Week 45
Nobody likes me, everybody hates me I think I’ll go eat worms![i]
Although these words have been spoken or sung in many different languages, and over several centuries, I have been unable to establish their exact origin. What I do know is that my land is crammed with worms. I see them nearly everywhere, especially as it has been raining extensively in recent times, with storms battering the UK. I also see worms whenever I dig. Invariably, an inquisitive robin[ii] is not far away, waiting his moment to gobble an earthworm when it appears. In milliseconds, the robin has it and the earthworm is no more. Even for those with scoleciphobia[iii], which is an extreme fear of worms, the importance of earthworms cannot be overstated. They are essential members of soil ecosystems, and play a critical role in nutrient cycling, soil structure, and plant growth.
Earthworms are classified into three categories: (1) leaf litter- or compost-dwelling worms that are nonburrowing. They live at the soil-litter interface and eat decomposing organic matter. These worms are epigeic[iv], (2) topsoil- or subsoil-dwelling worms that feed on soil and create horizontal burrows in the upper 10-30cm of soil. These worms are endogeic[v], and (3) worms that construct permanent deep vertical burrows which they use to visit the surface to obtain plant material for food. These worms are anecic[vi]. Occasionally, compost-dwelling earthworms are included in a separate category. They tend to be a stripy bright red and are sometimes called tiger worms.
Earthworm populations depend on both the physical and chemical properties of the soil, such as temperature, moisture, pH, salts, aeration, and texture, as well as available food, and the ability of the species to reproduce and disperse. One of the most important environmental factors is pH. Although earthworms have different preferences, most favour neutral to slightly acidic soils[vii]. The acidic nature of my land probably explains why I have so many earthworms.
It is a hard life being a worm, as not only can it perish from changes in the soil but is also targeted by many predators. For example, robins, starlings, thrushes, gulls, crows, snakes, foxes, hedgehogs, pigs, and moles, in addition to invertebrates such as ants, ground beetles, snails, spiders, and slugs. Each adores a diet of worms. Not only does an earthworm have these external threats, but from within it can carry different parasites, including protozoa, platyhelminths, mites, and nematodes. An earthworm's lifespan depends on its environment. Those in a rural setting may live for up to eight years, while those in city gardens can last barely two years[viii]. It is difficult to generalise about earthworms. Their population density is extremely variable, with roughly 7000 species[ix] in existence, and each species varying in habitat preference, feeding behaviour, and ecological function[x]. However, a typical garden might be expected to have 200 earthworms per square metre[xi]. That is plenty of worms.
Earthworms contribute to soil fertility by breaking down organic matter, which enhances nutrient availability for plants. Their burrowing activities improve soil structure and encourage water infiltration, aeration, and root growth[xii]. Burrowing also creates habitats for other soil organisms, such as bacteria, fungi, and microfauna[xiii], thereby promoting biodiversity[xiv]. Given their ecological significance, changes in earthworm populations or activity because of climate change can have profound impacts on soil health and plant productivity.
In appearance, a typical earthworm comprises 100-150 round segments, each segment containing layers of muscles, blood vessels, nerves, and internal organs. There are two types of muscle in an earthworm - longitudinal and circular. Longitudinal muscles run the length of the worm, while circular muscles go around it perpendicularly. The segments also feature paired setae, which are small bristles on the exterior of the earthworm. Meanwhile an earthworm’s skin has glands that secrete mucus. This mucus helps the earthworm breathe by keeping the body moist. An earthworm breathes through its thin skin, with oxygen dissolving in the skin’s moisture, and then passing into the body[xv].
On the outside of a worm is a smooth, thickened, non-segmented section of the body wall. This is the clitellumand is generally near the head of the earthworm. The clitellum secretes a viscous fluid in which the eggs are deposited, and thus forms part of a worm’s reproductive system. A clitellum can only be seen when a worm is sexually mature[xvi]. Earthworms are simultaneous hermaphrodites, meaning worms have both male and female reproductive organs. During sexual intercourse among earthworms, both sets of sex organs are used by both worms. If all goes well, the eggs of both mates become fertilised[xvii].
An earthworm’s skeleton is hydrostatic , which means instead of a true skeleton, its body is fluid-filled. This fluid helps maintain the worm's shape, even when underground. Earthworm movement involves the individual use of each segment's muscles. The worm expands part of its body, using a combination of hydrostatic pressure and setae to hold that section in place against the soil. It then tightens and lengthens the muscles of the next section to force itself forward through the soil[xviii].
As well as burrowing through the soil, earthworms can eat, sleep, taste, smell, and even feel. They may have only 302 neurones, compared with a human’s 100 billion, but are surprisingly clever. An earthworm uses different smells and tastes to find food it likes, while it will avoid food that makes it sick. It can also learn to change how it behaves in response to what its senses say[xix].
I am so far unable to explain why earthworms come to the surface when it rains, although I am aware there are several suggestions. The theory I favour is that earthworms find it easier to move across the soil surface when it is wet, to find food, new habitats, or a mate. As rain hits the ground, so it creates vibrations on the soil surface, which cause earthworms to emerge from their burrows onto the surface. Birds exploit this behaviour by drumming their feet on the ground to mimic rainfall, thereby encouraging earthworms to appear[xx].
The two primary climatic factors that influence earthworms are temperature and precipitation. Increased temperature has both direct and indirect effects on earthworms, which are ectothermic organisms. This means that their body temperature is regulated by the environment. While moderate warming may enhance earthworm activity and growth, extreme temperatures can be detrimental to their survival[xxi] and reproductive success[xxii].
