Happy as a pig in acorns: Nature 'fights back' with a bumper wild-fruit crop, the reward for enduring last year's heavy rain

The practice improves the pig's diet at the same time as reducing the volume of acorns available for cattle and ponies which can poison them (Alamy)

Hundreds of pigs will begin feasting on fallen acorns in the New Forest tomorrow as the ancient pannage season kicks off for another year.

The practice, which allows commoners’ pigs to forage on 60,000 acres of open forest, improves the animal’s diet at the same time as reducing the volume of acorns available for cattle and ponies, which have a habit of gorging on the smooth oval nut and poisoning themselves.

But while pannage takes place for 60 days every Autumn, this year will be a much bigger event than normal because Britain’s oaks are producing an unusually high volume of acorns.

As a result, an estimated 500 pigs are expected to be released into the forest over the period, almost double the 280 that were put out to pannage last year, according to the Verderers of the New Forest.

Nor is it just the acorn population that is burgeoning. This Autumn is truly living up to Keat’s observation that the season loads and blesses “with fruit the vines that around the thatch-eves run/To bend with apples the moss’d cottage-trees/And fill all fruit with ripeness to the core”.(To Autumn).

Shrub and tree watchers around the country are eagerly anticipating the greatest abundance of fruit, seed and berries since 2006 this autumn, with apple, haws (from Hawthorn), holly berry, rowan (Mountain ash), figs (sycamore) and blackberries all showing signs of unusually high yields.

“The rowan, or Mountain ash, is so heavily berried that the boughs look like they’re in danger of breaking,” said Matthew Oates, National Trust’s specialist on nature and wildlife.

“But it’s also a good autumn for most berry-bearing trees and shrubs. There will be plenty of holly berries this Christmas – and no, this doesn’t mean we have a bad winter ahead, as folklore would have you believe, but reflects the fact we had a good late spring. Sycamores, horse chestnuts, oak, beech, hawthorn – all have seized the windows of opportunity provided by nature,” Oates added.

The abundance is coming as a welcome relief for wildlife, which suffered badly from exceptionally poor crops of wild fruit last year as trees and shrubs were hammered by the poor weather.

Some 14 of the 16 species the Woodland Trust monitors recorded their worst season for fruiting since they began keeping score in 2001, including beech, holly and brambles.

But this year most have staged an astonishing recovery. Statistics are extremely thin on the ground at this stage of the fruiting season, but ripe blackberries have been spotted at 300 separate sites in the UK so far this year, which is “significantly higher” than normal for this time of the year, says the Woodland Trust.

This is largely thanks to near-perfect weather conditions for flowering, pollination and set (seeding) during much of April, May and June, of mostly fine weather with plenty of sunshine and just enough rain to keep the fruit moist, without stopping insects from pollinating.

Furthermore, the late spring has meant that many spring-flowering trees and shrubs are fruiting more closely together than in ‘standard’ years, rather than in their usual staggered fashion, as improving conditions lift the lid on pent-up growth. This makes the abundance seem even more dramatic.

“Nature is really good at fighting back. Most of this year’s comeback is down to the spring and early summer weather, but there may be other factors of which we are blissfully unaware. Wildlife has ways of compensating to make up for a bad year that we don’t fully understand,” Oates says.

Which brings us to the concept of the “mast” year.

The term mast – meaning fruit of the forest trees, such as acorns - is principally used to denote abundant harvests for oak, beech and sweet chestnuts, but the concept is often extended to include especially-fruity yields for other trees and shrubs. The frequency of mast years varies from species to species with no set timetable.

For beech, a mast year typically occurs every five to ten years, compared to six or seven for an oak and four or five for a sweet chestnut.

And this year, there seems to be an especially high level of mast years, with species such as beech, oak and sweet chestnut synchronising despite their differing cycles.

“It does seem that this year is a really good mast year in general. It’s certainly going to be a phenomenal year,” said John Tucker, of the Woodland Trust.

Although the weather plays a large part, the yields in a mast year are so disproportionately big that experts agree there must be other factors at play – it’s just that they don’t know what they are.

“There are some genetic factors at play. Would you get a mast year every year with those conditions? The answer is no. But we don’t know why I’m afraid,” Tucker said.

On some level, it seems that Nature is crying out “Enough” and defying science, experts say. After a prolonged period without enough food, wildlife needs to replenish itself and to build up energy levels for the future, while seeds need to be sown to build up the stock of trees and shrubs. And the result is a hugely bountiful supply of fruit, seed and berries to feed everything from blackbirds to door mice.

We need to harvest as many seeds as possible to plant so as to replace the ash trees that are rapidly dying out as a result of ash dieback disease, especially for oak, beech, lime and hornbeam trees, said Tucker, adding that people should also forage some of the fruit for themselves.

“There is a real opportunity to get more involved with nature through foraging. I was at Heartwood Forest near St Albans yesterday and the blackberries were phenomenal. From my observation there is plenty to accommodate people picking berries and the wildlife this year. And even in a bad year it’s ok as long as people are sensible and pick what they need rather than for commercial purposes,” Tucker said.

Simon Toomer, director of the Forestry Commission’s National Arboretum at Westonbirt agrees that there seems to be “some kind of trigger that exaggerates the response” of trees in some years to good weather conditions. Again, he doesn’t know what the trigger might be, although thinks that a spell of bad weather before “could be part of it”.

He also believes this year’s fruit was helped by last year’s incredibly heavy rain, a key ingredient in the process of photosynthesis, which creates energy in the form of starch and sugar that can be channelled into reproduction.

“It might not have been good for humans, but the rain was good for trees,” said Toomer.

An bountiful selection of fruit and berries this Autumn could be a delayed reward for enduring the second wettest year on record in 2012.