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Providing evidence to improve practice

The journal, Conservation Evidence

Our online journal publishes research, monitoring results and case studies on the effects of conservation interventions. All papers include some monitoring of the effects of the intervention and are written by, or in partnership with, those who did the conservation work. It includes interventions such as habitat creation, habitat restoration, translocations, reintroductions, invasive species control, and education or integrated conservation development programmes, from anywhere around the world.

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A volume is created each year with peer-reviewed papers published throughout the year. We now accept Short Communications as well as standard papers.

Special issues contain new papers on a specific topic.

Virtual collections collate papers published in the journal on specific topics such as management of particular groups of species.

To search for papers on a specific topic within the journal select Advanced search, enter your keyword(s) and within the Source box type: "conservation evidence". This will take you to a list of actions that contain Conservation Evidence papers. In order to see the list of individual Conservation Evidence papers on the topic, please click on 'You can also search Individual Studies' at the top of this page.

Shrubland and Heathland Conservation



This virtual collection contains 19 papers from the Conservation Evidence journal on the conservation and restoration of shrubland and heathland habitats.

At Cooper’s Hill Nature Reserve, Bedfordshire, England, areas of mature heather Calluna vulgaris have been lost and replaced by dense grassy swards. We hypothesised that any heather seedlings would have difficulty competing with the grasses and tested this by removing the turf to expose the nutrient-poor sandy soil in seven small plots across the reserve. These plots, together with control areas, were monitored annually to determine which vegetation types would re-establish. Five plots also received seed-rich brash (cut heather) on half of each plot to determine whether additional seeding of stripped areas was required. Analysis of the data collected over the first five years indicates that the technique increased the amount of heather seedlings establishing, as measured by percentage heather cover. Adding seed rich brash had no effect, implying a good amount of viable heather seed is present in the soil at this site. Grasses are also establishing in the stripped areas but are not dominating the plots.

We report the results of a nine year study of the effects of restoring low-intensity cattle grazing on the post-fire recovery of vegetation on the lowland valley mire and wet heath of Folly Bog, Surrey, UK. Four distinct vegetation communities were studied, with repeated recording of quadrats (n = 652) inside and outside grazing exclosures. Species richness increased across the valley mire, largely as a result of grazing-induced decreases in purple moor-grass Molinia caerulea and litter and increases in bare ground. Uncompetitive liverworts and waterlogging tolerant graminoids were particularly favoured. Purple moor-grass and litter removal also encouraged the spread of bog-mosses Sphagnum spp., although trampling in the wettest vegetation resulted in locally severe damage to the moss layer. On the firmer substrates of the wet heath, there were no such deleterious trampling impacts. Here, both bog-moss cover and species richness increased significantly, largely due to suppression of shade-producing heather Calluna vulgaris and litter, and the maintenance of bare ground. Our results reveal that the resumption of low intensity cattle grazing had many positive conservation benefits. However, site managers need to consider grazing on a site-by-site basis and retain flexibility to change stocking times and levels as conditions dictate. Other forms of management to supplement grazing will most likely continue to be required.

 

Trials were undertaken to assess the effectiveness of various treatments aimed at reinstating heathland vegetation at Hobbister RSPB Reserve (Orkney Islands) on a denuded area where no vascular plant growth had occurred since peat had been extracted commercially over 30 years previously. A management history of Hobbister was collated and information (derived from a literature search of restoration techniques) combined with observations of physical conditions at the site, was used to develop a list of possible impediments to heathland vegetation regeneration. Based upon these findings, eight sets of treatments were designed and applied to trial plots devoid of vegetation in June 2006. Plots were surveyed in August 2009. A combination of peat dust, heath mulch and geojute gave best results with 80% cover of vascular plants (including 70% by heather Calluna vulgaris). Although two grass-seed addition plots had higher cover values (91 and 86%) these were dominated by one of the sown species (red fescue Festuca rubra). Peat dust plus heath mulch addition also produced good cover (40%) of Calluna. Adding fertiliser did not assist in target heathland plant species re-colonisation. On the untreated control plot, vascular plant cover remained at zero.

 

Sulphur and clippings of heather Calluna vulgaris and bell heather Erica cinerea were added to an area of former arable land with the objective of creating heathland. Nine years later these two species had both become well established.

To restore an area of former heathland, soil nutrient levels were reduced by turf removal. Turf-stripping reduced dominance of wavy hair-grass Deschampsia flexuosa and promoted an increase in heather Calluna vulgaris.

At a site in southern England in September 2004, about 4 ha of mature, dense, non-native, maritime pine Pinus pinaster was cleared using a shear-head timber processor. One year later in August 2005, the cleared area was predominantly covered in purple moor-grass Molinia caerulea (approx. 80% cover). The remaining 20% was either bare ground (approx. 15%) or mature heather Calluna vulgaris and gorse Ulex plants (less than 5% cover) present prior to clearance, but no heather seedlings were found. There was no evidence of any pine regeneration.

In August 2004, an area of just over 1 ha of dense, mature Scots pine Pinus sylvestris was cleared using a shear-head timber processor. Prior to the clearance, the area supported little heathland vegetation and was predominantly bare ground with some bracken Pteridium aquilinum underneath the dense pine canopy. One year after the clearance, heather Calluna vulgaris seedlings had become established. Evidence suggests that control of bracken and tree seedlings may be required as part of long-term management in order to restore and maintain an open heath.

