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.  

Leaves have three main parts:  The petiole, a stalk-like structure that connects the blade of the leaf to the stem of the plant. Some leaves don’t have petioles,  and are known as sessile leaves. The blade or lamina, usually the largest part of the leaf.  The edge of the leaf or the leaf margin may be described as entire, toothed, or lobed. The oak leaf, for example, is clearly lobed. The blade has many veins, forming a network, carrying water and nutrients, The base, the base is the region of the blade that attaches to the petiole. A leaf is said to be simple if its blade / lamina is undivided, if the ‘teeth’ or lobes do not reach down to the main vein of the leaf.  A compound leaf has several leaflets, which join up with a single leaf stalk or petiole. When identifying tree leaves, it is always important to look for the petiole,   as a single leaflet of a compound leaf can look like a simple leaf.  More details of leaf and tree structure can be found on this link on our website. Now for a challenge.  Can you or your children find a leaf (and name the tree it came from), that Has a serrated / toothed edge Has a lobed margin Has a smooth edge / margin Is a compound, palmate leaf Is a compound, pinnate leaf Is hairy Is not green, but red or a mixture of colours Is more or less circular Is fleshy / succulent Has spines on its edges Is needle shaped Has a thick (waxy?) cuticle or is very shiny Has net venation  is marcescent (might keep you hanging around) Go forage!

The terms ghosts and zombies often feature in films or TV programmes, but across the country the terms can also be applied to many hundreds, possibly thousands of lost and abandoned ponds.  Ponds have featured in the landscape for centuries or millennia.  Pingos -  formed in the depressions left after the last ice age. The middle of the C20th saw not only the destruction of many hedgerows, but the removal of many ponds.  This was particularly true in farming areas like East Anglia.  The strategy was to increase field size and allow access of complex machinery that was becoming available at that time; for example large combine harvesters.  Whilst the loss of the hedgerows and associated wildlife is well documented, the loss of ponds has not attracted so much attention.  Many hundred of ponds were filled in (often using the debris and material from the destruction of the hedgerows), to give a few more metres of arable land, and with machinery replacing horses the need for ‘watering holes’ diminished.  The infilled ponds are sometimes referred to as ghost ponds.  The location of these 'ponds' can sometimes be found  By studying old ordnance survey (or tithe) maps or  They may be visible using aerial photography / drones and picking up a different colour or shade of the crop growing in a field Noticing the accumulation of water after heavy rain in a slight depression, or a mist hovering over a particular part of a field A zombie pond is somewhat different.  It is a pond or very wet, marsh area which is shadowed by a tree canopy.  The pond has filled over many, many years with dead leaves, so that it has a deep layer of decomposing organic material.  The pond margins is generally overgrown, with willow and other vegetation where have begun to ‘invade’.  The pond is half dead / half alive, hence the term 'zombie'.  The area / water becomes anaerobic / anoxic, as the dead leaves rot and use up oxygen. Few life forms call it home - perhaps midge larvae or the occasional beetle. Indeed, such ponds may release not only carbon dioxide but also methane; the latter is a particularly potent greenhouse gas.  Zombie ponds may be found in woodlands, particularly where active management has fallen by the wayside. However, not all is lost, both ghost and zombie ponds can be resurrected.  In the case of ghost ponds, the infilling material / soil is dug out until the original base layer is reached.   This may be recognised by the dark, fine silt layer / sediment, which may contain the remnants of water snail shells.  Ideally, the excavation should mirror the original outline of the pond.  This may be determined in part by digging two trenches at right angles to each other. Details of the restoration procedure may be found here.   Freshly excavated ghost ponds should be left to fill with rainwater through the winter months, and left for plants and animal to colonise naturally.  Amazingly, several pond restoration projects have demonstrated that the original silt layer of the pond is a valuable seedbed of many aquatic and emergent plant species, even though the seeds may have lain there dormant for decades , possibly centuries.  The refreshed pond should also have a surrounding margin of land to separate it from any adjacent farmland activities - to prevent nutrient run off / pesticide application etc.  Further details of the restoration of lost ponds can be found at:- https://norfolkponds.org/ https://www.ucl.ac.uk/geography/news/2023/nov/bringing-ghost-ponds-back-life https://www.essexwt.org.uk/recovering-lost-ponds In the case of zombie ponds, there is a similar approach to restoration but it begins with the cutting back and / or removal of trees from around the pond to let light in.  Then the layers of rotting leaves / organic materials are scooped out, so that the original sediments of the pond are exposed.  The depth of the decomposing material may be quite significant.  However, with light pouring in and the rotting material removing the pond can soon develop a diverse community of plants (from the seedbed and pond 'visitors' e.g water-crowfoot, stoneworts, and animals).  The restoration / renewal of ponds in fields, meadows or woodlands makes a significant contribution to the biodiversity of an area. There is an excellent video about the restoration of ghost and zombie ponds on YouTube, featuring Professor Carl Sayer (UCL). Professor Sayer grew up in Norfolk, where many of these ‘hidden’ / lost ponds are to be found.  Visit the Razor Science Show “Bringing 'ghost' and 'zombie' ponds back from the dead”. [https://youtu.be/SYkbDdaUMBY?si=gd2jbfxk4iXLSFL5]  

