Blog - Climate Change
Creating diverse woodlands and forests
We know that forests are important to all life on the planet. They have often been referred to as the ‘lungs of the earth’, a reference to the fact that they produce vast quantities of oxygen - which is essential for respiration for so many forms of life. They also take up carbon dioxide and ‘fix’ it into complex organic molecules - from starches, to cellulose and lignin. Thus, the carbon is locked away for months, years or even millennia. The equatorial forests of Brazil and Sumatra are species rich, incredibly diverse, but deforestation and the expansion of agriculture are threats to many biodiverse, forested areas across the world. As so many forests and woodlands have been felled, there is now a movement to plant millions and millions of trees (across the world) in an attempt to mitigate climate change and in the UK to increase our percentage tree cover from a pretty low base. Sadly, twentieth century forestry in the U.K was largely based on monocultures (for timber production). The trees planted were large stands or plantations of conifers - using Scots Pine, Larch and Spruce. These plantations not only lacked biodiversity, but were / are susceptible to wide scale pest infestation and extreme weather events. Woodlands and forests that have a diverse range of tree species are not only healthier but show greater growth and carbon fixation. They are more resilient. The diversity of trees ensures the each species accesses slightly different resources from the environment - from soil minerals, water and light. Diversity means that trees of the same species are less likely to be clustered together so pest and pathogen outbreaks are less common or less severe. One area that has undergone an extensive and diverse planting regime is Norbury Park Estate (near Stafford). Since 2009, over 100 different tree species have been planted, and the woodlands can now produce 1500 tonnes of new wood each year, and harvest 5000 tonnes of carbon dioxide from the air. Not only can diverse woodlands / forests fix carbon, supply harvestable timber but they also offer areas for rest and relaxation. Whilst it is not possible to plant an 'instant' forest or woodland, it is possible to plant a range of tree and shrub species that will in time grow and mature to form a diverse and species-rich area. As Charles Darwin said many years ago “more living beings can be supported on the same area the more they diverge in structure, habits, and constitution” [On the Origin of Species by means of Natural Selection, 1859] Managing woodlands for wildlife - see here. N.B. Opens a PDF.
Drought and pollinators
Climate change is affecting all parts of the world, from the melting of the ice caps in Antarctica, to droughts in Australia and California. On a more local level, we may see changes in our rainfall pattern. Certainly for many parts of the UK, it has been a very dry start to the Spring, coupled with some very cold nights. Cold and dry weather affects plant growth in significant ways. Warmth is needed for a plant’s enzymes (catalysts) to work, speeding up reactions and allowing growth. Similarly, if water is in short supply, growth is stunted; plants do not realise their full ‘potential’. They are smaller overall as is the number and size of flowers that they produce. Flowers attract visitors by colour, size and scent; or combinations thereof. Smaller and fewer flowers, in turn, have ‘knock-on effects’ for their pollinators - bees, bumble bees, hoverflies etc. The effects of drought on pollination has been recently investigated by researchers at Ulm University in Germany. They studied the effect of drought on field mustard (aka Charlock) : Sinapsis arvensis. This is an annual plant that is to be found in fields, waysides and field margins across Europe. It has bright yellow flowers, with four petals. It is visited by many different pollinators (it cannot self-pollinate). The researchers compared the number of visits by bumblebees (Bombus terrestris) to drought-stressed plants to well-watered ones. The data showed that as the number and size of the flowers decreased so did the number of pollinator visits. [caption id="attachment_21589" align="aligncenter" width="600"] Bumblebees also favour the teasels[/caption] The ‘attractiveness’ of the plants / flowers to pollinators was reduced, and it is possible that the smaller flowers were more difficult for relatively large pollinators (like the bumblebees) to ‘deal with’. If pollen movement is reduced, then fewer fruits / seeds will be set and (insect pollinated) plant populations could decline. The effects of reduced rainfall and water stress need to be considered alongside the declining number of pollinators. The reduction in pollen movement has lead some to speculate that it might lead to a selective pressure for self-pollination / self-fertilisation, with plants dispensing with the need for visiting insects. Other Woodlands blogs have reported on the falling numbers of insects / pollinators. Featured image : garlic mustard.
woodlands web updates 10.
