Earlier flowering times. A survey has shown that plants are flowering earlier in the year.  Cambridge University researchers compared the dates of flowering of some four hundred plus species before and after 1986. They found that plants are now flowering roughly one month earlier.  More recent decades have been associated with rising air temperatures. This change in flowering time may have profound consequences for the plants.  The vast majority of plants are dependent on pollinating insects (bees, bumblebees, hoverflies) to set seed and complete their life cycles.  By flowering early their cycle, plants may not match up  with the activities of their pollinators. They may flower but their pollinators bee ‘missing’. Their pollinators need to emerge from their overwintering stage earlier. Earlier flowering may not matter for those plants that are visited by several pollinators but for those that are dependent on one or two specific visitors - it may critical.  For example, Sainfoin.  Sainfoin is host to a particular (solitary) bee Melitta dimidiata (remote image here).   It is a monolectic bee; i.e., a bee that collects food (nectar and pollen) from only one species of flower - the sainfoin.  If the sainfoin flowers earlier in the year and the bee does not match the shift in flowering, then the bee has a problem. Work on the effects of climate change on pollinators has been somewhat limited to date, but studies in Japan suggest that bees / bumblebees are somewhat behind plants in their response to environmental changes. Bee and bumblebee news. Recent research data provide evidence that (buff tailed) bumblebees are not able to detect or avoid concentrations of pesticides [imidacloprid, thiamethoxam, clothianidin, or sulfoxaflor], as used ‘on the farm’ - from signals sent by their mouthparts. The mouthparts are covered with tiny hairs and these hairs have ‘pores’ in them. Chemicals pass through these ‘pores’ to sensory cells; this is how the bee tastes and smells. It seems likely that the bumblebees are at considerable risk of consuming pesticides in their search for nectar when visiting pesticide-treated crops. [caption id="attachment_19675" align="alignleft" width="300"] Bumbles foraging in artichoke[/caption] Another agrochemical,  Roundup,  has been found to affect the learning and memory of bumblebees. Roundup, which contains glyphosate, affects their ability to learn and memorise connections between colour and taste.  Impaired colour vision is likely to affect the foraging and nesting success of the bees.  The research was conducted in Finland by researchers at the University of Turku. In yet another concerning study, researchers at the University of Maryland have found that the life span of laboratory-raised honey bees has reduced considerably.    Five decades ago, the lifespan for a worker honeybee (Apis mellifera) under controlled laboratory conditions was about 34 days. Now it is some 17/ 18 days - according the report in Nature.  The study also reviewed the scientific literature [from the 1970s to now] and noted a trend in the life span of bees.   Shortened worker bee lifespan has implications for colony health and survivorship.  The work at the University of Maryland is ongoing. Methane release. Ghost forests are found in coastal areas.  As a consequence of climate change, sea water has ‘invaded’ low laying areas and trees have died. The dead trees are sometimes referred to as ‘snags.  A  number of woodland / forest communities along the eastern coast of the United States have been affected.  Recent work by North Carolina State University has shown that these ghost forests release methane.  The methane is generated by bacteria in the soil but then ‘escapes’ by means of the ‘snags’.  As it passes through the wood of the ‘snags’, microbes may consume and alter the methane.   As methane is a potent greenhouse gas, understanding the nature and extent of these methane emissions from ‘ghost forests’ is important. Tree rings The study of tree rings has been invaluable in dating many historic objects ./ archaeological sites.  Now, it seems that they could play a role in estimating the amount of carbon that trees are actually absorbing (carbon sequestration), if woodland / forest inventories are coupled with core samples of the trees. The measurement of the annual rings from such cores could create a record of ‘tree growth across space and time’, yielding a more accurate estimate of the amount of carbon being taken up by woodland and forests. Forests, soils and oceans are major ‘carbon sinks’.

