Following the first post of the two-part article Global Tree Cover: Regeneration and Sustainable Forestry, we will now elaborate on the extent and nature of monoculture forestry and forestry in Ireland. A high percentage of tree cover across a landscape should surely be a positive thing, however when non-native species dominate an area the negative impacts to soil, water quality and biodiversity can be extensive.
Biodiversity loss to monoculture
With the ever-increasing demand for cheap produce, monoculture agriculture has upheaved the integrity of traditional crop growing. Orchards align hundreds of fruit trees in military fashion, usually in sunny, arid climates and grow crops, such as almonds, for food and drink produce. Whilst production efficiency should be at its maximum, a growing trend of a decline in yields is beginning to emerge. In contrast to the closed canopy of the coniferous forest, the orchard hosts wide and open paths between rows of monoculture plantations. The expanse offers no shelter for any wildlife to make a home, nor does the preservation of the land allow for any other vegetation to grow. In the case of the almond tree, which is typically grown in the warm Californian climate, a reduction in air-bourne pollinator species is threatening future produce levels. California produces 80% of the World’s almonds for human consumption. Klein’s 2012, decline of honey bee populations study reported that state “requires the import of approximately one‐half of the hives in the USA” to maintain successful pollination of the trees fruit. As produce demands continue to soar, so too will the demand for honeybee colonies. Simple solutions to ecological sensitive almond farming can include allowing the land around the vine to grow naturally, adding to the fertility of the soil and preserving a biodiversity rich habitat. The image below shows the Ecological Orchard at Say Hay Farm in California where such practices are carried out.
Forestry in Ireland
Of a landscape, which was once dense with primeval native woodland, Ireland’s tree coverage was reduced to a mere 1% coverage in 1928 due to deforestation. Intensive afforestation in recent decades, has expanded forest cover across Ireland to approximately 11% of land area and according to The National Mitigation Plan, Ireland has a target to increase forest cover to 18% by 2046. The loss of 19% of original peatland to afforestation in recent years results in an extensive loss of biodiversity including a loss of breeding populations of birds, reduced nutrient cycles and soil formation. Although both systems sequester carbon, there is no carbon sink equivalent to compare with the levels of carbon dioxide stored in blanket bog. Unlike forestry, peatland habitats are not renewable in any human lifetime. Since the main incentive for afforestation in Ireland is for timber production, an established stand sequesters little carbon before it is felled on reaching maturity.
After analysing the habitat enriching and environmental benefits offered by the Białowieża Puszcza Forest in the previous post, and to a certain extent from the Taiga Forest, one would assume any type of tree coverage over a landscape would be advantageous. Currently Irish forests are rife with non-native conifer species such as sitka spruce and pine, dominating 71.2% of the total coverage. To walk through a sitka spruce plantation in Ireland, one would observe as sense of unnatural stillness. Little light reaches the forest floor from the dense canopy above and the dark enclosure is silent with the absence of rustling woodland creatures. The monoculture landscape hosts little habitat or subsistence for biodiversity to flourish within it.
Although less extensive to the vast clear-felling of the Taiga forest in Canada, patches of sitka spruce are clear-felled in Ireland generating acid sulphate which, is damaging to peripheral waterways. The low nutrient demanding species requires heavy use of chemical fertiliser, to boost stand growth. Algal blooms in adjacent water ways develop as a result of nutrient run-off leaching from the fertiliser application. This environmental contamination is potentially devastating for soil quality, insect, fish and animal life all of which, depend on the fresh waters. Open gaps in the canopy are created either by human interference (paths, thinning) or naturally (water ways, fallen stands) allow welcoming light into the forest floor. Through stand thinning or broadleaf integration a conifer plantation can reduce its negative impacts on the environment and increase its potential for hosting a wider range of biodiversity.
Considering that the broadleaf species represents the original native trees, which was once widespread across Ireland, their canopy accounts for only 28.7% of the area. Ideas that Irish native woodlands exist naturally as ancestors to the ancient Primeval Forests is idyllic, but a fantasy. Indeed the rolling landscape of native Irish woodlands are a collection of the vested interests of timber foresters and state owned recreational parks.
A sustainably managed forest such as ones developed under the Native Woodland Establishment scheme offer a rich landscape abundant with biodiversity. The scheme is as much about habitat enrichment as it is timber production. Sustainably managed forests fell a variety of native tree species in rotation, while the trees are still young enough to regenerate multiple trunks, prolonging the lifecycle of the tree.
Sustainable forestry solutions
The diverse integration of native species such as oak, ash, alder, birch and hazel offer unrivalled habitats for birds, insect, mammals and vegetation. Evergreen holly and coniferous yew provide shelter and food for birds during the harsher winter months when most of the woodland branches are bare. The wide open canopy above allows sunlight to enrich the forest floor prompting growth of mosses, shrubs, climbers, flowers and ferns.
Broadleaf woodlands also secure the physical structure of the surrounding environment. Deep roots stabilise a sloping landscape, reducing the risk of soil erosion and landslides. River bank erosion is reduced through the planting of trees along the riparian zone, which in turn reduces the risk of flooding. Soil quality is enriched with nutrients in gradual cycles as dead wood decays. Similarly the carbon rich decaying leaves from the deciduous natives in autumn fall to fertilise the forest floor and insulate the underlying bulbs from the imminent frost.
To conclude this three part article on tree cover and forestry we have discussed the historic forest coverage on the Earth’s surface and its recent decline due to anthropocentric change in land use, analysed and compared the extent and nature of both diverse native woodland forestry (Taiga and Białowieża Puszcza Forest case study) and monoculture forestry (almond tree in California and sitka spruce in Ireland). Forestry practises must radically change across the Globe in order to restore Eco-systems, preserve habitats and increase resilience against the effects of our changing climate.
Currently in Ireland, a Dáil (Irish Parliament) motion is being brought forward by the Green Party, calling for a shift from short rotation, non-native plantations to native woodlands which are sustainably managed. They have recommended, as a progressive start, to commission “every single farm across the country to plant a special hectare of native woodland” to help “us meet our immediate climate targets and helps create wildlife corridors that also help improve water quality” and “flood management systems.” For further reading you can read the full Dáil motion here.
Finally, I’d like to end this (lengthly!) three part article with one of my favourite quotes,
“When one tugs at a single thing in nature, he finds it attached to the rest of the world.”
― John Muir