Bees and solar parks As the country tries to move towards carbon zero, so we see more and more solar parks / farms ‘springing up’. Whilst they do create clean energy, they also take up a lot of land, and it is important to see if such solar parks can offer other commercial or environmental benefits. One suggestion is to place honeybee hives on such parks. The bees could provide a pollinating service to surrounding crops / farmland. Researchers at Reading and Lancaster Universities have studied detailed land cover maps / crop distribution patterns to estimate the economic value of deploying honeybees in solar parks. Their investigations suggest that a variety of crops from oil seed rape, soft fruits to apples and pears could benefit from such an arrangement. The benefits would vary across the UK, with the benefits being greatest in the East and South of the country. Care would need to be exercised though to ensure the placing of hives did not disturb the foraging of wild pollinators, such as carder bees, hoverflies etc. Are plants sulphur deficient? Much has been written about the importance of plants nutrients, especially NPK; that is to say nitrogen, phosphorus and potassium. However, little is said about sulphur. However, researchers in Groningen, Graz and Cologne have been looking at the effects of sulphur deficiency, particularly in relation to the colour and shape of the flowers formed. The work focused on Brassica rapa, a member of the mustard family. When it was subject to ‘mild’ sulphur stress (by limiting the sulphate in the growth medium), the flowers that formed were smaller and paler - not the usual bright yellow. They were also likely to be mis-shapen. Colour and shape are features by which pollinators recognise flowers and then visit them. Pollen production by the flowers was also affected; smaller pollen grains were formed. This may in turn affect the pollinators who visit the flowers foraging for food. In the relatively recent past, sulphur deficiency may not have been a problem due to acid rain, which would percolate through the soil, forming sulphates. [In the twentieth century, acid rain formed as a result of the release of sulphur dioxide (and nitrogen oxides) into the air through the burning of fossil fuels. However, various clean air acts have ensured that there is now much less SO2 in the air.] Annual rings, water availability and earthquakes. Christian Mohr (scientist from the University of Potsdam) was studying the transport of sediments in rivers in Chile in 2010 when a massive earthquake shook coastal areas of the country. When he was able to return to his studies, he noticed that streams in the valleys were flowing faster. He reasoned that this was because the earthquake has literally shaken up the soil, so that it was now more permeable and ground water could more easily flow down from the ridges. As a result of increased water supply, he thought that trees down in the valleys would grow more than those on the ridges. He and colleagues drilled out plugs of wood from valley trees and ridge trees, and back in Potsdam they examined the tree rings under a microscope. They also looked at the uptake of different isotopes of carbon as a measure of photosynthesis. They found that trees from the valley floor experienced a small but noticeable growth after the earthquake, and this lasted for weeks or months, whereas the trees of the ridges grew more slowly. It is possible that analyses like these, when combined with other information, could help identify significant historic disturbances. Rising temperatures. Recent years have seen periods of very hot temperatures, Such extreme weather events have been seen not only in the UK but across the globe (Arizona , Victoria Australia, Indonesia). Extreme heat (and drought) have been known throughout history, but it would seem that extreme events are now more common. The first two decades of this century are among the warmest on record; this warming is associated with increasing levels of greenhouse gases (due to human activity). Prolonged heat is not without its effects on us, it leads to sweating, teaches, fatigue, dehydration and heat exhaustion. The very young and the elderly are most at risk from ‘heat waves’. A 2003 heatwave across Europe is said to have caused several thousand 'excess' deaths’, mainly of the elderly. Even gradual but sustained warming of the climate can have its effects. For example, Silwood Park (Imperial’s research station) has commented that though it is now November, they have not recorded a single frosty night - normally they would expect to have three in a ‘normal’ October. Snowdrops are appearing earlier, and some migratory species are changing their pattern / timing of migration. Across the world, different species are being affected in different ways. Thick billed murres (type of guillemot, found in and around the Hudson Bay) have a high metabolism to deal with the cold waters into which they dive - they are cold adapted animals. On warm days (when the temperature is 21cC or above) they are dying whilst sitting on their nests - incubating their eggs. They struggle to keep cool, if they spend more time in the water then they leave their eggs exposed to predators (like gulls and arctic foxes). Similarly boreal and arctic bumblebee species are sensitive to heat stress, succumbing to stupor; other work indicates that some European / mediterranean species are now to be found in areas of the arctic circle - as a result of changing climatic ‘norms’. Wild dogs are adapted to deal with heat, but if the temperature goes beyond a certain point they stop hunting, consequently their pups / offspring are less likely to survive. Warming temperatures not only affect animals but they also contribute to the increasing number of harmful algal blooms (in lakes and off shore regions). These blooms can be dangerous to many animals (including humans) and when they die back they ‘suck’ oxygen out of the water - creating ‘dead zones’. One species of alga (Karlodinium veneficum) which is known to produce toxins has been shown to acclimatise to higher temperatures (up to 30cC). As climate change and research continues, we will no doubt see further examples of how animals and plants are being affected by changing temperatures / climate .
