Non-target and biodiversity impacts in soil

2010

Human societies rely on the vast diversity of benefits provided by nature, such as food, fibres, construction materials, clean water, clean air and climate regulation. All the elements required for these ecosystem services depend on soil, and soil biodiversity is the driving force behind their regulation. With 2010 being the international year of biodiversity and with the growing attention in Europe on the importance of soils to remain healthy and capable of supporting human activities sustainably, now is the perfect time to raise awareness on preserving soil biodiversity. The objective of this report is to review the state of knowledge of soil biodiversity, its functions, its contribution to ecosystem services and its relevance for the sustainability of human society. In line with the definition of biodiversity given in the 1992 Rio de Janeiro Convention 1 , soil biodiversity can be defined as the variation in soil life, from genes to communities, and the variation in soil habitats, from micro-aggregates to entire landscapes. THE IMPORTANCE OF SOIL BIODIVERSITY Soil biodiversity organisation Soils are home to over one fourth of all living species on earth, and one teaspoon of garden soil may contain thousands of species, millions of individuals, and a hundred metres of fungal networks. Bacterial biomass is particularly impressive and can amount to 1-2 t/ha-which is roughly equivalent to the weight of one or two cows-in a temperate grassland soil. For the sake of simplicity, this report has divided the organisms and microorganisms that can be found in soil into three broad functional groups called chemical engineers, biological regulators and ecosystem engineers. Most of the species in soil are microorganisms, such as bacteria, fungi and protozoans, which are the chemical engineers of the soil, responsible for the decomposition of plant organic matter into nutrients readily available for plants, animals and humans. Soils also comprise a large variety of small invertebrates, such as nematodes, pot worms, springtails, and mites, which act as predators of plants, other invertebrates or microorganisms, by regulating their dynamics in space and time. Most of these so-called biological regulators are relatively unknown to a wider audience, contrary to the larger invertebrates, such as insects, earthworms, ants and termites, ground beetles and small mammals, such as moles and voles, which show fantastic adaptations to living in a dark belowground world. For instance, about 50 000 mite species are known, but it has been estimated that up to 1 million species could be included in this group. European Commission-DG ENV Soil biodiversity: functions, threats and tools for policy makers February 2010 Earthworms, ants, termites and some small mammals are ecosystem engineers, since they modify or create habitats for smaller soil organisms by building resistant soil aggregates and pores. In this way, they also regulate the availability of resources for other soil organisms since soil structures become hotspots of microbial activities. Moles for instance, are capable of extending their tunnel system by 30 cm per hour and earthworms can produce soil casts at rates of several hundreds of tonnes per ha each year. Chemical engineers, biological regulators and ecosystem engineers act mainly over distinct spatio-temporal scales, which provide a clear framework for management options. This is because the size of organisms strongly determines their spatial aggregation patterns and dispersal distances, as well as their lifetimes, with smaller organisms acting at smaller spatio-temporal scales than larger ones. Thus, chemical engineers are typically influenced by local scale factors, ranging from micrometres to metres and short-term processes, ranging from seconds to minutes. Biological regulators and soil ecosystem engineers, on the other hand, are influenced essentially by factors acting at intermediate spatio-temporal scales, ranging from a few to several hundreds of metres and from days to years. This provides land managers with two distinct management options for soil biodiversity: direct actions on the functional group concerned, or indirect actions at greater spatio-temporal scales than that of the functional group concerned. Factors influencing soil biodiversity The activity and diversity of soil organisms are regulated by a hierarchy of abiotic and biotic factors. The main abiotic factors are climate, including temperature and moisture, soil texture and soil structure, salinity and pH. Overall, climate influences the physiology of soil organisms, such that their activity and growth increases at higher temperatures and soil moistures. As climate conditions differ across the globe and also, in the same places, between seasons, the climatic conditions to which soil organisms are exposed vary strongly. Soil organisms vary in their optimal temperature and moisture ranges, and this variation is life-stage specific, e.g. larvae may prefer other optima than adults. For instance, for springtails, the optimum average temperature for survival is just above 20 °C, and the higher limit is around 50 °C, while some bacteria can survive up to 100 °C in resistant forms. Soil texture and structure also strongly influences the activity of soil biota. For example, medium-textured loam and clay soils favour microbial and earthworm activity, whereas fine textured sandy soils, with lower water retention potentials, are less favourable. Soil salinity, which may increase near the soil surface, can also cause severe stress to soil organisms, leading to their rapid desiccation. However, the sensitivity towards salinity differs among species, and increased salinity may sometimes have positive effects, by making more organic matter available. Similarly, changes in soil pH can affect the metabolism of species (by affecting the activity of certain enzymes) and nutrient availability, and are thereby often lethal to soil organisms. The availability of phosphorus (P), for example, is maximised when soil pH is neutral or slightly acidic, between 5.5 and 7.5. Soil organisms influence plants and organisms that live entirely aboveground, and these influences take place into two directions. Plants can strongly influence the activity and community composition of microorganisms in the vicinity of their roots (called the rhizosphere). In turn, plant growth may be limited, or promoted by these soil microorganisms. Added to this, plants can influence the composition, abundance and activity of regulators and ecosystem engineers, whereas these February 2010 European Commission-DG ENV Soil biodiversity: functions, threats and tools for policy makers 5 species in turn can influence vegetation composition and productivity. Finally, soil organisms can induce plant defence responses to aboveground pests and herbivores and the aboveground interactions can feed back in a variety of ways to the biodiversity, abundance and activities of the soil organisms. In addition, within the soil food webs, each functional group can be controlled by bottom-up or topdown biotic interactions. Top-down effects are mainly driven by predation, grazing, and mutualist relationships. Bottom-up effects depend largely on competitive interactions for access to resources. Services provided by soil biodiversity Many of the functions performed by soil organisms can provide essential services to human society. Most of these services are supporting services, or services that are not directly used by humans but which underlie the provisioning of all other services. These include nutrient cycling, soil formation and primary production. In addition, soil biodiversity influences all the main regulatory services, namely the regulation of atmospheric composition and climate, water quantity and quality, pest and disease incidence in agricultural and natural ecosystems, and human diseases. Soil organisms may also control, or reduce environmental pollution. Finally, soil organisms also contribute to provisioning services that directly benefit people, for example the genetic resources of soil microorganisms can be used for developing novel pharmaceuticals. More specifically, the contributions of soil biodiversity can be grouped under the six following categories: • Soil structure, soil organic matter and fertility: soil organisms are affected by but also contribute to modifying soil structure and creating new habitats. Soil organic matter is an important 'building block' for soil structure, contributing to soil aeration, and enabling soils to absorb water and retain nutrients. All three functional groups are involved in the formation and decomposition of soil organic matter, and thus contribute to structuring the soil. For example, some species of fungi produce a protein which plays an important role in soil aggregation due to its sticky nature. The decomposition of soil organic matter by soil organisms releases nutrients in forms usable by plants and other organisms. The residual soil organic matter forms humus, which serves as the main driver of soil quality and fertility. As a result, soil organisms indirectly support the quality and abundance of plant primary production. It should be underlined that soil organic matter as humus can only be produced by the diversity of life that exists in soils-it cannot be man-made. When the soil organic matter recycling and fertility service is impaired, all life on earth is threatened, as all life is either directly or indirectly reliant on plants and their products, including the supply of food, energy, nutrients (e.g. nitrogen produced by the rhizobium bacteria in synergy with the legumes), construction materials and genetic resources. This service is crucial in all sorts of ecosystems, including agriculture and forestry. Plant biomass production also contributes to the water cycle and local climate regulation, through evapo-transpiration. 10 European Commission-DG ENV Soil...

