Large trees are important in terms of carbon storage - with large quantities of above ground biomass, lots of carbon is locked away for years. Trees like Sequoiadendron giganteum, the giant redwoods, are truly large trees;. They are, by volume, amongst the largest trees in the world and incredibly long lived.  Some are thought to be over 3000 years old. Seeds of Sequoiadendron giganteum only arrived in the UK in the 1850’s, brought in by Patrick Matthew and William Lobb.  Lobb was employed by the Veitch Nurseries, based in Exeter.  He travelled extensively in both North and South America (including Argentina and Chile), and brought back not only seeds of the giant redwood but also some 3000 seeds of the monkey puzzle tree (Araucaria araucana).  He made a second trip to South America and brought back many different species of flower, including the chilean bellflower, the flame nasturtium, species of myrtle, and Escallonia macrantha. Exotic trees and shrubs were much prized by wealthy Victorians, and redwoods were planted in the estates and at the entrances of many grand country properties.  They also make appearances in many public parks and gardens, see for example the redwoods at the Lower Pond at Whinfell Quarry Garden in Sheffield. Forestry England estimates that there are half a million Sequoias (giganteum & sempervirens) in the country, and nearly 5000 giganteum trees are recorded by location by redwoodworld.co.uk, the woodland trust ancient tree index and the Forestry Commission.   Though it is only some 170 years since their introduction to the UK, some of these trees are amongst the largest trees in the country. This despite the fact that the climate here is not the same as that on the West Coast of America, their 'natural home'.  Due to their growth rate and carbon sequestration potential, there has been some discussion as to whether they might be included in commercial planting initiatives as they seem resilient to changes in climate, rainfall, soil moisture etc.  Disease resistance in another consideration.  The growth and biomass of some 97 Sequoias at three different sites (Lakehurst, Havering and Benmore) has recently been investigated (using laser scanning)*.  The growth of the trees at Havering was less than that at the other sites, possibly due to lower rainfall (and increased competition) in the East.  However, the growth rates of the trees studied were in the region of 150kg above ground biomass per year (this equates to 81kg of carbon per year).   Such growth is broadly similar to that of their American counterparts of a similar age.  It would seem that Sequoias might be a good choice for planting in terms of carbon uptake.   *Full details of this work here : https://royalsocietypublishing.org/doi/10.1098/rsos.230603    

Back to one’s roots? Some of the effects of agriculture are very obvious, such as the vast areas of land now covered by monocultures of wheat or oil seed rape.  The expansion of mechanised agriculture has resulted in significant reductions in biodiversity, for example, through the loss of hedgerows and ponds (see the post on ghost ponds in Norfolk).  However, agriculture has others effects that are not quite so obvious.   Soils are ‘filled’ with roots, and roots help engineer landscapes.  They help: break up bedrock, improve permeability of the soil to water  stabilise the soil,  store carbon transport water and minerals to the plants.   They have been doing this for millions of years since the colonisation of land by plants. Now, research by scientists in the United States, has shown that the roots of agricultural crops are significantly less deep than those of  the  natural vegetation in an area.  Indeed, the root depth may be shallower by some 60 cm, compared to the natural root systems of an area.  If the soil is less root material then there is  decreased carbon storage,  reduced nutrient recycling and  possibly reduced soil stability.   Whilst there are some areas where “woody encroachment” is occurring (for example, shrubland taking over in some grasslands and forest advance into regions of tundra so root depth is increasing) -  the onward march of agriculture is dominant. Full details of this analysis / research : https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022EF002897 Shrinking in winter Recent research has shown that some small mammals (like moles and shrews) shrink in size during periods of cold temperature.   This shrinking is thought to be a response to cold temperature rather than lack of resources.   This change in form has been known for some 70 years and is referred to as Dehnel’s phenomenon.  Professor Dehnel observed this change in form in shrews [in Poland in 1949].  However, shrews have a short lifespan so an extended studied of this phenomenon with these animals was not / is not possible.   Recent studies by German researchers have focused on moles, who can survive harsh winters by becoming  smaller.  It is thought that this reduction in size enables energy savings.  According to Dr Dina Dechmann this reduction in size comes at a cost, as the animals’ cognitive behaviour is affected. Further information here : https://royalsocietypublishing.org/doi/10.1098/rsos.220652 Farming and sustainability With the expansion of farming, less and less of the land is available for our native plants and animals,  Hedgerows and ponds have been lost / removed, natural habitats have been reduced. The government has produced new guidance on environmental land management schemes (ELMs).  That is subsidies that will be paid to farmers if they help promote and protect nature and improve the environment (e.g. using less insecticide and reducing pollution). There would be payment /subsidies for some 280 measures, for example : Creating fenland from lowland peat Maintaining sphagnum moss Creating land that could produce organic fruit Establishing a skylark plot Adding organic matter to the soil Creating green cover over winter (on 70% of the land) Welcome as these measures might be, there is criticism that they favour big arable farmers and do not really help those working on more marginal land (such as upland and moorland regions). Further information available here. Trees - From Root to Leaf For those who like their trees, here is a new book about them.  Written by Paul Smith -who was head of the Millennium Seed Bank of the Royal Botanic Garden, Kew.  Not read or seen a copy but the Sunday Times comment "'Stunningly illustrated and detailed ... a celebration of all things arboreal, from the seeds, leaves, flowers and fruit to the diversity of trees and how they have influenced art, culture and science' suggests that it might interest.  See "https://press.uchicago.edu/ucp/books/book/chicago/T/bo186012850.html"  