 

Approximately 0.5 ha of dense, mature Scots pine Pinus sylvestris and rhododendron Rhododendron ponticum was cleared using a shear-head timber processor. Prior to clearance the area under the canopy supported little heathland vegetation. One year later, heather Calluna vulgaris seedlings had become established; other heathland vegetation included purple moor grass Molinia caerulea and cross-leaved heath Erica tetralix. There was also evidence of vigorous rhododendron regrowth from the cut stumps.

 

Approximately one third of a hectare of mature heather Calluna vulgaris was burnt in January 2000. Five years later, the burnt strip was revisited. It had fewer heather flowers and the sward was shorter (20-25 cm) than the surrounding vegetation (35-40 cm). Bristle bent grass Agrostis curtisii was more abundant (25% cover) than in adjacent unburned areas (5%).

 

A forage harvester was used to cut swathes of heathland vegetation at a site in southern England to increase habitat heterogeneity. Areas selected were predominantly dry heath or on the margins of humid heath and were cut to ground level. Six years later the cut areas were still clearly visible. In a humid heath area purple moor-grass Molinia caerulea had been greatly reduced, heather Calluna vulgaris had increased slightly, and open patches of bare ground (important for early successional plants) were present. On dry heath, heather cover was reduced substantially but the shorter and more open sward had allowed lichen communities to develop.

 

On a heathland in southern England, mature gorse Ulex europaeus was coppiced and the area fenced to prevent rabbit Oryctolagus cuniculus browsing in an attempt to create a varied gorse age structure. Twelve years later little gorse had regrown from the cut stumps and the cleared area had been invaded by bracken Pteridium aquilinum.

 

Approximately 0.5 ha of dense Scots pine Pinus sylvestris and maritime pine P.pinaster woodland was cleared using a shear-head timber processor with the objective of restoring heathland. Prior to clearance the area supported little heathland vegetation and was predominantly bare ground with some bracken Pteridium aquilinum, underneath the thick pine canopy. One year after clearance, there was deep litter layer (7-8 cm), little regeneration of heather Calluna vulgaris, and bracken was becoming dominant.

 

In January 2002, with the aim being to reinstate heathland vegetation, an area of 0.75 ha was cleared of Scots pine Pinus sylvestris and some maritime pine P.pinaster trees. Prior to clearance the area supported little heathland vegetation, predominantly comprising bare ground with some bracken Pteridium aquilinum. Three and a half years after clearance, the area supported a range of common generalist, non-heathland plant species, and was being invaded by silver birch Betula pendula saplings.

 

A number of pine Pinus trees were ring-barked using either single or double cuts, two trees also had their crown removed. One to two years later, all the ring-barked trees were still standing. The only two which had died were the ones with their crown removed. The remaining trees were all alive, but had some dead needles and needles showing signs of discolouration. There was no clear difference between trees cut using a single or a double cut.

 

Two adjacent mature Scots pine Pinus sylvestris trees were ring-barked using a chainsaw. Five years later, both trees had died. One tree had blown over just above the ring-bark cuts, leaving a jagged stump 1.25 m high; the other tree had lost its crown, resulting in 10 m of standing deadwood. Saproxylic invertebrates had colonised and great spotted woodpeckers Dendrocopus major had used the taller ring-barked stump for nesting. This management method proved to be a low-cost and easy way to produce standing deadwood.

During the winter of 1995-1996 on a heathland in southern England, 1.6 ha of invading silver birch Betula pendula (40% cover) and gorse Ulex europaeus were cleared using chainsaws and burnt on site. Ten years later, the cut birch and gorse stumps were still visible; the area was largely covered in dense bracken Pteridium aquilinum (average cover of 70% over 5 plots), the only gaps being the fire sites (predominantly bare) and a few patches of purple moor grass Molinia caerulea. Little heather Calluna vulgaris was present and there was considerable evidence of birch regeneration, suggesting that further management would be necessary to prevent invasion by scrub.

 

In 1991, 5.7 ha of Scots pine Pinus sylvestris scrub was removed from a heathland in southern England. Trees with diameters less than 25 cm were cut using bow saws and loppers; mature trees were left untouched. Fourteen years later, the area could still be identified by the presence of cut stumps; considerable pine regeneration (330 trees/ha) was apparent as there had been no ongoing management.

 

During the winter of 2000-2001, approximately 2.4 ha of dense (75-100% tree cover) and 0.6 ha of medium (25-50% tree cover) birch Betula was cut and removed. In August 2002, the cleared birch had regenerated resulting in a dense stand of 2 m high birch. The regrowth was sprayed with Timbrel using knapsack sprayers. The regrowth kill rate of sprayed areas was 100%; no regrowth was subsequently recorded.

 

An area of about 13 ha of former open heathland in southern England was cleared of Scots pine Pinus sylvestris, maritime pine P.pinaster and birch Betula spp.; prior to management it contained 50-75% scrub and mature tree cover. Clearance was conducted using chainsaws; brash was burnt. Five years later, there was considerable evidence of pine regeneration (2,600 seedlings per ha). To maintain open heath, control of tree seedlings is required after tree clearance.