Biodiversity after the Black Death. The plague or black death swept across Europe and the UK (from 1347 - 1353, resulting in millions of deaths.  Some studies suggest that it killed between a third and half of the population.  As a result, there was a much reduced workforce, villages were deserted, farmland was abandoned, traditional land and woodland management fell by the wayside.  It was suggested that all of this lead to a significant rewilding event and an increase in biodiversity - both plant and animal. However, an analysis at York University of fossil pollen studies across Europe suggests a 'different story’.  Plant diversity did not increase after the plague, in fact it fell. Plant diversity fell for the next 150 years.  This suggests that some plant species depend on the human disturbance within the various ecosystems (farming, grazing, woodland management, all help seed dispersal etc).  However, mediaeval practices were far gentler than today’s mechanised, industrial scale farming and the clear cut felling of woodlands. Ploughs were pulled by oxen or hand, woodlands were managed by coppicing etc.  So reducing human activity does not always lead to a 'rebound of nature’. The contribution of small woodlands. Over the centuries, our woodlands and forests have been ‘decimated’.  Our woodland / forest cover has been reduced to a small percentage of what it was by farming, felling, building of transport networks and the expansion of towns and cities.  Consequently, there now exist many small patches of woodland in an an agricultural landscape. These ‘islands’ differ in size, degree of isolation, and age. It would be easy to dismiss such ‘islands’ are being of no importance.  However, recent studies suggest that they can make a significant contribution to the biodiversity of the landscape, partly through the ‘edge effect’. The edges of woodlands are exposed to the surrounding environment. Consequently, they receive more sunlight and often nutrients from the surrounding agricultural land.  They are generally richer in species like brambles, hawthorn, willow, offering food for deer, butterflies and other species.  They may also store more carbon in the topsoil than older woodlands - acting as carbon sinks.  As the edges of these woodlands tend to be drier and hotter than woodland itself, there is a lower risk of tick borne disease as fewer tick larvae survive under such conditions.  They are therefore making a significant contribution to diversity and ecosystem services in an agricultural landscape. Such small and often isolated woodlands need to be managed. so they do not become overrun by ivy and bracken if they are to contribute to the diversity of the landscape. A singular advantage of owning a woodland with an edge is that it may offer a good view of the surrounding landscape, which one might sit and enjoy. [caption id="attachment_43124" align="aligncenter" width="675"] View from a scottish woodland[/caption] For further information about the edge effect see  Julian Evans' video on woodlandTV at YouTube : [embed]https://youtu.be/D2buIXiz1sk?si=zhsUiter2pjvyZAv[/embed]

Most months, Jasper has introduced us to a new fungus or group of fungi that have made their appearance in woodlands,  some on trees or branches or leaves, others simply emerging from the soil.  Some fungi are parasitic or biotrophic requiring a living host organism on which they feed.  Then there are those that live in and feed on dead and decaying matter in the soil; these are termed saprobic or saprophytic.  The structures that we normally see (particularly at this time of the year) are the fruiting or reproductive bodies of the fungus / fungi.  The majority of a fungus exists as a network of microscopic ‘tubes’ that permeate either the host organism, or the soil / decaying matter in which the fungus has made its ‘home’.  An individual tube is known as a hypha and collectively they form a complex network - the mycelium. The fungal mycelia present in the soil form a vast underground network.   Some of these fungi enter into beneficial associations with plants - mycorrhizal associations.  The fungal hyphae wrap themselves around (and sometimes into) the roots of plants and trees, with whom they share minerals and nutrients. Generally speaking, the fungus helps to supply the plant with mineral nutrients (like nitrates / phosphates) and in return receives carbohydrate material from the plant’s photosynthetic capacity.  These mycorrhizal systems form part of what has been termed the ‘wood wide web’.  Dr. Suzanne Simard, a forest ecologist from the University of British Columbia, coined the term to describe the complex relationships between fungi and plants in woodland and forest ecosystems. It has been suggested that (millions of years ago) fungi helped plants transition from their aquatic home to life on land, with the fungal network serving as a ‘root system’.  Fungi (and bacteria) release enzymes (biological catalysts) and these help break down the complex compounds (like lignin, cellulose and starch) present in dead plants and animals.  As a result of this decomposition, humus is formed. Humus is a colloid.  A complex mixture of materials, some in solution, some in suspension. Humus binds the inorganic mineral particles of the soil together, is a store of nutrients and helps water retention.  The fungal network in the soil sequesters enormous amounts of carbon.  The soil is one of the Earth’s main carbon ‘sinks’.   If soil is over-worked or damaged by the intensive and extensive use of chemicals in farming, then it degrades and with it the rich microbial network. Damage to the soil and its complex microbial population can impact on the growth of plants - from the simplest green plants to the largest trees. Not only are soil fungi and bacteria involved in the cycling of carbon and nitrogen, but they help maintain the fertility and structure of the soil.  Soil is the ultimate recycling system, we need to cherish the soil and its fungal and bacterial populations - it helps maintain the ecosystem services on which we all depend.  Without healthy soils, we face a very bleak future.  

The blog has reported on moorland fires and the importance of peat-based ecosystems on a number of occasions.  However, a new report has raised serious concerns about the state of peatlands, not just in the U.K but across Europe and Scandinavia.   Many ‘peatlands are in a dry and fragile state’, so that rather than acting as natural carbon sinks, they start to release carbon.   Peatlands actually store about five times more carbon than forests (across Europe). Read more...

One of the gold medal winners at this year’s Chelsea Flower show was the garden entitled “Gardening for Champions”.  This garden shows how simple changes to urban gardens can help the environment through Encouraging pollinating insects Saving water Cutting carbon dioxide emissions The garden, which was designed by Martin Walker, is based on research carried out by academics ** from the University of Leeds; it shows how simple changes to urban gardens can make a positive contribution to ecosystem services.  The garden offers a number of practical suggestions, Read more...