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.    

Images of deer in a woodland clearing may seem charming, but quite how deer and woodlands interact is not fully understood. It is certainly the case that deer affect tree regeneration;  they browse on saplings and can cause extensive damage to bark (through territorial behaviour / antler rubbing) to larger trees.  The lower levels of the plant communities are also affected by deer.  By changing these, deer also can change the animals to be found in this lower layer of a woodland. Research by Dr. Simon Chollet and colleagues showed that deer interaction can influence soil water availability,  and soil fertility. Their study looked at the role of Sitka black-tailed deer on the plant communities in forests in parts of western Canada. Chollet et al. examined twenty areas where deer were excluded for some two decades. An exclosure is a limited area from which browsing animals, such as deer, are excluded by fencing or other means. Unsurprisingly, they found that deer did have a significant effect on the plant communities. The exclusion of deer resulted in an increase in vascular plant richness and cover, though bryophyte (mosses etc) cover declined. They also found that with the deer gone,  the exclosures started to develop broadly similar plant communities.  There was no increase in beta diversity - that is the development small, localised communities of varying character. It was suggested that the dominance of certain species within the exclosures was linked to historic over-browsing.   Consequently, those plants that are able to withstand the presence of deer over time are best placed to achieve ‘dominance’ once this grazing pressure is removed.  This might explain why the different enclosures developed similar vegetation and plant species.    Biotic homogenisation has been seen in the UK woodlands, as was discussed in a previous blog.  It can be the result of introduced species, pollution (eutrophication - increased nitrate and phosphate levels), which allows botanical thugs (like nettles) to dominate, or poor woodland management.

Most regard woodlands as a beautiful and important part of our countryside, and feel that they can exert a profound and positive influence on our emotional state.    Time spent wandering through the woods can have a relaxing and calming effect. Woodland only forms a small percentage of our countryside (about 13%), and some of that is dominated by conifers planted in the post-war period for timber production; however, the area covered by broad leaved trees is now increasing.    Despite this, our woodlands do harbour a wonderful variety of wildlife (think of the red squirrel, the nightingale, the dormouse) but there is concern that woodland plants and animals face a number of threats - many species are in decline.   Why is this ? Read more...

Plants need to protect themselves from the vagaries of the environment - they need to prevent or resist the entry of disease pathogens (bacteria, fungi and viruses) and also restrict the loss of water from their tissues.   The flow of water through a plant (the transpiration stream) is important in the supply of minerals to the growing regions and the ’control' of leaf temperature (as water evaporates it uses heat energy -  exerting a cooling effect). However, uncontrolled water loss would soon result in wilting and death, so the outer layer of plants - the epidermis, has a special layer, the cuticle.  The cuticle is made from waxes, which often form complex and intricate patterns (when viewed with an electron microscope).   Read more...

Nitrogen is an important plant nutrient.  Generally, it is taken up in the form of nitrate (NO3) and it is used in the formation of amino acids, proteins and the constituents of the genetic material (DNA).  Some plants fix atmospheric nitrogen through the use of symbiotic bacteria in root nodules. However, modern / intensive farming involves the addition of nitrogen compounds in the form of manure, sewage sludge and chemical fertilisers. Couple this with the aerial deposition of nitrogen compounds, estimated at 400,000 tonnes / yr from car exhausts etc. (in the form of ammonia, nitrogen oxides) to give the total burden of nitrogen pollution. Pollution from such widespread sources is referred to as diffuse contamination. Read more...

Nitrogen pollution, in the form of nitrates, ammonia and various oxides of nitrogen, is a threat to ecosystems, ecosystem services and biodiversity.   Monitoring and measuring such pollutants in rain and air borne particles is expensive and, ideally, needs frequent samples. It has been estimated that some 400,000 tonnes of airborne pollution are deposited over Britain each year.  Research by Dr H Harmens et al at the Centre for Ecology and Hydrology (Bangor) has indicated that there may be a simpler and cheaper way of gauging nitrogen pollution  - through the assessment of the state of local moss populations. Read more...

Stinging or common nettles (Urtica dioica) are widespread across the UK, as can been on the BSBI map which shows the distribution of the nettle across the country.  They can be found in woodlands, hedgerows, gardens and disturbed ground. Read more...

It’s half-term and an excellent opportunity to get the children outside, particularly if the beautiful weather we’ve had for the last few days holds up.    Even if it doesn’t, just put on another layer and your waterproofs.  Here are Woodlands.co.uk’s suggestions for some woody half-term activities – and best of all, they’re absolutely FREE. go for a walk (and take a notebook to record/sketch what you see) explore build a camp cook sausages/toast marshmallows make some bannock bread brew some nettle tea build a den make a swing make a bird box to mark National Nest Box Week play hide and seek make a bow and arrows play at Robin Hood  take a map and a compass and try orienteering climb a tree learn your trees lie on your back and look up at the canopy take photographs take a magnifying glass and look at the lichens really close up look for an ancient / veteran tree see how many creepy crawlies you can find in an old fallen tree make your own nature trail research the history of your local woodland through old maps and its woodbanks listen to the birds do some animal tracking count the snowdrops put your wellies on and paddle in the stream make a dam play pooh sticks take a jam jar and do some pond dipping fish make a toy boat make pictures with fallen leaves, etc look for interestingly-shaped pieces of wood – it’s a sculpture! try wood whittling write a haiku or poem or a story take your paints and pencils get muddy just sit and listen to the silence or the sounds of the wood [caption id="attachment_42221" align="alignleft" width="675"] Bluebells[/caption]