Perhaps it all started with a "No-shave November" (or "Movember") when men realised that they could go for a month without shaving and no one would mind.  It may also have been good for them as they thought more about men's health and they let nature take its course.  A few years later people started wondering about other habitual cutting, such as mowing their lawns religiously.  "No Mow May" was invented in 2019 by Plantlife with the idea that less cutting of grass would allow wildflowers to flourish.  The official reason for this concession to conservation was to allow the wild flowers and pollinators to thrive, but it may also have become popular because it allows maintenance teams to work a bit less hard during May.  In any event it's now so popular that about 36% of lawn owners now join in every year.  But it's spilled over well beyond just the month of May - many owners of lawns have questioned whether they really want so much short grass when alternatives are more interesting - and better for wildlife.  Even at the 2022 Chelsea Flower show there were several gardens demonstrating rewilding. So rethinking the scorched earth policy has now spread from men's chins to gardens and parks - but will it spread further?  What about our hillsides? For eighty years we have been intensively grazing these with sheep and cattle as if our lives depended on it - which maybe they did in 1942, when war-time convoys of food from the US were being torpedoed.  Even after grazing ceased to be a necessity sheep continued to dominate our hillsides with grants to sheep farmers making it profitable to use their four-legged lawnmowers at scale.  Farmers even grubbed out hedges in the 1970s, described by Oliver Rackham as the locust years, which made the countryside look even neater and tidier.  According to DEFRA there are currently about 32 million sheep in the UK, a third of them in Wales.  Land used for rough grazing and grassland makes up about 50% of the UK's total land area.  So for several generations now the UK has used half of its land to raise animals for eating, but times are changing rapidly.  Whereas those with meat-free diets used to be a tiny minority their numbers are growing rapidly - already at least 14% of the population is meat-free and for those of university age (18-23) the number is up to 25%, and rising. The combination of reduced demand for meat and increasing awareness that we can happily stop cutting the grass is prompting a rethink of how we use the British countryside.  Much of the grazing land is not suitable for growing agricultural crops so that leaves owners wondering what to do with their land.  Some are choosing rewilding in various ways but usually with far fewer grazing animals, longer grass and more wildflowers. [caption id="attachment_38426" align="aligncenter" width="600"] 'rewilding' of roadsides and verges[/caption] Others are planting trees and creating new woodlands.  Where the land is sold it's often to people who want to plant trees or simply to fence out sheep and allow "natural regeneration" allowing trees to self-select and grow on their own.  It's an appealing project for many families to take on 5 acres of grazing land, plant trees and convert it into a wood of their own. This re-evaluation of how grazing land is used is happening right across the world as plant based diets become more popular and there is potential to re-establish wilder habitats.  It's good for carbon emissions - not only because woodland fixes carbon but also because rewilding cuts the number of grazing animals releasing methane: belching by sheep and cattle creates a third of the total emissions of UK agriculture. Despite this, there may be resistance from the powerful National Union of Farmers which mostly represents bigger farmers and which promotes farming as an industry.  Farmers already complain about reductions in headcounts of livestock - since the peak in 1992, sheep headcount is down by about a third.  But it's also about the way the grant system is structured - millions of sheep only exist because of the farm payments, financed by taxpayers, and the condition of receiving these annual grants is that "unwanted" vegetation and wild plants have to be removed.  So even if the sheep don't chomp up biodiversity the farmers have to do it to get their grants. [caption id="attachment_21282" align="aligncenter" width="600"] Sheep grazing around solar array[/caption] Even beyond this suppression of diversity, sheep and cattle are damaging in many other ways such as compacting the soil which contributes to flooding and droughts. Meanwhile the number of men keeping their beards after no-shave November has increased and there are more gardens and parks with wild meadows so maybe the much bigger revolution in rural land use might follow. Governments have had it within their power for decades to reform the grant system but real change may be driven by people's behaviour - eating less meat and planting up their own woodlands.

Recent times have seen a recognition that livestock farming contributes to global warming.  Ruminants such as cows, sheep and goats produce methane as a by-product of their digestion, not only that but their urine can release nitrous oxide - another potent greenhouse gas.  It has been suggested that farming might account for some 10% of UK emissions. However, some new research (published this January) conducted by Professor Chris Stoate (of The Game and Wildlife Conservation Trust) suggests that there might be a way of mitigating these emissions by changing the diet of certain ruminants slightly. Read more...

