# A Novel Tool for Biodiversity Studies: Earthworm Classification via NGS and Neural Networks
## 1 Introduction  
Increasing mechanization of forestry techniques leads to problems of soil compaction and tree growth, and contributes to the degradation of forest soils [1]. Since natural regeneration of the soil is slow [2] and because the timber industry is socio-economicallyimportant, solutions to restore the quality of forest soils are needed. Several studies showed that the properties of degraded agroecosystem soils can be restored using earthworms [3; 4]. The earthworms are highly diverse in both color and size, ranging from green to pink or bluish, with some species having black or deep red heads. Adult earthworms can vary greatly in size, measuring between 1 and 40 cm in length. These invertebrates belong to the annelid group and the family of oligochaetes, playing a crucial role in agriculture through soil fertilization. By transporting organic matter and nutrients from deeper layers to the surface, they improve soil fertility and structure. The earthworms can bring up to 6 tons of organic matter per hectare annually, enhancing nutrient availability and soil drainage. Their tunneling creates pathways for plant roots to access deeper moisture and nutrients [5]. The earthworms generally live between 2 and 8 years, with peak activity in spring and autumn. During extreme weather conditions, such as drought or winter, many species migrate to deeper soil layers, where they slow down their metabolism. The earthworms can also migrate from undisturbed areas, such as field margins, into cropland, contributing to soil health by feeding on organic residues mixed with soil particles. Species like _Lumbricus terrestris_ prefer soils rich in organic carbon, while others, like _Aporrectodea calignosa_, thrive in soils with lower carbon content. Lumbricidae have sometimes been used for soil restoration, and several studies have shown their positive impact on soil properties [4; 6]. Earthworms serve as natural mixers, modifying the biological, physical, and chemical properties of organic matter. They lower the carbon-to-nitrogen (C/N) ratio, increase the surface area available for microbial activity, and create a more favorable environment for microbes. By breaking down complex compounds, earthworms contribute significantly to the efficient recycling of organic waste. By digesting organic matter, earthworms enrich the soil with beneficial microorganisms that fix nitrogen and activate phosphorus, making these nutrients more accessible to plants. Earthworm excretions contain growth stimulants such as auxins and gibberellins, which enhance plant growth and yield [7; 8]. By consuming and breaking down a variety of materials, it plays a crucial role in recycling nutrients and improving soil health [9]. Their activity also fosters the growth of beneficial bacteria and fungi, while breaking down pathogens and pests [10]. Studies have shown its role in reducing nematode populations like _Halicphalobus gingivalis_, which helps mitigate risks to both plants and animals [11]. The sensitivity of earthworms to changes in the environment makes them reliable bio-indicators of soil health and sustainable agricultural practices [12]. The species found in Poland include _Dendrobaena octahedra_, _Lumbricus terrestris_, _Lumbricus rubellus_, and several others, with meadows and pastures typically harboring a greater variety of species compared to cultivated soils. The presence, biomass, and diversity of earthworms are indicators of soil fertility. In fertile grasslands, there can be as many as 1 to 3 million earthworms per hectare. Though there are around 250 species globally, only 40 are present in Central Europe, with about 32 species documented in Poland, most of which are highly adaptable and widespread [8]. Stabilization through vermicomposting is an eco-friendly method for managing solid waste, widely recognized for its sustainability and effectiveness. Numerous studies have highlighted its potential in reducing organic waste and converting it into nutrient-rich compost through the action of earthworms [13; 14].