinction is made into perennial and non-perennial water persistence. Non-perennial water regimes can be further subdivided according to surface aspect of the land exposed when no water is covering the surface: bare rock, bare soil and sand.
The water covers the surface for more than 9 months each year in all years.
The water covers the surface for less than 9 months each year in all years. The surface cover in the absence of water can be further specified.
A regular rise and fall in the level of the sea, caused by the attraction of the moon leads to various combinations of water cover and substrate exposure (Cowardin et al., 1979). The four combinations are:
� The substrate is permanently flooded with tidal water (subtidal).
The substrate surface exposed when water is not persistent. This rock is continuous except for a few cracks. The remainder is covered by shallow layers of soil or sand or by isolated pockets that consist of soil or sand or a mixture of both.
The substrate surface exposed when water is not persistent.
The substrate surface exposed when water is not persistent.
This class is subdivided into Deep to Medium Deep and Shallow depth. The classification of Snow and Ice is indicative.
The mean water depth during water presence comes to 2 m and more. The lower level of 2 m represents the maximum depth in which rooted emergent water plants can normally grow (Cowardin et al., 1979).
The mean water depth is less than 2 m during water presence. The level of 2 m represents the maximum depth in which rooted emergent water plants can normally grow (Cowardin et al., 1979).
Sediment load refers to the suspended load in any kind of water system, comprising very fine soil particles which remain in suspension in water for a certain period of time and the coarser sand-sized particles moved by turbulence of the water (Soil Cons. Soc., 1982). Subdivision is made into Almost No Sediment and Sediment.
The water is clear because sediment concentration is too little to be visible.
The sediment concentration is visible, with a concentration ranging from low to high. To classify concentration, data that are defined by the amount of dry sediment per unit volume of water can be applied, giving the following classification (Walling and Webb, 1983):
Water salinity is described according to the concentration of Total Dissolved Solids (TDS), expressed in part per million (ppm), giving the following classification:
The landforms refer to the shape of the land surface. Landforms are described primarily by their morphology and not by their genetic origin or by the process responsible for their shape. The dominant slope is the most important differentiating criterion, followed by relief intensity. The SOTER approach (UNEP/ISSS/ISRIC/FAO, 1995) has been adopted at the higher levels.
The topography refers to the differences in elevation of the land surface on a broad scale. It is derived from the most representative or characteristic slope gradient of the area around, and defined as follows (FAO, 1990):
The parent material can be identified as well as the age of the geological parent material. Three major groupings are distinguished: Igneous rock, Sedimentary rock and Metamorphic rock (provided by Kroonenberg, 1998).
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Geological Parent Materials | ||
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Igneous rock Igneous plutonic rock |
Unconsolidated clastic sedimentary rock |
Contact metamorphic rock |
The age of the geological parent materials can be specified as follows:
The surface aspect of bare areas is described. In contrast to the major land cover type, no distinction is made at this level between Consolidated and Unconsolidated, but more detailed options are available: Bare Rock, Soil Surface, Loose and Shifting Sands and Hardpans.
The rock surface is continuous except perhaps for a few cracks in the material. The remainder of the area may be covered by shallow layers of soil or by isolated pockets of soil or a mixture of both.
This class includes the naturally occurring unconsolidated material on the earth's surface, which may result from weathering of parent material, climate (including the effects of moisture and temperature), and macro- and micro-organisms.
Between 5 and 40 percent of the soil surface is covered with stones. This class can only be applied in combination with Soil Surface and Loose and Shifting Sands.
Between 40 and 80 percent of the soil surface is covered with stones. This class can be applied with Soil Surface and Loose and Shifting Sands.
These areas are covered by soil particles between 0.05 mm and 2 mm in diameter. These particles may be moved by regularly occurring winds and form distinct patterns (see Dunes).
Between 5 and 40 percent of the soil surface is covered with stones. This class can only be applied in combination with Soil Surface and Loose and Shifting Sands.
Between 40 and 80 percent of the soil surface is covered with stones. This class can be applied with Soil Surface and Loose and Shifting Sands.
Dunes are defined as low ridges or hillocks of drifted sand, mainly moved by wind. They occur in deserts or along coasts. The formation of the dunes is dependent on the load of sand, strength and direction of wind, nature of the surface on which sand is moved (sand or rock), presence of any obstacle and the presence of groundwater.
