Trees are remarkably resilient.  In various forms they have been arounds for millions of years.  They have survived asteroid impact (66 million years ago), and a series of successive ice ages.  However, in more recent times they have faced a new challenge, the relentless march of humankind. Early societies felled trees for timber for dwellings, boats*, wood for fire, making tools, as part of ‘flash and burn’ agriculture to create a ‘swidden’ to grow food.  The material felled to create a swidden was allowed to dry and then burnt, the ash released mineral nutrients into the soil for the crops.  As more complex civilisations / societies evolved, there were attempts to restore degraded forests / bare land, and  to protect forests.  The Zhou (Chou) dynasty established a ‘forestry service’ over two thousand years ago, and in India the emperor Ashoka (268 -232 BCE) ordered wide scale reforestation.  Much later in the Middles Ages there were efforts to restore degraded areas, for example, around Nuremberg in the C12th.  Most of these early efforts were concerned with increasing timber production or the mitigation of natural disasters.  In the last two centuries, significant areas of natural forest and woodland have been lost, increasing the risk of soil erosion, flooding and disease (as animals are displaced). In the last century, the percentage cover by forest / woodland in some countries (for example, the UK) was low so vast areas were planted with a single species. Fast growing species (conifers such as pines, spruce and larch) were often grown on what was regarded as marginal land, creating plantations.   In some parts of the Mediterranean, Eucalyptus was planted.  These were species that could cope with the challenging nature of the soil and / or the  topography.   Many of the European initiatives met with some success in terms of timber production and / or the stabilisation of degraded areas (for example, reducing erosion).  Such schemes also created jobs, contributing to the local economy.  But when grassland or heathland were used to create single species plantations, this was often accompanied by a loss in biodiversity. In places, the introduction of non-native species has been challenging as they have become invasive, for example, black cherry. The success of any scheme is dependent on Sound planting techniques and aftercare Selection of the right species for the area The co-operation / involvement of local peoples. Mass planting of a single species can also contribute to the rapid spread of disease / pests (e.g.bark beetles, pine procesionary moth).  Vast swathes of coniferous forest were affected by acid rain (associated with sulphur dioxide from the burning of fossil fuels) in the last century.  This was termed Waldsterben [Wald=forest + sterben=to die].   Problems such as these, coupled with increasing environmental awareness contributed to a rethink of the aims and objectives of forest management / renewal / restoration. However, there were examples where ecological recovery was good, for example, some spruce and black pine ‘monocultures’ were diversified through the planting of a understorey of broadleaved trees, as in Slovenia. In recent times, timber production, control of erosion and reduction of disaster risk remain relevant still, but the importance of biodiversity, resilience and ecosystem services are now uppermost.  There is a move from ‘quantity to quality’ of forest and woodland.  In many countries, a growing interest in recreation and tourism (recognising the importance of green space for mental and physical well being), coupled with growing environmental concerns and recognition of climate change has emerged.   Forest and woodlands across the world, from the boreal regions to the Equator are under threat.  Many have been lost or badly degraded, and are in desperate need of restoration.  Forests are no longer regarded as sources of timber, but are important providers of ecosystem services, such as the mitigation of flooding. So, in more recent times they have been efforts to restore and repair forests and woodlands.  Homogenous and dense plantations / forests in boreal regions had clearings created to allow light demanding species to establish.  Limitations have been placed on clear cutting, and the use of fencing, tree protectors have [caption id="attachment_41889" align="alignleft" width="300"] squirrel[/caption] helped to reduce browsing pressure (by deer / squirrels etc).  One means of promoting biodiversity is ensuring that the woodland / forests offer deadwood.  This provides a ‘home’ to species as varied as woodpeckers to saproxylic beetles. These beetles help break down wood so that it can be further broken down by fungi and bacteria, returning nutrients to the soil. Tree girdling was a technique used in Finland to create deadwood, it severs the conducting tissue (phloem) so that the supply of sugars is interrupted.  Thought is now given to the selection and introduction of tree species that are adapted and resilient to anticipated climate change impacts.   Though countries have adopted a variety of techniques in recent times, the extent of forest and woodland restoration has been largely limited by the funding available.  Restoration does not come cheap, funding over significant period of time is needed, and time itself for the effects of  the measures to become apparent. For detailed information on forest restoration see - https://link.springer.com/article/10.1007/s40725-024-00235-3 Intereesting facts : Henry V111’s flag ship, the Mary Rose , was built using oak and elm. It was the first big ship of the Tudor naval fleet and it is estimated that over 600 trees were needed for its construction,. That is equivalent to about 16 hectares of forest / woodland.  And Cver 370 species are supported in the territories of the Karen swidden farmers in northern Thailand.  

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.