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.

The soil in many arid ecosystems (for example, savanna, deserts, & shrublands) is often covered by a thin layer of organisms, a community of lichens, mosses, liverworts, fungi, cyanobacteria and other microbes. They form a biocrust in the very top layer of the soil.  These organisms produce a variety of chemicals that glues together the soil particles.  Most biocrusts start of with a single type of organism (often a lichen or cyanobacteria, they are hardy). As these grow, they change the immediate environment so that others can then colonise the area so slowly the community grows.. The resulting biocrusts are important in helping reducing soil erosion and dust production.  Whilst dust can hold nutrients that will benefit plants as and when it is deposited, it can also have negative effects. Dust reduces water and air quality.  Dust storms can be truly massive and terrifying, for example, the 2009 Australian Dust storm. Occasionally, in this country we experience saharan dust that his been carried hundreds of miles on the wind.  If wind-blown dust lands on glaciers, snow or ice sheets then it affects the albedo.  The albedo is a measure of a surface’s ability to absorb and retain energy, or putting it the other way round, the ability to reflect heat / light energy.  Dark coloured objects tend to absorb more light energy than light coloured surfaces.  So if snow or ice becomes coated with dust, it will absorb more heat and may melt.   Biocrusts prevent many millions of tonnes of dusts entering the atmosphere each year.  It is thought that they may cover some 12% of the earth’s land surface.  Soil with a biocrust needs a far stronger wind before it starts to erode.  Sadly, like many other things, biocrusts are under threat due to climate change and shifting patterns of land use. [caption id="attachment_41261" align="aligncenter" width="675"] Church wall being colonised by Lichens[/caption] Biocrusts can also form on walls and buildings, for example, lichens and mosses colonise gravestones.  Whilst biocrusts have positive effects when they form on soils, it is thought that they can have deleterious effects on stone / brick surfaces due to the various organic acids and other chemicals that the colonising organisms can produce.  The production of these chemicals can degrade (weather) structures and lose their integrity / aesthetic appeal.   The Great Wall of China, which once stretched for some 8000+ kilometres, is protected by biocrusts in parts.  Construction of the wall started about. 200 BCE and continued (on and off) till the 1600’s CE.  Much of the wall has now been lost.  Some parts of the wall were made from stone and bricks (held together by sticky rice mortar). Other sections were constructed from ‘rammed earth’, made by compressing natural materials (eg. chalk, gravel, lime) with soil.  Some have regarded these sections of the wall as ‘weak points’.  Recent work by Bo Xiang and colleagues found that the ‘rammed earth’ sections were often covered by a biocrust, (of lichens, mosses and cyanobacteria).  This biocrust actually helps maintain the integrity of the wall by protecting it from wind and water erosion.  It reduces temperature extremes and the porosity of the wall, reducing infiltration and its water holding capacity.  All of these help maintain the integrity of these sections of the wall. If biocrusts are lost, through fire, climate change or human intervention then recovery can be problematic.  Organisms like cyanobacteria may recolonise a site quite quickly by organisms blowing in from nearby and undisturbed areas.  Full recovery of the crust and composition generally occurs more rapidly where the soil is fine  textured and moist. When the soil is coarse and dry then re-establishment of a biocrust may take hundreds or thousands of years. Thanks to Art for lichen image on church wall.  

