Plants are good for the planet...right? They sequester carbon, produce oxygen and provide habitat for our wonderful wildlife. So why is the removal of certain species warranted and sometimes even necessary?

Well, it's not always so straight forward as planting trees and saving the world. To do our bit in averting the climate crisis with wildlife at the heart of our strategy we must also encourage biodiversity and give habitat a helping hand in the interests of our native, nationally and internationally rare species.

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Plants in the Past and Pittosporum in the Present...

The history of Scilly's vegetation is not particularly well documented but it is fairly well reported that the hedges and shelter belts, which we are familiar with today, are relatively recent in terms of Scilly's historical timeline. Evergreens, such as pittosporum (Pittosporum crassifolium, actually called by its Maori name karo in plant books) and tree bedstraw (commonly known as coprosma, after its scientific name Coprosma repens), both native to New Zealand, have been introduced during the last 150 years. Prior to this, the only protection from wind was in the form of stone walls or hedges.  

Though once confined to the inhabited islands, due to our mild climate and seed dispersal by wildlife, fast-growing non-native Pittosporum has flourished at the cost of native plants and animals; dominating even our uninhabited islands. Over the past two decades, this spread has been expedited by continuing temperature increases (evidenced in warmer summers and wetter winters) and, as a result, this non-native species has expanded its range across the islands; to such an extent that it is now affecting the native vegetation of the archipelago and the islands Sites of Special Scientific Interest (SSSIs). These designated sites are protected by law because of the native species that can be found within them.  

In order for the islands to become more resilient to the effects of climate change we (as a community) will need to adapt and anticipate what changes will positively or negatively affect the islands. 

Non-native pittosporum spreads rapidly across grassland and heathland, blocking out light for smaller species and causing them to suffer or even vanish completely. This resilient evergreen also poses a threat to our breeding seabirds, decimating optimal breeding habitat of open grassland and heathland characterised by clean, clear views, turning it into wooded areas, unfavourable for breeding. Our breeding seabirds are naturally fearful of predators and favour the granite boulder and carn vantage points of the open habitat that can only thrive in the absence of pittosporum.

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Gugh SSSI looking across to neighbouring St Agnes.  Photo: BareFoot Photographer

Gugh SSSI

In January 2016, the Isles of Scilly Wildlife Trust Ranger Team embarked on a programme of habitat management, restoration and maintenance on the island of Gugh. They have since returned each year, predominantly in the early parts of the season, to expand our work programme and maintain areas worked on in previous years. Gugh forms just one of the islands' Sites of Special Scientific Interest (SSSI), being provided statutory protection for being one of the best examples of the UK's flora, fauna, geological and physiographical features.  Scilly is home to a whopping 27 SSSIs, with 24 of these being cared for by the team here at the Isles of Scilly Wildlife Trust!

Gugh is designated a SSSI for presence of species such as the nationally rare orange bird's-foot, rare lichens like golden hair-lichen (Teloschistes flavicans), and an internationally important breeding colony of lesser black-backed gull all of which call this tiny island home.

The Isles of Scilly is the only place in Britain that the nationally rare orange bird's-foot grows!  Photo: BareFoot Photographer.

The island was also previously home to three rare plant species, all now extinct. One, the shore dock, first discovered in 1893, still extant in the 1960s, may well have been lost due to the impacts of erosion and increased storminess (related to climate change) on its coastal niche. The other two species, small adder's-tongue, not seen since at least the mid-1980s and four-leaved allseed, last recorded in 1940, may well have been lost due to vegetation succession with the cessation of grazing and invasion of scrub. Though it may be too late for species such as this, it is important that other native species are supported and encouraged where possible.

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Since early 2016, when the Rangers embarked on this piece of work, they have been concentrating their efforts on various areas of Gugh in order to manage the spread of invasive non-native pittosporum; restoring and maintaining habitat for wildlife, in this especially beautiful corner of Scilly.  Pittosporum has been cut, brash burnt and stumps treated to prevent re-growth. 

Head Ranger, Darren, explains that the aim of this work "is to stop any further encroachment by the trees onto the grassland and heathland of Gugh; with the Rangers working to create a mosaic of different grassland vegetation heights.  Allowing delicate species, such as orange bird's-foot and clovers in the short turf areas and the nationally scarce balm-leaved figwort and Babington's leek to thrive in the longer areas.  The boundary between the short and tall vegetation creates shelter and areas of different temperatures which is also excellent for insects."  

The Isles of Scilly Wildlife Trust has a legal responsibility to manage these SSSIs (as would any other landowner/manager) to ensure that the biological interest of these sites are not comprised, but at the least maintained and ideally enhanced.

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Right Tree, Right Place

The idea that planting millions of trees to offset global emissions is not that straight forward and the Trust believes that “right tree in the right place” is vitally important. Many other habitats (if managed correctly) can be just as valuable in the sequestration of carbon to combat the Climate Emergency. For example UK lowland heathland is known to hold 88 tonnes per hectare of Carbon in the soil and a further 2 tonnes of Carbon within the vegetation!

The tree planting that is being talked about by Government is based on planting native species, those species that work alongside our native vegetation and not against it, as the shrub pittosporum does. For example, the Isles of Scilly Wildlife Trust has planted over 1,000 native trees on St Mary’s in the last 12 months.

Many of the SSSI’s across Scilly are designated for species of bird and wild flower which will not survive under tree or shrub cover, consequently the Trust cannot, and will not, be planting native trees where the pittosporum shrubs have been cut (this would also see us in direct violation of the legal responsibilities we have towards SSSIs).

We will, however, be continuing to plant native trees (following on from this winter’s project on St Mary’s), whilst encouraging and supporting our local community to do the same on appropriate sites across Scilly; to ensure enrichment of our Island environment for the benefit of nature and people. Any tree planting on Trust land will take place in conjunction with the ongoing management and maintenance of Scilly's incredibly valuable native habitats, many of which are in the Trust's care.

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How's It Going On Gugh?

As of the end of 2019 the Isles of Scilly Wildlife Trust Rangers have removed 1.2 hectares of pittosporum (leaving some scattered groups of trees and existing hedgerow boundaries) and 2.2 hectares of coastal grassland/scrub mosaic are now under management for orange birds-foot, other maritime grassland species, balm-leaved figwort and more.

Regular survey and monitoring of the heathland and maritime grassland shows that they remain healthy across the whole of the island with increases in maritime areas of species such as Portland spurge, wild thyme and Sea carrot; indicator species including birds-foot-trefoil, thrift and bucks-horn plantain, lousewort, tormentil and heath milkwort have also been recorded.

Since 2016, when this phased programme of habitat management and restoration began, we have also seen increases in some of our breeding seabird species across the island too; including the lesser black-backed gull, Manx shearwater and storm petrel.  This will no doubt be for a variety of reasons, including the removal of rats, but we cannot underestimate the importance of vegetation management in this positive outcome either.

Additionally our annual programme of management means that scrub across the island is at different ages and stages of its development throughout the year. This provides species like the extremely localised (only occuring in Scilly, Lundy and a few places in Cornwall) nothris moth (Nothris congressariella) with its foodplant, balm-leaved figwort.

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This project is part funded by DEFRA through the Isles of Scilly AONB