Many hedgerows were planted originally to keep livestock, such as sheep, cattle, pigs, chickens in specific areas. Some hedgerows were planted to define boundaries – ‘who owned which bit of land’.  Hedgerows often surround fields.   The word ‘field’ comes from Old English ‘feld’, meaning 'an area of felled trees / open country'.   The establishment of many hedgerows was associated with the process of enclosure; a change in land use from arable to pasture (for sheep). Open fields and common land were enclosed by hedgerows, over many years the landscape of England changed. The C20th witnessed the opposite process, the removal of hedgerows for the creation of larger fields to accommodate larger machinery.  In the decades following the end of the second Word War, it has been estimated that a quarter of a million miles of hedgerow have been ripped out / lost.  Fortunately, there are now policies in place to halt or even reverse the loss of hedgerow.  Hedgerows are recognised as an integral part of our landscape and play an important role in the maintenance of biodiversity.  They provide habitats for a variety of animals and plants. Many species of birds nest in hedgerows, such as song thrush, yellowhammer and tree sparrow. Different species favour different heights within the hedgerow. Some species nest near the ground such as wrens and dunnocks, whereas others nest higher up (eg. Bullfinches).   The greater the variety of plant species in a hedgerow, the better the supply of pollen, nectar, fruits and seeds.  Ivy for example will produce flowers late in the year and offers a source of nectar and pollen.  Hawthorn, blackthorn and holly offer fruits in the winter months for birds and small mammals. Hedgerows and hedges have to be be maintained.  Such management may involve planting of trees or shrubs to fill gaps, coppicing, laying or cutting back. [youtube=http://uk.youtube.com/watch?v=Andv7a0NPEc 425 350] However, the effects of pruning and cutting back during the bird-nesting season can be disastrous. Mechanical flailing of a hedgerow is fast, effective and the regrowth is generally slower, but its effects can be particularly bad on birds. They may abandon their nests and / or  their eggs or chicks may be destroyed. The pruning / flailing may also reduce the insect populations of the hedgerow (or other other food sources) on which the birds depend.  Hedge pruning maintenance is :- ideally undertaken outside of the nesting season. and  only done every second or third year. [caption id="attachment_25527" align="aligncenter" width="600"] A flailed hedge[/caption] Hedgerows also support vital insect pollinators : butterflies, hover flies, moths and bees. These insects help with the pollination of crops such as oilseed rape, legumes and fruit trees. Other insects can help with crop yields by predating upon crop pests, such as green fly and blackfly (these may spread viral diseases on crops such as sugar beet).  Insects may overwinter in the hedgerow and move into the fields come the Spring, as the aphids start to increase in number.  If trees are left in situ, they may achieve veteran status.  Then their rough bark, cracks, holes and dead wood will support a diverse range of species. Owls, kestrels and bats may come to nest. There are also niches that offer opportunities for epiphytes, mosses and lichens.     The dead wood may be home for saproxylic beetles.   Hedgerows also act as corridors linking to other hedgerows, woodlands etc along which animals can pass (for example, hedgehogs and other small mammals). Hedgerows provide important wildlife corridors across agricultural landscapes. They provide food for insects, small mammals and birds (due to the range of plants and their different flowering and fruiting times). They provide nesting and roosting sites for birds and bats, and ‘homes’ for a variety of small mammals.  Many insect species over winter in hedgerows. The trees and woody shrubs help with carbon sequestration. Hedgerows offer a windbreak, reducing wind speed and hence lowering soil erosion, they may also offer shelter to animal stock.  The roots also help stabilise the soil. [caption id="attachment_40483" align="aligncenter" width="675"] Hedge with beech, nettle, dog rose, brambles, hazel and ash - amongst others[/caption]  

Mesquite is the name given to a number of leguminous shrubs or trees that belong to the genus Prosopis. Many of these plants are native to southern parts of the United  States and Mexico, though one species is native to South America - Argentina. Generally, they are plants of very dry (arid or xeric) regions.  They have the capacity to form very long, deep roots that seek water deep underground. The trees / shrubs are deciduous and their leaves are pinnate (a compound form of leaf); they are also thorny.  The trees produce flowers through Spring and Summer, and the seeds (beans) form in pods.  The trees can be used as a source of timber (for furniture, and in the past ship building). Read more...

The National Forest scheme has celebrated its 25th anniversary.  It was and is a bold project, focusing on some 500 square kilometers of central England (parts of Derbyshire, Leicestershire and Staffordshire).  Whilst the area included farmland and some pockets of ancient woodland, e.g. Charnwood Forest to the east and Needwood Forest to the west, it also included many abandoned industrial workings such as opencast mines, quarries, clay pits and spoil heaps. Some 8.5 million trees have been planted to date and now the area generates income through tourism Read more...