Individual study: The introduction of native plant species on industrial waste heaps at Darcy Lever, Kirklees Lane and Westwood, Lancashire, England
Ash H.J. Gemmell R.P. & Bradshaw A.D. (1994) The introduction of native plant species on industrial waste heaps: a test of immigration and other factors affecting primary succession. Journal of Applied Ecology, 31, 74-84
Some industrial waste heaps in northwest England have been colonised by floras including some regionally uncommon species. To explore the possible improvement of such habitats for nature conservation and public amenity, introduction of additional native vascular plant species was undertaken on four man-made 'waste heap' habitats located at Darcy Lever and Kirklees Lane near Bolton, and Westwood, Wigan, Lancashire, northwest England.
Waste heap sites: One site was characterised by leblanc waste (a highly alkaline substrate), one by blast furnace slag (moderately alkaline), one by pulverized fuel ash (around neutral pH) and the last colliery spoil (moderately acidic). The characteristics of each are summarised in Table 1 (attached).
Plant species sown: Species sown were determined by availability and comprised species considered both suitable and unsuitable for the soil conditions of each site. Where possible seed came from populations originating in northwest England. The species introduced are shown in Tables 2-5, attached). Experimental plots were set up in autumn 1979 and spring 1981. Five introduction techniques were used:
1) Wild seed - sown in autumn and spring in six replicate 1 m² plots on each site at one viable seed /cm². On alkaline sites, seeds of tall and short species were sown and lightly raked in in two separate lots;
2) Commercial grass and legume cultivar seeds - sown in autumn 1980, a mix of low and slow-growing types in 0.5 m² plots on each site with three fertilizer treatments, each with three replicates/site;
3) Young transplants - less than 1-year old, transferred in spring, five plants in each of six replicates;
4) Litter - acid sites only, collected from heather Calluna vulgaris moorland in spring and spread by hand in layer less than 1 cm thick, in six replicate 1 per m² plots per site. Litter, as with seeds, was lightly raked in;
5) Small turves - alkaline sites only, transferred in autumn from an unimproved limestone pasture, 25 x 25 cm x 5 cm thick, three replicate turves per site.
In introduction techniques 1, 3 and 5, half the plots were fertilized annually in spring with N, P and K (at 30,13 and 25 kg/ha respectively). In method 2 the application rates were 100:44:83, 50:22:42 and nil.
Leblanc waste: Seventeen of the 36 species introduced became established (Table 2 - attached). Those most successful were characteristic of calcareous grassland. More nutrient demanding species either died (even with fertilizer added) or grew poorly.
Blast furnace slag: Twenty one out of 41 species introduced became established, all of which were characteristic of calcareous grasslands (Table 3 - attached).
Pulverised fuel ash: Only nine of 39 introduced species became established (Table 4 - attached). Survival patterns were difficult to explain, species established having no obvious characteristics in common. However, the success of legumes (generally borate tolerant) suggests that high levels of borate may be a factor.
Colliery spoil: Ten out of 17 species introduced became established (Table 5 - attached). There is no data regards area and mode of spread at year 6 as the site was destroyed in the fourth year of the experiment.
Conclusions: The experiment demonstrates how plant community development at isolated sites may be limited due to lack of plant immigration opportunities. When suitable species are introduced, appropriate niches for their establishment appear available. Failure of more nutrient demanding species suggests that nutrient deficiency can be a major factor controlling plant colonization of these waste sites.
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