Particular soil layers or surfaces are indurated due to chemical or physical processes. They form impenetrable layers for water and/or plant roots.
Soils rich in iron are irreversibly hardened. Iron is the "cement" and these pans contain little or no organic matter. Often, the organic matter is only present in traces.
The surface of the soil is cemented or indurated by calcium carbonate to the extent that dry fragments do not slake in water and roots can not penetrate.
The surface of the soil is cemented or indurated by gypsum to the extent that dry fragments do not slake in water and roots can not penetrate.
The soil profile is described and its characteristics. In the classification presented here, the classes followed are as described in the Soil Map of the World - Revised Legend (FAO/UNESCO, 1988).
Histosols are formed of incompletely decomposed plant remains. They are characterized by a thick soil horizon that is rich in organic material. These soils formed mainly because of very low temperatures or very wet conditions, or both, throughout the year. Most Histosols are loosely packed in their natural state, and virgin peats retain considerable quantities of water. Histosols are estimated to cover 270 million ha worldwide, mainly in boreal and cold climates, but they also occur in swampy areas throughout the tropical world.
Anthrosols occur whenever human activities have resulted in profound modifications or burial of the original soils through removal or disturbance of surface horizons, cuts and fills, additions of organic materials, long-continued irrigation, or dumps of waste materials from towns or mines in which soils have developed. These soils are estimated to occupy about 0.5 million ha, mainly in areas of very intensive horticulture and agriculture in Western Europe.
Andosols are soils developed in volcanic ash, tuff, pumice and other volcanic ejects of various compositions. The rapid weathering of the porous parent material results in the accumulation of amorphous clays with a high specific surface. In general, Andosols have a fluffy consistency and a dark colour. These soils are further characterized by their high porosity, high permeability and their large soil moisture storage capacity. They are rich in nutrients, but show a great affinity for phosphate ions that they bind and which become unavailable for crops. The total extent of Andosols is estimated at about 110 million ha, concentrated in the circum-Pacific region, corresponding with areas where volcanoes are active.
Arenosols are defined by their sandy particle size and the absence of significant soil profile development. Arenosols are very permeable soils, and their storage capacity for soil moisture is low within the normal rooting depths of crops. Their surface horizon is often pale and poor in organic matter. Their inherent fertility status is low. They are easy to till and tend to form a dry surface quickly, which protects soil moisture against evaporation. For these reasons, they are often preferred over heavier soils for agriculture in semi-arid regions. Arenosols are one of the most extensive soils of the world. They occupy about 900 million ha in the Sahel zone, the Kalahari basin and Australia.
Vertisols are characterized by their high clay contents. They are often dark coloured. Due to their smectite clay mineralogy, they are very hard and crack when dry, but become sticky and plastic (often impassable) when wet. These are chemically rich soils, but they may develop an undulating micro relief (gilgai) which hampers mechanization. Vertisols have great agricultural potential, but special management practices are required to secure sustained agricultural production. Unless mechanization or irrigation is feasible, they are best suited for grazing. These soils occupy about 340 million ha, mainly concentrated in the Deccan Plateau of India, the Gezira in Sudan, South Africa, Ethiopia, Tanzania, eastern Australia, Argentina and Texas.
Fluvisols are soils developed in recent fluviatile, lacustrine or marine deposits, particularly in periodically flooded places. They occur in all climates and are mainly associated with great river deltas. Fluvisols receive fresh sediments regularly, show stratified layers and an irregular distribution of organic matter with depth. They are often fertile and occur generally on flat lands. The total area of Fluvisols is estimated at 355 million ha, concentrated in river plains, deltas and coastal lowlands. They are often very productive, except for those on tidal flats that are normally under mangrove in the tropics.
The formation of Gleysols is conditioned by waterlogging at shallow depth for some or all of the year. The prolonged saturation of soils by groundwater in the presence of organic matter results in the reduction of iron, that is partly leached from the soil and forms a grey, olive or blue coloured soil horizon. Subsequent re-oxidation takes place in fissures and brown, yellowish or reddish mottles may appear in the soil.
The total area of Gleysols is estimated at 720 million ha, of which nearly half occurs in Siberia and Alaska. The remainder occurs in the lowland tropics and subtropics, where they are often used for bunded rice growing.
These soils are characterized by their shallow depth over an impermeable layer, rock or ironpan (less than 30 cm). Their limited soil volume makes them subject to drought, but also to waterlogging and runoff. They are the most extensive soil group in the world, with 1 655 million ha, concentrated in mountainous, desert or boreal areas. Most Leptosols remain under their natural vegetation.
