Long and diverse hedges are so important for insects and birds.
A report by the botanist, Dr Ambroise Baker, University of Teesside:
Within the allotments, the habitats to be noted are the larger trees, the hedgerows, the grasslands (common plot and on many plots grassy path, etc.), and small features in individual plots (piles of bricks, ponds, etc.). In addition, the presence of a mature alder buckthorn (Frangula alnus) is noteworthy. To a lesser extend the large field maple on the common plot is also to be noted as large specimens of this species are uncommon in the North of England.
In the cemeteries, there are mature trees, with understory, comprising both native and planted species. These form valuable habitat for a variety of wildlife, including for example, birds, bats, and other mammals. There is also some nutrient rich grassland. The headstones themselves can be an excellent habitat for bryophytes and lichen, however, most of them are very shaded, decreasing the quality of habitat for these groups.
A bit more detail about the alder buckthorn: This species is widespread at low abundance in the South of Britain and rare North of York, where it is at the limit of its Norther distribution (see e.g. https://plantatlas2020.org/atlas/2cd4p9h.c18). The shrubs or trees are associated with a species of butterfly, the brimstone butterfly, at its northern limit in the area too. It is also known as a valuable source of fruits for a variety of birds, especially thrushes, a declining species in Britain.
A bit more detail about the hedgerows: Some of the hedgerows would qualify as native species-rich hedgerows, some as native hedgerows and finally other sections simply as hedgerows. As new hedgerows are planted, it would be worth promoting a variety of native species, including alder buckthorn already present at the site. Seeds from alder buckthorn could be germinated, grown and planted in the hedges.