Solar farms have sprung up across the country with hundreds or thousands of solar panels, linked together in fields.  Now, researchers in the States have shown that sowing grasses and wild flowers in-between the panels on solar farms resulted in: A significant increase in the number of beneficial insects (bees in particular benefitted) An increase in insect diversity beneficial 'spillover effects' on adjacent farmland. The solar farms under study were sown with specially designed seed mixes. See also the previous woodlands  blog on solar panels and wildlife The seeding of solar farms would seem to offer support to : Renewable Energy Generation: Biodiversity Pollination services Habitat restoration: in fields that may have been damaged by intensive agriculture and / or development. They can also act as a refuge for native plants and wildlife. Erosion control: the root systems of native plant species (which penetrate to different depths) help prevent soil erosion. Reduced maintenance costs: as less mowing / weed control needed. The cabbage white butterfly is generally regarded as the enemy by the keen vegetable gardener.  If you are growing brassicas - cabbages, cauliflowers, brussels sprouts, broccoli, kale or pak choi, it is likely that you will have these butterflies as summer visitors.  The butterfly is white with black spots on the wings.  Males have a single spot on each of the forewings, whereas the females have paired spots. The butterflies are attracted to the plants as they produce the chemical - glucobrassicin. The butterflies can sense the glucobrassicin through the hairs on their front legs (they have three pairs of legs, a pair on each segment of the thorax). This chemical, glucobrassin, stimulates them to lay their eggs on the leaves of cabbage and other brassicas.  A female can lay up to 800 yellow eggs. These eggs may hatch and the green / black caterpillars emerge.  These caterpillars can double their mass in a day through their voracious feeding.  The adults are attracted to the glucobrassicin in the brassicas just as the caterpillars ‘enjoy’ the chemical - SINIGRIN.   When leaf tissue is damaged, the sinigrin is broken down into a mustard oil, responsible for the pungent taste of Cruciferous vegetables. There are a number of strategies that may help keep the butterfliess away from your crops, and reduce the damage by the caterpillars. Cover the plants with an insect proof mesh Offer ‘sacrificial brassicas’ away from the main crop Use companion / mixed planting, so that beneficial insects have 'hiding places' and it is more difficult for the female cabbage whites to find the brassicas.  Also, by mixing up the planting with herbs and other veg, it makes it a bit more difficult for the caterpillars to move from cabbage to cabbage etc. If you do need to use an insecticide, consider using the products derived from Bacillus thuringiensis.

NaturScot is Scotland’s nature agency.  It monitors and reports on all aspects of the natural environment.  It has published a report on its terrestrial bird breeding species and it is a somewhat mixed report. Some of the most ‘famous’ species associated with Scotland, such as the black grouse have declined significantly during the period of study (1994 - 2019).  The grouse population has halved, and the kestrel, greenfinch and lapwing populations are also in decline.  Woodland populations of Capercaillie have also fallen.  The largest grouse in the world, the capercaillie was once widespread but suffered local extinction in the eighteenth century and was reintroduced in the C19th. It is now only found in old pine forests and mainly in the Cairngorms National Park. The Capercaillie are now red-listed and protected in the UK. [The Pine Marten which feeds in part on the eggs of game birds was almost lost in the nineteenth century, due to farmers and gamekeepers trapping them.] The fall in bird numbers has been associated with changes in climate, notably warmer and wetter weather coupled with extreme events (such as flooding and heat waves).  Whilst some species have suffered as a result of the changing weather, others seem to have prospered, including some that do not ‘traditonally’ make their way to Scotland.  The great spotted woodpecker is one such species, its numbers have increase by 500%, bullfinch and red numbers have also increased.  Gold finches and magpies are now more common on farmlands in Scotland. various measures could help offset some of these declines,.such as  the diversification of woodland (more tree species) restoration of peatlands Creation of habitats on farmland legal predator control deer exclusion to allow regeneration removal of deer fencing, (where feasible) as capercaillie and black grouse are known to fly into this and injured as a result. One example of the benefits of deer fencing is to be seen in the Glen Lyone woodlands.  Historically, this area was part of the royal hunting grounds of Cluanie and was home to capercaillies, wildcats and lynx.    Nineteenth century maps show a significant area of woodland, but by the 1990’s less than a hundred of the ancient pines were left.  The oldest pine in the area dates back to the C14th century, and many others are several centuries old.  However, the area was heavily grazed by deer, which reduces regeneration as young seedlings / saplings get eaten.  Now “Trees for Life” have erected new deer fencing, which hopefully will allow natural regeneration of pine forest in the area.  Calendonian Forest once covered much of the Highlands but now less than 2% of it survives.  Full details of this project (and a video) may be found here ; https://treesforlife.org.uk/scotlands-oldest-wild-pine-saved/