Agriculture, Ecosystems & Environment, 1991

Paoletti, M.G., Favretto, M.R., Stinner, B.R., Purrington, F.F. and Bater, J.E., 1991. Invertebrates as bioindicators of soil use. Agric. Ecosystems Environ., 34: 341-362.

European Journal of Soil Science, 2006

2010

Human societies rely on the vast diversity of benefits provided by nature, such as food, fibres, construction materials, clean water, clean air and climate regulation. All the elements required for these ecosystem services depend on soil, and soil biodiversity is the driving force behind their regulation. With 2010 being the international year of biodiversity and with the growing attention in Europe on the importance of soils to remain healthy and capable of supporting human activities sustainably, now is the perfect time to raise awareness on preserving soil biodiversity. The objective of this report is to review the state of knowledge of soil biodiversity, its functions, its contribution to ecosystem services and its relevance for the sustainability of human society. In line with the definition of biodiversity given in the 1992 Rio de Janeiro Convention 1 , soil biodiversity can be defined as the variation in soil life, from genes to communities, and the variation in soil habitats, from micro-aggregates to entire landscapes. THE IMPORTANCE OF SOIL BIODIVERSITY Soil biodiversity organisation Soils are home to over one fourth of all living species on earth, and one teaspoon of garden soil may contain thousands of species, millions of individuals, and a hundred metres of fungal networks. Bacterial biomass is particularly impressive and can amount to 1-2 t/ha-which is roughly equivalent to the weight of one or two cows-in a temperate grassland soil. For the sake of simplicity, this report has divided the organisms and microorganisms that can be found in soil into three broad functional groups called chemical engineers, biological regulators and ecosystem engineers. Most of the species in soil are microorganisms, such as bacteria, fungi and protozoans, which are the chemical engineers of the soil, responsible for the decomposition of plant organic matter into nutrients readily available for plants, animals and humans. Soils also comprise a large variety of small invertebrates, such as nematodes, pot worms, springtails, and mites, which act as predators of plants, other invertebrates or microorganisms, by regulating their dynamics in space and time. Most of these so-called biological regulators are relatively unknown to a wider audience, contrary to the larger invertebrates, such as insects, earthworms, ants and termites, ground beetles and small mammals, such as moles and voles, which show fantastic adaptations to living in a dark belowground world. For instance, about 50 000 mite species are known, but it has been estimated that up to 1 million species could be included in this group. European Commission-DG ENV Soil biodiversity: functions, threats and tools for policy makers February 2010 Earthworms, ants, termites and some small mammals are ecosystem engineers, since they modify or create habitats for smaller soil organisms by building resistant soil aggregates and pores. In this way, they also regulate the availability of resources for other soil organisms since soil structures become hotspots of microbial activities. Moles for instance, are capable of extending their tunnel system by 30 cm per hour and earthworms can produce soil casts at rates of several hundreds of tonnes per ha each year. Chemical engineers, biological regulators and ecosystem engineers act mainly over distinct spatio-temporal scales, which provide a clear framework for management options. This is because the size of organisms strongly determines their spatial aggregation patterns and dispersal distances, as well as their lifetimes, with smaller organisms acting at smaller spatio-temporal scales than larger ones. Thus, chemical engineers are typically influenced by local scale factors, ranging from micrometres to metres and short-term processes, ranging from seconds to minutes. Biological regulators and soil ecosystem engineers, on the other hand, are influenced essentially by factors acting at intermediate spatio-temporal scales, ranging from a few to several hundreds of metres and from days to years. This provides land managers with two distinct management options for soil biodiversity: direct actions on the functional group concerned, or indirect actions at greater spatio-temporal scales than that of the functional group concerned. Factors influencing soil biodiversity The activity and diversity of soil organisms are regulated by a hierarchy of abiotic and biotic factors. The main abiotic factors are climate, including temperature and moisture, soil texture and soil structure, salinity and pH. Overall, climate influences the physiology of soil organisms, such that their activity and growth increases at higher temperatures and soil moistures. As climate conditions differ across the globe and also, in the same places, between seasons, the climatic conditions to which soil organisms are exposed vary