Britain's landscape is full of hedges, but they can take many different forms. The higher and wider the hedge the more carbon it will sequester.
But also consider the frequency at which they are encouraged to throw out fresh growth. Traditional laying created hedges, in rotation, that grew vigorously, were stockproof and absorbed a lot of carbon. This can be replicated to an extent by well-planned mechanical management.
Trees have an astonishing capacity to absorb carbon. Recent research has shown that all species absorb CO2right from planting in to old age (200 years plus). However the peak period for sequestration is in a tree's teenage years! Depending on the species this ranges from years 10 to 45 after planting, where sequestration rates are in excess of 12 tonnes of CO2 per hectare per year.
If your farm has a policy of continual tree planting you will ensure that there are always trees in the age-classes that maximise sequestration. Of course it also means you will always have a ready supply of timber!
Traditional orchards are Britain's ancient form of agroforestry, with ancient trees providing fruit and wildlife habitat, whilst underneath the trees permanent pasture provides grazing for livestock. Carbon is absorbed in the wood of the trees and the grassland builds organic matter in the soil.
Modern bush orchards may not have the capacity for livestock grazing, but if well managed can still provide significant carbon benefits as well as high fruit and/or nut yields. It's their perennial nature which makes orchards so important in carbon terms. Orchards, whether bush or traditional, are important carbon sinks that, unlike woodland and hedges, also provide food for humans.
Any grassland that is not cultivated is an important carbon asset, for organic matter can build and is not lost when cultivated. All fields have margins that are carbon sinks. Whilst there is always a trade-off between margin area and annual crops in a cultivated field, it's worth considering that margins have greater value than just being able to turn a tractor around on.
There are many novel ways to integrate perennial crops with annual crops, such as agroforestry. Forest gardens are a way of essentially creating woodland that is entirely edible and useful to humans as well as wildlife.
Coppice woodland offers potential for huge sequestration rates, meaning less land has to be given over to trees for the same carbon benefit. Coppice typically has a range of useful wood products following cutting, such as stakes, poles, weaving material and fuel. Any perennial crops are worth considering for carbon and other benefits, whether for biofuel like Miscanthus or even soft fruit like blackcurrants.