• Abstract and Figures
• Public Full-text

Growing Green Energy Project (Phase 1) Skares Planting Trial Final Report July 2016 1.0 Introduction Eadha Enterprises (Eadha) is an environmental charity and social enterprise based in Renfrewshire. We conserve, research, propagate and plant rare native trees with a focus on aspen. We have developed and maintain the national aspen clone collection which numbers in excess of three hundred clones from across Scotland and Northern England. The collection is housed within our tree nursery although ex-situ clone gardens and arboreta are also being developed. Eadha was awarded funding through the Central Scotland Green Network (CSGN) in 2011 to initiate its Growing Green Energy Project (GGE). Eadha has a vision for ecological restoration on a landscape scale across the Scottish coalfields area where the landscape has been destroyed by large scale opencast coal mining activity and is plagued by communities struggling to find new employment opportunities. GGE initially focused on an area of East Ayrshire (North Kyle) which was regarded as having the greatest concentration of mining activity and was of an upland nature with significant existing forestry activity. The area was also designated as a “Preferred Area” for new woodland planting and included areas with “Potential for Environmental Enhancement” identified in the now superseded Ayrshire and Arran Woodland Strategy (AAWS). The project was initiated in 2012 and included the following activities: • A trial planting of aspen on marginal ground within a reclaimed opencast site; • A feasibility study including a mapping exercise and market research to develop a working model to deliver the vision within a defined study area; • Consideration of how green jobs can be created as a result of rolling out such a project. 2.0 The Skares Trial The site at Skares Opencast Coal Site (OCCS), part of the Netherton complex in East Ayrshire was formerly operated by ATH who have since gone into liquidation with the care and maintenance now undertaken by Hargreaves. The ownership of the site is under Foresty Commission Scotlamd (FCS). The site was initially identified as being suitable for a trial on the basis of the poor quality of the earthworks restoration, with very limited topsoil cover and compacted soils. FCS undertook a topsoil depth and elevation survey prior to planting (Appendix 1). Topsoil depths were shown to vary between 17cm and 68cm and site elevation varies between 244m and 267m above sea level. Direct observations during tree planting confirmed that the quality of the soil was extremely poor with very limited organic matter within the upper soils layers. Furthermore the quality of the topsoil is likely to have had deteriorated during storage as it loses its biological activity. The underlying subsoils comprised of replaced and compacted glacial till. There was widespread evidence of shallow perched water being retained above the clay. Most of the pits that were excavated during ground preparation have retained water and this was observed to be the case during a prolonged dry period. The nature of the colonising vegetation is also suggestive of poor growing conditions with water logging and nutrient poor compacted soils, for example with a predominance of rushes and mosses. Clearly loose tipping of surface soil, the recommended method of soil placement (FC Best Practice Guidance For Land Regeneration, Note 4) has not taken place at this site. The purpose of the trial was to prove the efficacy of aspen and other pioneer native tree species including juniper and downy willow in colonising poor quality reclaimed land without significant inputs, for example ground ripping, deep cultivation, soil amendments, herbicide treatment, fertilizing and ongoing maintenance which would typically be specified for such sites according to best practice guidance, and to inform future large scale planting projects across the coalfields area. Fig 1 Skares Trial location plan A 3 Ha area was initially enclosed by a deer fence, funded by FCS. A larger area was fenced than was required by the initial trial planting to provide additional land for other possible future trials. Mechanical ground preparation involving mounding was then undertaken. Trees were subsequently planted in March 2012, with protection using vole guards and canes. Despite the original proposal to undertake weed treatment using herbicides, this was never done. Furthermore, no soil amendments or fertilizers were applied to the trees. Three replicated block were planted, each comprising the following: • Aspen trees propagated from root cuttings by Eadha, comprising 14 clones from a range of provenances from across Scotland. These were supplied as relatively small bare-rooted plants; • Mixed aspen clones provided as cell grown plugs by a commercial nursery (Christie-Elite) • Bare-rooted Downy willow plants of Galloway provenance grown by Cree Valley Community Woodland Trust and supplied to FCS. • Pot-grown Juniper plants supplied by