Dartmoor is famous for is diverse landscapes, many of which which sit on top of one of the largest granite areas in the country.   There are wet heaths, dry heaths, oak woodlands and blanket bogs.  The oak woodlands contribute massively to biological diversity of the area as the trees are covered with rich flora of mosses, liverworts and lichens. The SW area often experiences strong winds and has acidic soils.  The biodiversity of the area explains why it has been designated as a Special Area of Conservation.  It is one of our National Parks, which attracts many thousands of visitors.  A ‘normal‘ feature of heath and moorland is swathes of heather.   Due to its tolerance of acidic conditions and relative infertility, heather is generally a prominent member of the local flora.  This was once true of the moorland communities on Dartmoor, but the situation is changing. The change is due to a grass - known as purple moor grass (Molinia caerulea). Molinia is native to the UK but is also found in Europe, Asia and parts of Africa. It grows well on acid soils with a pH between 3.5 and 5, and it too can tolerate poor soils. During of the last 50 years,  Molinia has spread extensively in Dartmoor, Exmoor, the Pennines, the Peak District, the Yorkshire Dales and  parts of Wales.  Sadly, areas of purple moor grass support little in terms of insect or indeed bird life.  Herbivores like sheep and cattle tend to avoid it preferring other sources of vegetation, such as heather.  Indeed its nutritional value is not great and actually falls as summer progresses.  The grass is relatively unaffected by fungal / bacterial disease.  It forms deep roots and tussocks, which help protect its buds. The cover of heather on Dartmoor has fallen substantially in recent times, and in places has been replaced by an expanse of purple moor grass.  The features that made Dartmoor special are being lost. Possible factors contributing to changes on the moor: The practice of burning the moorland to encourage fresh shoots for sheep, cows, livestock.  Fires destroys many species but the young shoots of Molinia are ‘protected’ to a degree within the tussocks, and the deep roots also help ensure survival. Nitrogen deposition may be another factor.   A range of nitrogen compounds from farming (fertilisers, animal waste), traffic emissions and industry are released into the atmosphere and are deposited in significant amounts (circa 29 kg per hectare / year). Changes to moorland drainage.  As peat dries, the purple moor grass seems to thrive. There are limited funds available to the National Park for maintenance / repair. The subsidies (termed Headage payments) paid to farmers for the number of animals that graze on the moor. The combined effect of the above means that the moorland ecosystem is struggling, losing its integrity and climate changes (e.g. hotter, drier summers) do not help.   Essentially, the moorland is dying. There are places where the natural vegetation / flora of heather, bilberry and mountain ash are to be found, which suggests that restoration might be possible. What can be done? Create dams and embankments to retain water so that areas become wetter, and plant clumps of the moss - Sphagnum, which is vital for peat formation.  The water / wetness would also help reduce the risk of fire. Plant trees, like those found in woodland areas of the moor, which once established would tend to shade out the purple moor grass. Reducing the grazing pressure on the moorlands. Further reading https://www.theguardian.com/environment/2025/jul/16/dartmoor-is-dying-how-the-uks-national-parks-turned-into-biodiversity-deserts https://www.theguardian.com/commentisfree/2025/jul/15/sheep-destroying-british-habitats-taxpayers-dartmoor-farming https://dartmoorpreservation.co.uk/is-dartmoor-dying/

Loss of nitrogen fixing species. Some plants can ‘fix’ atmospheric nitrogen.  That is they can take nitrogen from the air and use it to make complex nitrogen-containing organic compounds (such as amino acids / proteins).  This fixation of nitrogen is due to the presence of symbiotic bacteria in root nodules.  Gardeners often make use of ‘nitrogen fixers’, such clover, peas and beans to augment soil fertility. A recent study has investigated the changes in the makeup of the flora in European forests (over several decades) from 1940 to 2019.  What they found was that the proportion of nitrogen fixing plants has declined.  The changes did not seem correspond to any changes in temperature  or aridity / rainfall during the time period, but to nitrogen accumulation in the environment.  When nitrogen levels are low, nitrogen fixing plants have an advantage, but when nitrogen levels increase their advantage over other plants is lost. Nitrogen compounds in the soil can result from the intensive use of fertilisers on nearby agricultural land or atmospheric deposition of various pollutants.  Nitrogen levels have increased tenfold since the start date of the surveys.  This loss of nitrogen fixing plants might, in the long term, result in a loss of ecosystem resilience. For further info - visit https://www.science.org/doi/full/10.1126/sciadv.adp7953 The great green wall project. There are a number of large scale tree planting projects, many associated with offsetting global warming.  The great green wall aims to grow a belt of trees some 8000 km in length, and 15 km wide in the Sahara.  The planned route supported trees in the past.  The aim is to ‘stabilise’ the desert, limiting further expansion into the Sahel, as the tree roots help to stabilise the soil, limiting erosion.  Desertification is associated with drought and overgrazing.  The idea of such a barrier was taken up and approved by countries south of the Sahara in 2002, during a special summit.  The trees selected are drought resistant species, that also serve to fertilise the soil and contribute fruits, fodder and fuel wood for local communities. Though millions of trees have been planted, the project needs more funding if it is to succeed. Further details about the great green wall can be found here and here. Dealing with drought ? [caption id="attachment_35526" align="alignleft" width="300"] drought[/caption] Drought is a problem not only for woodlands but also for crops, resulting in substantial food loss across the globe.  The damage to crops is likely to increase as fresh water availability declines.  During drought, the availability of water in the topsoil decreases, leaving water only accessible in the  deeper subsoil.  Plants seek water through their roots and whilst roots generally grow downwards, they also tend to spread outwards to form a network. So, if the roots are mainly located in the upper layer of the soil, they may not be able to absorb water as the soil dries.   Now, research at the University of Nottingham has found that the plant growth regulator abscisic acid plays a critical role in a plant’s response to drought.  The abscisic acid  promotes the production of another growth regulator - auxin.  The two enhance the plant’s geotropic response* - so that the roots permeate deeper into the soil in search of water. Full details in the research paper here : https://www.sciencedirect.com/science/article/abs/pii/S0960982224016439?dgcid=coauthor * Geotropism is a plant’s response to gravity.