Tree health and forest management - A practitioners perspective. Scottish Lowlands Forest District Tree health and forest management - A practitioners perspective.

Scottish Lowlands Forest District – Forest management and tree health. Geographical location Scottish Lowlands Forest District encompasses 25,800 hectares of forest and open land spread across the central belt of Scotland, and is a geographic convergence for tree pests and diseases.

Scottish Lowlands Forest District – Forest management and tree health. New forests providing a new host 5,783 hectares of new land have been acquired over the past 5 years, for woodland creation and habitat management with around 8 million new trees planted. A perfect opportunity for tree pests and diseases.

Scottish Lowlands Forest District – Forest management and tree health. Vulnerability Historically many forests are made up of large extents of single or few tree species, such as Sitka Spruce and Lodgepole Pine, making them potentially vulnerable to incidences of pests and disease. The recent outbreak of Phytophthora Ramorum in south-west Scotland, where several thousand hectares of Larch have been affected, is a case in point.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current issues The past 5 years have seen dramatic increases in the level of incidence of Dothistroma Needle Blight, Chalara Fraxinea, Birch Canker and Phytophthora Ramorum in Scottish Lowlands and across Scotland. An increase in the frequency and extremity of weather events, appears to be a factor.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current tree health issues Dothistroma Needle Blight affecting Lodgepole, Corsican and Scots Pine, is now endemic in the district. DNB is present in over 3,100 hectares of pine woodlands, causing annual incremental losses of growth and complete mortalities in some cases. In SLFD Corsican Pine is no longer a component having been eradicated by DNB. DNB is present in all stands of Scots Pine, from young restock and new planting sites through to mature final spacing crops. Dothistroma infected Corsican Pine, Benarty Forest, Fife.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current tree health issues Dothistroma infected Corsican Pine. Two rounds of surveys have been carried out annually to detect the spread of DNB, - intensive and extensive. These involve visual assessments of needle retention and lab testing of samples to confirm presence of the disease. ( 50 man days to complete surveying). Dothistroma infected Lodgepole Pine.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current tree health issues Needle retention is measured by how much live growth remains on the tree. Results are compared and used to formulate management prescriptions for each site. The general trend in SLFD for Scots Pine, is for sites to deteriorate slowly over a number of years. Lodgepole Pine is the least affected pine species in SLFD, contrary to the trend in the northern districts, where it has been drastically affected, causing widespread mortalities.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current tree health issues Chalara Fraxinea (Ash Dieback), is present on nearly all new woodland creation sites and appears to have been present on nursery stock. Wider environment occurrences are also now present across much of the central belt. Approximately 500k young Ash are affected on new planting sites. Initial outbreaks, were treated under a Statutory Plant Health Notice to remove all Ash – this included cutting, removing all shoots, branches and leaves and burning. SPHN’s are no longer being issued for such outbreaks. Chalara Fraxinea infected Ash tree in new woodland planting at Knockmountain, Renfrewshire.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current tree health issues Chalara Fraxinea infected Ash being disposed of as a result of a Statutory Plant Health Notice.

Scottish Lowlands Forest District – Forest management and tree health. Extent of current issues Birch Canker (Marssonina betulae), is present on much of the Silver Birch planted on new woodland creation sites in SLFD. Mortalities on some sites are in the region of 70-80% losses. Downy Birch is much less susceptible, and is being used more widely. Silver Birch dying as a result of Birch Canker.

Work in progress – an example Devilla Forest, Fife – A continuous cover forest of 708 hectares with predominantly Scots Pine, planted mainly in the 1950’s. DNB is endemic throughout the block, with an annual increase in loss of increment. Current needle retention is averaging 1.5 years worth of growth remaining. The general trend is for this slow decline to continue. A transition is now being made away from SP to alternative species such as NS, DF, SEQ, WRC, JC, Birch and Aspen. Restocking is being carried out in the mini-coupes, rather than waiting for SP natural regeneration. DNB infected SP. Devilla Forest, predominantly even-aged Scots Pine. Norway Spruce planted in a mini-coupe. Mini-coupes to be planted with alternative species.

Scottish Lowlands Forest District – Forest management and tree health. Added complexities In addition to standard forest management there are the added complexities of tree health issues – Surveying – increase in ground and aerial surveys. Planning – strategic planning constantly shifting, forest management plans being reconfigured. Roading – pre-emptive planning for potential outbreak of Phytophthora Ramorum. Timber harvesting – clearfelling and thinning programmes altered at short notice. Tree species choices - alter forest plans to implment species diversity. Key species (in SLFD) are not currently being planted or only in small numbers – Scots Pine, Larch, Ash. Plant supply – alternative species can be difficult to source from nurseries. Restocking – increased programmes due to increased clearfells of infected sites. Deer management – increased programmes, more complex management due to species diversity including ‘softer’ conifers and broadleaves. Biosecurity – increased measures and costs. 150 man days annually in Scottish Lowlands Forest District alone, spent on Tree Health issues.

Scottish Lowlands Forest District – Forest management and tree health. Future proofing Tree species diversity is a key aim in all new forest management plans. Species such as Western Red Cedar, Japanese Cedar, Coastal Redwood, Douglas Fir, Serbian Spruce, Aspen, Sweet Chestnut, Red Oak, Birch, Norway Maple and Sycamore are being planted for timber production, to mitigate against climate change and to provide a more robust barrier to pests and disease. Kilpatrick Hills – existing large scale blocks dominated by 2-3 main tree species. Kilpatrick Hills – the new land management plan, showing a much wider palette of future tree species.

Scottish Lowlands Forest District – Forest management and tree health. Sweet Chestnut, year 1. Future proofing Tree species diversity in action. Sycamore, year 5. Aspen, year 5. Norway Spruce, year 1. Grand Fir, year 3.

Scottish Lowlands Forest District – Forest management and tree health. Future proofing The current crop of pests and disease coupled with a changing climate, present both challenges and opportunities. Standard forest practices and monocultures with a small range of tree species should be reviewed where possible, to ensure todays and future forests are ready to meet the combined threats of pests, disease and climate change.