These soils are characterized by their little soil development due or to the very cold climate in which they occur, or due to steep slopes on which they form in other climates. Surface horizons are often thin and poor in organic matter, and the subsoil reflects the parent material. Their extent is estimated at about 580 million ha.
The land use of Regosols depends mainly on the climate and the relief. Those in the arctic are under natural vegetation, those in warmer and wetter climates can be used for dry farming, but often require supplementary irrigation. Most Regosols remain under natural vegetation.
Cambisols are the second most extensive soils in the world, with an estimated extent of about 1 575 million ha. They are characterized by moderate weathering and an absence of clay immigration. Although their other properties may vary considerably, they generally have good structural stability, a high porosity, good water holding capacity, and good internal drainage. They have a moderate to high natural fertility status and an active soil fauna. They are common in boreal and polar climates, in deserts and mountainous areas.
Ferralsols are extremely weathered soils developed in a humid or very humid tropical climates. They are characterized by the presence of kaolinitic clays and (hydr)oxides of iron and aluminium, and with a very low content of weatherable minerals. They are deep to very deep and generally show reddish or yellowish colours. Ironstone nodules and ironpans are common. The estimated area of Ferralsols is 745 million ha, mainly concentrated in the areas of tropical rain forests. Ferralsols are very poor in nutrients and the level of aluminium may reach toxic levels in these soils. At the same time, their physical characteristics are favourable. Careful fertilization including liming and phosphorus applications, may make yield reasonably productive soils, particularly for tropical tree crops such as oil palm, coffee and rubber.
Acrisols are soils developed on old land surfaces with a hilly or undulating topography in seasonal dry and humid tropical and monsoon climates. Closed and open woodland is their natural climax vegetation type, often replaced by a tree savannah maintained by seasonal fires. They are characterized by a horizon in which clay has accumulated and by their low base status. They are poor in nutrients and often suffer from aluminium toxicity and phosphorus deficiency. In contrast to the Ferralsols, they are easily eroded and have severe limitations for agriculture. Acrisols cover about 1 000 million ha throughout Southeast Asia, West Africa and the southeastern United States, where they occur with Alisols.
Most Lixisols developed in similar conditions to Acrisols. However, the prevailing present climate is drier and the combined influence of the dry season and the changing vegetation results in a higher nutrient status of these soils. They are characterized by a horizon in which clay has accumulated and by a high base status. These soils are particularly prone to erosion, and they require minimum tillage and conservation measures if brought under agriculture. Lixisols have an estimated extent of 440 million ha, mainly in east central Brazil, the Indian subcontinent and southeast Africa.
Nitisols are characterized by a deep accumulation or clay and a very strong angular blocky structure that shows shiny pressure faces. These soils contain more then 35 percent clay and have a very active soil fauna . They have excellent chemical and physical properties and they are consequently among the most productive soils of the tropics. Their total extent is estimated at 200 million ha, mainly in eastern Africa, the west coast of India, the Philippines, Java, Cuba and Central America.
Plinthisols develop in tropical conditions and are characterized by the dominant presence of an iron-rich mixture of clay and silica (plinthite) that irreversibly hardens into ironstone concretions and pans on exposure. A groundwater table normally influences these soils. They occupy about 60 million ha, mainly in Brazil and West Africa. Most Plinthisols are poor in nutrients. When the plinthite hardens, the soils suffer from insufficient rooting depths and seasonal dry spells. They are best kept under natural vegetation with associated extensive grazing or fuelwood production. From a civil engineering point of view, plinthite is a good material to make building blocks.
These are characterized by a mixed clay mineralogy, clay migration and a very low base status. They are very acid and have generally a very high aluminium content.
The physical characteristics are also unfavourable: a low structural stability of the surface horizon results in slaking and a reduced permeability and internal drainage.
Their extent is unknown, but probably about 100 million ha, mainly in the tropics and subtropics, but they may occur under forest in more temperate and colder climates.
Liming and fertilizer application may overcome their low chemical fertility, while minimum tillage helps to preserve the surface soil.
Solonchaks are saline soils formed when evaporation greatly exceeds evaporation as in arid and semi-arid areas, or where salts are present in the parent material of the soil.
