Soil biodiversity

Soil biodiversity refers to the relationship of soil to biodiversity and to aspects of the soil that can be managed in relation to biodiversity. Soil biodiversity relates to some catchment management considerations. Soil biodiversity refers to the relationship of soil to biodiversity and to aspects of the soil that can be managed in relation to biodiversity. Soil biodiversity relates to some catchment management considerations. According to the Australian Department of the Environment and Water Resources, biodiversity is 'the variety of life: the different plants, animals and micro-organisms, their genes and the ecosystems of which they are a part.' Biodiversity and soil are strongly linked, because soil is the medium for a large variety of organisms, and interacts closely with the wider biosphere. Conversely, biological activity is a primary factor in the physical and chemical formation of soils. Soil provides a vital habitat, primarily for microbes (including bacteria and fungi), but also for microfauna (such as protozoa and nematodes), mesofauna (such as microarthropods and enchytraeids), and macrofauna (such as earthworms, termites, and millipedes). The primary role of soil biota is to recycle organic matter that is derived from the 'above-ground plant-based food web'. Soil is in close cooperation with the wider biosphere. The maintenance of fertile soil is 'one of the most vital ecological services the living world performs', and the 'mineral and organic contents of soil must be replenished constantly as plants consume soil elements and pass them up the food chain'. The correlation of soil and biodiversity can be observed spatially. For example, both natural and agricultural vegetation boundaries correspond closely to soil boundaries, even at continental and global scales. A 'subtle synchrony' is how Baskin (1997) describes the relationship that exists between the soil and the diversity of life, above and below the ground. It is not surprising that soil management has a direct effect on biodiversity. This includes practices that influence soil volume, structure, biological, and chemical characteristics, and whether soil exhibits adverse effects such as reduced fertility, soil acidification, or salinisation. Soil acidity (or alkalinity) is the concentration of hydrogen ions (H+) in the soil. Measured on the pH scale, soil acidity is an invisible condition that directly affects soil fertility and toxicity by determining which elements in the soil are available for absorption by plants. Increases in soil acidity are caused by removal of agricultural product from the paddock, leaching of nitrogen as nitrate below the root zone, inappropriate use of nitrogenous fertilizers, and buildup of organic matter. Many of the soils in the Australian state of Victoria are naturally acidic; however, about 30,000 square kilometres or 23% of Victoria's agricultural soils suffer reduced productivity due to increased acidity. Soil acidity has been seen to damage the roots of the plants. Plants in higher acidity have smaller, less durable roots. Some evidence has shown that the acidity damages the tips of the roots restricting further growth. The height of the plants has also seen a marked restriction when grown in acidic soils, as seen in American and Russian wheat populations. The number of seeds that are even able to germinate in acidic soil is much lower than the amount of seeds that can sprout in a more neutral pH soil. These limitations to the growth of plants can have a very negative effect on plant health, leading to a decrease in overall plant population. These effects occur regardless of the biome. A study in the Netherlands examined the correlation between soil pH and soil biodiversity in soils with pH below 5. A strong correlation was discovered, wherein the lower the pH the lower the biodiversity. The results were the same in grasslands as well as heathlands. Particularly concerning is the evidence showing that this acidification is directly linked to the decline in endangered species of plants, a trend recognized since 1950. Soil acidification reduces soil biodiversity. It reduces the numbers of most macrofauna, including, for example, earthworm numbers (important in maintaining structural quality of the topsoil for plant growth). Also affected is rhizobium survival and persistence. Decomposition and nitrogen fixation may be reduced, which affects the survival of native vegetation. Biodiversity may further decline as certain weeds proliferate under declining native vegetation.