strongly. Soil organisms vary in their optimal temperature and moisture ranges, and this variation is life-stage specific, e.g. larvae may prefer other optima than adults. For instance, for springtails, the optimum average temperature for survival is just above 20 °C, and the higher limit is around 50 °C, while some bacteria can survive up to 100 °C in resistant forms. Soil texture and structure also strongly influences the activity of soil biota. For example, medium-textured loam and clay soils favour microbial and earthworm activity, whereas fine textured sandy soils, with lower water retention potentials, are less favourable. Soil salinity, which may increase near the soil surface, can also cause severe stress to soil organisms, leading to their rapid desiccation. However, the sensitivity towards salinity differs among species, and increased salinity may sometimes have positive effects, by making more organic matter available. Similarly, changes in soil pH can affect the metabolism of species (by affecting the activity of certain enzymes) and nutrient availability, and are thereby often lethal to soil organisms. The availability of phosphorus (P), for example, is maximised when soil pH is neutral or slightly acidic, between 5.5 and 7.5. Soil organisms influence plants and organisms that live entirely aboveground, and these influences take place into two directions. Plants can strongly influence the activity and community composition of microorganisms in the vicinity of their roots (called the rhizosphere). In turn, plant growth may be limited, or promoted by these soil microorganisms. Added to this, plants can influence the composition, abundance and activity of regulators and ecosystem engineers, whereas these February 2010 European Commission-DG ENV Soil biodiversity: functions, threats and tools for policy makers 5 species in turn can influence vegetation composition and productivity. Finally, soil organisms can induce plant defence responses to aboveground pests and herbivores and the aboveground interactions can feed back in a variety of ways to the biodiversity, abundance and activities of the soil organisms. In addition, within the soil food webs, each functional group can be controlled by bottom-up or topdown biotic interactions. Top-down effects are mainly driven by predation, grazing, and mutualist relationships. Bottom-up effects depend largely on competitive interactions for access to resources. Services provided by soil biodiversity Many of the functions performed by soil organisms can provide essential services to human society. Most of these services are supporting services, or services that are not directly used by humans but which underlie the provisioning of all other services. These include nutrient cycling, soil formation and primary production. In addition, soil biodiversity influences all the main regulatory services, namely the regulation of atmospheric composition and climate, water quantity and quality, pest and disease incidence in agricultural and natural ecosystems, and human diseases. Soil organisms may also control, or reduce environmental pollution. Finally, soil organisms also contribute to provisioning services that directly benefit people, for example the genetic resources of soil microorganisms can be used for developing novel pharmaceuticals. More specifically, the contributions of soil biodiversity can be grouped under the six following categories: • Soil structure, soil organic matter and fertility: soil organisms are affected by but also contribute to modifying soil structure and creating new habitats. Soil organic matter is an important 'building block' for soil structure, contributing to soil aeration, and enabling soils to absorb water and retain nutrients. All three functional groups are involved in the formation and decomposition of soil organic matter, and thus contribute to structuring the soil. For example, some species of fungi produce a protein which plays an important role in soil aggregation due to its sticky nature. The decomposition of soil organic matter by soil organisms releases nutrients in forms usable by plants and other organisms. The residual soil organic matter forms humus, which serves as the main driver of soil quality and fertility. As a result, soil organisms indirectly support the quality and abundance of plant primary production. It should be underlined that soil organic matter as humus can only be produced by the diversity of life that exists in soils-it cannot be man-made. When the soil organic matter recycling and fertility service is impaired, all life on earth is threatened, as all life is either directly or indirectly reliant on plants and their products, including the supply of food, energy, nutrients (e.g. nitrogen produced by the rhizobium bacteria in synergy with the legumes), construction materials and genetic resources. This service is crucial in all sorts of ecosystems, including agriculture and forestry. Plant biomass production also contributes to the water cycle and local climate regulation, through evapo-transpiration. 10 European Commission-DG ENV Soil...