Solonchaks cover about 190 million ha, with vast areas occurring in Chad, Namibia and Australia, along the Gulf, in Paraguay and Uruguay.
The high salt content limits plant growth to salt tolerant plants and halophytes. Solonchaks can not be used for agriculture unless an excess of irrigation water leaches the salts out, while a drainage system that keeps the groundwater table at sufficient depth is often required.
Solonetz are formed in environments with a pronounced dry season and where sodium is present in excess over calcium, due to saline groundwater, or sodium-containing minerals in the parent material. Clay is dispersed and forms a dense accumulation horizon at shallow depth with a typical columnar or prismatic soil structure.
The extent of these soils is estimated at about 135 million ha in the same areas where Solonchaks occur, but they are also important in colder climates with a pronounced dry season, such as Canada and the former Soviet Union.
The high sodium content directly affects plant growth. Most Solonetz are used for extensive grazing, but they can be reclaimed in colder climates through deep ripping, irrigation with calcium-rich water, and pyrite or gypsum applications.
In arid regions, Gypsisols form through dissolution from calcium sulphate contained in weathering materials and precipitation of gypsum in the subsoil as a fine white powder, crystals, pebbles, stones or even at the surface of the soil as desert roses. If sufficiently abundant, a hard gypsum crust may be formed.
The total extent of Gypsisols is estimated at about 90 million ha, mainly concentrated in the driest part of the arid climatic zone: the Libyan and Namibian deserts, Yemen, Somalia, northern Iraq and Syria.
Chemical fertility of these soils is low and their physical characteristics unfavourable. With irrigation, drainage and heavy fertilization, good yields may be obtained for alfalfa, wheat, apricots and grapes.
The most prominent feature of Calcisols is the translocation of calcium carbonate from the surface layers to an accumulation layer at some depth in the soil. This layer may be soft and powdery, or consists of hard concretions and can eventually become indurated and cemented.
The extent of Calcisols is estimated at about 800 million ha, mainly concentrated in semi-arid and Mediterranean climates.
Most Calcisols have a medium to fine texture and a good water holding capacity. They are generally well drained. These are potentially fertile soils, but their high calcium carbonate content is not favourable for many crops and may result in iron and zinc deficiency in crops. These soils are mainly used for grazing.
In the colder areas of steppe climates, Chernozems develop, which are soils with a very dark, deep, humus- and nutrient-rich topsoil. These soils may contain 4 to 16 percent of organic matter and show an intense activity of earthworms and other small burrowing animals.
Chernozems cover about 230 million ha worldwide, mainly in Eurasia and North America. The chemical and physical properties of these soils are very favourable for agriculture.
In the dry and warmer areas of the steppe region the natural vegetation is dominated by early ripening grasses resulting in Kastanozems with a brown soil surface horizon, rich in organic matter (2 to 4 percent) and characterized by an accumulation of calcium carbonate (or even gypsum) in the subsoil.
Kastanozems have an estimated extent of 465 million ha, mainly concentrated in areas bordering deserts: the southern republics of the former Soviet Union, central Mongolia, northern Argentina and Paraguay, and throughout north and central America.
The physical characteristics of Kastanozems are slightly less favourable than those of the Chernozems, but otherwise these soil groups are comparable.
In the narrow belt north of the zone of the Chernozems, the climate favourable for a steppe-like vegetation no longer exists and deciduous forests have invaded former grasslands. The characteristic nutrient- and humus-rich surface horizon of the steppe soils still persists however .Greyzems are further characterized by clay accumulation and the occurrence of bleached sand and silt particles in the surface horizon.
Most Greyzems are well drained, have a good soil moisture storage capacity and a good chemical fertility. They may suffer from dry and from wet spells and from surface crusting.
Normally they remain under forest but they can be used for cryophylic cereals and spring-grown crops.
Phaeozems occur in more humid and warmer environments than other steppe soils and their weathering and leaching are more pronounced. Phaeozems are characterized by their humus-rich surface horizon and the absence of calcium carbonate accumulations in the subsoil.
Phaeozems are estimated at about 155 million ha, mainly in the North American prairie region, the pampas of Argentina and Uruguay and the subtropical steppe of Eastern Asia.
Phaeozems are porous, well aerated soils with stable structures, relatively rich in nutrients and make excellent farmland.
These soils are characterized by clay migration from the surface horizon to an accumulation horizon at some depth, and a rich nutrient status. They are common in flat or gently sloping land in cool temperate climates and in Mediterranean zones with a distinct dry and wet season.