Wetlands. In the past, many areas of wetlands have been drained and ‘dried out’.  Now it is recognised that this is counter-productive in terms of carbon storage / sequestration and biodiversity, so there are now measures to restore wetlands. The hope has been that restoration of wetlands will do much to restore the variety of plants and animals (and help carbon storage).  However, research by the University of Copenhagen suggests that such projects might be ‘struggling’. The study examined ten wetlands (near the River Odense) that were restored between 2001 and 2011.  The restoration involved the removal of drains and ditches, and allowed streams to meander again instead of flowing in ‘straight channels’.  The aim of the project was primarily to reduce the leaching of nitrogen and phosphorus from adjacent farmlands, and hope to see greater diversity of plants (e.g. marsh orchids, globeflower, tussock-sedge and ragged-robin).   The ‘restored’ wetlands were botanically poor (whether restored in 2001 or 2011), they had only a quarter of the plant species compared to natural wetlands.  This may be due to  the continued input of nutrients (from agriculture), which encourages species that are ‘nutrient hungry’ at the expense of others. the ‘difficulty’ of wetland species to disperse from one area to another. It may be that future restoration programs will need to include planting / seeding of additional wetland species. It has been suggested  that it could take the best part of a hundred years for the restored wetlands to resemble natural wetlands. Redwoods and relatives. Previous posts have talked about the special features of the giant redwoods (their height, age etc).  Over the last 150 years, they have ben subject to the pressures of commercial logging, clear felling and more recently high intensity fires.  Indeed, the fires have been of such an intensity that seed banks in the soil have been destroyed. Now they have been subject to genomic analysis, that is their DNA has been analysed and sequenced.  The first conifer genome to be sequenced was that of Norway Spruce, then that of loblolly pine.  These suggested that conifer genomes are large (3 to 10 times larger than the human genome), with repetitive sequences.  Coast Redwoods are hexaploid, that is, they ave six copies of each chromosome (we are diploid, that is, have only two copies of each chromosome).   The DNA of a coast redwood has  27 billion base pairs of DNA, the giant sequoia has 8 billion; by contrast we have circa 3 billion.   It is hoped that the Redwood Genome project will see the restoration of areas of coast redwood and giant sequoia that have been lost over the years. The genomic analysis will help inform and guide management strategies, ensuring genetic diversity in the newly planted tree seedlings. Such a strategy will (hopefully) enable newly planted areas to survive and thrive — in the Anthropocene. More on chromosomes Just as it has recently been shown that Coast redwoods are polyploids (i.e. have extra sets of chromosomes), so recent research in the Czech Republic has shown that the common nettle [Urtica dioica] has different ecological ‘preferences’ depending on its chromosomal status.  Nettles can be diploid (2n = 26) or tetraploid (2n = 52).  The tetraploid nettles seemingly have a broader ecological tolerance and a wide geographical distribution, whilst the diploid nettles occur in a narrower range of ecological conditions. Details of this research can be accessed here (note link opens a PDF) and Plants for a future has lots of information on nettles.    

Recently, researchers have looked at the significance of small patches of woodland / forest in agricultural landscapes. Woodland and forest fragmentation has occurred as agriculture has expanded, as had the loss of hedgerows, Alicia Valdes and colleagues at the University of Stockholm have examined over two hundred patches of woodland / forest in farming areas in France, Belgium, Germany and Sweden. Read more...

Gabriel Hemery, Chief Executive of Sylva Foundation and lead author of the British Woodlands Survey 2017, provides some insights into the perceived murky world of payment for ecosystem services. Some readers may be aware of the recent publication of a report for the British Woodlands Survey 2017 (BWS2017). Over the last two years I’ve led a collaborative group of researchers from Sylva Foundation, Forest Research, Woodland Trust, and Oxford University in seeking to gain deeper understanding of awareness, actions and aspirations among woodland owners and agents, forestry professionals, businesses, and others with a stake in the future of forestry in the UK. Read more...