Human activity over the last twelve thousand years has responded to the natural history of the North Pennines to create the landscape we all enjoy today. Woodland is no exception. At first, woodland clearings were made by hunter gatherers to attract large game such as deer. With the adoption of agriculture, woodland was progressively cleared and by the time of the Roman occupation in the early centuries AD woodland was only a minor component of the North Pennines landscape. After the collapse of the Roman Empire there was a period of woodland regeneration and medieval communities of the North Pennines benefitted from an extensive fringe of scrubby wood pasture around many of the North Pennine Fells. This provided habitat for red deer and black grouse and much of it was included in areas designated as hunting forest for the benefit of the local lords such as the Bishop of Durham. By the time of the Black Death in the mid-14th century most of the wood pasture was cleared or grazed out and is now represented by small areas of gill woodland and juniper scrub. The North Pennines is now amongst the least wooded landscapes in England, itself among the most least wooded countries in Europe.
In the absence of grazing or browsing by livestock, deer, rabbits or voles, trees and shrubs would be ubiquitous on drier ground in the North Pennines. Establishing more trees and scrub in the landscape is, therefore, mostly a matter of managing this grazing or browsing.
Ancient woodlands are woodlands where there is evidence of continuous woodland cover since at least 1600AD. It is divided into two categories; ancient semi-natural woodland which comprises native tree and shrub species, and ancient replanted woodland, where the native woodland has been cleared and replaced by a commercial plantation crop. Ensuring that ancient semi-natural woodlands are safeguarded and managed appropriately is the highest priority because of the wide range of plants, fungi and animals that are only or mainly found within such woodland or on ancient or veteran trees.
Long-established woodland is a category of woodland comprising native woodlands that were recorded on the first edition Ordnance Survey maps in the 1840s and remain to this day. While they don’t have the longevity of ancient woodlands, their continuity of woodland cover is still significant enough to sustain ecological value missing from more recent woodland, and so they are worthy of protection for this reason. Importantly it also captures woodlands where there isn’t the documentary evidence to provide continuity of woodland cover since at least 1600, but which are likely to be ancient woodlands.
In the absence of now-extinct native predators such as lynx and wolf, deer numbers have risen in the UK to the point that they have serious negative effects on new woodland establishment, on the structure of existing woodland and on natural colonisation of trees and shrubs to form new woodland. See Box 5 Deer Management.
Within existing woodlands, browsing pressure prevents a new generation of trees from becoming established, and also reduces or eliminates the shrub layer of lower growing species including bramble and honeysuckle. This leads to an absence of many important woodland habitats, structures and species, and ultimately threatens the existence of the woodland as a whole.
Grey squirrels can also severely affect tree regeneration by killing young trees by stripping the bark from them. As with deer, control of grey squirrels requires co-ordination between land managers.
Large numbers of pheasants are reared and then released into woodlands for shooting each year. They have a range of ecological impacts including the loss of ground flora around their feeding sites due to trampling, intense predation pressure on woodland invertebrates, and soil enrichment from their droppings (which enables fast-growing species such as nettles to displace less competitive woodland plants). See Box 4 Non-native game birds.
The reference to ‘more trees in the landscape’ describes any increase in the number or cover of native tree and shrub species in appropriate locations across the full altitudinal range (through natural colonisation where possible and planting where necessary). These trees and shrub species could be in the form of closed canopy woodland, open wooded pasture, low density scrub, individual trees in fields or on field boundaries, and could be the result of natural colonisation, assisted colonisation or. A more tree-rich landscape does not imply total woodland cover; a mosaic of wooded and more open species-rich habitats can be beneficial for many species.
Establishing trees and shrubs is only the first step in developing new woodland and scrub habitats. Given how poor many woodland plants, fungi and invertebrates are at colonising new sites, the establishment of new woodland ecosystems is likely to yield quite different results depending on their distance from sources of potential flora and fungi colonists. Land adjacent to ancient and long-established woodland should be prioritised for tree establishment. Elsewhere methods for introducing native woodland fungi and ground flora should be considered.
Integrated with low density livestock grazing, wood pasture provides a valuable mix of mature trees, dead wood, scrub and grassland/heathland. It provides a wide range of conditions for wildlife to live, and can support a large number of wildlife species, including many rare invertebrates, fungi and lichens. It can also be a very valuable habitat for bats.
Scrub is now a rare but very important habitat for wildlife - providing different conditions for nesting/shelter as well as a range of food (berries, nuts, insects, seeds) for wildlife to eat. Allowing scrub to develop within other habitats provides a better mix of places for wildlife to thrive.
Trees and shrubs are long-lived species and those which establish or are planted now will live through major changes in our climate. Some species will be better adapted to the changing conditions than others and species which are currently absent from the North Pennines may become suited to the new climate. Tree diseases are increasing in frequency and impact, and this also affects species chosen for planting schemes. For example, ash is not currently available as planting stock due to the spread of ash dieback fungus (Hymenoscyphus fraxineus). When planting trees, the choice of species should not be limited to just those species which have thrived here in the recent past, but consideration given to others which can provide similar ecological function in the future, considering future climate scenarios [31,32], and which may contribute to a more resilient future landscape.
In the rush to plant trees for wildlife and climate benefits there has often been a failure to plan for, or deal with, the negative consequences of releasing many tonnes of microplastics into the environment via degrading tree guards and shelters. There are alternatives under trial, and recycling schemes for used guards, but neither of these solutions is without its own problems. Better still, there are techniques to help establish trees in the uplands without guards. However current funding criteria often mitigate against using them.
Decisions around planting, natural or assisted colonisation, and the grazing and browsing control needed to achieve more tree cover must consider existing semi-natural and species-rich habitats and key species, and other nature recovery priority outcomes. Of particular sensitivity in the North Pennines is Outcome NR2 wading birds.
Trees, scrub and woodlands play an important role in natural flood management by intercepting rainwater and slowing surface run off into watercourses and drainage systems. They also have a positive impact on air quality as their leaves can filter atmospheric pollutants such as sulphur dioxide or particulate matter, and their roots and associated fungi improve soil structure and health.
Riparian tree planting can also have a localised cooling effect on rivers, helping to reduce climate change impacts on fish and other aquatic wildlife, and trees in or around pasture play the same role in providing shade (and shelter) to livestock. Woodlands also act as important carbon stores, sequestering and storing atmospheric carbon dioxide.
Trees on farms can have multiple benefits for livestock management, and these are described with case studies in a booklet published by the National Sheep Association and the Woodland Trust [33]. They include shelter and shade leading to reduced lamb losses, increased liveweight gains, increases in grass growth and reduced risk of mastitis; Increased infiltration into soils leading to drier ground and reduced risk from liver fluke and lameness.