Luvisols cover about 650 million ha in west-central Russia, the USA and Central Europe. In warmer regions, they are common in the Mediterranean basin and in southern Australia.
Luvisols are in general fertile soils with a high nutrient content and moderate to high soil moisture storage capacity. Luvisols are often intensively used for agriculture.
Podzoluvisols are characterized by a distinct bleached, iron- and clay-depleted horizon overlying and penetrating into a brownish horizon of clay accumulation. They have developed in flat and undulating landscapes previously covered by ice. Their natural vegetation is taiga or coniferous and mixed forest.
Podzoluvisols cover about 320 million ha, mainly concentrated in a broad belt extending from Poland to western Russia, and eastward into central Siberia, and in central Canada extending westward from Baffin Bay.
Most of the Podzoluvisols are acid, have a low nutrient content and their structure is easily destroyed. Many of these soils remain under natural forest vegetation.
Podzols are characterized by a horizon in which iron and aluminium, or organic matter, or both, have accumulated. Normally this layer underlies a bleached horizon.
The topsoil of Podzols shows little biological activity. In the Northern Hemisphere, Podzols occur generally in boreal and cold climates under heather or coniferous forest. In the humid tropics they occur exclusively in sandy materials and are under open forest or savannah.
Podzols occupy about 400 million ha worldwide, mainly concentrated in Scandinavia, Russia, and Canada south of Baffin Bay. Tropical Podzols occur along the Rio Negro, in the Guineas, in northern Australia, in Indonesia and in western Zambia.
Podzols are chemically poor and may suffer from waterlogging. They are normally left under their natural vegetation.
These soils are characterized by a coarse-textured layer abruptly overlying a deeper horizon with considerably more clay. Planosols mainly occur in water-receiving sites on flat or gently undulating terrain, with a natural vegetation of grasses or open forest.
Planosols worldwide cover about 130 million ha, with important concentrations in Brazil, northern Argentina, South Africa and eastern Australia.
Chemical properties of Planosols are variable, but they generally have a moderate to low fertility level. They have low structural stability and, due to the compactness of the subsoil, they often suffer from seasonal waterlogging. They are difficult to manage or improve, and are often used for extensive grazing.
The climate is classified according to the Agro-Ecological Zoning methodology as developed by FAO (De Pauw et al., 1995). Two items need to be determined: the Thermal Climate and the Length of Growing Period (LGP).
Thermal Climate
1. Tropics Monthly mean temperature (Tmean) more than12_ to18�C in every month.
2. Subtropics - Summer Rainfall (Tmean) in every month more than 5�C and at least one month with Tmean less than 18 �C.
Precipitation (P) concentrated in summer (Psummer more than Pwinter).
3. Subtropics - Winter rainfall As for 2, but Pwinter more than Psummer.
4. Temperate Oceanic Four or more months have Tmean more than 10�C and at least one month has Tmean less than 5�C. The difference between the Tmean of warmest and coldest month is less than 20�C.
5. Temperate Continental As for 4, but the difference between Tmean warmest and coldest is more than 20�C.
6. Boreal Oceanic One to four months have Tmean more than 10�C and at least one month has Tmean less than 5�C. Difference in Tmean between warmest and coldest month is less than 20�C.
7. Boreal continental As for 6 but difference in Tmean between warmest and coldest months is more than 20�C.
8. Polar/Arctic All months have a Tmean less than 10�C.
This is the period of the year that moisture and temperature are not inhibiting crop growth. In technical terms, it is calculated as the period starting when rainfall is more than 0.5 Potential Evapotranspiration (PET) or Tmean is bigger than 5�C, whichever comes last, and ends when a maximum soil moisture storage of 100 mm has been depleted or rainfall is less than 0.5 PET or Tmean is less than 5�C, whichever comes first. The growing period can be broken by a dormancy period. Killing temperatures, snow cover and a soil moisture depletion factor are all taken into account in the calculation.
The following classes are suggested:
The following altitude ranges, based on their ecological meaning, are distinguished:
1. Less than 50 - 300 m. This altitude range is further subdivided into:
less than 50 m
50 - 100 m
100 - 300 m
2. 300 - 1 500 m. This altitude range is further subdivided into:
300 - 600 m
600 - 1 000 m
1 000 - 1 500 m
3. 1 500 - 3 000 m. This altitude range is further subdivided into:
1 500 - 2 000 m
2 000 - 2 500 m
2 500 - 3 000 m
4. 3 000 to more than 5 000 m. This altitude range is further subdivided into:
3 000 - 3 500 m
3 500 - 5 000 m
more than 5 000 m
No visible traces of erosion can be recognized on the surface.
