Autumn is here, whether you follow the definition of meteorological autumn, which starts on the first of September or the astronomical autumn which starts at the autumn equinox.  The equinox is when day and night length are equal, after that time the days get shorter. Or it might be that you are noting the signs of the seasons changing.  The BBC, the Woodland Trust and Nature’s Calendar chart the advance of autumn by recording events in the life of key species, for example blackberry, hawthorn, swifts, conkers, ivy and oak.  The information collected helps build a picture of how climate change is affecting the time of flowering, fruiting  etc. of many species. The blog has already commented on the early flowering of the blackberries but now woodlands are starting to transform into a mosaic of reds, yellows, and oranges as the leaves prepare to be shed and the woodland floor becomes a fungal jungle, (as Jasper has described). Hawthorn, Blackthorn and other bushes are laden with berries, conkers and acorns will be strewn across woodland floors. Squirrels eat hazelnuts (and hide some of them as a winter food store).  This banquet of fruits and seeds may be a response to the long, hot and very dry summer we have just experienced.  Trees and shrubs have been stressed by the heat and drought. Some have responded by mobilising their reserves / efforts into producing more fruits and seeds, to ensure that they pass on their genes to the next generation.   [caption id="attachment_24651" align="aligncenter" width="600"] Sloes on Blackthorn[/caption] If it seems like you have been noticing more acorns on the trees than normal that could be down to a "mast year”. Mast years occur roughly every five to ten years and refer to years when certain species of trees Like oak & beech) and shrubs produce a larger than normal crop of berries, nuts and fruit.  This boost in production means far more is produced than can be eaten  by the usual herbivores, squirrels, dormice etc, thus ensuring at least some of the mast goes on to grow new plants.  However, this ‘over-production’ can come at a cost to the tree, using vital resources so that growth in the subsequent year may be reduced.  Quite what causes trees and shrubs to ‘go mad’ and overproduce is not known but some theories are explored in a previous blog, though the weather in Spring is an important factor. [caption id="attachment_42689" align="aligncenter" width="675"] Collecting acorns.[/caption]

‘The Fall’ in the eastern United States has been colourful and plentiful this year.  There have been bumper crops of acorns, maple seeds and pine cones.  It is a Mast Year.  The trees have produced enormous numbers of potential offspring. These seeds and fruits will have significant 'knock on effects' in the ecosystems for some years.   Beeches and oaks can release so many seeds that they significantly increase the organic content of the soil and its nutrient value.  This fuels fungal and microbial growth. Small mammals feast on the acorns / mast and their numbers increase.  They, in turn, are food for foxes, owls and other predators *.   Quite what drives a mast year has long been a cause of speculation.  Ideas have included  masting evolved to overwhelm seed predators (mice, squirrels etc.) and thus ensure that at least some seeds survive to germinate and grow on.  fluctuations in nutrient availability affect the trees and flower / fruit production environmental prediction - that masting occurs in those years when seeds are likely to have good weather for sprouting in the following Spring.   even sunspot activity has been invoked Recently, a database [MASTREE] was created of mast years (for Beech and Norway Spruce) that extends back centuries.  This has enabled scientists to explore the environmental prediction idea, that is, whether masting is correlated with climatic events and occurs when seeds are likely to have favourable weather for germination and growth in the Spring after their production. On comparing the data with climate records, they found masting events [in beeches] correlated with climate patterns associated with the NAO - North Atlantic Oscillation, i.e. changes in air pressure between Iceland (low) and the Azores (high).  A “positive” NAO phase favours both masting and subsequent seedling growth; that is warm wet winters promote seed production and dry springs favour seedling growth.  Quite how the trees turn such climatic events into ‘signals’ for masting is another matter. Not all are convinced however. Some argue that the resources used up in producing so many seeds / fruits mean that the trees are exhausted and it takes time for these resources to be replaced and for the tree to flower and fruit fully again.   Professor David Kelly has a somewhat different hypothesis related to weather .  He suggests greater warmth in the previous growing season(s) may be the trigger.  Quite how the trees ‘remember’ the warmth that they have experienced is not known; but one thought is that it is due to what is termed ‘epigenetic marking’.  It is possible that the DNA of the genes that affect flowering is changed by the warm temperatures.   The activation of particular genes can be altered by their DNA undergoing methylation - a process where methyl (-CH3) groups are added (or removed) from the DNA.  Further information on masting and climatic effects on trees - visit science.org * [Sadly, a Swiss study found good masting years were later associated with a rise in tick-borne disease.]  

Wild boar became extinct in the U.K. in the thirteenth century –so we have been ‘boar free’ for circa 700 years.  However, towards the end of the last century commercial pig farming developed; seemingly some escaped and have established free living and breeding populations. Attitudes to these pigs / boars fall into two broad categories : those who welcome the return / reintroduction of a missing species and its ecological impact those who have a more negative perception of the boar – in that, they do damage, have the potential to harbour disease and can cause direct damage to people. Read more...

That seeds are dispersed by animals is well known; most elementary texts on biology are littered with a variety of examples. Fruits (and their seeds) attract animals with the edible parts; from fleshy fruits - plums, mangoes, berries,  cherries etc for frugivores, to various nuts.  As the animal searches for and collects the fruits (monkeys in the forests, squirrels in the woodlands), some may be lost or discarded on the journey ‘home’.  Other fruits / seeds cling to an animals by attaching to their fur / clothing using various hooks or barbs – a classic example being cleavers or goosegrass. Some seeds are dispersed incidentally; they may be lurking in muddy soil and adhere to the hoof or foot of an animal, bird or human, or be carried some distance by car or tractor tyres. However, many species of plants have an ‘unseen’ army of helpers – ANTS.  Ants disperse seeds in two distinct ways.  Read more...

Mast is the ‘nut crop’ of the beech tree (Fagus sylvatica), but, in a broader sense, is the production of an enormous number of seeds. And the phenomenon is not restricted to beeches.It can also been seen in oaks, firs, spruces and pines.Such species are said to have ‘mast years’ and in such years it is basically impossible for animals to eat all the seeds ("predator satiation") so many seeds survive to the following spring and germinate. Read more...