In a previous woodlands.co.uk blog, Professor Dave Goulson (University of Sussex) has written about the problems that bees and bumblebees face. Recently, he joined with Clipper teas (who produce organic tea products) to again emphasise the problems that bees and other pollinators face, and to explain how our lives would be affected if they were to be lost. Bee, bumblebee and other pollinator populations are at risk or in decline. Professor Goulson estimates that there are some 6,000 different species of pollinating insects in the U.K alone, but they face risks as a result of Habitat loss Pollution Climate change Use of pesticides (insecticides, herbicides, fungicides) [caption id="attachment_36158" align="aligncenter" width="650"] Hoverfly foraging[/caption] Whilst it is true that insecticides such as neonicotinoids are directly toxic to bees and bumblebees, many other compounds used as herbicides and fungicides are also harmful to these insects. Obviously herbicides get rid of weeds, but weeds or wild flowers are a food source for these pollinators. Pesticides can have what are termed ‘sub-lethal effects’, so that the learning ability of the insects is reduced. Bees and bumblebees can learn which flowers are best as food sources, they can navigate to and from their nests / hives through open countryside. Also these compounds can affect their resistance to disease, and their fertility / reproduction. It is a concern that that bees’ honey stores may contain a cocktail of several pesticides that the bees have encountered during their foraging. In collecting pollen and nectar, a single bee may visit / pollinate four thousands flowers in a day. Not only are many thousands of wild flowers species dependent on bees for pollination but some three quarters of our food crops also need bees and other insects. Without them, the range and availability fo fruit and vegetables in our supermarkets would be substantially reduced. Whilst going organic and reducing reliance on the many forms of pesticide agriculturally is great help to pollinators, there is also good news in that small growers and even domestic gardeners can have a positive impact on the numbers of bees and others pollinators, such as : Planting a range bee-friendly plants in their gardens Creating a wild flower area in the garden or Allowing the lawn to grow up to form a small meadow like area Reducing the use of all pesticides - insecticides, herbicides, fungicides etc.
Woodlands web updates 7
The British Dragonfly Society has produced a report “State of Dragonflies, 2021”. Dragonflies display the usual characteristics of insects, three pairs of jointed legs, three clear divisions to the body, compound eyes and a pair of antennae. They also have two pairs of (transparent) wings. The hindwings are broader than the forewings so they belong to the group - Anisoptera (from the greek unequal wings). They can fly fast and manoeuvre well. Their ancestors were some of the first winged insects to evolve. The report notes that Many species have increased their distribution (since 1970), for example, the emperor dragonfly, the ruddy darter. Though some like the black darter seem to be in decline; this may be associated with a lack of heathland management and the drying of blanket bog areas. Several species have arrived in Britain from Southern Europe for the first time, with others returning after long absences. The vagrant emperor is a long distance migrant from Africa and the Middle East. It is thought that it might now be breeding more regularly in Southern Europe so that some now migrate northwards more often. Dragonflies are moving northwards across Britain and Ireland (associated with warming temperatures and climate change) Whilst the distribution of species has increased, the actual numbers of different species is not known so it is not possible to say if dragonfly numbers have increased overall. However, compared to many reports on the collapse of insect numbers, it would seem that that many dragonfly species are responding to climate warming and an increase in the number of ponds (for example, see the woodlands blog of the restoration of ghost ponds in Norfolk), lakes, gravel pits in recent years. The larval stages of dragonflies (nymphs) are spent in water. Apart from changing the distribution of various animals (and plants), climate change can have other effects. Some homeotherms ‘warm blooded’ animals (birds and mammals) are undergoing changes in their body form or ‘shape shifting’. Sara Ryder et al of Deakin University, Australia has studied several species of Australian parrot and has found that their beak size has increased since the nineteenth century: this increase in beak size is thought to be associated with better heat exchange. Other research has reported on changes to tail length in wood mice, also tail and leg size in masked shrews. The changes are generally less than 10% but they do seem to be responses to changing climatic conditions. Pampas grass (Cortaderia selloana) is a tall, clump forming grass with attractive plumes that can find a home at the coast, in town or in your garden. It was originally a species native to South America. However, it now has a much wider distribution, mainly due to its use as an ornamental plant though it was also used in South Africa to control erosion on dumps around mines. Each plume can produce tens of thousands of seeds. Consequently, it is now regarded as an invasive species in many countries. It has expanded across industrial and urban areas, squeezing out native species in coastal regions of France, Spain and Portugal, Now the IUCN (International Union for the Conservation of Nature) has introduced a system to recognise the threats posed by harmful species (such as Pampas Grass) - The Environmental Impacts Classification of Alien Taxa.
Heat, bumblebees and foraging
Silwood Park is part of Imperial College, a postgraduate campus, located some 25 miles west of central London, near Ascot. It is a centre for research and teaching in ecology and allied disciplines. The campus includes areas of wet woodlands, acid grasslands, traditional orchards and parkland. The veteran and ancient trees support an significant number of rare species of insects, lichens and fungi that depend on decaying wood. Silwood is the heart of the wildlife corridors for the surrounding area. Read more...
“tropical nights’ and greening our cities
Much of England experienced a series of ‘tropical nights’ last summer, when night time temperatures were 20oC or above. These tropical nights were associated with the heat wave that affected most of south east England. Central London experienced its longest stretch of extreme daytime temperatures since the 1960’s - temperatures of 30+oC were recorded on six consecutive days. A number of experts have said that such heatwaves and associated tropical nights are likely to become more common as a consequence of climate change. We were not alone in experiencing high temperatures by day and night, much of western Europe sweltered in the heat this August. The problem was most marked in urban areas and large cities. Some three-quarters of the population of Europe now live in urban areas. Extreme heat affects our health causing general discomfort, malaise, respiratory problems, headaches, heat stroke, heat cramps and heat-related mortality. Read more...
Greenhouse Gases, Goats Willow and sheep.
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...