Visible traces of erosion can be recognized on the surface but are not further specified. A further distinction can be made into Water Erosion, Wind Erosion and Mass Movement.
Raindrop erosion or splash erosion, the result from the impact of water drops directly on the soil particles, is the initial step in all water erosion. The transport of soil particles by water either in sheet, rill or gully erosion is defined below.
In the classic concept, sheet erosion was defined as the uniform removal of soil in thin layers from sloping land, resulting in sheet or overland flow in thin layers. However, studies have revealed that minute rilling take place almost simultaneously with the first detachment and movement of soil particles (Hudson, 1981; Schwab et al., 1981). The constant change of position of these tiny rills obscure their presence from normal observation. Raindrops cause soil particles to be detached and the increased sediment load reduces the infiltration rate by sealing the soil pores. The soil particles are subsequently transported by runoff.
During development of sheet erosion, pedestals may be formed, boulders may be left with a soil "collar," roots of trees may get exposed, or subsurface soil horizons may appear at the surface.
Rill erosion is the removal of soil by water from small but well-defined channels or streamlets when there is a concentration of overland flow. Rills are defined as less than 30 cm deep and they are small enough to be easily removed by normal tillage operations. They disappear normally after proper land preparation (e.g., ploughing) and are no longer mappable.
Gully erosion is the removal of soil by water from channels larger than rills. These channels carry water during and immediately after rains, and unlike rills, gullies can not be removed by tillage operations. A gully develops by processes that take place either simultaneously or during different periods of its growth:
Soil movement is initiated as a result of turbulence and velocity of wind. The sediment is transported in suspension, by saltation or creep. The quantity of soil moved is influenced by the particle size, gradation of particles, wind velocity and distance across the eroding area. The rate of movement increases with distance from the windward edge of the field or eroded area. These increased rates of soil movement with distance from the windward edge of the area subject to erosion are the result of increasing amounts of erosive particles, thus causing greater abrasion and a gradual decrease in surface roughness. The rate of erosion varies for different soils. Deposition of sediment occurs when gravitational force is greater than the forces holding the particles in the air. This usually occurs when there is a decrease in wind velocity caused by vegetation or other physical barriers.
Masses of locally saturated soil move downhill, usually in one single movement before coming to rest. This type of erosion usually occurs after protracted rains. Although quite large quantities of soil may be moved, there is relatively little disturbance within this soil mass. A small crescent shaped slip scar is formed where the faster moving downslope soil tears away from the slower moving upslope soil.
Depending on the level of Total Dissolved Solids (TDS) expresses in part per million (ppm), three classes are distinguished: fresh, brackish and saline water (Cowardin et al., 1979).
In areas with less than 4 percent vegetative cover, some vegetation may be present and usually this vegetation is scattered over the whole area. The life forms composing this type of vegetation can be any life form and, due to their scattered distribution, it may be difficult to further specify them.
Perennial plants with stem(s) and branches from which buds and shoots develop (Ford-Robertson, 1971). Semi-woody plants are included here (Eiten, 1968).
The life forms composing Woody vegetation can be trees or shrubs but, due to their scattered distribution, it may be difficult to distinguish one from the other.
Plants without persistent stem or shoots above ground and lacking definite firm structure (Scoggan, 1978). There are two categories depending on the physiognomy (Kuechler and Zonneveld, 1988; UNESCO, 1973): Forbs and Graminoids.
The life forms composing Herbaceous vegetation can be Forbs or Graminoids, but, due to their scattered distribution, it may be difficult to distinguish one from the other.
All broad-leaved herbaceous plants in the common sense (e.g., sunflower, clover, etc.) and all non-graminoid herbaceous plants (UNESCO, 1973). Therefore ferns, except tree ferns (Kuechler and Zonneveld, 1988) and very low non-leafy succulents (Eiten, 1968) are included.
This subdivision can only be applied if Forbs comprise more than 75 percent of the herbaceous coverage.
