Which trees?
Sometimes you may want to collect seed from a particular individual tree, which perhaps has special historical significance or personal connections. Unusually prolific seeding of a particular tree or species may also be the spur to collection.
At other times you may want to collect a selection of species to produce stock for planting a new wood or hedgerow. Note the following:
- Contact the landowner to gain permission before you collect.
- In order to maintain local genetic stock, choose trees which, as far as you know, are least likely to have been planted. Trees which are obviously newly planted, for example along new roads, should be avoided. Also avoid collecting from woods which have trees in lines or remnants of planting patterns. Instead choose trees in old hedgerows, old woodlands, coppices or on common land.
- Choose groups of trees, rather than very isolated trees which are more likely to have infertile seeds.
- Within the guidelines above, choose trees nearest to the site you want to plant, as these are most likely to be of a genotype to suit local conditions.
- Avoid collecting from trees with obvious signs of disease, such as canker on the bark, or from deformed or stunted trees. However, some trees in exposed positions or on very poor soil may be stunted by the conditions, but the seed is still worth collecting, because such trees are likely to be from natural stock.
- Some of the smaller trees and shrubs are easy to spot and identify when in flower, but are less obvious at other times of year, including fruiting time. Keep a look out for species you want to propagate, and note their locations in readiness for collection time.
Note that trees do not produce seed every year. Different species have different average yearly intervals for producing a good seed crop (see species details). Some individual trees tend to be good seed bearers, possibly due to genetic strain, site or other factors. Species such as beech and sweet chestnut may produce seed, but when the husk is opened the seed inside is shrivelled or absent. you will need to wait for a year when plump, viable seed is produced. Acorns and other large seeds can be checked for viability by putting them in a bucket of water. Viable seeds sink, non- viable seeds float.
Local provenance and origin
Provenance is a term used to describe the location of the group or ‘stand’ of trees from which reproductive material is collected. Provenance has been used for many years to describe particular strains of trees which are valued for their timber quality. Origin is a term used to describe the part of the natural range from which the reproductive material originally derived. However, as many stands of trees were themselves planted, their origin is not usually known. Reproductive material is considered to be of ‘local provenance’ if it is from stands of trees which appear well adapted to the location in which they are growing. Under the voluntary system outlined below, a certificate of local provenance may be issued by the Forestry commission to identify reproductive material which has been gathered and recorded following the procedures set out under the system.
Local seed zones
The 23 local seed zones in Britain are based on major geological and climatic variations. Elevation, above and below 300m, is considered as an additional factor because of its important effect on local climate. From the approximate natural distribution of native trees and shrubs over recent centuries, a list has been compiled of the species which are thought to be native to each zone. A voluntary system is encouraging seed collectors, nurserymen and planters to follow these zones in matching seed sources to planting sites. In this way the local genetic stock of trees and shrubs in Britain can be perpetuated. For full details see Forestry Commission practice note Using Local Stock for Planting Native Trees and Shrubs (August 1999).
How to collect seed
See the species details for the appropriate months to collect seeds.
Ordinary supermarket carrier bags are fine for collecting seeds, as long as they are kept in the bag for no more than a few hours. Otherwise, use buckets or hessian bags for collecting nuts and larger seeds which have wings. Smaller seeds can be collected in paper bags, envelopes or small hessian bags. Berries can be collected and kept for a few days in plastic bags as it does not matter if the flesh begins to rot.
Every bag or other container should be labelled with the species name, date of collection and location of the tree.
Secateurs or loppers are useful for clipping off bunches of seeds or terminal seed-bearing twigs. Long-handled pruners or treetop pruners enable the reaching and removal of seeds up to 3m (10’) above ground level. Alternatively, a long pole with a hook can be improvised for pulling branches down to within reach. A step-ladder may also be useful, but must only be used with at least one other person to steady it. Tree-climbing should not be used by non-specialists as a method of reaching seeds. When using long-handled pruners or long poles, take great care to avoid overhead power lines.
Seed can also be collected from the ground. Heavy seeds such as oak, sweet chestnut or beech can be picked up where they fall, or tarpaulins can be spread before the seeds fall to make gathering easier. The first fruits to fall are the empty and malformed fruits. The main seed fall will follow shortly after. you need to be prompt to collect before squirrels and other animals find them. Strong gales may bring down a large quantity of seed.
Where light seeds such as birch fall on hard surfaces they can be swept up and collected.
Records
In addition to the labelling of seed, records can be kept of seed collecting operations in order to build up a picture of the most reliable seed trees in the area. Include the following:
- A map showing the exact location of the trees from which seed has been collected.
- A brief description of flowering and fruiting habits of each tree.
- The yield of processed seed from each tree.
- The growing performance of each seed lot collected, on a yearly basis.