Precipitation patterns also affect earthworms, as they require moist soil for survival and movement. Precipitation extremes can be a problem. Prolonged periods of drought can lead to desiccation and death. In contrast, excessive rainfall can cause flooding, which may reduce soil oxygen, and thereby kill earthworms. Changes in moisture levels also influence the availability of organic matter, which is a critical food source for earthworms[xxiii].
However, earthworms can also help mitigate the effects of global warming on soil ecosystems. For example, they can enhance carbon sequestration by incorporating organic matter into the soil, which can help reduce atmospheric CO2 levels[xxiv]. Additionally, burrowing can improve water infiltration and reduce soil erosion, which can be beneficial in the face of increased precipitation and extreme weather events.
There is also the so-called earthworm dilemma, as some researchers claim that earthworms do more harm than good. This is based on the theory that when earthworms feed, they can release into the atmosphere much of the carbon stored in the soil[xxv],[xxvi]. It may just be that earthworms are not all good.
These days there appears to be one storm after another, somewhere on the planet or in UK. I find it astonishing that anyone questions climate change at all, yet there are still plenty of people who are carrying on regardless. Perhaps they have not read the State of the UK Climate 2022 Report[xxvii], a recipe for sleepless nights. This report has five key findings:
i. The UK climate continues to change, but UK temperature extremes are changing faster than average.
ii. 2022 was a record warm year for the UK, made more likely by climate change.
iii. In 2022, the UK received 6% below average rainfall, but there has been a slight increase in heavy rainfall in recent decades.
iv. Sea level around the UK has risen by 18.5cm since the 1900s, but the rate is increasing with over 60% (11.4cm) occurring in the last 30 years.
v. The 2022 leaf-on season was 7 to 16 days longer than average because of extended spring and autumn seasons.
It has long been known that Nature has a profound impact on wellbeing. Whether it is the green canopy of a forest, the soothing rhythm of ocean waves, or maintaining my own patch of land, natural environments have consistently been associated with tranquillity and rejuvenation.
As urban sprawl regrettably consumes more natural landscape, and mankind appears to do less rather than more to avoid calamity, the rewilding movement, renaturing in my case, is gathering slow pace. When I return from a day working on my land, those around me notice a difference. Should I become irritable when indoors, I am sent outside to work my land. I never protest as, within moments, I am transformed. I cannot explain why.
Nature's therapeutic effects on mental health have been well-documented[xxviii]. The Japanese practice of shinrin-yoku or forest bathing epitomises these benefits[xxix]. Immersion in natural environments is known to reduce stress hormones, lower anxiety, improve mood, boost concentration, reduce blood pressure, and enhance immunity[xxx],[xxxi]. Such green spaces offer an escape from the constant bombardment of urban stimuli, which are associated with cognitive fatigue[xxxii]. Urban life, despite its conveniences, poses distinct mental health challenges. The World Health Organization links urban environments to escalating rates of depression and anxiety[xxxiii]. Urban stressors, such as noise pollution and limited access to natural spaces, exacerbate feelings of disconnection and burnout[xxxiv]. Rewilding and renaturing can counteract these effects.
A renatured landscape is more than a refuge for biodiversity, or a means of allowing an ecosystem to thrive[xxxv]. It is also a sanctuary for the human psyche. Engaging with Nature has been shown to foster a profound sense of connection[xxxvi], which I strongly feel when I am out and about.
Ecotherapy, which is a therapy rooted in a direct interaction with Nature, is an emerging field that taps into mankind’s intrinsic bond with the environment[xxxvii]. A renatured area provides an ideal location for such therapeutic interactions. Renaturing also instils a sense of purpose, as contributing to global well-being has profound psychological benefits[xxxviii].
I am not alone in my thoughts about renaturing, certainly if one sees what I do as a form of gardening. The beneficial effects of gardening have long been recognised as a therapeutic activity. The act of planting and nurturing plants provides a sense of accomplishment and pride, as well as a connection to the natural world. Studies have shown that gardening can reduce symptoms of depression and anxiety, improve mood, and increase feelings of calm and relaxation[xxxix]. Gardening has also been found to reduce stress levels, with one study showing that just 30 minutes of gardening can lower cortisol levels, a hormone associated with stress[xl].
One important way in which working with Nature can improve mental health is by providing opportunities for physical activity. Exercise has a range of benefits for mental health, including reducing symptoms of depression and anxiety, improving mood, and increasing feelings of calm and relaxation[xli]. In addition, renaturing has given me many opportunities for social interaction, a critical factor in mental health. Social support is of great benefit in protecting mental health and has been shown to reduce the risk of depression and anxiety[xlii].
Then there is mindfulness, much debated in modern times. This describes paying attention to the present moment in a non-judgmental way, and clearly benefits mental health. This includes reducing symptoms of depression and anxiety, improving mood, and increasing feelings of calm and relaxation[xliii].
Renaturing thus embodies the deep-rooted symbiosis between humans and the environment. In the act of healing our planet - shame on you if you are not doing at least a little - we are not just influencing climate, we are helping ourselves as well.
***
Acknowledgement
Take it from me - none of this would be possible without the help of RSG Horticulture. Rufus, who runs it, has far more energy than me and is full of ideas and skills. Do contact him through https://www.rsghorticulture.com.
Hashtags
#EarthwormEcology #SoilHealth #Biodiversity #ClimateChangeImpact #Ecotherapy #Renaturing #SustainableLiving #EnvironmentalAwareness #ClimateCrisisUK #EcosystemServices #WormsForWellbeing #SoilScience #UrbanRewilding #MentalHealthAndNature #GreenGardening #NatureTherapy #Conservation #ClimateAction #NaturalWorld #EarthwormsAndClimate
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