All herbaceous grasses and other narrowleaved grass-like plants that are not grasses according to the taxonomic definition (Kuechler and Zonneveld, 1988). Bamboos are also grasses but they are woody and therefore classed with shrubs or trees.
This subdivision can only be applied if Graminoids comprise more than 75 percent of the herbaceous coverage.
Lichens are composite organisms formed from the symbiotic association of fungi and algae. They encrust rocks, tree trunks, etc., and are often found under extreme environmental conditions (Lawrence, 1989). In tundras of North America and Eurasia, lichens (e.g., Cladonia spp.) may cover large areas (Kuechler and Zonneveld, 1988).
Mosses are a group of photo-autotrophic land plants without true leaves, stems, roots, but with leaf- and stemlike organs (e.g., sphagnum) (Gray, 1970). Several plants commonly called mosses belong to other groups: reindeer moss is a lichen; Spanish moss is a vascular plant (parasite); Irish moss is an algae (Lawrence, 1989).
This category is only applied if the other life forms are not present and when Lichen/Mosses cover is more than 4 percent but less than 20 percent. Otherwise they do not form a specific class, but their presence can be mentioned in the description of another land cover class.
Lichens is only applied when both lichens and mosses are present but Lichens comprise more than 75 percent of the total cover.
Mosses is only applied when both lichens and mosses are present but Mosses comprise more than 75 percent of the total cover.
The Crop Cover/Crop Density can be considered as the proportion of a particular area of the ground or substrate covered by a layer of plants considered at the greatest horizontal perimeter level of each plant in the layer (according to Eiten, 1968). A distinction is made for Permanent Life Forms into Closed (more than 60-70 percent), Open ((70-60 percent) to (20-10 percent)) and Sparse (less than 20-10 percent), and for Temporary Life Forms into.High (more than 60 percent), Medium (60 - 30 percent) and Low (30-15 percent) The reason for expressing the Crop Cover/Crop Density through ranges instead of using absolute values will be described under the respective guidelines. As herbaceous plants are seasonal in character, it has to be stressed that the cover of herbaceous vegetation is always considered at the time of its fullest development.
In addition to specification of the Crop Cover/Density, the user can add to the land cover class of Permanent Life Forms the attribute Plantation or Orchard. In practice, many tree or shrub crops are described in those terms (e.g. rubber plantation, tea plantation) and that is the reason why they have been included.
A layer of a certain Permanent Life Form covers more than 60-70 percent of a defined area. The crowns interlock, touch or are very slightly separated. In the latter case the distance between two perimeters is at least 1/6 of the crown average diameter (Eiten, 1968). The crowns can form an even or uneven closed canopy layer.
If plants are growing in a defined area with the crowns being tangent to each other, presuming that the crowns of a woody Life Form are round, the cover of the canopy will be approximately 78 percent. As crowns are in reality interlocking and small open space of the canopy are frequent in a closed canopy layer, the lower limit of closed vegetation is set at 60 percent. Because of the great variability of the horizontal character of closed vegetation, namely different crown shapes of the plant species, the value range can vary from 60 to 70 percent.
Between 70-60 percent and 20-10 percent of a defined area is covered by a certain layer of a Permanent Life Form. The crowns are usually not interlocking. The distance between the perimeters can range from very slightly more than the average diameter, up to twice the average diameter (Eiten, 1968).
In the case of woody vegetation with a cover of (70-60) -40 percent, the plants are standing rather close together and from a distance, they may appear to grow continuously (Kuechler and Zonneveld, 1988).
A certain layer of Permanent Life Forms covers (20-10) percent of a defined area. The distance between two perimeters of a Life Form is more than twice the average perimeter diameter (Eiten, 1968). In many cases, a sparse Life Form might be associated with another Life Form of greater cover continuity (e.g., a young rubber tree plantation with graminoids).
The range of 20 to 10 percent is applied because sparse cover is rarely homogenous and therefore cannot be easily defined as one single value. Please note the difference in the lower threshold value compared to Natural and Semi-Natural Terrestrial Vegetation (A12).
For Temporary Life Forms the Crop Density can be described. This cover information will inform the user of a possible crop failure. Description of the Crop Density for seasonal plants should take place at the time of its fullest development.
A certain layer of a Temporary Life Form covers more than 60 percent of a defined area.
A certain layer of a Temporary Life Form covers between 60 and 30 percent of a defined area.
A certain layer of a Temporary Life Form covers between 30 and 15 percent of a defined area.
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