March 2012. A new trial to investigate the success of targeted habitat management techniques for Intermediate Wintergreen was set up on Glen Tanar Estate this month.
Recent surveys and research on Intermediate Wintergreen by the Cairngorms Rare Plants Project have revealed that the species thrives best where field-layer vegetation is kept short and open and there is a degree of localised disturbance, such as sites which are grazed by deer or domestic livestock or where heather is managed by rotational muirburn. Where grazing and disturbance levels are low, or heathland management absent, tall and dense growth of sub-shrubs, which cast heavy shade on plants below, create conditions less favourable for the growth and survival of Intermediate Wintergreen and other flowering herbs ultimately leading to their gradual decline.
To address this issue, the Cairngorms Rare Plants project has developed a new trial to test the potential application of brush-cutting and controlled heather burning as a means of maintaining a patchwork of suitable open habitat for Intermediate Wintergreen. This is particularly relevant to sites where red deer numbers are currently highly controlled, grazing by domestic livestock has been removed and/or heathland management has ceased in favour of promoting natural regeneration of woodland. In these situations, targeted habitat management is clearly required to maintain areas of short and open vegetation within the field-layer to ensure the long term persistence and spread of Intermediate Wintergreen.
Following detailed baseline surveys of Intermediate Wintergreen sites on Glen Tanar Estate, and with much assistance from the owner Michael Bruce, a series of 20 x 20 m experimental plots have been set up with brush-cutting, heather burning and control treatments applied to vegetation surrounding existing Intermediate Wintergreen populations. Prior to application of the treatments, groups of Intermediate Wintergreen rosettes within the plots were counted, measured and marked with stakes to enable measurements of vegetative spread, flowering and recruitment to be conducted over a 5 year period so the response of Intermediate Wintergreen to the different treatments can be assessed.
Plans are in place to set up similar experimental plots on a number of additional estates in the Cairngorms National Park during autumn/winter 2012. This trial will provide important information on the effectiveness of targeted habitat management techniques for the conservation and recovery of Intermediate Wintergreen, and other associated flowering herbs, and will contribute to the development of best practice management guidelines for the species.