Just as many animal species are threatened with extinction, so are many species of tree.  In fact, one estimate suggests that up to a third of tree species are under threat - that is more than 17,000 species.  This equates to more that the number of endangered mammals, birds, reptiles and amphibians put together.  In 2021, the IUCN (the International Union for the Conservation of Nature) produced a report on some 58,497 tree species which identified 17,510 species as being threatened (and 142 extinct in the wild). In Mauritius, some 57% of tree species are at risk of extinction! Ideally, no single tree species should be lost, a single species can be an integral part of an ecological network. Its loss could result in the disappearance of many species and even an ecosystem collapse.  Some tree species are now represented by single numbers of specimens.  The ‘lonesome palm’ (Hyophorbe amaricaulis) is probably the last surviving member of its species. It is to be found in a botanic garden in Mauritius. It is an old, damaged and spindly specimen. It has problems with fruit formation; each of its fruits contains but one seed and the seeds are difficult to germinate (even the botanists at Kew could not persuade them to grow). The best approach to saving vulnerable trees is to protect their natural habitats.  This might mean controlling grazing by herbivores, or banning logging in sensitive areas.  Sometimes a change in cultivation techniques can make a difference.  The Lansan Tree produces a valuable, aromatic resin.  It is endemic to the Windward Islands and its fleshy fruits provide for native pigeons and other wildlife.  The resin is collected (tapped) from the tree by slashing the bark every one-to-two weeks. However, over-tapping for the resin can lead to the trees becoming infected with pathogens, then rotting, or subject to termite attack. The pathogens may spread to untapped trees.  Unregulated tapping and conversion of land from rainforest to agriculture have led to Lansan Tree populations all but disappearing in places. On Saint Lucia, where there is a large but threatened population of Lansan Trees, there is hope after the introduction of a sustainable resin harvesting technique.  This technique does not damage the tree but still allows a good yield of the resin.  This,  coupled with training of licensed resin tappers should protect the trees. Some species have reduced populations because their pollinators have been lost, so fruit and seed production has ceased.  Other species have separate male and female plants (dioecism) and the small populations that remain are represented by only one sex.  This was true for the catkin yew population in Hong Kong, where all the trees were males.  A global search found a female specimen in the Royal Botanic Garden in Edinburgh.  Cuttings from the Edinburgh tree have now been planted in a managed site in Hong Kong.  Hopefully when they flower, fruit and seed production will occur;  but it may be a long wait for the young trees to reach sexual maturity.  Another species, the oleander podocarp (Podocarpus neriifolius) has been nursed back to viability by similar techniques. Some rare and isolated trees produce seeds but getting them to germinate is another matter.  Many seeds enter a state of dormancy and have extremely specific requirements for them to germinate and grow on.  In many cases, their needs are simply not known.  The seeds may need a particular temperature regime, or exposure to cold, fire, smoke or light of a particular wavelength. Some seeds may need to travel through the gut of a particular animal before they will germinate.  Sometimes, scientists have used to embryo culture. The embryonic radicle (root) and plumule (shoot) is extracted from a seed and then grown in a sterile nutrient culture medium.  This technique was used at Kew with the ‘lonesome palm’ as attempts to grow its seeds had failed.   Embryo culture resulted in plantlets forming but after a while their roots turned brown and the young plants died.  There are success stories.  A Cypress species Widdringtonia whytei, was reduced to a few trees in Malawi, as a result of illegal logging for timber. Many seedlings have been  planted on Mount Mulanje and  a good number of these have survived. [caption id="attachment_25196" align="aligncenter" width="675"] Entrance to the Millennium Seed Bank[/caption] When and where seeds are actually available, they can be dried or frozen (cryopreservation) and placed in seed banks, for example the Millennium Seed Bank at Wakehurst Place.   We have to hope that through various interventions, the use of seed banks, botanic gardens and arboreta that we will be able to save many rare and threatened tree species,  you never know when one might be needed.