Biodiversity and Conservation, 1994

Different approaches to biodiversity yield global totals as small as 3 million or as large as 80 million species. Erwin's calculation and estimation leads to an estimate of ca 30 million species and relies on four assumptions of which one concerns the ratio between the number of canopy insects and those found elsewhere, especially in the soil. A short survey of the microarthropods living in coastal sand dunes and collected with a new flotation method yielded amazing results. In spite of the severity of the habitat (low organic matter content and extreme dryness), the density of microarthropods varied between 175 000 and 1 400 000 individuals per square metre, i.e., densities 3 to 10 times higher than densities usually observed in any other type of soil. A total of 31 species was recorded, most undescribed and smaller than 200 μm. The consequences of these findings on the estimation of the number of species are discussed. It is suggested that the soil, including the deepest horizons and the rhizosphere, might constitute a huge reservoir for biodiversity.

Soil life or soil biota is a collective term for all the organisms living within the soil. Soil biology is the study of microbial and faunal activity and ecology in soil. These organisms include earthworms, nematodes, protozoa, fungi and bacteria. Soil biology plays a vital role in determining many soil characteristics yet, being a relatively new science, much remains unknown about soil biology and about how the nature of soil is affected. Overview The soil is home to a large proportion of the world's genetic diversity. The linkages between soil organisms and soil functions are observed to be incredibly complex. The interconnectedness and complexity of this soil 'food web' means any appraisal of soil function must necessarily take into account interactions with the living communities that exist within the soil. We know that soil organisms break down organic matter, making nutrients available for uptake by plants and other organisms. The nutrients stored in the bodies of soil organisms prevent nutrient loss by leaching. Microbial exudates act to maintain soil structure, and earthworms are important in bioturbation. However, we find that we don't understand critical aspects about how these populations function and interact. The discovery of glomalin in 1995 indicates that we lack the knowledge to correctly answer some of the most basic questions about the biogeochemical cycle in soils. We have much work ahead to gain a better understanding of how soil biological components affect us and the planet they share with us. In a balanced soil, plants grow in an active and vibrant environment. The mineral content of the soil and its physical structure are important for their well-being, but it is the life in the earth that powers its cycles and provides its fertility. Without the activities of soil organisms, organic materials would accumulate and litter the soil surface, and there would be no food for plants. The soil biota includes: Megafauna: size range 20 mm upwards, e.g. moles, rabbits, and rodents. Mesofauna: size range 100 micrometre-2 mm, e.g. tardigrades, mites and springtails.

American Journal of Life Sciences

Pesquisa Agropecuária Brasileira, 2009

Going underground: ecological studies in forest soils, Publisher: Research Signpost, Trivandrum, India, Editors: Nayerah Rastin, Jürgen Bauhus, 1999

Interactions between soil animals and their environment can be described in terms of positive and negative feed-back loops taking place in the build-up and steady-state of soil ecosystems, respectively. The size of animals determines the scale at which they interact with their physical and biotic environment. Nevertheless varying scales at which animals intervene in functional processes is not relevant to any hierarchical position within the ecosystem, due to symmetrical patterns in the relationships between microbes, animals, humus forms and vegetation types. The present knowledge has been reviewed and discussed to the light of an integrated view of the soil ecosystem, with a particular accent put on soil acidity.

Revista Ciência Agronômica, 2014