There is considerable debate as to the virtues or otherwise of buying a real Christmas tree over an artificial one.  This comes into focus somewhat more sharply in the post-Christmas period.   A  6 to 7 foot high natural tree (bought with no roots) would be between ten to fifteen years old and it has a fairly low carbon footprint.   As it has been growing, it has been absorbing carbon dioxide from the atmosphere and locking it away in the form of cellulose and lignin, whilst releasing oxygen.  However, this footprint changes dramatically if its fate is to be consigned to land fill.   As it decomposes, it will produce methane, a potent greenhouse gas and the carbon footprint of the tree will increase quite dramatically.   If, however, the tree is carefully composted, then its environmental impact can remain relatively low (visit the Carbon Trust for detail).   The cultivation and growth of natural Christmas trees provides a wildlife habitat, and the trees help stabilise and protect soil.  But in some parts of the world, notably Canada and the USA, the growth and supply of Christmas trees has been affected by heatwaves (as in Oregon in 2017 / 2018 - which killed many very young trees), insect damage and wildfires. The effects of climate change are particularly marked in Canada.  It may be that climate change will intensify the effect of these factors, and that Christmas tree ‘farms’ may need to move to higher elevations - where it is cooler and insect pests (e.g. balsam twig aphid) are less of a problem.  Read more...

Radiant energy from the sun falls on the Earth; some of this energy is absorbed by the planet and its atmosphere.  Some of the energy is radiated back into space.  The balance between the absorbed and radiated energy determines global temperature.  This balance is changed by a number of factors - the intensity of the solar energy, cloud reflectivity, the absorption of energy by various gases or surfaces. The reflectivity of the Earth’s surface  (the albedo) influences the amount of light energy that is reflected back into space. Snow has a high albedo, that is, it reflects much of the light back out into space.  Dark objects (like conifer plantations) reflect less light / radiation and absorb more thereby trapping heat that would otherwise be reflected back into space. The amount of energy that is ‘retained’ is also influenced by the presence of particular gases in the atmosphere - the so-called 'greenhouse gases', notably carbon dioxide and methane.  The amount of carbon dioxide in the atmosphere has increased dramatically from 280 ppm during the 10,000 years up to the mid-18th century to 415 ppm (as of 2019).  This increase has certainly contributed to the changes in climate that we have witnessed in recent years - extreme weather events such as heat waves and flooding.   Read more...

Methane might be a clean fossil fuel when in a pipeline but it is second only to carbon dioxide in terms of contributing to global warming, when present in the atmosphere.  Over the last two centuries, the level of methane in the atmosphere has increased dramatically (and now stands at approximately 1800 parts per billion). Much of this increase has been linked to certain agricultural practices (farming of cattle and other ruminants, paddy fields) plus the emissions from decomposing landfill etc.  However, recent work in a number of forested and woodland areas (for example, The Amazon, Borneo, China, Hungary etc) has suggested that the release of methane by trees is significant, and given that methane is an extremely potent greenhouse gas - this has to be considered in relation to climate change.  The methane contribution from  trees has not really been considered when working out the global methane budget but it now seems that they make a contribution.   Read more...

Some sixty six million years ago, much of the Earth ‘caught fire’.  A large asteroid smashed into the Earth (on the Yucatan Peninsula, Mexico).   The force of the impact has been estimated to have been a billion times greater than the force of the atomic bombs deployed at the end of WW2.   The impact of the asteroid and its effects were devastating, resulting in catastrophe on a global scale.   The event has been mainly associated with the extinction of the dinosaurs.  Immediate to the impact, rocks and material was ejected high into the atmosphere - as this material fell back to earth, searing heat was generated and fires were ignited; indeed, intense forest fires were ignited certainly across the Americas.    Read more...

A recent woodlands blog discussed the millions of Christmas trees that end up as landfill material.  This is also true for a material that is generated in cafes and restaurants across the U.K - the ‘waste material’ is coffee grounds. Coffee is the second largest traded commodity after petroleum.  One estimate suggests that six million tonnes of spent coffee grounds go to landfill every year.  Landfill sites account for a fifth of the UK’s methane emissions; methane is an extremely potent greenhouse gas associated with global warming & climate change. Read more...