Poyntzfield Nursery and believed to be of north of Scotland provenance. A total of 336 aspen, 168 downy willow and 56 juniper were planted in each block. The planting layout is included in Appendix 2 and 3. A summary of the aspen clones is provided in the table below: Table 1 Aspen Clones Clone Seed Zone Elevation (m) Height (cm) EECG116 102 38 10cm bare root “ rootlings ” EECG119 102 80 10cm bare root “rootlings” EECG120 102 30 10cm bare root “rootlings” EECG127 102 194 10cm bare root “rootlings” EECG048 106 15 10cm bare root “rootlings” EERE005 107 340 20 -30cm bare root “rootlings” EECG036 108 50 10cm bare root “rootlings” EEDG009 108 330 10cm bare root “rootlings” EECG067 109 200 10 -20cm bare root “rootlings” Christie -Elite Mix 201 na 40 -60 cm cell grown (microprop agated) EECG069 201 230 10 -20cm bare root “rootlings” EECG042 202 210 10 -15 cm bare root “rootlings” EECG037 203 40 10cm bare root “rootlings” EECG018 na na 10 -20 cm bare root “rootlings” EECG129 na na 10 -15 cm bare root “rootlings” Planting Positions During the planting is was observed that due to the very limited topsoil cover across the site, typically it was the subsoil, comprising compacted clay/glacial till, that was exposed on the topside of the planting mounds. It was therefore decided to vary the planting position to compare performance in a range of challenging conditions. Consequently some trees were planted on the mounds while others were planted on the sides or lower parts of the mounds where there was more likely to be topsoil exposed. Other trees were planted directly into the undisturbed ground adjacent to the mounds or within the exposed soil on the sides of the pits (below ground level). The key to the various planting positions is included at the foot of the monitoring results spreadsheets. In the process of monitoring, the presence of standing water around the trees was found to be a common occurrence and was noted as part of the planting position description. Plate 1 Planting on mounds and exposed clay subsoil Monitoring The monitoring protocol was as follows: 1. Trees will be planted in blocks according to clone type or species. 2. Immediately following planting, 10 trees in each aspen clone block, or if there is less than 10 in a block then the whole block, will be measured for height in cm above ground level to the nearest 1.0 cm. 3. Tree damage will be recorded at the same time as height and will include shoot/branch death, development of multiple leaders, browsing animal damage, physical damage and mortality. 4. 10 trees in each of the Juniper and Downy Willow blocks will also be recorded for mortality. 5. Planting positions/conditions will be recorded. The objective was therefore to assess comparable survival and growth rates between aspen, juniper and downy willow and between aspen clones and to assess how different sizes of planting stock and varying planting positions and conditions affect this. 3.0 Field Observations Groundcover Vegetation The site has been subject to revegetation during the four year monitoring period. However the range of species has been constrained by the poor ground conditions. Waterlogging has led to the domination of rushes and mosses within a grassland matrix across most of the site. Dominant flowering species observed include Creeping Thistle, Marsh Bedstraw, Buttercup and Tormentil, with lesser amounts of Ragged Robin, Purple Loosestrife, Sneezewort, Rosebay Willowherb, Forget-me-not, Orchid, Wild Rose, Birdsfoot Trefoil and vetches. The pioneer leguminous species will help to increase soil fertility over time and act as a nurse crop for other species including tree regeneration. Tree Regeneration Willow regeneration is particularly prolific in the area immediately to the north of the trial enclosure. Within the enclosure itself, natural regeneration has also occurred to a lesser extent. It is estimated that approximately 600 well established naturally regenerated trees are now growing within the enclosure comprising 90% willow, 10% sitka spruce. Hawthorn was also noted. The dominant willow species appeared to be Grey willow (Salix cinerea) and Eared willow (Salix aurita) with hybrids between the two occurring widely (Salix multinervis). Willows were observed to be up to approximately 2m in height and the spruce up to approximately 3m in height. Photos are included in Appendix 4 4.0 Monitoring Results and Analysis A total of three monitoring rounds were undertaken in May 2012, October 2014, and July 2016. The full results of the final monitoring round are included in Appendix 5. The results have been analysed in an attempt to understand the factors governing survival and growth rates. Overall survival rates for the three species were Aspen (63%), Downy Willow (93%) and Juniper (61%). At first glance, the willow appears to have been significantly more successful than juniper and aspen which show rates of survival that you would expect from a poor ground site. However these figures don’t tell the whole story.

Load more

  39

Copy Link